Aminet 48/Aminet 48 (2002)(GTI - Schatztruhe)[!][Apr 2002].iso/Aminet/text/edit/vim60src.lha/Vim/vim60/src/memline.c

C/C++ Source or Header | 2001-09-09 | 115.2 KB | 4,364 lines

/* vi:set ts=8 sts=4 sw=4:
 *
 * VIM - Vi IMproved    by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/* for debugging */
/* #define CHECK(c, s)    if (c) EMSG(s) */
#define CHECK(c, s)

/*
 * memline.c: Contains the functions for appending, deleting and changing the
 * text lines. The memfile functions are used to store the information in blocks
 * of memory, backed up by a file. The structure of the information is a tree.
 * The root of the tree is a pointer block. The leaves of the tree are data
 * blocks. In between may be several layers of pointer blocks, forming branches.
 *
 * Three types of blocks are used:
 * - Block nr 0 contains information for recovery
 * - Pointer blocks contain list of pointers to other blocks.
 * - Data blocks contain the actual text.
 *
 * Block nr 0 contains the block0 structure (see below).
 *
 * Block nr 1 is the first pointer block. It is the root of the tree.
 * Other pointer blocks are branches.
 *
 *  If a line is too big to fit in a single page, the block containing that
 *  line is made big enough to hold the line. It may span several pages.
 *  Otherwise all blocks are one page.
 *
 *  A data block that was filled when starting to edit a file and was not
 *  changed since then, can have a negative block number. This means that it
 *  has not yet been assigned a place in the file. When recovering, the lines
 *  in this data block can be read from the original file. When the block is
 *  changed (lines appended/deleted/changed) or when it is flushed it gets a
 *  positive number. Use mf_trans_del() to get the new number, before calling
 *  mf_get().
 */

#if defined(MSDOS) || defined(WIN32) || defined(_WIN64)
# include <io.h>
#endif

#include "vim.h"

#ifdef HAVE_FCNTL_H
# include <fcntl.h>
#endif
#ifndef UNIX        /* it's in os_unix.h for Unix */
# include <time.h>
#endif

#ifdef SASC
# include <proto/dos.h>        /* for Open() and Close() */
#endif

typedef struct block0        ZERO_BL;    /* contents of the first block */
typedef struct pointer_block    PTR_BL;        /* contents of a pointer block */
typedef struct data_block    DATA_BL;    /* contents of a data block */
typedef struct pointer_entry    PTR_EN;        /* block/line-count pair */

#define DATA_ID        (('d' << 8) + 'a')        /* data block id */
#define PTR_ID        (('p' << 8) + 't')        /* pointer block id */
#define BLOCK0_ID0  'b'                /* block 0 id 0 */
#define BLOCK0_ID1  '0'                /* block 0 id 1 */

/*
 * pointer to a block, used in a pointer block
 */
struct pointer_entry
{
    blocknr_T    pe_bnum;    /* block number */
    linenr_T    pe_line_count;    /* number of lines in this branch */
    linenr_T    pe_old_lnum;    /* lnum for this block (for recovery) */
    int        pe_page_count;    /* number of pages in block pe_bnum */
};

/*
 * A pointer block contains a list of branches in the tree.
 */
struct pointer_block
{
    short_u    pb_id;        /* ID for pointer block: PTR_ID */
    short_u    pb_count;    /* number of pointer in this block */
    short_u    pb_count_max;    /* maximum value for pb_count */
    PTR_EN    pb_pointer[1];    /* list of pointers to blocks (actually longer)
                 * followed by empty space until end of page */
};

/*
 * A data block is a leaf in the tree.
 *
 * The text of the lines is at the end of the block. The text of the first line
 * in the block is put at the end, the text of the second line in front of it,
 * etc. Thus the order of the lines is the opposite of the line number.
 */
struct data_block
{
    short_u    db_id;        /* ID for data block: DATA_ID */
    unsigned    db_free;    /* free space available */
    unsigned    db_txt_start;    /* byte where text starts */
    unsigned    db_txt_end;    /* byte just after data block */
    linenr_T    db_line_count;    /* number of lines in this block */
    unsigned    db_index[1];    /* index for start of line (actually bigger)
                 * followed by empty space upto db_txt_start
                 * followed by the text in the lines until
                 * end of page */
};

/*
 * The low bits of db_index hold the actual index. The topmost bit is
 * used for the global command to be able to mark a line.
 * This method is not clean, but otherwise there would be at least one extra
 * byte used for each line.
 * The mark has to be in this place to keep it with the correct line when other
 * lines are inserted or deleted.
 */
#define DB_MARKED    ((unsigned)1 << ((sizeof(unsigned) * 8) - 1))
#define DB_INDEX_MASK    (~DB_MARKED)

#define INDEX_SIZE  (sizeof(unsigned))        /* size of one db_index entry */
#define HEADER_SIZE (sizeof(DATA_BL) - INDEX_SIZE)  /* size of data block header */

#define B0_FNAME_SIZE    900
#define B0_UNAME_SIZE    40
#define B0_HNAME_SIZE    40
/*
 * Restrict the numbers to 32 bits, otherwise most compilers will complain.
 * This won't detect a 64 bit machine that only swaps a byte in the top 32
 * bits, but that is crazy anyway.
 */
#define B0_MAGIC_LONG    0x30313233L
#define B0_MAGIC_INT    0x20212223L
#define B0_MAGIC_SHORT    0x10111213L
#define B0_MAGIC_CHAR    0x55

/*
 * Block zero holds all info about the swap file.
 *
 * NOTE: DEFINITION OF BLOCK 0 SHOULD NOT CHANGE! It would make all existing
 * swap files unusable!
 *
 * If size of block0 changes anyway, adjust MIN_SWAP_PAGE_SIZE in vim.h!!
 *
 * This block is built up of single bytes, to make it portable accros
 * different machines. b0_magic_* is used to check the byte order and size of
 * variables, because the rest of the swap file is not portable.
 */
struct block0
{
    char_u    b0_id[2];    /* id for block 0: BLOCK0_ID0 and BLOCK0_ID1 */
    char_u    b0_version[10];    /* Vim version string */
    char_u    b0_page_size[4];/* number of bytes per page */
    char_u    b0_mtime[4];    /* last modification time of file */
    char_u    b0_ino[4];    /* inode of b0_fname */
    char_u    b0_pid[4];    /* process id of creator (or 0) */
    char_u    b0_uname[B0_UNAME_SIZE]; /* name of user (uid if no name) */
    char_u    b0_hname[B0_HNAME_SIZE]; /* host name (if it has a name) */
    char_u    b0_fname[B0_FNAME_SIZE]; /* name of file being edited */
    long    b0_magic_long;    /* check for byte order of long */
    int        b0_magic_int;    /* check for byte order of int */
    short    b0_magic_short;    /* check for byte order of short */
    char_u    b0_magic_char;    /* check for last char */
};
#define   b0_dirty b0_fname[B0_FNAME_SIZE-1]

#define STACK_INCR    5    /* nr of entries added to ml_stack at a time */

/*
 * The line number where the first mark may be is remembered.
 * If it is 0 there are no marks at all.
 * (always used for the current buffer only, no buffer change possible while
 * executing a global command).
 */
static linenr_T    lowest_marked = 0;

/*
 * arguments for ml_find_line()
 */
#define ML_DELETE    0x11        /* delete line */
#define ML_INSERT    0x12        /* insert line */
#define ML_FIND        0x13        /* just find the line */
#define ML_FLUSH    0x02        /* flush locked block */
#define ML_SIMPLE(x)    (x & 0x10)  /* DEL, INS or FIND */

static void set_b0_fname __ARGS((ZERO_BL *, buf_T *buf));
static time_t swapfile_info __ARGS((char_u *));
static int recov_file_names __ARGS((char_u **, char_u *, int prepend_dot));
static int ml_append_int __ARGS((buf_T *, linenr_T, char_u *, colnr_T, int, int));
static int ml_delete_int __ARGS((buf_T *, linenr_T, int));
static char_u *findswapname __ARGS((buf_T *, char_u **, char_u *));
static void ml_flush_line __ARGS((buf_T *));
static bhdr_T *ml_new_data __ARGS((memfile_T *, int, int));
static bhdr_T *ml_new_ptr __ARGS((memfile_T *));
static bhdr_T *ml_find_line __ARGS((buf_T *, linenr_T, int));
static int ml_add_stack __ARGS((buf_T *));
static char_u *makeswapname __ARGS((buf_T *, char_u *));
static void ml_lineadd __ARGS((buf_T *, int));
static int b0_magic_wrong __ARGS((ZERO_BL *));
#ifdef CHECK_INODE
static int fnamecmp_ino __ARGS((char_u *, char_u *, long));
#endif
static void long_to_char __ARGS((long, char_u *));
static long char_to_long __ARGS((char_u *));
#if defined(UNIX) || defined(WIN3264)
static char_u *make_percent_swname __ARGS((char_u *dir, char_u *name));
#endif
#ifdef FEAT_BYTEOFF
static void ml_updatechunk __ARGS((buf_T *buf, long line, int len, int updtype));
#endif

/*
 * open a new memline for 'curbuf'
 *
 * return FAIL for failure, OK otherwise
 */
    int
ml_open()
{
    memfile_T    *mfp;
    bhdr_T    *hp = NULL;
    ZERO_BL    *b0p;
    PTR_BL    *pp;
    DATA_BL    *dp;

/*
 * init fields in memline struct
 */
    curbuf->b_ml.ml_stack_size = 0;    /* no stack yet */
    curbuf->b_ml.ml_stack = NULL;    /* no stack yet */
    curbuf->b_ml.ml_stack_top = 0;    /* nothing in the stack */
    curbuf->b_ml.ml_locked = NULL;    /* no cached block */
    curbuf->b_ml.ml_line_lnum = 0;    /* no cached line */
#ifdef FEAT_BYTEOFF
    curbuf->b_ml.ml_chunksize = NULL;
#endif

/*
 * When 'updatecount' is non-zero, flag that a swap file may be opened later.
 */
    if (p_uc && curbuf->b_p_swf)
    curbuf->b_may_swap = TRUE;
    else
    curbuf->b_may_swap = FALSE;

/*
 * Open the memfile.  No swap file is created yet.
 */
    mfp = mf_open(NULL, 0);
    if (mfp == NULL)
    goto error;

    curbuf->b_ml.ml_mfp = mfp;
    curbuf->b_ml.ml_flags = ML_EMPTY;
    curbuf->b_ml.ml_line_count = 1;

#if defined(MSDOS) && !defined(DJGPP)
    /* for 16 bit MS-DOS create a swapfile now, because we run out of
     * memory very quickly */
    if (p_uc != 0)
    ml_open_file(curbuf);
#endif

/*
 * fill block0 struct and write page 0
 */
    if ((hp = mf_new(mfp, FALSE, 1)) == NULL)
    goto error;
    if (hp->bh_bnum != 0)
    {
    EMSG(_("E298: Didn't get block nr 0?"));
    goto error;
    }
    b0p = (ZERO_BL *)(hp->bh_data);

    b0p->b0_id[0] = BLOCK0_ID0;
    b0p->b0_id[1] = BLOCK0_ID1;
    b0p->b0_dirty = curbuf->b_changed ? 0x55 : 0;
    b0p->b0_magic_long = (long)B0_MAGIC_LONG;
    b0p->b0_magic_int = (int)B0_MAGIC_INT;
    b0p->b0_magic_short = (short)B0_MAGIC_SHORT;
    b0p->b0_magic_char = B0_MAGIC_CHAR;

    STRNCPY(b0p->b0_version, "VIM ", 4);
    STRNCPY(b0p->b0_version + 4, Version, 6);
    set_b0_fname(b0p, curbuf);
    long_to_char((long)mfp->mf_page_size, b0p->b0_page_size);
    (void)get_user_name(b0p->b0_uname, B0_UNAME_SIZE);
    b0p->b0_uname[B0_UNAME_SIZE - 1] = NUL;
    mch_get_host_name(b0p->b0_hname, B0_HNAME_SIZE);
    b0p->b0_hname[B0_HNAME_SIZE - 1] = NUL;
    long_to_char(mch_get_pid(), b0p->b0_pid);

    /*
     * Always sync block number 0 to disk, so we can check the file name in
     * the swap file in findswapname(). Don't do this for help files though.
     * Only works when there's a swapfile, otherwise it's done when the file
     * is created.
     */
    mf_put(mfp, hp, TRUE, FALSE);
    if (!curbuf->b_help)
    (void)mf_sync(mfp, 0);

/*
 * fill in root pointer block and write page 1
 */
    if ((hp = ml_new_ptr(mfp)) == NULL)
    goto error;
    if (hp->bh_bnum != 1)
    {
    EMSG(_("E298: Didn't get block nr 1?"));
    goto error;
    }
    pp = (PTR_BL *)(hp->bh_data);
    pp->pb_count = 1;
    pp->pb_pointer[0].pe_bnum = 2;
    pp->pb_pointer[0].pe_page_count = 1;
    pp->pb_pointer[0].pe_old_lnum = 1;
    pp->pb_pointer[0].pe_line_count = 1;    /* line count after insertion */
    mf_put(mfp, hp, TRUE, FALSE);

/*
 * allocate first data block and create an empty line 1.
 */
    if ((hp = ml_new_data(mfp, FALSE, 1)) == NULL)
    goto error;
    if (hp->bh_bnum != 2)
    {
    EMSG(_("E298: Didn't get block nr 2?"));
    goto error;
    }

    dp = (DATA_BL *)(hp->bh_data);
    dp->db_index[0] = --dp->db_txt_start;    /* at end of block */
    dp->db_free -= 1 + INDEX_SIZE;
    dp->db_line_count = 1;
    *((char_u *)dp + dp->db_txt_start) = NUL;    /* emtpy line */

    return OK;

error:
    if (mfp != NULL)
    {
    if (hp)
        mf_put(mfp, hp, FALSE, FALSE);
    mf_close(mfp, TRUE);        /* will also free(mfp->mf_fname) */
    }
    curbuf->b_ml.ml_mfp = NULL;
    return FAIL;
}

/*
 * ml_setname() is called when the file name has been changed.
 * It may rename the swap file.
 */
    void
ml_setname()
{
    int        success = FALSE;
    memfile_T    *mfp;
    char_u    *fname;
    char_u    *dirp;
#if defined(MSDOS) || defined(MSWIN)
    char_u    *p;
#endif

    mfp = curbuf->b_ml.ml_mfp;
    if (mfp->mf_fd < 0)            /* there is no swap file yet */
    {
    /*
     * When 'updatecount' is 0 and 'noswapfile' there is no swap file.
     * For help files we will make a swap file now.
     */
    if (p_uc != 0)
        ml_open_file(curbuf);    /* create a swap file */
    return;
    }

    /*
     * Try all directories in the 'directory' option.
     */
    dirp = p_dir;
    for (;;)
    {
    if (*dirp == NUL)        /* tried all directories, fail */
        break;
    fname = findswapname(curbuf, &dirp, mfp->mf_fname); /* alloc's fname */
    if (fname == NULL)        /* no file name found for this dir */
        continue;

#if defined(MSDOS) || defined(MSWIN)
    /*
     * Set full pathname for swap file now, because a ":!cd dir" may
     * change directory without us knowing it.
     */
    p = FullName_save(fname, FALSE);
    vim_free(fname);
    fname = p;
    if (fname == NULL)
        continue;
#endif
    /* if the file name is the same we don't have to do anything */
    if (fnamecmp(fname, mfp->mf_fname) == 0)
    {
        vim_free(fname);
        success = TRUE;
        break;
    }
    /* need to close the swap file before renaming */
    if (mfp->mf_fd >= 0)
    {
        close(mfp->mf_fd);
        mfp->mf_fd = -1;
    }

    /* try to rename the swap file */
    if (vim_rename(mfp->mf_fname, fname) == 0)
    {
        success = TRUE;
        vim_free(mfp->mf_fname);
        mfp->mf_fname = fname;
        vim_free(mfp->mf_ffname);
#if defined(MSDOS) || defined(MSWIN)
        mfp->mf_ffname = NULL;  /* mf_fname is full pathname already */
#else
        mf_set_ffname(mfp);
#endif
        break;
    }
    vim_free(fname);        /* this fname didn't work, try another */
    }

    if (mfp->mf_fd == -1)        /* need to (re)open the swap file */
    {
    mfp->mf_fd = mch_open((char *)mfp->mf_fname, O_RDWR | O_EXTRA, 0);
    if (mfp->mf_fd < 0)
    {
        /* could not (re)open the swap file, what can we do???? */
        EMSG(_("E301: Oops, lost the swap file!!!"));
        return;
    }
    }
    if (!success)
    EMSG(_("E302: Could not rename swap file"));
}

/*
 * Open a file for the memfile for all buffers that are not readonly or have
 * been modified.
 * Used when 'updatecount' changes from zero to non-zero.
 */
    void
ml_open_files()
{
    buf_T    *buf;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
    if (!buf->b_p_ro || buf->b_changed)
        ml_open_file(buf);
}

/*
 * Open a swap file for an existing memfile, if there is no swap file yet.
 * If we are unable to find a file name, mf_fname will be NULL
 * and the memfile will be in memory only (no recovery possible).
 */
    void
ml_open_file(buf)
    buf_T    *buf;
{
    memfile_T    *mfp;
    char_u    *fname;
    char_u    *dirp;

    mfp = buf->b_ml.ml_mfp;
    if (mfp == NULL || mfp->mf_fd >= 0 || !buf->b_p_swf)
    return;        /* nothing to do */

    /*
     * Try all directories in 'directory' option.
     */
    dirp = p_dir;
    for (;;)
    {
    if (*dirp == NUL)
        break;
    /* There is a small chance that between chosing the swap file name and
     * creating it, another Vim creates the file.  In that case the
     * creation will fail and we will use another directory. */
    fname = findswapname(buf, &dirp, NULL);    /* allocates fname */
    if (fname == NULL)
        continue;
    if (mf_open_file(mfp, fname) == OK)    /* consumes fname! */
    {
#if defined(MSDOS) || defined(MSWIN) || defined(RISCOS)
        /*
         * set full pathname for swap file now, because a ":!cd dir" may
         * change directory without us knowing it.
         */
        mf_fullname(mfp);
#endif
        /* Flush block zero, so others can read it */
        if (mf_sync(mfp, MFS_ZERO) == OK)
        break;
        /* Writing block 0 failed: close the file and try another dir */
        mf_close_file(buf, FALSE);
    }
    }

    if (mfp->mf_fname == NULL)        /* Failed! */
    {
    need_wait_return = TRUE;    /* call wait_return later */
    ++no_wait_return;
    (void)EMSG2(_("E303: Unable to open swap file for \"%s\", recovery impossible"),
            buf_spname(buf) != NULL
            ? (char_u *)buf_spname(buf)
            : buf->b_fname);
    --no_wait_return;
    }

    /* don't try to open a swap file again */
    buf->b_may_swap = FALSE;
}

/*
 * If still need to create a swap file, and starting to edit a not-readonly
 * file, or reading into an existing buffer, create a swap file now.
 */
    void
check_need_swap(newfile)
    int        newfile;        /* reading file into new buffer */
{
    if (curbuf->b_may_swap && (!curbuf->b_p_ro || !newfile))
    ml_open_file(curbuf);
}

/*
 * Close memline for buffer 'buf'.
 * If 'del_file' is TRUE, delete the swap file
 */
    void
ml_close(buf, del_file)
    buf_T    *buf;
    int        del_file;
{
    if (buf->b_ml.ml_mfp == NULL)        /* not open */
    return;
    mf_close(buf->b_ml.ml_mfp, del_file);    /* close the .swp file */
    if (buf->b_ml.ml_line_lnum != 0 && (buf->b_ml.ml_flags & ML_LINE_DIRTY))
    vim_free(buf->b_ml.ml_line_ptr);
    vim_free(buf->b_ml.ml_stack);
#ifdef FEAT_BYTEOFF
    vim_free(buf->b_ml.ml_chunksize);
    buf->b_ml.ml_chunksize = NULL;
#endif
    buf->b_ml.ml_mfp = NULL;

    /* Reset the "recovered" flag, give the ATTENTION prompt the next time
     * this buffer is loaded. */
    buf->b_flags &= ~BF_RECOVERED;
}

/*
 * Close all existing memlines and memfiles.
 * Only used when exiting.
 * When 'del_file' is TRUE, delete the memfiles.
 */
    void
ml_close_all(del_file)
    int        del_file;
{
    buf_T    *buf;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
    ml_close(buf, del_file);
#ifdef TEMPDIRNAMES
    vim_deltempdir();        /* delete created temp directory */
#endif
}

/*
 * Close all memfiles for not modified buffers.
 * Only use just before exiting!
 */
    void
ml_close_notmod()
{
    buf_T    *buf;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
    if (!bufIsChanged(buf))
        ml_close(buf, TRUE);    /* close all not-modified buffers */
}

/*
 * Update the timestamp in the .swp file.
 * Used when the file has been written.
 */
    void
ml_timestamp(buf)
    buf_T    *buf;
{
    memfile_T    *mfp;
    bhdr_T    *hp;
    ZERO_BL    *b0p;

    mfp = buf->b_ml.ml_mfp;

    if (mfp == NULL || (hp = mf_get(mfp, (blocknr_T)0, 1)) == NULL)
    return;
    b0p = (ZERO_BL *)(hp->bh_data);
    if (b0p->b0_id[0] != BLOCK0_ID0 || b0p->b0_id[1] != BLOCK0_ID1)
    EMSG(_("E304: ml_timestamp: Didn't get block 0??"));
    else
    set_b0_fname(b0p, buf);
    mf_put(mfp, hp, TRUE, FALSE);
}

/*
 * Write file name and timestamp into block 0 of a swap file.
 * Also set buf->b_mtime.
 * Don't use NameBuff[]!!!
 */
    static void
set_b0_fname(b0p, buf)
    ZERO_BL    *b0p;
    buf_T    *buf;
{
    struct stat    st;

    if (buf->b_ffname == NULL)
    b0p->b0_fname[0] = NUL;
    else
    {
#if defined(MSDOS) || defined(MSWIN) || defined(AMIGA) || defined(RISCOS)
    /* systems that cannot translate "~user" back into a path: copy the
     * file name unmodified */
    STRNCPY(b0p->b0_fname, buf->b_ffname, B0_FNAME_SIZE);
#else
    size_t    flen, ulen;
    char_u    uname[B0_UNAME_SIZE];

    /*
     * For a file under the home directory of the current user, we try to
     * replace the home directory path with "~user". This helps when
     * editing the same file on different machines over a network.
     * First replace home dir path with "~/" with home_replace().
     * Then insert the user name to get "~user/".
     */
    home_replace(NULL, buf->b_ffname, b0p->b0_fname, B0_FNAME_SIZE, TRUE);
    if (b0p->b0_fname[0] == '~')
    {
        flen = STRLEN(b0p->b0_fname);
        /* If there is no user name or it is too long, don't use "~/" */
        if (get_user_name(uname, B0_UNAME_SIZE) == FAIL
             || (ulen = STRLEN(uname)) + flen > B0_FNAME_SIZE - 1)
        STRNCPY(b0p->b0_fname, buf->b_ffname, B0_FNAME_SIZE);
        else
        {
        mch_memmove(b0p->b0_fname + ulen + 1, b0p->b0_fname + 1, flen);
        mch_memmove(b0p->b0_fname + 1, uname, ulen);
        }
    }
#endif
    if (mch_stat((char *)buf->b_ffname, &st) >= 0)
    {
        long_to_char((long)st.st_mtime, b0p->b0_mtime);
#ifdef CHECK_INODE
        long_to_char((long)st.st_ino, b0p->b0_ino);
#endif
        buf_store_time(buf, &st, buf->b_ffname);
        buf->b_mtime_read = buf->b_mtime;
    }
    else
    {
        long_to_char(0L, b0p->b0_mtime);
#ifdef CHECK_INODE
        long_to_char(0L, b0p->b0_ino);
#endif
        buf->b_mtime = 0;
        buf->b_mtime_read = 0;
        buf->b_orig_size = 0;
        buf->b_orig_mode = 0;
    }
    }
}

/*
 * try to recover curbuf from the .swp file
 */
    void
ml_recover()
{
    buf_T    *buf = NULL;
    memfile_T    *mfp = NULL;
    char_u    *fname;
    bhdr_T    *hp = NULL;
    ZERO_BL    *b0p;
    PTR_BL    *pp;
    DATA_BL    *dp;
    infoptr_T    *ip;
    blocknr_T    bnum;
    int        page_count;
    struct stat    org_stat, swp_stat;
    int        len;
    int        directly;
    linenr_T    lnum;
    char_u    *p;
    int        i;
    long    error;
    int        cannot_open;
    linenr_T    line_count;
    int        has_error;
    int        idx;
    int        top;
    int        txt_start;
    off_t    size;
    int        called_from_main;
    int        serious_error = TRUE;
    long    mtime;
    int        attr;

    recoverymode = TRUE;
    called_from_main = (curbuf->b_ml.ml_mfp == NULL);
    attr = hl_attr(HLF_E);
/*
 * If the file name ends in ".sw?" we use it directly.
 * Otherwise a search is done to find the swap file(s).
 */
    fname = curbuf->b_fname;
    if (fname == NULL)            /* When there is no file name */
    fname = (char_u *)"";
    len = (int)STRLEN(fname);
    if (len >= 4 &&
#if defined(VMS) || defined(RISCOS)
        STRNICMP(fname + len - 4, "_sw" , 3)
#else
        STRNICMP(fname + len - 4, ".sw" , 3)
#endif
        == 0)
    {
    directly = TRUE;
    fname = vim_strsave(fname); /* make a copy for mf_open() */
    }
    else
    {
    directly = FALSE;

    /* count the number of matching swap files */
    len = recover_names(&fname, FALSE, 0);
    if (len == 0)            /* no swap files found */
    {
        EMSG2(_("E305: No swap file found for %s"), fname);
        goto theend;
    }
    if (len == 1)            /* one swap file found, use it */
        i = 1;
    else                /* several swap files found, choose */
    {
        /* list the names of the swap files */
        (void)recover_names(&fname, TRUE, 0);
        msg_putchar('\n');
        MSG_PUTS(_("Enter number of swap file to use (0 to quit): "));
        i = get_number(FALSE);
        if (i < 1 || i > len)
        goto theend;
    }
    /* get the swap file name that will be used */
    (void)recover_names(&fname, FALSE, i);
    }
    if (fname == NULL)
    goto theend;            /* out of memory */

    /* When called from main() still need to initialize storage structure */
    if (called_from_main && ml_open() == FAIL)
    getout(1);

/*
 * allocate a buffer structure (only the memline in it is really used)
 */
    buf = (buf_T *)alloc((unsigned)sizeof(buf_T));
    if (buf == NULL)
    {
    vim_free(fname);
    goto theend;
    }

/*
 * init fields in memline struct
 */
    buf->b_ml.ml_stack_size = 0;    /* no stack yet */
    buf->b_ml.ml_stack = NULL;        /* no stack yet */
    buf->b_ml.ml_stack_top = 0;        /* nothing in the stack */
    buf->b_ml.ml_line_lnum = 0;        /* no cached line */
    buf->b_ml.ml_locked = NULL;        /* no locked block */
    buf->b_ml.ml_flags = 0;

/*
 * open the memfile from the old swap file
 */
    p = vim_strsave(fname);        /* save fname for the message
                       (mf_open() may free fname) */
    mfp = mf_open(fname, O_RDONLY);    /* consumes fname! */
    if (mfp == NULL || mfp->mf_fd < 0)
    {
    if (p != NULL)
    {
        EMSG2(_("E306: Cannot open %s"), p);
        vim_free(p);
    }
    goto theend;
    }
    vim_free(p);
    buf->b_ml.ml_mfp = mfp;

    /*
     * The page size set in mf_open() might be different from the page size
     * used in the swap file, we must get it from block 0.  But to read block
     * 0 we need a page size.  Use the minimal size for block 0 here, it will
     * be set to the real value below.
     */
    mfp->mf_page_size = MIN_SWAP_PAGE_SIZE;

/*
 * try to read block 0
 */
    if ((hp = mf_get(mfp, (blocknr_T)0, 1)) == NULL)
    {
    msg_start();
    MSG_PUTS_ATTR(_("Unable to read block 0 from "), attr | MSG_HIST);
    msg_outtrans_attr(mfp->mf_fname, attr | MSG_HIST);
    MSG_PUTS_ATTR(
       _("\nMaybe no changes were made or Vim did not update the swap file."),
        attr | MSG_HIST);
    msg_end();
    goto theend;
    }
    b0p = (ZERO_BL *)(hp->bh_data);
    if (STRNCMP(b0p->b0_version, "VIM 3.0", 7) == 0)
    {
    msg_start();
    msg_outtrans_attr(mfp->mf_fname, MSG_HIST);
    MSG_PUTS_ATTR(_(" cannot be used with this version of Vim.\n"),
                                    MSG_HIST);
    MSG_PUTS_ATTR(_("Use Vim version 3.0.\n"), MSG_HIST);
    msg_end();
    goto theend;
    }
    if (b0p->b0_id[0] != BLOCK0_ID0 || b0p->b0_id[1] != BLOCK0_ID1)
    {
    EMSG2(_("E307: %s does not look like a Vim swap file"), mfp->mf_fname);
    goto theend;
    }
    if (b0_magic_wrong(b0p))
    {
    msg_start();
    msg_outtrans_attr(mfp->mf_fname, attr | MSG_HIST);
#if defined(MSDOS) || defined(MSWIN)
    if (STRNCMP(b0p->b0_hname, "PC ", 3) == 0)
        MSG_PUTS_ATTR(_(" cannot be used with this version of Vim.\n"),
                                 attr | MSG_HIST);
    else
#endif
        MSG_PUTS_ATTR(_(" cannot be used on this computer.\n"),
                                 attr | MSG_HIST);
    MSG_PUTS_ATTR(_("The file was created on "), attr | MSG_HIST);
    /* avoid going past the end of a currupted hostname */
    b0p->b0_fname[0] = NUL;
    MSG_PUTS_ATTR(b0p->b0_hname, attr | MSG_HIST);
    MSG_PUTS_ATTR(_(",\nor the file has been damaged."), attr | MSG_HIST);
    msg_end();
    goto theend;
    }
    /*
     * If we guessed the wrong page size, we have to recalculate the
     * highest block number in the file.
     */
    if (mfp->mf_page_size != (unsigned)char_to_long(b0p->b0_page_size))
    {
    mfp->mf_page_size = (unsigned)char_to_long(b0p->b0_page_size);
    if ((size = lseek(mfp->mf_fd, (off_t)0L, SEEK_END)) <= 0)
        mfp->mf_blocknr_max = 0;        /* no file or empty file */
    else
        mfp->mf_blocknr_max = (blocknr_T)(size / mfp->mf_page_size);
    mfp->mf_infile_count = mfp->mf_blocknr_max;
    }

/*
 * If .swp file name given directly, use name from swap file for buffer.
 */
    if (directly)
    {
    expand_env(b0p->b0_fname, NameBuff, MAXPATHL);
    if (setfname(NameBuff, NULL, TRUE) == FAIL)
        goto theend;
    }

    home_replace(NULL, mfp->mf_fname, NameBuff, MAXPATHL, TRUE);
    smsg((char_u *)_("Using swap file \"%s\""),
#ifdef VMS
        vms_fixfilename(NameBuff)
#else
        NameBuff
#endif
        );

    if (buf_spname(curbuf) != NULL)
    STRCPY(NameBuff, buf_spname(curbuf));
    else
    home_replace(NULL, curbuf->b_ffname, NameBuff, MAXPATHL, TRUE);
    smsg((char_u *)_("Original file \"%s\""),
#ifdef VMS
        vms_fixfilename(NameBuff)
#else
        NameBuff
#endif
        );
    msg_putchar('\n');

/*
 * check date of swap file and original file
 */
    mtime = char_to_long(b0p->b0_mtime);
    if (curbuf->b_ffname != NULL
        && mch_stat((char *)curbuf->b_ffname, &org_stat) != -1
        && ((mch_stat((char *)mfp->mf_fname, &swp_stat) != -1
            && org_stat.st_mtime > swp_stat.st_mtime)
        || org_stat.st_mtime != mtime))
    {
    EMSG(_("E308: Warning: Original file may have been changed"));
    }
    out_flush();
    mf_put(mfp, hp, FALSE, FALSE);    /* release block 0 */
    hp = NULL;

    /*
     * Now that we are sure that the file is going to be recovered, clear the
     * contents of the current buffer.
     */
    while (!(curbuf->b_ml.ml_flags & ML_EMPTY))
    ml_delete((linenr_T)1, FALSE);

    bnum = 1;        /* start with block 1 */
    page_count = 1;    /* which is 1 page */
    lnum = 0;        /* append after line 0 in curbuf */
    line_count = 0;
    idx = 0;        /* start with first index in block 1 */
    error = 0;
    buf->b_ml.ml_stack_top = 0;
    buf->b_ml.ml_stack = NULL;
    buf->b_ml.ml_stack_size = 0;    /* no stack yet */

    if (curbuf->b_ffname == NULL)
    cannot_open = TRUE;
    else
    cannot_open = FALSE;

    serious_error = FALSE;
    for ( ; !got_int; line_breakcheck())
    {
    if (hp != NULL)
        mf_put(mfp, hp, FALSE, FALSE);    /* release previous block */

    /*
     * get block
     */
    if ((hp = mf_get(mfp, (blocknr_T)bnum, page_count)) == NULL)
    {
        if (bnum == 1)
        {
        EMSG2(_("E309: Unable to read block 1 from %s"), mfp->mf_fname);
        goto theend;
        }
        ++error;
        ml_append(lnum++, (char_u *)_("???MANY LINES MISSING"),
                                (colnr_T)0, TRUE);
    }
    else        /* there is a block */
    {
        pp = (PTR_BL *)(hp->bh_data);
        if (pp->pb_id == PTR_ID)        /* it is a pointer block */
        {
        /* check line count when using pointer block first time */
        if (idx == 0 && line_count != 0)
        {
            for (i = 0; i < (int)pp->pb_count; ++i)
            line_count -= pp->pb_pointer[i].pe_line_count;
            if (line_count != 0)
            {
            ++error;
            ml_append(lnum++, (char_u *)_("???LINE COUNT WRONG"),
                                (colnr_T)0, TRUE);
            }
        }

        if (pp->pb_count == 0)
        {
            ml_append(lnum++, (char_u *)_("???EMPTY BLOCK"),
                                (colnr_T)0, TRUE);
            ++error;
        }
        else if (idx < (int)pp->pb_count)    /* go a block deeper */
        {
            if (pp->pb_pointer[idx].pe_bnum < 0)
            {
            /*
             * Data block with negative block number.
             * Try to read lines from the original file.
             * This is slow, but it works.
             */
            if (!cannot_open)
            {
                line_count = pp->pb_pointer[idx].pe_line_count;
                if (readfile(curbuf->b_ffname, NULL, lnum,
                    pp->pb_pointer[idx].pe_old_lnum - 1,
                    line_count, NULL, 0) == FAIL)
                cannot_open = TRUE;
                else
                lnum += line_count;
            }
            if (cannot_open)
            {
                ++error;
                ml_append(lnum++, (char_u *)_("???LINES MISSING"),
                                (colnr_T)0, TRUE);
            }
            ++idx;        /* get same block again for next index */
            continue;
            }

            /*
             * going one block deeper in the tree
             */
            if ((top = ml_add_stack(buf)) < 0)    /* new entry in stack */
            {
            ++error;
            break;            /* out of memory */
            }
            ip = &(buf->b_ml.ml_stack[top]);
            ip->ip_bnum = bnum;
            ip->ip_index = idx;

            bnum = pp->pb_pointer[idx].pe_bnum;
            line_count = pp->pb_pointer[idx].pe_line_count;
            page_count = pp->pb_pointer[idx].pe_page_count;
            continue;
        }
        }
        else        /* not a pointer block */
        {
        dp = (DATA_BL *)(hp->bh_data);
        if (dp->db_id != DATA_ID)    /* block id wrong */
        {
            if (bnum == 1)
            {
            EMSG2(_("E310: Block 1 ID wrong (%s not a .swp file?)"),
                                   mfp->mf_fname);
            goto theend;
            }
            ++error;
            ml_append(lnum++, (char_u *)_("???BLOCK MISSING"),
                                (colnr_T)0, TRUE);
        }
        else
        {
            /*
             * it is a data block
             * Append all the lines in this block
             */
            has_error = FALSE;
            /*
             * check length of block
             * if wrong, use length in pointer block
             */
            if (page_count * mfp->mf_page_size != dp->db_txt_end)
            {
            ml_append(lnum++, (char_u *)_("??? from here until ???END lines may be messed up"),
                                (colnr_T)0, TRUE);
            ++error;
            has_error = TRUE;
            dp->db_txt_end = page_count * mfp->mf_page_size;
            }

            /* make sure there is a NUL at the end of the block */
            *((char_u *)dp + dp->db_txt_end - 1) = NUL;

            /*
             * check number of lines in block
             * if wrong, use count in data block
             */
            if (line_count != dp->db_line_count)
            {
            ml_append(lnum++, (char_u *)_("??? from here until ???END lines may have been inserted/deleted"),
                                (colnr_T)0, TRUE);
            ++error;
            has_error = TRUE;
            }

            for (i = 0; i < dp->db_line_count; ++i)
            {
            txt_start = (dp->db_index[i] & DB_INDEX_MASK);
            if (txt_start <= HEADER_SIZE
                      || txt_start >= (int)dp->db_txt_end)
            {
                p = (char_u *)"???";
                ++error;
            }
            else
                p = (char_u *)dp + txt_start;
            ml_append(lnum++, p, (colnr_T)0, TRUE);
            }
            if (has_error)
            ml_append(lnum++, (char_u *)_("???END"), (colnr_T)0, TRUE);
        }
        }
    }

    if (buf->b_ml.ml_stack_top == 0)    /* finished */
        break;

    /*
     * go one block up in the tree
     */
    ip = &(buf->b_ml.ml_stack[--(buf->b_ml.ml_stack_top)]);
    bnum = ip->ip_bnum;
    idx = ip->ip_index + 1;        /* go to next index */
    page_count = 1;
    }

    /*
     * The dummy line from the empty buffer will now be after the last line in
     * the buffer. Delete it.
     */
    ml_delete(curbuf->b_ml.ml_line_count, FALSE);
    curbuf->b_flags |= BF_RECOVERED;

    recoverymode = FALSE;
    if (got_int)
    EMSG(_("E311: Recovery Interrupted"));
    else if (error)
    EMSG(_("E312: Errors detected while recovering; look for lines starting with ???"));
    else
    {
    MSG(_("Recovery completed. You should check if everything is OK."));
    MSG_PUTS(_("\n(You might want to write out this file under another name\n"));
    MSG_PUTS(_("and run diff with the original file to check for changes)\n"));
    MSG_PUTS(_("Delete the .swp file afterwards.\n\n"));
    cmdline_row = msg_row;
    }
    redraw_curbuf_later(NOT_VALID);

theend:
    recoverymode = FALSE;
    if (mfp != NULL)
    {
    if (hp != NULL)
        mf_put(mfp, hp, FALSE, FALSE);
    mf_close(mfp, FALSE);        /* will also vim_free(mfp->mf_fname) */
    }
    vim_free(buf);
    if (serious_error && called_from_main)
    ml_close(curbuf, TRUE);
#ifdef FEAT_AUTOCMD
    else
    {
    apply_autocmds(EVENT_BUFREADPOST, NULL, curbuf->b_fname, FALSE, curbuf);
    apply_autocmds(EVENT_BUFWINENTER, NULL, curbuf->b_fname, FALSE, curbuf);
    }
#endif
    return;
}

/*
 * Find the names of swap files in current directory and the directory given
 * with the 'directory' option.
 *
 * Used to:
 * - list the swap files for "vim -r"
 * - count the number of swap files when recovering
 * - list the swap files when recovering
 * - find the name of the n'th swap file when recovering
 */
    int
recover_names(fname, list, nr)
    char_u    **fname;    /* base for swap file name */
    int        list;        /* when TRUE, list the swap file names */
    int        nr;        /* when non-zero, return nr'th swap file name */
{
    int        num_names;
    char_u    *(names[6]);
    char_u    *tail;
    char_u    *p;
    int        num_files;
    int        file_count = 0;
    char_u    **files;
    int        i;
    char_u    *dirp;
    char_u    *dir_name;

    if (list)
    {
        /* use msg() to start the scrolling properly */
    msg((char_u *)_("Swap files found:"));
    msg_putchar('\n');
    }

    /*
     * Do the loop for every directory in 'directory'.
     * First allocate some memory to put the directory name in.
     */
    dir_name = alloc((unsigned)STRLEN(p_dir) + 1);
    dirp = p_dir;
    while (dir_name != NULL && *dirp)
    {
    /*
     * Isolate a directory name from *dirp and put it in dir_name (we know
     * it is large enough, so use 31000 for length).
     * Advance dirp to next directory name.
     */
    (void)copy_option_part(&dirp, dir_name, 31000, ",");

    if (dir_name[0] == '.' && dir_name[1] == NUL)    /* check current dir */
    {
        if (fname == NULL || *fname == NULL)
        {
#ifdef VMS
        names[0] = vim_strsave((char_u *)"*_sw%");
#else
# ifdef RISCOS
        names[0] = vim_strsave((char_u *)"*_sw#");
# else
        names[0] = vim_strsave((char_u *)"*.sw?");
# endif
#endif
#ifdef UNIX
        /* for Unix names starting with a dot are special */
        names[1] = vim_strsave((char_u *)".*.sw?");
        names[2] = vim_strsave((char_u *)".sw?");
        num_names = 3;
#else
# ifdef VMS
        names[1] = vim_strsave((char_u *)".*_sw%");
        num_names = 2;
# else
        num_names = 1;
# endif
#endif
        }
        else
        num_names = recov_file_names(names, *fname, TRUE);
    }
    else                /* check directory dir_name */
    {
        if (fname == NULL || *fname == NULL)
        {
#ifdef VMS
        names[0] = concat_fnames(dir_name, (char_u *)"*_sw%", TRUE);
#else
# ifdef RISCOS
        names[0] = concat_fnames(dir_name, (char_u *)"*_sw#", TRUE);
# else
        names[0] = concat_fnames(dir_name, (char_u *)"*.sw?", TRUE);
# endif
#endif
#ifdef UNIX
        /* for Unix names starting with a dot are special */
        names[1] = concat_fnames(dir_name, (char_u *)".*.sw?", TRUE);
        names[2] = concat_fnames(dir_name, (char_u *)".sw?", TRUE);
        num_names = 3;
#else
# ifdef VMS
        names[1] = concat_fnames(dir_name, (char_u *)".*_sw%", TRUE);
        num_names = 2;
# else
        num_names = 1;
# endif
#endif
        }
        else
        {
#if defined(UNIX) || defined(WIN3264)
        p = dir_name + STRLEN(dir_name);
        if (vim_ispathsep(p[-1]) && p[-1] == p[-2])
        {
            /* Ends with '//', Use Full path for swap name */
            tail = make_percent_swname(dir_name, *fname);
        }
        else
#endif
        {
            tail = gettail(*fname);
            tail = concat_fnames(dir_name, tail, TRUE);
        }
        if (tail == NULL)
            num_names = 0;
        else
        {
            num_names = recov_file_names(names, tail, FALSE);
            vim_free(tail);
        }
        }
    }

        /* check for out-of-memory */
    for (i = 0; i < num_names; ++i)
    {
        if (names[i] == NULL)
        {
        for (i = 0; i < num_names; ++i)
            vim_free(names[i]);
        num_names = 0;
        }
    }
    if (num_names == 0)
        num_files = 0;
    else if (expand_wildcards(num_names, names, &num_files, &files,
                           EW_FILE|EW_SILENT) == FAIL)
        num_files = 0;

    /*
     * When no swap file found, wildcard expansion might have failed (e.g.
     * not able to execute the shell).
     * Try finding a swap file by simply adding ".swp" to the file name.
     */
    if (*dirp == NUL && file_count + num_files == 0
                       && fname != NULL && *fname != NULL)
    {
        struct stat        st;
        char_u        *swapname;

#if defined(VMS) || defined(RISCOS)
        swapname = modname(*fname, (char_u *)"_swp", FALSE);
#else
        swapname = modname(*fname, (char_u *)".swp", TRUE);
#endif
        if (swapname != NULL)
        {
        if (mch_stat((char *)swapname, &st) != -1)        /* It exists! */
        {
            files = (char_u **)alloc((unsigned)sizeof(char_u *));
            if (files != NULL)
            {
            files[0] = swapname;
            swapname = NULL;
            num_files = 1;
            }
        }
        vim_free(swapname);
        }
    }

    /*
     * remove swapfile name of the current buffer, it must be ignored
     */
    if (curbuf->b_ml.ml_mfp != NULL
                   && (p = curbuf->b_ml.ml_mfp->mf_fname) != NULL)
    {
        for (i = 0; i < num_files; ++i)
        if (fullpathcmp(p, files[i], TRUE) & FPC_SAME)
        {
            vim_free(files[i]);
            --num_files;
            for ( ; i < num_files; ++i)
            files[i] = files[i + 1];
        }
    }
    if (nr)
    {
        file_count += num_files;
        if (nr <= file_count)
        {
        *fname = vim_strsave(files[nr - 1 + num_files - file_count]);
        dirp = (char_u *)"";            /* stop searching */
        }
    }
    else if (list)
    {
        if (dir_name[0] == '.' && dir_name[1] == NUL)
        {
        if (fname == NULL || *fname == NULL)
            MSG_PUTS(_("   In current directory:\n"));
        else
            MSG_PUTS(_("   Using specified name:\n"));
        }
        else
        {
        MSG_PUTS(_("   In directory "));
        msg_home_replace(dir_name);
        MSG_PUTS(":\n");
        }

        if (num_files)
        {
        for (i = 0; i < num_files; ++i)
        {
            /* print the swap file name */
            msg_outnum((long)++file_count);
            MSG_PUTS(".    ");
            msg_puts(gettail(files[i]));
            msg_putchar('\n');
            (void)swapfile_info(files[i]);
        }
        }
        else
        MSG_PUTS(_("      -- none --\n"));
        out_flush();
    }
    else
        file_count += num_files;

    for (i = 0; i < num_names; ++i)
        vim_free(names[i]);
    FreeWild(num_files, files);
    }
    vim_free(dir_name);
    return file_count;
}

#if defined(UNIX) || defined(WIN3264)  /* Need _very_ long file names */
/*
 * Append the full path to name with path separators made into percent
 * signs, to dir. An unnamed buffer is handled as "" (<currentdir>/"")
 */
    static char_u *
make_percent_swname(dir, name)
    char_u    *dir;
    char_u    *name;
{
    char_u *d, *s, *f, *p;

    f = fix_fname(name != NULL ? name : (char_u *) "");
    d = NULL;
    if (f != NULL)
    {
    s = alloc((unsigned)(STRLEN(f) + 1));
    if (s != NULL)
    {
        for (d = s, p = f; *p; p++, d++)
        *d = vim_ispathsep(*p) ? '%' : *p;
        *d = 0;
        d = concat_fnames(dir, s, TRUE);
        vim_free(s);
    }
    vim_free(f);
    }
    return d;
}
#endif

#if (defined(UNIX) || defined(__EMX__) || defined(VMS)) && (defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG))
static int process_still_running;
#endif

/*
 * Give information about an existing swap file
 * Returns timestamp (0 when unknown).
 */
    static time_t
swapfile_info(fname)
    char_u    *fname;
{
    struct stat        st;
    int            fd;
    struct block0   b0;
    time_t        x = (time_t)0;
#ifdef UNIX
    char_u        uname[B0_UNAME_SIZE];
#endif

    /* print the swap file date */
    if (mch_stat((char *)fname, &st) != -1)
    {
#ifdef UNIX
    /* print name of owner of the file */
    if (mch_get_uname(st.st_uid, uname, B0_UNAME_SIZE) == OK)
    {
        MSG_PUTS(_("          owned by: "));
        msg_outtrans(uname);
        MSG_PUTS(_("   dated: "));
    }
    else
#endif
        MSG_PUTS(_("             dated: "));
    x = st.st_mtime;            /* Manx C can't do &st.st_mtime */
    MSG_PUTS(ctime(&x));            /* includes '\n' */

    }

    /*
     * print the original file name
     */
    fd = mch_open((char *)fname, O_RDONLY | O_EXTRA, 0);
    if (fd >= 0)
    {
    if (read(fd, (char *)&b0, sizeof(b0)) == sizeof(b0))
    {
        if (STRNCMP(b0.b0_version, "VIM 3.0", 7) == 0)
        {
        MSG_PUTS(_("         [from Vim version 3.0]"));
        }
        else if (b0.b0_id[0] != BLOCK0_ID0 || b0.b0_id[1] != BLOCK0_ID1)
        {
        MSG_PUTS(_("         [does not look like a Vim swap file]"));
        }
        else
        {
        MSG_PUTS(_("         file name: "));
        if (b0.b0_fname[0] == NUL)
            MSG_PUTS(_("[No File]"));
        else
            msg_outtrans(
#ifdef VMS
                vms_fixfilename(b0.b0_fname)
#else
                b0.b0_fname
#endif
                );

        MSG_PUTS(_("\n          modified: "));
        MSG_PUTS(b0.b0_dirty ? _("YES") : _("no"));

        if (*(b0.b0_uname) != NUL)
        {
            MSG_PUTS(_("\n         user name: "));
            msg_outtrans(b0.b0_uname);
        }

        if (*(b0.b0_hname) != NUL)
        {
            if (*(b0.b0_uname) != NUL)
            MSG_PUTS(_("   host name: "));
            else
            MSG_PUTS(_("\n         host name: "));
            msg_outtrans(b0.b0_hname);
        }

        if (char_to_long(b0.b0_pid) != 0L)
        {
            MSG_PUTS(_("\n        process ID: "));
            msg_outnum(char_to_long(b0.b0_pid));
#if defined(UNIX) || defined(__EMX__)
            /* EMX kill() not working correctly, it seems */
            if (kill((pid_t)char_to_long(b0.b0_pid), 0) == 0)
            {
            MSG_PUTS(_(" (still running)"));
# if defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG)
            process_still_running = TRUE;
# endif
            }
#endif
        }

        if (b0_magic_wrong(&b0))
        {
#if defined(MSDOS) || defined(MSWIN)
            if (STRNCMP(b0.b0_hname, "PC ", 3) == 0)
            MSG_PUTS(_("\n         [not usable with this version of Vim]"));
            else
#endif
            MSG_PUTS(_("\n         [not usable on this computer]"));
        }
        }
    }
    else
        MSG_PUTS(_("         [cannot be read]"));
    close(fd);
    }
    else
    MSG_PUTS(_("         [cannot be opened]"));
    msg_putchar('\n');

    return x;
}

    static int
recov_file_names(names, path, prepend_dot)
    char_u    **names;
    char_u    *path;
    int        prepend_dot;
{
    int        num_names;

#ifdef SHORT_FNAME
    /*
     * (MS-DOS) always short names
     */
    names[0] = modname(path, (char_u *)".sw?", FALSE);
    num_names = 1;
#else /* !SHORT_FNAME */
    /*
     * (Win32 and Win64) never short names, but do prepend a dot.
     * (Not MS-DOS or Win32 or Win64) maybe short name, maybe not: Try both.
     * Only use the short name if it is different.
     */
    char_u    *p;
    int        i;
# ifndef WIN3264
    int        shortname = curbuf->b_shortname;

    curbuf->b_shortname = FALSE;
# endif

    num_names = 0;

    /*
     * May also add the file name with a dot prepended, for swap file in same
     * dir as original file.
     */
    if (prepend_dot)
    {
    names[num_names] = modname(path, (char_u *)".sw?", TRUE);
    if (names[num_names] == NULL)
        goto end;
    ++num_names;
    }

    /*
     * Form the normal swap file name pattern by appending ".sw?".
     */
#ifdef VMS
    names[num_names] = concat_fnames(path, (char_u *)"_sw%", FALSE);
#else
# ifdef RISCOS
    names[num_names] = concat_fnames(path, (char_u *)"_sw#", FALSE);
# else
    names[num_names] = concat_fnames(path, (char_u *)".sw?", FALSE);
# endif
#endif
    if (names[num_names] == NULL)
    goto end;
    if (num_names >= 1)        /* check if we have the same name twice */
    {
    p = names[num_names - 1];
    i = (int)STRLEN(names[num_names - 1]) - (int)STRLEN(names[num_names]);
    if (i > 0)
        p += i;        /* file name has been expanded to full path */

    if (STRCMP(p, names[num_names]) != 0)
        ++num_names;
    else
        vim_free(names[num_names]);
    }
    else
    ++num_names;

# ifndef WIN3264
    /*
     * Also try with 'shortname' set, in case the file is on a DOS filesystem.
     */
    curbuf->b_shortname = TRUE;
#ifdef VMS
    names[num_names] = modname(path, (char_u *)"_sw%", FALSE);
#else
# ifdef RISCOS
    names[num_names] = modname(path, (char_u *)"_sw#", FALSE);
# else
    names[num_names] = modname(path, (char_u *)".sw?", FALSE);
# endif
#endif
    if (names[num_names] == NULL)
    goto end;

    /*
     * Remove the one from 'shortname', if it's the same as with 'noshortname'.
     */
    p = names[num_names];
    i = STRLEN(names[num_names]) - STRLEN(names[num_names - 1]);
    if (i > 0)
    p += i;        /* file name has been expanded to full path */
    if (STRCMP(names[num_names - 1], p) == 0)
    vim_free(names[num_names]);
    else
    ++num_names;
# endif

end:
# ifndef WIN3264
    curbuf->b_shortname = shortname;
# endif

#endif /* !SHORT_FNAME */

    return num_names;
}

/*
 * sync all memlines
 *
 * If 'check_file' is TRUE, check if original file exists and was not changed.
 * If 'check_char' is TRUE, stop syncing when character becomes available, but
 * always sync at least one block.
 */
    void
ml_sync_all(check_file, check_char)
    int        check_file;
    int        check_char;
{
    buf_T        *buf;
    struct stat        st;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
    {
    if (buf->b_ml.ml_mfp == NULL || buf->b_ml.ml_mfp->mf_fname == NULL)
        continue;                /* no file */

    ml_flush_line(buf);            /* flush buffered line */
                        /* flush locked block */
    (void)ml_find_line(buf, (linenr_T)0, ML_FLUSH);
    if (bufIsChanged(buf) && check_file && mf_need_trans(buf->b_ml.ml_mfp)
                             && buf->b_ffname != NULL)
    {
        /*
         * If the original file does not exist anymore or has been changed
         * call ml_preserve() to get rid of all negative numbered blocks.
         */
        if (mch_stat((char *)buf->b_ffname, &st) == -1
            || st.st_mtime != buf->b_mtime_read
            || (size_t)st.st_size != buf->b_orig_size)
        {
        ml_preserve(buf, FALSE);
        did_check_timestamps = FALSE;
        need_check_timestamps = TRUE;    /* give message later */
        }
    }
    if (buf->b_ml.ml_mfp->mf_dirty)
    {
        (void)mf_sync(buf->b_ml.ml_mfp, (check_char ? MFS_STOP : 0)
                    | (bufIsChanged(buf) ? MFS_FLUSH : 0));
        if (check_char && ui_char_avail())    /* character available now */
        break;
    }
    }
}

/*
 * sync one buffer, including negative blocks
 *
 * after this all the blocks are in the swap file
 *
 * Used for the :preserve command and when the original file has been
 * changed or deleted.
 *
 * when message is TRUE the success of preserving is reported
 */
    void
ml_preserve(buf, message)
    buf_T    *buf;
    int        message;
{
    bhdr_T    *hp;
    linenr_T    lnum;
    memfile_T    *mfp = buf->b_ml.ml_mfp;
    int        status;
    int        got_int_save = got_int;

    if (mfp == NULL || mfp->mf_fname == NULL)
    {
    if (message)
        EMSG(_("E313: Cannot preserve, there is no swap file"));
    return;
    }

    /* We only want to stop when interrupted here, not when interrupted
     * before. */
    got_int = FALSE;

    ml_flush_line(buf);                    /* flush buffered line */
    (void)ml_find_line(buf, (linenr_T)0, ML_FLUSH); /* flush locked block */
    status = mf_sync(mfp, MFS_ALL | MFS_FLUSH);

    /* stack is invalid after mf_sync(.., MFS_ALL) */
    buf->b_ml.ml_stack_top = 0;

    /*
     * Some of the data blocks may have been changed from negative to
     * positive block number. In that case the pointer blocks need to be
     * updated.
     *
     * We don't know in which pointer block the references are, so we visit
     * all data blocks until there are no more translations to be done (or
     * we hit the end of the file, which can only happen in case a write fails,
     * e.g. when file system if full).
     * ml_find_line() does the work by translating the negative block numbers
     * when getting the first line of each data block.
     */
    if (mf_need_trans(mfp) && !got_int)
    {
    lnum = 1;
    while (mf_need_trans(mfp) && lnum <= buf->b_ml.ml_line_count)
    {
        hp = ml_find_line(buf, lnum, ML_FIND);
        if (hp == NULL)
        {
        status = FAIL;
        goto theend;
        }
        CHECK(buf->b_ml.ml_locked_low != lnum, "low != lnum");
        lnum = buf->b_ml.ml_locked_high + 1;
    }
    (void)ml_find_line(buf, (linenr_T)0, ML_FLUSH);    /* flush locked block */
    /* sync the updated pointer blocks */
    if (mf_sync(mfp, MFS_ALL | MFS_FLUSH) == FAIL)
        status = FAIL;
    buf->b_ml.ml_stack_top = 0;        /* stack is invalid now */
    }
theend:
    got_int |= got_int_save;

    if (message)
    {
    if (status == OK)
        MSG(_("File preserved"));
    else
        EMSG(_("E314: Preserve failed"));
    }
}

/*
 * NOTE: The pointer returned by the ml_get_*() functions only remains valid
 * until the next call!
 *  line1 = ml_get(1);
 *  line2 = ml_get(2);    // line1 is now invalid!
 * Make a copy of the line if necessary.
 */
/*
 * get a pointer to a (read-only copy of a) line
 *
 * On failure an error message is given and IObuff is returned (to avoid
 * having to check for error everywhere).
 */
    char_u  *
ml_get(lnum)
    linenr_T    lnum;
{
    return ml_get_buf(curbuf, lnum, FALSE);
}

/*
 * ml_get_pos: get pointer to position 'pos'
 */
    char_u *
ml_get_pos(pos)
    pos_T    *pos;
{
    return (ml_get_buf(curbuf, pos->lnum, FALSE) + pos->col);
}

/*
 * ml_get_curline: get pointer to cursor line.
 */
    char_u *
ml_get_curline()
{
    return ml_get_buf(curbuf, curwin->w_cursor.lnum, FALSE);
}

/*
 * ml_get_cursor: get pointer to cursor position
 */
    char_u *
ml_get_cursor()
{
    return (ml_get_buf(curbuf, curwin->w_cursor.lnum, FALSE) +
                            curwin->w_cursor.col);
}

/*
 * get a pointer to a line in a specific buffer
 *
 * "will_change": if TRUE mark the buffer dirty (chars in the line will be
 * changed)
 */
    char_u  *
ml_get_buf(buf, lnum, will_change)
    buf_T    *buf;
    linenr_T    lnum;
    int        will_change;        /* line will be changed */
{
    bhdr_T    *hp;
    DATA_BL *dp;
    char_u  *ptr;

    if (lnum > buf->b_ml.ml_line_count)    /* invalid line number */
    {
    EMSGN(_("E315: ml_get: invalid lnum: %ld"), lnum);
errorret:
    STRCPY(IObuff, "???");
    return IObuff;
    }
    if (lnum <= 0)            /* pretend line 0 is line 1 */
    lnum = 1;

    if (buf->b_ml.ml_mfp == NULL)    /* there are no lines */
    return (char_u *)"";

/*
 * See if it is the same line as requested last time.
 * Otherwise may need to flush last used line.
 */
    if (buf->b_ml.ml_line_lnum != lnum)
    {
    ml_flush_line(buf);

    /*
     * Find the data block containing the line.
     * This also fills the stack with the blocks from the root to the data
     * block and releases any locked block.
     */
    if ((hp = ml_find_line(buf, lnum, ML_FIND)) == NULL)
    {
        EMSGN(_("E316: ml_get: cannot find line %ld"), lnum);
        goto errorret;
    }

    dp = (DATA_BL *)(hp->bh_data);

    ptr = (char_u *)dp + ((dp->db_index[lnum - buf->b_ml.ml_locked_low]) & DB_INDEX_MASK);
    buf->b_ml.ml_line_ptr = ptr;
    buf->b_ml.ml_line_lnum = lnum;
    buf->b_ml.ml_flags &= ~ML_LINE_DIRTY;
    }
    if (will_change)
    buf->b_ml.ml_flags |= (ML_LOCKED_DIRTY | ML_LOCKED_POS);

    return buf->b_ml.ml_line_ptr;
}

/*
 * Check if a line that was just obtained by a call to ml_get
 * is in allocated memory.
 */
    int
ml_line_alloced()
{
    return (curbuf->b_ml.ml_flags & ML_LINE_DIRTY);
}

/*
 * append a line after lnum (may be 0 to insert a line in front of the file)
 *
 *   newfile: TRUE when starting to edit a new file, meaning that pe_old_lnum
 *        will be set for recovery
 * Check: The caller of this function should probably also call
 * appended_lines().
 *
 * return FAIL for failure, OK otherwise
 */
    int
ml_append(lnum, line, len, newfile)
    linenr_T    lnum;        /* append after this line (can be 0) */
    char_u    *line;        /* text of the new line */
    colnr_T    len;        /* length of new line, including NUL, or 0 */
    int        newfile;    /* flag, see above */
{
    /* When starting up, we might still need to create the memfile */
    if (curbuf->b_ml.ml_mfp == NULL && open_buffer(FALSE, NULL) == FAIL)
    return FAIL;

    if (curbuf->b_ml.ml_line_lnum != 0)
    ml_flush_line(curbuf);
    return ml_append_int(curbuf, lnum, line, len, newfile, FALSE);
}

    static int
ml_append_int(buf, lnum, line, len, newfile, mark)
    buf_T    *buf;
    linenr_T    lnum;        /* append after this line (can be 0) */
    char_u    *line;        /* text of the new line */
    colnr_T    len;        /* length of line, including NUL, or 0 */
    int        newfile;    /* flag, see above */
    int        mark;        /* mark the new line */
{
    int        i;
    int        line_count;    /* number of indexes in current block */
    int        offset;
    int        from, to;
    int        space_needed;    /* space needed for new line */
    int        page_size;
    int        page_count;
    int        db_idx;        /* index for lnum in data block */
    bhdr_T    *hp;
    memfile_T    *mfp;
    DATA_BL    *dp;
    PTR_BL    *pp;
    infoptr_T    *ip;

                    /* lnum out of range */
    if (lnum > buf->b_ml.ml_line_count || buf->b_ml.ml_mfp == NULL)
    return FAIL;

    if (lowest_marked && lowest_marked > lnum)
    lowest_marked = lnum + 1;

    if (len == 0)
    len = (colnr_T)STRLEN(line) + 1;    /* space needed for the text */
    space_needed = len + INDEX_SIZE;    /* space needed for text + index */

    mfp = buf->b_ml.ml_mfp;
    page_size = mfp->mf_page_size;

/*
 * find the data block containing the previous line
 * This also fills the stack with the blocks from the root to the data block
 * This also releases any locked block.
 */
    if ((hp = ml_find_line(buf, lnum == 0 ? (linenr_T)1 : lnum,
                              ML_INSERT)) == NULL)
    return FAIL;

    buf->b_ml.ml_flags &= ~ML_EMPTY;

    if (lnum == 0)        /* got line one instead, correct db_idx */
    db_idx = -1;        /* careful, it is negative! */
    else
    db_idx = lnum - buf->b_ml.ml_locked_low;
        /* get line count before the insertion */
    line_count = buf->b_ml.ml_locked_high - buf->b_ml.ml_locked_low;

    dp = (DATA_BL *)(hp->bh_data);

/*
 * If
 * - there is not enough room in the current block
 * - appending to the last line in the block
 * - not appending to the last line in the file
 * insert in front of the next block.
 */
    if ((int)dp->db_free < space_needed && db_idx == line_count - 1
                        && lnum < buf->b_ml.ml_line_count)
    {
    /*
     * Now that the line is not going to be inserted in the block that we
     * expected, the line count has to be adjusted in the pointer blocks
     * by using ml_locked_lineadd.
     */
    --(buf->b_ml.ml_locked_lineadd);
    --(buf->b_ml.ml_locked_high);
    if ((hp = ml_find_line(buf, lnum + 1, ML_INSERT)) == NULL)
        return FAIL;

    db_idx = -1;            /* careful, it is negative! */
            /* get line count before the insertion */
    line_count = buf->b_ml.ml_locked_high - buf->b_ml.ml_locked_low;
    CHECK(buf->b_ml.ml_locked_low != lnum + 1, "locked_low != lnum + 1");

    dp = (DATA_BL *)(hp->bh_data);
    }

    ++buf->b_ml.ml_line_count;

    if ((int)dp->db_free >= space_needed)    /* enough room in data block */
    {
/*
 * Insert new line in existing data block, or in data block allocated above.
 */
    dp->db_txt_start -= len;
    dp->db_free -= space_needed;
    ++(dp->db_line_count);

    /*
     * move the text of the lines that follow to the front
     * adjust the indexes of the lines that follow
     */
    if (line_count > db_idx + 1)        /* if there are following lines */
    {
        /*
         * Offset is the start of the previous line.
         * This will become the character just after the new line.
         */
        if (db_idx < 0)
        offset = dp->db_txt_end;
        else
        offset = ((dp->db_index[db_idx]) & DB_INDEX_MASK);
        mch_memmove((char *)dp + dp->db_txt_start,
                      (char *)dp + dp->db_txt_start + len,
                 (size_t)(offset - (dp->db_txt_start + len)));
        for (i = line_count - 1; i > db_idx; --i)
        dp->db_index[i + 1] = dp->db_index[i] - len;
        dp->db_index[db_idx + 1] = offset - len;
    }
    else                    /* add line at the end */
        dp->db_index[db_idx + 1] = dp->db_txt_start;

    /*
     * copy the text into the block
     */
    mch_memmove((char *)dp + dp->db_index[db_idx + 1], line, (size_t)len);
    if (mark)
        dp->db_index[db_idx + 1] |= DB_MARKED;

    /*
     * Mark the block dirty.
     */
    buf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
    if (!newfile)
        buf->b_ml.ml_flags |= ML_LOCKED_POS;
    }
    else        /* not enough space in data block */
    {
/*
 * If there is not enough room we have to create a new data block and copy some
 * lines into it.
 * Then we have to insert an entry in the pointer block.
 * If this pointer block also is full, we go up another block, and so on, up
 * to the root if necessary.
 * The line counts in the pointer blocks have already been adjusted by
 * ml_find_line().
 */
    long        line_count_left, line_count_right;
    int        page_count_left, page_count_right;
    bhdr_T        *hp_left;
    bhdr_T        *hp_right;
    bhdr_T        *hp_new;
    int        lines_moved;
    int        data_moved = 0;        /* init to shut up gcc */
    int        total_moved = 0;        /* init to shut up gcc */
    DATA_BL        *dp_right, *dp_left;
    int        stack_idx;
    int        in_left;
    int        lineadd;
    blocknr_T   bnum_left, bnum_right;
    linenr_T    lnum_left, lnum_right;
    int        pb_idx;
    PTR_BL        *pp_new;

    /*
     * We are going to allocate a new data block. Depending on the
     * situation it will be put to the left or right of the existing
     * block.  If possible we put the new line in the left block and move
     * the lines after it to the right block. Otherwise the new line is
     * also put in the right block. This method is more efficient when
     * inserting a lot of lines at one place.
     */
    if (db_idx < 0)        /* left block is new, right block is existing */
    {
        lines_moved = 0;
        in_left = TRUE;
        /* space_needed does not change */
    }
    else            /* left block is existing, right block is new */
    {
        lines_moved = line_count - db_idx - 1;
        if (lines_moved == 0)
        in_left = FALSE;    /* put new line in right block */
                    /* space_needed does not change */
        else
        {
        data_moved = ((dp->db_index[db_idx]) & DB_INDEX_MASK) -
                                dp->db_txt_start;
        total_moved = data_moved + lines_moved * INDEX_SIZE;
        if ((int)dp->db_free + total_moved >= space_needed)
        {
            in_left = TRUE;    /* put new line in left block */
            space_needed = total_moved;
        }
        else
        {
            in_left = FALSE;        /* put new line in right block */
            space_needed += total_moved;
        }
        }
    }

    page_count = ((space_needed + HEADER_SIZE) + page_size - 1) / page_size;
    if ((hp_new = ml_new_data(mfp, newfile, page_count)) == NULL)
    {
            /* correct line counts in pointer blocks */
        --(buf->b_ml.ml_locked_lineadd);
        --(buf->b_ml.ml_locked_high);
        return FAIL;
    }
    if (db_idx < 0)        /* left block is new */
    {
        hp_left = hp_new;
        hp_right = hp;
        line_count_left = 0;
        line_count_right = line_count;
    }
    else            /* right block is new */
    {
        hp_left = hp;
        hp_right = hp_new;
        line_count_left = line_count;
        line_count_right = 0;
    }
    dp_right = (DATA_BL *)(hp_right->bh_data);
    dp_left = (DATA_BL *)(hp_left->bh_data);
    bnum_left = hp_left->bh_bnum;
    bnum_right = hp_right->bh_bnum;
    page_count_left = hp_left->bh_page_count;
    page_count_right = hp_right->bh_page_count;

    /*
     * May move the new line into the right/new block.
     */
    if (!in_left)
    {
        dp_right->db_txt_start -= len;
        dp_right->db_free -= len + INDEX_SIZE;
        dp_right->db_index[0] = dp_right->db_txt_start;
        if (mark)
        dp_right->db_index[0] |= DB_MARKED;

        mch_memmove((char *)dp_right + dp_right->db_txt_start,
                               line, (size_t)len);
        ++line_count_right;
    }
    /*
     * may move lines from the left/old block to the right/new one.
     */
    if (lines_moved)
    {
        /*
         */
        dp_right->db_txt_start -= data_moved;
        dp_right->db_free -= total_moved;
        mch_memmove((char *)dp_right + dp_right->db_txt_start,
            (char *)dp_left + dp_left->db_txt_start,
            (size_t)data_moved);
        offset = dp_right->db_txt_start - dp_left->db_txt_start;
        dp_left->db_txt_start += data_moved;
        dp_left->db_free += total_moved;

        /*
         * update indexes in the new block
         */
        for (to = line_count_right, from = db_idx + 1;
                     from < line_count_left; ++from, ++to)
        dp_right->db_index[to] = dp->db_index[from] + offset;
        line_count_right += lines_moved;
        line_count_left -= lines_moved;
    }

    /*
     * May move the new line into the left (old or new) block.
     */
    if (in_left)
    {
        dp_left->db_txt_start -= len;
        dp_left->db_free -= len + INDEX_SIZE;
        dp_left->db_index[line_count_left] = dp_left->db_txt_start;
        if (mark)
        dp_left->db_index[line_count_left] |= DB_MARKED;
        mch_memmove((char *)dp_left + dp_left->db_txt_start,
                               line, (size_t)len);
        ++line_count_left;
    }

    if (db_idx < 0)        /* left block is new */
    {
        lnum_left = lnum + 1;
        lnum_right = 0;
    }
    else            /* right block is new */
    {
        lnum_left = 0;
        if (in_left)
        lnum_right = lnum + 2;
        else
        lnum_right = lnum + 1;
    }
    dp_left->db_line_count = line_count_left;
    dp_right->db_line_count = line_count_right;

    /*
     * release the two data blocks
     * The new one (hp_new) already has a correct blocknumber.
     * The old one (hp, in ml_locked) gets a positive blocknumber if
     * we changed it and we are not editing a new file.
     */
    if (lines_moved || in_left)
        buf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
    if (!newfile && db_idx >= 0 && in_left)
        buf->b_ml.ml_flags |= ML_LOCKED_POS;
    mf_put(mfp, hp_new, TRUE, FALSE);

    /*
     * flush the old data block
     * set ml_locked_lineadd to 0, because the updating of the
     * pointer blocks is done below
     */
    lineadd = buf->b_ml.ml_locked_lineadd;
    buf->b_ml.ml_locked_lineadd = 0;
    ml_find_line(buf, (linenr_T)0, ML_FLUSH);   /* flush data block */

    /*
     * update pointer blocks for the new data block
     */
    for (stack_idx = buf->b_ml.ml_stack_top - 1; stack_idx >= 0;
                                  --stack_idx)
    {
        ip = &(buf->b_ml.ml_stack[stack_idx]);
        pb_idx = ip->ip_index;
        if ((hp = mf_get(mfp, ip->ip_bnum, 1)) == NULL)
        return FAIL;
        pp = (PTR_BL *)(hp->bh_data);   /* must be pointer block */
        if (pp->pb_id != PTR_ID)
        {
        EMSG(_("E317: pointer block id wrong 3"));
        mf_put(mfp, hp, FALSE, FALSE);
        return FAIL;
        }
        /*
         * TODO: If the pointer block is full and we are adding at the end
         * try to insert in front of the next block
         */
        /* block not full, add one entry */
        if (pp->pb_count < pp->pb_count_max)
        {
        if (pb_idx + 1 < (int)pp->pb_count)
            mch_memmove(&pp->pb_pointer[pb_idx + 2],
                &pp->pb_pointer[pb_idx + 1],
            (size_t)(pp->pb_count - pb_idx - 1) * sizeof(PTR_EN));
        ++pp->pb_count;
        pp->pb_pointer[pb_idx].pe_line_count = line_count_left;
        pp->pb_pointer[pb_idx].pe_bnum = bnum_left;
        pp->pb_pointer[pb_idx].pe_page_count = page_count_left;
        pp->pb_pointer[pb_idx + 1].pe_line_count = line_count_right;
        pp->pb_pointer[pb_idx + 1].pe_bnum = bnum_right;
        pp->pb_pointer[pb_idx + 1].pe_page_count = page_count_right;

        if (lnum_left != 0)
            pp->pb_pointer[pb_idx].pe_old_lnum = lnum_left;
        if (lnum_right != 0)
            pp->pb_pointer[pb_idx + 1].pe_old_lnum = lnum_right;

        mf_put(mfp, hp, TRUE, FALSE);
        buf->b_ml.ml_stack_top = stack_idx + 1;        /* truncate stack */

        if (lineadd)
        {
            --(buf->b_ml.ml_stack_top);
            /* fix line count for rest of blocks in the stack */
            ml_lineadd(buf, lineadd);
                            /* fix stack itself */
            buf->b_ml.ml_stack[buf->b_ml.ml_stack_top].ip_high +=
                                      lineadd;
            ++(buf->b_ml.ml_stack_top);
        }

        /*
         * We are finished, break the loop here.
         */
        break;
        }
        else            /* pointer block full */
        {
        /*
         * split the pointer block
         * allocate a new pointer block
         * move some of the pointer into the new block
         * prepare for updating the parent block
         */
        for (;;)    /* do this twice when splitting block 1 */
        {
            hp_new = ml_new_ptr(mfp);
            if (hp_new == NULL)        /* TODO: try to fix tree */
            return FAIL;
            pp_new = (PTR_BL *)(hp_new->bh_data);

            if (hp->bh_bnum != 1)
            break;

            /*
             * if block 1 becomes full the tree is given an extra level
             * The pointers from block 1 are moved into the new block.
             * block 1 is updated to point to the new block
             * then continue to split the new block
             */
            mch_memmove(pp_new, pp, (size_t)page_size);
            pp->pb_count = 1;
            pp->pb_pointer[0].pe_bnum = hp_new->bh_bnum;
            pp->pb_pointer[0].pe_line_count = buf->b_ml.ml_line_count;
            pp->pb_pointer[0].pe_old_lnum = 1;
            pp->pb_pointer[0].pe_page_count = 1;
            mf_put(mfp, hp, TRUE, FALSE);   /* release block 1 */
            hp = hp_new;        /* new block is to be split */
            pp = pp_new;
            CHECK(stack_idx != 0, _("stack_idx should be 0"));
            ip->ip_index = 0;
            ++stack_idx;    /* do block 1 again later */
        }
        /*
         * move the pointers after the current one to the new block
         * If there are none, the new entry will be in the new block.
         */
        total_moved = pp->pb_count - pb_idx - 1;
        if (total_moved)
        {
            mch_memmove(&pp_new->pb_pointer[0],
                &pp->pb_pointer[pb_idx + 1],
                (size_t)(total_moved) * sizeof(PTR_EN));
            pp_new->pb_count = total_moved;
            pp->pb_count -= total_moved - 1;
            pp->pb_pointer[pb_idx + 1].pe_bnum = bnum_right;
            pp->pb_pointer[pb_idx + 1].pe_line_count = line_count_right;
            pp->pb_pointer[pb_idx + 1].pe_page_count = page_count_right;
            if (lnum_right)
            pp->pb_pointer[pb_idx + 1].pe_old_lnum = lnum_right;
        }
        else
        {
            pp_new->pb_count = 1;
            pp_new->pb_pointer[0].pe_bnum = bnum_right;
            pp_new->pb_pointer[0].pe_line_count = line_count_right;
            pp_new->pb_pointer[0].pe_page_count = page_count_right;
            pp_new->pb_pointer[0].pe_old_lnum = lnum_right;
        }
        pp->pb_pointer[pb_idx].pe_bnum = bnum_left;
        pp->pb_pointer[pb_idx].pe_line_count = line_count_left;
        pp->pb_pointer[pb_idx].pe_page_count = page_count_left;
        if (lnum_left)
            pp->pb_pointer[pb_idx].pe_old_lnum = lnum_left;
        lnum_left = 0;
        lnum_right = 0;

        /*
         * recompute line counts
         */
        line_count_right = 0;
        for (i = 0; i < (int)pp_new->pb_count; ++i)
            line_count_right += pp_new->pb_pointer[i].pe_line_count;
        line_count_left = 0;
        for (i = 0; i < (int)pp->pb_count; ++i)
            line_count_left += pp->pb_pointer[i].pe_line_count;

        bnum_left = hp->bh_bnum;
        bnum_right = hp_new->bh_bnum;
        page_count_left = 1;
        page_count_right = 1;
        mf_put(mfp, hp, TRUE, FALSE);
        mf_put(mfp, hp_new, TRUE, FALSE);
        }
    }

    /*
     * Safety check: fallen out of for loop?
     */
    if (stack_idx < 0)
    {
        EMSG(_("E318: Updated too many blocks?"));
        buf->b_ml.ml_stack_top = 0;    /* invalidate stack */
    }
    }

#ifdef FEAT_BYTEOFF
    /* The line was inserted below 'lnum' */
    ml_updatechunk(buf, lnum + 1, len, ML_CHNK_ADDLINE);
#endif
    return OK;
}

/*
 * replace line lnum, with buffering, in current buffer
 *
 * If copy is TRUE, make a copy of the line, otherwise the line has been
 * copied to allocated memory already.
 *
 * Check: The caller of this function should probably also call
 * changed_lines(), unless update_screen(NOT_VALID) is used.
 *
 * return FAIL for failure, OK otherwise
 */
    int
ml_replace(lnum, line, copy)
    linenr_T    lnum;
    char_u    *line;
    int        copy;
{
    if (line == NULL)        /* just checking... */
    return FAIL;

    /* When starting up, we might still need to create the memfile */
    if (curbuf->b_ml.ml_mfp == NULL && open_buffer(FALSE, NULL) == FAIL)
    return FAIL;

    if (curbuf->b_ml.ml_line_lnum != lnum)        /* other line buffered */
    ml_flush_line(curbuf);                /* flush it */
    else if (curbuf->b_ml.ml_flags & ML_LINE_DIRTY) /* same line allocated */
    vim_free(curbuf->b_ml.ml_line_ptr);        /* free it */
    if (copy && (line = vim_strsave(line)) == NULL) /* allocate memory */
    return FAIL;
    curbuf->b_ml.ml_line_ptr = line;
    curbuf->b_ml.ml_line_lnum = lnum;
    curbuf->b_ml.ml_flags = (curbuf->b_ml.ml_flags | ML_LINE_DIRTY) & ~ML_EMPTY;

    return OK;
}

/*
 * delete line 'lnum'
 *
 * Check: The caller of this function should probably also call
 * deleted_lines() after this.
 *
 * return FAIL for failure, OK otherwise
 */
    int
ml_delete(lnum, message)
    linenr_T    lnum;
    int        message;
{
    ml_flush_line(curbuf);
    return ml_delete_int(curbuf, lnum, message);
}

    static int
ml_delete_int(buf, lnum, message)
    buf_T    *buf;
    linenr_T    lnum;
    int        message;
{
    bhdr_T    *hp;
    memfile_T    *mfp;
    DATA_BL    *dp;
    PTR_BL    *pp;
    infoptr_T    *ip;
    int        count;        /* number of entries in block */
    int        idx;
    int        stack_idx;
    int        text_start;
    int        line_start;
    int        line_size;
    int        i;

    if (lnum < 1 || lnum > buf->b_ml.ml_line_count)
    return FAIL;

    if (lowest_marked && lowest_marked > lnum)
    lowest_marked--;

/*
 * If the file becomes empty the last line is replaced by an empty line.
 */
    if (buf->b_ml.ml_line_count == 1)        /* file becomes empty */
    {
    if (message)
    {
        set_keep_msg((char_u *)_(no_lines_msg));
        keep_msg_attr = 0;
    }
    /* FEAT_BYTEOFF already handled in there, dont worry 'bout it below */
    i = ml_replace((linenr_T)1, (char_u *)"", TRUE);
    buf->b_ml.ml_flags |= ML_EMPTY;

    return i;
    }

/*
 * find the data block containing the line
 * This also fills the stack with the blocks from the root to the data block
 * This also releases any locked block.
 */
    mfp = buf->b_ml.ml_mfp;
    if (mfp == NULL)
    return FAIL;

    if ((hp = ml_find_line(buf, lnum, ML_DELETE)) == NULL)
    return FAIL;

    dp = (DATA_BL *)(hp->bh_data);
    /* compute line count before the delete */
    count = (long)(buf->b_ml.ml_locked_high)
                    - (long)(buf->b_ml.ml_locked_low) + 2;
    idx = lnum - buf->b_ml.ml_locked_low;

    --buf->b_ml.ml_line_count;

    line_start = ((dp->db_index[idx]) & DB_INDEX_MASK);
    if (idx == 0)        /* first line in block, text at the end */
    line_size = dp->db_txt_end - line_start;
    else
    line_size = ((dp->db_index[idx - 1]) & DB_INDEX_MASK) - line_start;

/*
 * special case: If there is only one line in the data block it becomes empty.
 * Then we have to remove the entry, pointing to this data block, from the
 * pointer block. If this pointer block also becomes empty, we go up another
 * block, and so on, up to the root if necessary.
 * The line counts in the pointer blocks have already been adjusted by
 * ml_find_line().
 */
    if (count == 1)
    {
    mf_free(mfp, hp);    /* free the data block */
    buf->b_ml.ml_locked = NULL;

    for (stack_idx = buf->b_ml.ml_stack_top - 1; stack_idx >= 0; --stack_idx)
    {
        buf->b_ml.ml_stack_top = 0;        /* stack is invalid when failing */
        ip = &(buf->b_ml.ml_stack[stack_idx]);
        idx = ip->ip_index;
        if ((hp = mf_get(mfp, ip->ip_bnum, 1)) == NULL)
        return FAIL;
        pp = (PTR_BL *)(hp->bh_data);   /* must be pointer block */
        if (pp->pb_id != PTR_ID)
        {
        EMSG(_("E317: pointer block id wrong 4"));
        mf_put(mfp, hp, FALSE, FALSE);
        return FAIL;
        }
        count = --(pp->pb_count);
        if (count == 0)        /* the pointer block becomes empty! */
        mf_free(mfp, hp);
        else
        {
        if (count != idx)    /* move entries after the deleted one */
            mch_memmove(&pp->pb_pointer[idx], &pp->pb_pointer[idx + 1],
                      (size_t)(count - idx) * sizeof(PTR_EN));
        mf_put(mfp, hp, TRUE, FALSE);

        buf->b_ml.ml_stack_top = stack_idx;    /* truncate stack */
            /* fix line count for rest of blocks in the stack */
        if (buf->b_ml.ml_locked_lineadd)
        {
            ml_lineadd(buf, buf->b_ml.ml_locked_lineadd);
            buf->b_ml.ml_stack[buf->b_ml.ml_stack_top].ip_high +=
                        buf->b_ml.ml_locked_lineadd;
        }
        ++(buf->b_ml.ml_stack_top);

        break;
        }
    }
    CHECK(stack_idx < 0, _("deleted block 1?"));
    }
    else
    {
    /*
     * delete the text by moving the next lines forwards
     */
    text_start = dp->db_txt_start;
    mch_memmove((char *)dp + text_start + line_size,
          (char *)dp + text_start, (size_t)(line_start - text_start));

    /*
     * delete the index by moving the next indexes backwards
     * Adjust the indexes for the text movement.
     */
    for (i = idx; i < count - 1; ++i)
        dp->db_index[i] = dp->db_index[i + 1] + line_size;

    dp->db_free += line_size + INDEX_SIZE;
    dp->db_txt_start += line_size;
    --(dp->db_line_count);

    /*
     * mark the block dirty and make sure it is in the file (for recovery)
     */
    buf->b_ml.ml_flags |= (ML_LOCKED_DIRTY | ML_LOCKED_POS);
    }

#ifdef FEAT_BYTEOFF
    ml_updatechunk(buf, lnum, line_size, ML_CHNK_DELLINE);
#endif
    return OK;
}

/*
 * set the B_MARKED flag for line 'lnum'
 */
    void
ml_setmarked(lnum)
    linenr_T lnum;
{
    bhdr_T    *hp;
    DATA_BL *dp;
                    /* invalid line number */
    if (lnum < 1 || lnum > curbuf->b_ml.ml_line_count
                           || curbuf->b_ml.ml_mfp == NULL)
    return;                /* give error message? */

    if (lowest_marked == 0 || lowest_marked > lnum)
    lowest_marked = lnum;

    /*
     * find the data block containing the line
     * This also fills the stack with the blocks from the root to the data block
     * This also releases any locked block.
     */
    if ((hp = ml_find_line(curbuf, lnum, ML_FIND)) == NULL)
    return;            /* give error message? */

    dp = (DATA_BL *)(hp->bh_data);
    dp->db_index[lnum - curbuf->b_ml.ml_locked_low] |= DB_MARKED;
    curbuf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
}

/*
 * find the first line with its B_MARKED flag set
 */
    linenr_T
ml_firstmarked()
{
    bhdr_T    *hp;
    DATA_BL    *dp;
    linenr_T    lnum;
    int        i;

    if (curbuf->b_ml.ml_mfp == NULL)
    return (linenr_T) 0;

    /*
     * The search starts with lowest_marked line. This is the last line where
     * a mark was found, adjusted by inserting/deleting lines.
     */
    for (lnum = lowest_marked; lnum <= curbuf->b_ml.ml_line_count; )
    {
    /*
     * Find the data block containing the line.
     * This also fills the stack with the blocks from the root to the data
     * block This also releases any locked block.
     */
    if ((hp = ml_find_line(curbuf, lnum, ML_FIND)) == NULL)
        return (linenr_T)0;            /* give error message? */

    dp = (DATA_BL *)(hp->bh_data);

    for (i = lnum - curbuf->b_ml.ml_locked_low;
                lnum <= curbuf->b_ml.ml_locked_high; ++i, ++lnum)
        if ((dp->db_index[i]) & DB_MARKED)
        {
        (dp->db_index[i]) &= DB_INDEX_MASK;
        curbuf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
        lowest_marked = lnum + 1;
        return lnum;
        }
    }

    return (linenr_T) 0;
}

#if 0  /* not used */
/*
 * return TRUE if line 'lnum' has a mark
 */
    int
ml_has_mark(lnum)
    linenr_T    lnum;
{
    bhdr_T    *hp;
    DATA_BL    *dp;

    if (curbuf->b_ml.ml_mfp == NULL
            || (hp = ml_find_line(curbuf, lnum, ML_FIND)) == NULL)
    return FALSE;

    dp = (DATA_BL *)(hp->bh_data);
    return (int)((dp->db_index[lnum - curbuf->b_ml.ml_locked_low]) & DB_MARKED);
}
#endif

/*
 * clear all DB_MARKED flags
 */
    void
ml_clearmarked()
{
    bhdr_T    *hp;
    DATA_BL    *dp;
    linenr_T    lnum;
    int        i;

    if (curbuf->b_ml.ml_mfp == NULL)        /* nothing to do */
    return;

    /*
     * The search starts with line lowest_marked.
     */
    for (lnum = lowest_marked; lnum <= curbuf->b_ml.ml_line_count; )
    {
    /*
     * Find the data block containing the line.
     * This also fills the stack with the blocks from the root to the data
     * block and releases any locked block.
     */
    if ((hp = ml_find_line(curbuf, lnum, ML_FIND)) == NULL)
        return;        /* give error message? */

    dp = (DATA_BL *)(hp->bh_data);

    for (i = lnum - curbuf->b_ml.ml_locked_low;
                lnum <= curbuf->b_ml.ml_locked_high; ++i, ++lnum)
        if ((dp->db_index[i]) & DB_MARKED)
        {
        (dp->db_index[i]) &= DB_INDEX_MASK;
        curbuf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
        }
    }

    lowest_marked = 0;
    return;
}

/*
 * flush ml_line if necessary
 */
    static void
ml_flush_line(buf)
    buf_T    *buf;
{
    bhdr_T    *hp;
    DATA_BL    *dp;
    linenr_T    lnum;
    char_u    *new_line;
    char_u    *old_line;
    colnr_T    new_len;
    int        old_len;
    int        extra;
    int        idx;
    int        start;
    int        count;
    int        i;

    if (buf->b_ml.ml_line_lnum == 0 || buf->b_ml.ml_mfp == NULL)
    return;        /* nothing to do */

    if (buf->b_ml.ml_flags & ML_LINE_DIRTY)
    {
    lnum = buf->b_ml.ml_line_lnum;
    new_line = buf->b_ml.ml_line_ptr;

    hp = ml_find_line(buf, lnum, ML_FIND);
    if (hp == NULL)
        EMSGN(_("E320: Cannot find line %ld"), lnum);
    else
    {
        dp = (DATA_BL *)(hp->bh_data);
        idx = lnum - buf->b_ml.ml_locked_low;
        start = ((dp->db_index[idx]) & DB_INDEX_MASK);
        old_line = (char_u *)dp + start;
        if (idx == 0)    /* line is last in block */
        old_len = dp->db_txt_end - start;
        else        /* text of previous line follows */
        old_len = (dp->db_index[idx - 1] & DB_INDEX_MASK) - start;
        new_len = (colnr_T)STRLEN(new_line) + 1;
        extra = new_len - old_len;        /* negative if lines gets smaller */

        /*
         * if new line fits in data block, replace directly
         */
        if ((int)dp->db_free >= extra)
        {
        /* if the length changes and there are following lines */
        count = buf->b_ml.ml_locked_high - buf->b_ml.ml_locked_low + 1;
        if (extra != 0 && idx < count - 1)
        {
            /* move text of following lines */
            mch_memmove((char *)dp + dp->db_txt_start - extra,
                (char *)dp + dp->db_txt_start,
                (size_t)(start - dp->db_txt_start));

            /* adjust pointers of this and following lines */
            for (i = idx + 1; i < count; ++i)
            dp->db_index[i] -= extra;
        }
        dp->db_index[idx] -= extra;

        /* adjust free space */
        dp->db_free -= extra;
        dp->db_txt_start -= extra;

        /* copy new line into the data block */
        mch_memmove(old_line - extra, new_line, (size_t)new_len);
        buf->b_ml.ml_flags |= (ML_LOCKED_DIRTY | ML_LOCKED_POS);
#ifdef FEAT_BYTEOFF
        /* The else case is already covered by the insert and delete */
        ml_updatechunk(buf, lnum, extra, ML_CHNK_UPDLINE);
#endif
        }
        else
        {
        /*
         * Cannot do it in one data block: Delete and append.
         * Append first, because ml_delete_int() cannot delete the
         * last line in a buffer, which causes trouble for a buffer
         * that has only one line.
         * Don't forget to copy the mark!
         */
        /* How about handling errors??? */
        (void)ml_append_int(buf, lnum, new_line, new_len, FALSE,
                         (dp->db_index[idx] & DB_MARKED));
        (void)ml_delete_int(buf, lnum, FALSE);
        }
    }
    vim_free(new_line);
    }

    buf->b_ml.ml_line_lnum = 0;
}

/*
 * create a new, empty, data block
 */
    static bhdr_T *
ml_new_data(mfp, negative, page_count)
    memfile_T    *mfp;
    int        negative;
    int        page_count;
{
    bhdr_T    *hp;
    DATA_BL    *dp;

    if ((hp = mf_new(mfp, negative, page_count)) == NULL)
    return NULL;

    dp = (DATA_BL *)(hp->bh_data);
    dp->db_id = DATA_ID;
    dp->db_txt_start = dp->db_txt_end = page_count * mfp->mf_page_size;
    dp->db_free = dp->db_txt_start - HEADER_SIZE;
    dp->db_line_count = 0;

    return hp;
}

/*
 * create a new, empty, pointer block
 */
    static bhdr_T *
ml_new_ptr(mfp)
    memfile_T    *mfp;
{
    bhdr_T    *hp;
    PTR_BL    *pp;

    if ((hp = mf_new(mfp, FALSE, 1)) == NULL)
    return NULL;

    pp = (PTR_BL *)(hp->bh_data);
    pp->pb_id = PTR_ID;
    pp->pb_count = 0;
    pp->pb_count_max = (short_u)((mfp->mf_page_size - sizeof(PTR_BL)) / sizeof(PTR_EN) + 1);

    return hp;
}

/*
 * lookup line 'lnum' in a memline
 *
 *   action: if ML_DELETE or ML_INSERT the line count is updated while searching
 *         if ML_FLUSH only flush a locked block
 *         if ML_FIND just find the line
 *
 * If the block was found it is locked and put in ml_locked.
 * The stack is updated to lead to the locked block. The ip_high field in
 * the stack is updated to reflect the last line in the block AFTER the
 * insert or delete, also if the pointer block has not been updated yet. But
 * if if ml_locked != NULL ml_locked_lineadd must be added to ip_high.
 *
 * return: NULL for failure, pointer to block header otherwise
 */
    static bhdr_T *
ml_find_line(buf, lnum, action)
    buf_T    *buf;
    linenr_T    lnum;
    int        action;
{
    DATA_BL    *dp;
    PTR_BL    *pp;
    infoptr_T    *ip;
    bhdr_T    *hp;
    memfile_T    *mfp;
    linenr_T    t;
    blocknr_T    bnum, bnum2;
    int        dirty;
    linenr_T    low, high;
    int        top;
    int        page_count;
    int        idx;

    mfp = buf->b_ml.ml_mfp;

    /*
     * If there is a locked block check if the wanted line is in it.
     * If not, flush and release the locked block.
     * Don't do this for ML_INSERT_SAME, because the stack need to be updated.
     * Don't do this for ML_FLUSH, because we want to flush the locked block.
     */
    if (buf->b_ml.ml_locked)
    {
    if (ML_SIMPLE(action) && buf->b_ml.ml_locked_low <= lnum
                      && buf->b_ml.ml_locked_high >= lnum)
    {
        /* remember to update pointer blocks and stack later */
        if (action == ML_INSERT)
        {
        ++(buf->b_ml.ml_locked_lineadd);
        ++(buf->b_ml.ml_locked_high);
        }
        else if (action == ML_DELETE)
        {
        --(buf->b_ml.ml_locked_lineadd);
        --(buf->b_ml.ml_locked_high);
        }
        return (buf->b_ml.ml_locked);
    }

    mf_put(mfp, buf->b_ml.ml_locked, buf->b_ml.ml_flags & ML_LOCKED_DIRTY,
                        buf->b_ml.ml_flags & ML_LOCKED_POS);
    buf->b_ml.ml_locked = NULL;

        /*
         * if lines have been added or deleted in the locked block, need to
         * update the line count in pointer blocks
         */
    if (buf->b_ml.ml_locked_lineadd)
        ml_lineadd(buf, buf->b_ml.ml_locked_lineadd);
    }

    if (action == ML_FLUSH)        /* nothing else to do */
    return NULL;

    bnum = 1;                /* start at the root of the tree */
    page_count = 1;
    low = 1;
    high = buf->b_ml.ml_line_count;

    if (action == ML_FIND)    /* first try stack entries */
    {
    for (top = buf->b_ml.ml_stack_top - 1; top >= 0; --top)
    {
        ip = &(buf->b_ml.ml_stack[top]);
        if (ip->ip_low <= lnum && ip->ip_high >= lnum)
        {
        bnum = ip->ip_bnum;
        low = ip->ip_low;
        high = ip->ip_high;
        buf->b_ml.ml_stack_top = top;    /* truncate stack at prev entry */
        break;
        }
    }
    if (top < 0)
        buf->b_ml.ml_stack_top = 0;        /* not found, start at the root */
    }
    else    /* ML_DELETE or ML_INSERT */
    buf->b_ml.ml_stack_top = 0;    /* start at the root */

/*
 * search downwards in the tree until a data block is found
 */
    for (;;)
    {
    if ((hp = mf_get(mfp, bnum, page_count)) == NULL)
        goto error_noblock;

    /*
     * update high for insert/delete
     */
    if (action == ML_INSERT)
        ++high;
    else if (action == ML_DELETE)
        --high;

    dp = (DATA_BL *)(hp->bh_data);
    if (dp->db_id == DATA_ID)    /* data block */
    {
        buf->b_ml.ml_locked = hp;
        buf->b_ml.ml_locked_low = low;
        buf->b_ml.ml_locked_high = high;
        buf->b_ml.ml_locked_lineadd = 0;
        buf->b_ml.ml_flags &= ~(ML_LOCKED_DIRTY | ML_LOCKED_POS);
        return hp;
    }

    pp = (PTR_BL *)(dp);        /* must be pointer block */
    if (pp->pb_id != PTR_ID)
    {
        EMSG(_("E317: pointer block id wrong"));
        goto error_block;
    }

    if ((top = ml_add_stack(buf)) < 0)    /* add new entry to stack */
        goto error_block;
    ip = &(buf->b_ml.ml_stack[top]);
    ip->ip_bnum = bnum;
    ip->ip_low = low;
    ip->ip_high = high;
    ip->ip_index = -1;        /* index not known yet */

    dirty = FALSE;
    for (idx = 0; idx < (int)pp->pb_count; ++idx)
    {
        t = pp->pb_pointer[idx].pe_line_count;
        CHECK(t == 0, _("pe_line_count is zero"));
        if ((low += t) > lnum)
        {
        ip->ip_index = idx;
        bnum = pp->pb_pointer[idx].pe_bnum;
        page_count = pp->pb_pointer[idx].pe_page_count;
        high = low - 1;
        low -= t;

        /*
         * a negative block number may have been changed
         */
        if (bnum < 0)
        {
            bnum2 = mf_trans_del(mfp, bnum);
            if (bnum != bnum2)
            {
            bnum = bnum2;
            pp->pb_pointer[idx].pe_bnum = bnum;
            dirty = TRUE;
            }
        }

        break;
        }
    }
    if (idx >= (int)pp->pb_count)        /* past the end: something wrong! */
    {
        if (lnum > buf->b_ml.ml_line_count)
        EMSGN(_("E322: line number out of range: %ld past the end"),
                          lnum - buf->b_ml.ml_line_count);

        else
        EMSGN(_("E323: line count wrong in block %ld"), bnum);
        goto error_block;
    }
    if (action == ML_DELETE)
    {
        pp->pb_pointer[idx].pe_line_count--;
        dirty = TRUE;
    }
    else if (action == ML_INSERT)
    {
        pp->pb_pointer[idx].pe_line_count++;
        dirty = TRUE;
    }
    mf_put(mfp, hp, dirty, FALSE);
    }

error_block:
    mf_put(mfp, hp, FALSE, FALSE);
error_noblock:
/*
 * If action is ML_DELETE or ML_INSERT we have to correct the tree for
 * the incremented/decremented line counts, because there won't be a line
 * inserted/deleted after all.
 */
    if (action == ML_DELETE)
    ml_lineadd(buf, 1);
    else if (action == ML_INSERT)
    ml_lineadd(buf, -1);
    buf->b_ml.ml_stack_top = 0;
    return NULL;
}

/*
 * add an entry to the info pointer stack
 *
 * return -1 for failure, number of the new entry otherwise
 */
    static int
ml_add_stack(buf)
    buf_T    *buf;
{
    int        top;
    infoptr_T    *newstack;

    top = buf->b_ml.ml_stack_top;

    /* may have to increase the stack size */
    if (top == buf->b_ml.ml_stack_size)
    {
    CHECK(top > 0, _("Stack size increases"));    /* more than 5 levels??? */

    newstack = (infoptr_T *)alloc((unsigned)sizeof(infoptr_T) *
                    (buf->b_ml.ml_stack_size + STACK_INCR));
    if (newstack == NULL)
        return -1;
    mch_memmove(newstack, buf->b_ml.ml_stack, (size_t)top * sizeof(infoptr_T));
    vim_free(buf->b_ml.ml_stack);
    buf->b_ml.ml_stack = newstack;
    buf->b_ml.ml_stack_size += STACK_INCR;
    }

    buf->b_ml.ml_stack_top++;
    return top;
}

/*
 * Update the pointer blocks on the stack for inserted/deleted lines.
 * The stack itself is also updated.
 *
 * When a insert/delete line action fails, the line is not inserted/deleted,
 * but the pointer blocks have already been updated. That is fixed here by
 * walking through the stack.
 *
 * Count is the number of lines added, negative if lines have been deleted.
 */
    static void
ml_lineadd(buf, count)
    buf_T    *buf;
    int        count;
{
    int        idx;
    infoptr_T    *ip;
    PTR_BL    *pp;
    memfile_T    *mfp = buf->b_ml.ml_mfp;
    bhdr_T    *hp;

    for (idx = buf->b_ml.ml_stack_top - 1; idx >= 0; --idx)
    {
    ip = &(buf->b_ml.ml_stack[idx]);
    if ((hp = mf_get(mfp, ip->ip_bnum, 1)) == NULL)
        break;
    pp = (PTR_BL *)(hp->bh_data);    /* must be pointer block */
    if (pp->pb_id != PTR_ID)
    {
        mf_put(mfp, hp, FALSE, FALSE);
        EMSG(_("E317: pointer block id wrong 2"));
        break;
    }
    pp->pb_pointer[ip->ip_index].pe_line_count += count;
    ip->ip_high += count;
    mf_put(mfp, hp, TRUE, FALSE);
    }
}

/*
 * make swap file name out of the file name and a directory name
 */
    static char_u *
makeswapname(buf, dir_name)
    buf_T    *buf;
    char_u    *dir_name;
{
    char_u    *r, *s;

#if defined(UNIX) || defined(WIN3264)  /* Need _very_ long file names */
    s = dir_name + STRLEN(dir_name);
    if (vim_ispathsep(s[-1]) && s[-1] == s[-2])
    {                   /* Ends with '//', Use Full path */
    r = NULL;
    if ((s = make_percent_swname(dir_name, buf->b_fname)) != NULL)
    {
        r = modname(s, (char_u *)".swp", FALSE);
        vim_free(s);
    }
    return r;
    }
#endif

    r = buf_modname(
#ifdef SHORT_FNAME
        TRUE,
#else
        (buf->b_p_sn || buf->b_shortname),
#endif
#ifdef RISCOS
        /* Avoid problems if fname has special chars, eg <Wimp$Scrap> */
        buf->b_ffname,
#else
        buf->b_fname,
#endif
        (char_u *)
#if defined(VMS) || defined(RISCOS)
        "_swp",
#else
        ".swp",
#endif
#ifdef SHORT_FNAME        /* always 8.3 file name */
        FALSE
#else
        /* Prepend a '.' to the swap file name for the current directory. */
        dir_name[0] == '.' && dir_name[1] == NUL
#endif
           );
    if (r == NULL)        /* out of memory */
    return NULL;

    s = get_file_in_dir(r, dir_name);
    vim_free(r);
    return s;
}

/*
 * Get file name to use for swap file or backup file.
 * Use the name of the edited file "fname" and an entry in the 'dir' or 'bdir'
 * option "dname".
 * - If "dname" is ".", return "fname" (swap file in dir of file).
 * - If "dname" starts with "./", insert "dname" in "fname" (swap file
 *   relative to dir of file).
 * - Otherwise, prepend "dname" to the tail of "fname" (swap file in specific
 *   dir).
 *
 * The return value is an allocated string and can be NULL.
 */
    char_u *
get_file_in_dir(fname, dname)
    char_u  *fname;
    char_u  *dname;    /* don't use "dirname", it is a global for Alpha */
{
    char_u    *t;
    char_u    *tail;
    char_u    *retval;
    int        save_char;

    tail = gettail(fname);

    if (dname[0] == '.' && dname[1] == NUL)
    retval = vim_strsave(fname);
    else if (dname[0] == '.' && vim_ispathsep(dname[1]))
    {
    if (tail == fname)        /* no path before file name */
        retval = concat_fnames(dname + 2, tail, TRUE);
    else
    {
        save_char = *tail;
        *tail = NUL;
        t = concat_fnames(fname, dname + 2, TRUE);
        *tail = save_char;
        if (t == NULL)        /* out of memory */
        retval = NULL;
        else
        {
        retval = concat_fnames(t, tail, TRUE);
        vim_free(t);
        }
    }
    }
    else
    retval = concat_fnames(dname, tail, TRUE);

    return retval;
}

/*
 * Find out what name to use for the swap file for buffer 'buf'.
 *
 * Several names are tried to find one that does not exist
 *
 * Note: If BASENAMELEN is not correct, you will get error messages for
 *     not being able to open the swapfile
 */
    static char_u *
findswapname(buf, dirp, old_fname)
    buf_T    *buf;
    char_u    **dirp;        /* pointer to list of directories */
    char_u    *old_fname;    /* don't give warning for this file name */
{
    char_u    *fname;
    int        n;
    time_t    x, sx;
    char_u    *dir_name;
#ifdef AMIGA
    BPTR    fh;
#endif
#ifndef SHORT_FNAME
    int        r;
#endif

#if !defined(SHORT_FNAME) \
             && ((!defined(UNIX) && !defined(OS2)) || defined(ARCHIE))
# define CREATE_DUMMY_FILE
    FILE    *dummyfd = NULL;

/*
 * If we start editing a new file, e.g. "test.doc", which resides on an MSDOS
 * compatible filesystem, it is possible that the file "test.doc.swp" which we
 * create will be exactly the same file. To avoid this problem we temporarily
 * create "test.doc".
 * Don't do this when the check below for a 8.3 file name is used.
 */
    if (!(buf->b_p_sn || buf->b_shortname) && buf->b_fname != NULL
                         && mch_getperm(buf->b_fname) < 0)
    dummyfd = mch_fopen((char *)buf->b_fname, "w");
#endif

/*
 * Isolate a directory name from *dirp and put it in dir_name.
 * First allocate some memory to put the directory name in.
 */
    dir_name = alloc((unsigned)STRLEN(*dirp) + 1);
    if (dir_name != NULL)
    (void)copy_option_part(dirp, dir_name, 31000, ",");

/*
 * we try different names until we find one that does not exist yet
 */
    if (dir_name == NULL)        /* out of memory */
    fname = NULL;
    else
    fname = makeswapname(buf, dir_name);

    for (;;)
    {
    if (fname == NULL)    /* must be out of memory */
        break;
    if ((n = (int)STRLEN(fname)) == 0)    /* safety check */
    {
        vim_free(fname);
        fname = NULL;
        break;
    }
#if (defined(UNIX) || defined(OS2)) && !defined(ARCHIE) && !defined(SHORT_FNAME)
/*
 * Some systems have a MS-DOS compatible filesystem that use 8.3 character
 * file names. If this is the first try and the swap file name does not fit in
 * 8.3, detect if this is the case, set shortname and try again.
 */
    if (fname[n - 2] == 'w' && fname[n - 1] == 'p'
                    && !(buf->b_p_sn || buf->b_shortname))
    {
        char_u        *tail;
        char_u        *fname2;
        struct stat        s1, s2;
        int            f1, f2;
        int            created1 = FALSE, created2 = FALSE;
        int            same = FALSE;

        /*
         * Check if swapfile name does not fit in 8.3:
         * It either contains two dots, is longer than 8 chars, or starts
         * with a dot.
         */
        tail = gettail(buf->b_fname);
        if (       vim_strchr(tail, '.') != NULL
            || STRLEN(tail) > (size_t)8
            || *gettail(fname) == '.')
        {
        fname2 = alloc(n + 2);
        if (fname2 != NULL)
        {
            STRCPY(fname2, fname);
            /* if fname == "xx.xx.swp",        fname2 = "xx.xx.swx"
             * if fname == ".xx.swp",        fname2 = ".xx.swpx"
             * if fname == "123456789.swp", fname2 = "12345678x.swp"
             */
            if (vim_strchr(tail, '.') != NULL)
            fname2[n - 1] = 'x';
            else if (*gettail(fname) == '.')
            {
            fname2[n] = 'x';
            fname2[n + 1] = NUL;
            }
            else
            fname2[n - 5] += 1;
            /*
             * may need to create the files to be able to use mch_stat()
             */
            f1 = mch_open((char *)fname, O_RDONLY | O_EXTRA, 0);
            if (f1 < 0)
            {
            f1 = open(
#ifdef VMS
                vms_fixfilename((char *)fname),
#else
                (char *)fname,
#endif
                O_RDWR|O_CREAT|O_EXCL|O_EXTRA
#if defined(UNIX) || defined(VMS)  /* open in rw------- mode */
                                  , (mode_t)0600
#endif
#if defined(MSDOS) || defined(MSWIN) || defined(OS2)  /* open read/write */
                            , S_IREAD | S_IWRITE
#endif
                                        );
#if defined(OS2)
            if (f1 < 0 && errno == ENOENT)
                same = TRUE;
#endif
            created1 = TRUE;
            }
            if (f1 >= 0)
            {
            f2 = mch_open((char *)fname2, O_RDONLY | O_EXTRA, 0);
            if (f2 < 0)
            {
                f2 = open(
#ifdef VMS
                    vms_fixfilename((char *)fname2),
#else
                    (char *)fname2,
#endif
                    O_RDWR|O_CREAT|O_EXCL|O_EXTRA
#if defined(UNIX) || defined(VMS)  /* open in rw------- mode */
                                  , (mode_t)0600
#endif
#if defined(MSDOS) || defined(MSWIN) || defined(OS2)  /* open read/write */
                            , S_IREAD | S_IWRITE
#endif
                                        );
                created2 = TRUE;
            }
            if (f2 >= 0)
            {
                /*
                 * Both files exist now. If mch_stat() returns the
                 * same device and inode they are the same file.
                 */
                if (mch_fstat(f1, &s1) != -1
                    && mch_fstat(f2, &s2) != -1
                    && s1.st_dev == s2.st_dev
                    && s1.st_ino == s2.st_ino)
                same = TRUE;
                close(f2);
                if (created2)
                mch_remove(fname2);
            }
            close(f1);
            if (created1)
                mch_remove(fname);
            }
            vim_free(fname2);
            if (same)
            {
            buf->b_shortname = TRUE;
            vim_free(fname);
            fname = makeswapname(buf, dir_name);
            continue;    /* try again with b_shortname set */
            }
        }
        }
    }
#endif
    /*
     * check if the swapfile already exists
     */
    if (mch_getperm(fname) < 0)    /* it does not exist */
    {
#ifdef HAVE_LSTAT
        struct stat sb;

        /*
         * Extra security check: When a swap file is a symbolic link, this
         * is most likely a symlink attack.
         */
        if (mch_lstat((char *)fname, &sb) < 0)
#else
# ifdef AMIGA
        fh = Open((UBYTE *)fname, (long)MODE_NEWFILE);
        /*
         * on the Amiga mch_getperm() will return -1 when the file exists
         * but is being used by another program. This happens if you edit
         * a file twice.
         */
        if (fh != (BPTR)NULL)    /* can open file, OK */
        {
        Close(fh);
        mch_remove(fname);
        break;
        }
        if (IoErr() != ERROR_OBJECT_IN_USE
                        && IoErr() != ERROR_OBJECT_EXISTS)
# endif
#endif
        break;
    }

    /*
     * A file name equal to old_fname is OK to use.
     */
    if (old_fname != NULL && fnamecmp(fname, old_fname) == 0)
        break;

    /*
     * get here when file already exists
     */
    if (fname[n - 2] == 'w' && fname[n - 1] == 'p')    /* first try */
    {
#ifndef SHORT_FNAME
        /*
         * on MS-DOS compatible filesystems (e.g. messydos) file.doc.swp
         * and file.doc are the same file. To guess if this problem is
         * present try if file.doc.swx exists. If it does, we set
         * buf->b_shortname and try file_doc.swp (dots replaced by
         * underscores for this file), and try again. If it doesn't we
         * assume that "file.doc.swp" already exists.
         */
        if (!(buf->b_p_sn || buf->b_shortname))    /* not tried yet */
        {
        fname[n - 1] = 'x';
        r = mch_getperm(fname);        /* try "file.swx" */
        fname[n - 1] = 'p';
        if (r >= 0)            /* "file.swx" seems to exist */
        {
            buf->b_shortname = TRUE;
            vim_free(fname);
            fname = makeswapname(buf, dir_name);
            continue;        /* try again with '.' replaced with '_' */
        }
        }
#endif
        /*
         * If we get here the ".swp" file really exists.
         * Give an error message, unless recovering, no file name, we are
         * viewing a help file or when the path of the file is different
         * (happens when all .swp files are in one directory).
         */
        if (!recoverymode && buf->b_fname != NULL && !buf->b_help)
        {
        int        fd;
        struct block0    b0;
        int        differ = FALSE;

        /*
         * Try to read block 0 from the swap file to get the original
         * file name (and inode number).
         */
        fd = mch_open((char *)fname, O_RDONLY | O_EXTRA, 0);
        if (fd >= 0)
        {
            if (read(fd, (char *)&b0, sizeof(b0)) == sizeof(b0))
            {
            /*
             * The name in the swap file may be "~user/path/file".
             * Expand it first.
             */
            expand_env(b0.b0_fname, NameBuff, MAXPATHL);
#ifdef CHECK_INODE
            if (fnamecmp_ino(buf->b_ffname, NameBuff,
                             char_to_long(b0.b0_ino)))
                differ = TRUE;
#else
            if (fnamecmp(NameBuff, buf->b_ffname) != 0)
                differ = TRUE;
#endif
            }
            close(fd);
        }
#ifdef RISCOS
        else
            /* Can't open swap file, though it does exist.
             * Assume that the user is editing two files with
             * the same name in different directories. No error.
             */
            differ = TRUE;
#endif

        /* give the ATTENTION message when there is an old swap file
         * for the current file, and the buffer was not recovered. */
        if (differ == FALSE && !(curbuf->b_flags & BF_RECOVERED)
            && vim_strchr(p_shm, SHM_ATTENTION) == NULL)
        {
            struct stat st;
#ifdef CREATE_DUMMY_FILE
            int        did_use_dummy = FALSE;

            /* Avoid getting a warning for the file being created
             * outside of Vim, it was created at the start of this
             * function.  Delete the file now, because Vim might exit
             * here if the window is closed. */
            if (dummyfd != NULL)
            {
            fclose(dummyfd);
            dummyfd = NULL;
            mch_remove(buf->b_fname);
            did_use_dummy = TRUE;
            }
#endif
#ifdef FEAT_GUI
            /* If we are supposed to start the GUI but it wasn't
             * completely started yet, start it now.  This makes the
             * messages displayed in the Vim window when loading a
             * session from the .gvimrc file. */
            if (gui.starting && !gui.in_use)
            gui_start();
#endif

#if (defined(UNIX) || defined(__EMX__) || defined(VMS)) && (defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG))
            process_still_running = FALSE;
#endif
            ++no_wait_return;
            (void)EMSG(_("E325: ATTENTION"));
            MSG_PUTS(_("\nFound a swap file by the name \""));
            msg_home_replace(fname);
            MSG_PUTS(_("\"\n"));
            sx = swapfile_info(fname);
            MSG_PUTS(_("While opening file \""));
            msg_outtrans(buf->b_fname);
            MSG_PUTS(_("\"\n"));
            if (mch_stat((char *)buf->b_fname, &st) != -1)
            {
            MSG_PUTS(_("             dated: "));
            x = st.st_mtime;    /* Manx C can't do &st.st_mtime */
            MSG_PUTS(ctime(&x));
            if (sx != 0 && x > sx)
                MSG_PUTS(_("      NEWER than swap file!\n"));
            }
            /* Some of these messages are long to allow translation to
             * other languages. */
            MSG_PUTS(_("\n(1) Another program may be editing the same file.\n    If this is the case, be careful not to end up with two\n    different instances of the same file when making changes.\n"));
            MSG_PUTS(_("    Quit, or continue with caution.\n"));
            MSG_PUTS(_("\n(2) An edit session for this file crashed.\n"));
            MSG_PUTS(_("    If this is the case, use \":recover\" or \"vim -r "));
            msg_outtrans(buf->b_fname);
            MSG_PUTS(_("\"\n    to recover the changes (see \":help recovery\").\n"));
            MSG_PUTS(_("    If you did this already, delete the swap file \""));
            msg_outtrans(fname);
            MSG_PUTS(_("\"\n    to avoid this message.\n"));
            cmdline_row = msg_row;
            --no_wait_return;

            /* We don't want a 'q' typed at the more-prompt interrupt
             * loading a file. */
            got_int = FALSE;

#if defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG)
            if (swap_exists_action)
            {
            char_u    *name;

            name = alloc((unsigned)(STRLEN(fname)
                + STRLEN(_("Swap file \""))
                + STRLEN(_("\" already exists!")) + 5));
            if (name != NULL)
            {
                STRCPY(name, _("Swap file \""));
                home_replace(NULL, fname, name + STRLEN(name),
                                  1000, TRUE);
                STRCAT(name, _("\" already exists!"));
            }
            switch (do_dialog(VIM_WARNING,
                    (char_u *)_("VIM - ATTENTION"),
                    name == NULL
                    ?  (char_u *)_("Swap file already exists!")
                    : name,
# if defined(UNIX) || defined(__EMX__) || defined(VMS)
                    process_still_running
                    ? (char_u *)_("&Open Read-Only\n&Edit anyway\n&Recover\n&Quit") :
# endif
                    (char_u *)_("&Open Read-Only\n&Edit anyway\n&Recover\n&Quit\n&Delete it"), 1, NULL))
            {
                case 1:
                buf->b_p_ro = TRUE;
                break;
                case 2:
                break;
                case 3:
                swap_exists_action = SEA_RECOVER;
                break;
                case 4:
                swap_exists_action = SEA_QUIT;
                break;
                case 5:
                mch_remove(fname);
                break;
            }
            vim_free(name);

            /* pretend screen didn't scroll, need redraw anyway */
            msg_scrolled = 0;
            redraw_all_later(NOT_VALID);

            /* If the file was deleted this fname can be used. */
            if (mch_getperm(fname) < 0)
                break;
            }
            else
#endif
            {
            MSG_PUTS("\n");
            need_wait_return = TRUE; /* call wait_return later */
            }

#ifdef CREATE_DUMMY_FILE
            /* Going to try another name, need the dummy file again. */
            if (did_use_dummy)
            dummyfd = mch_fopen((char *)buf->b_fname, "w");
#endif
        }
        }
    }

    /*
     * Change the ".swp" extension to find another file that can be used.
     * First decrement the last char: ".swo", ".swn", etc.
     * If that still isn't enough decrement the last but one char: ".svz"
     * Can happen when editing many "No File" buffers.
     */
    if (fname[n - 1] == 'a')    /* ".s?a" */
    {
        if (fname[n - 2] == 'a')    /* ".saa": tried enough, give up */
        {
        EMSG(_("E326: Too many swap files found"));
        vim_free(fname);
        fname = NULL;
        break;
        }
        --fname[n - 2];        /* ".svz", ".suz", etc. */
        fname[n - 1] = 'z' + 1;
    }
    --fname[n - 1];            /* ".swo", ".swn", etc. */
    }

    vim_free(dir_name);
#ifdef CREATE_DUMMY_FILE
    if (dummyfd != NULL)    /* file has been created temporarily */
    {
    fclose(dummyfd);
    mch_remove(buf->b_fname);
    }
#endif
    return fname;
}

    static int
b0_magic_wrong(b0p)
    ZERO_BL *b0p;
{
    return (b0p->b0_magic_long != (long)B0_MAGIC_LONG
        || b0p->b0_magic_int != (int)B0_MAGIC_INT
        || b0p->b0_magic_short != (short)B0_MAGIC_SHORT
        || b0p->b0_magic_char != B0_MAGIC_CHAR);
}

#ifdef CHECK_INODE
/*
 * Compare current file name with file name from swap file.
 * Try to use inode numbers when possible.
 * Return non-zero when files are different.
 *
 * When comparing file names a few things have to be taken into consideration:
 * - When working over a network the full path of a file depends on the host.
 *   We check the inode number if possible.  It is not 100% reliable though,
 *   because the device number cannot be used over a network.
 * - When a file does not exist yet (editing a new file) there is no inode
 *   number.
 * - The file name in a swap file may not be valid on the current host.  The
 *   "~user" form is used whenever possible to avoid this.
 *
 * This is getting complicated, let's make a table:
 *
 *        ino_c  ino_s  fname_c  fname_s    differ =
 *
 * both files exist -> compare inode numbers:
 *        != 0   != 0    X     X    ino_c != ino_s
 *
 * inode number(s) unknown, file names available -> compare file names
 *        == 0    X    OK     OK    fname_c != fname_s
 *         X     == 0    OK     OK    fname_c != fname_s
 *
 * current file doesn't exist, file for swap file exist, file name(s) not
 * available -> probably different
 *        == 0   != 0    FAIL     X    TRUE
 *        == 0   != 0    X    FAIL    TRUE
 *
 * current file exists, inode for swap unknown, file name(s) not
 * available -> probably different
 *        != 0   == 0    FAIL     X    TRUE
 *        != 0   == 0    X    FAIL    TRUE
 *
 * current file doesn't exist, inode for swap unknown, one file name not
 * available -> probably different
 *        == 0   == 0    FAIL     OK    TRUE
 *        == 0   == 0    OK    FAIL    TRUE
 *
 * current file doesn't exist, inode for swap unknown, both file names not
 * available -> probably same file
 *        == 0   == 0    FAIL    FAIL    FALSE
 *
 * Note that when the ino_t is 64 bits, only the last 32 will be used.  This
 * can't be changed without making the block 0 incompatible with 32 bit
 * versions.
 */

    static int
fnamecmp_ino(fname_c, fname_s, ino_block0)
    char_u    *fname_c;        /* current file name */
    char_u    *fname_s;        /* file name from swap file */
    long    ino_block0;
{
    struct stat    st;
    ino_t    ino_c = 0;        /* ino of current file */
    ino_t    ino_s;            /* ino of file from swap file */
    char_u    buf_c[MAXPATHL];    /* full path of fname_c */
    char_u    buf_s[MAXPATHL];    /* full path of fname_s */
    int        retval_c;        /* flag: buf_c valid */
    int        retval_s;        /* flag: buf_s valid */

    if (mch_stat((char *)fname_c, &st) == 0)
    ino_c = (ino_t)st.st_ino;

    /*
     * First we try to get the inode from the file name, because the inode in
     * the swap file may be outdated.  If that fails (e.g. this path is not
     * valid on this machine), use the inode from block 0.
     */
    if (mch_stat((char *)fname_s, &st) == 0)
    ino_s = (ino_t)st.st_ino;
    else
    ino_s = (ino_t)ino_block0;

    if (ino_c && ino_s)
    return (ino_c != ino_s);

    /*
     * One of the inode numbers is unknown, try a forced vim_FullName() and
     * compare the file names.
     */
    retval_c = vim_FullName(fname_c, buf_c, MAXPATHL, TRUE);
    retval_s = vim_FullName(fname_s, buf_s, MAXPATHL, TRUE);
    if (retval_c == OK && retval_s == OK)
    return (STRCMP(buf_c, buf_s) != 0);

    /*
     * Can't compare inodes or file names, guess that the files are different,
     * unless both appear not to exist at all.
     */
    if (ino_s == 0 && ino_c == 0 && retval_c == FAIL && retval_s == FAIL)
    return FALSE;
    return TRUE;
}
#endif /* CHECK_INODE */

/*
 * Move a long integer into a four byte character array.
 * Used for machine independency in block zero.
 */
    static void
long_to_char(n, s)
    long    n;
    char_u  *s;
{
    s[0] = (char_u)(n & 0xff);
    n = (unsigned)n >> 8;
    s[1] = (char_u)(n & 0xff);
    n = (unsigned)n >> 8;
    s[2] = (char_u)(n & 0xff);
    n = (unsigned)n >> 8;
    s[3] = (char_u)(n & 0xff);
}

    static long
char_to_long(s)
    char_u  *s;
{
    long    retval;

    retval = s[3];
    retval <<= 8;
    retval |= s[2];
    retval <<= 8;
    retval |= s[1];
    retval <<= 8;
    retval |= s[0];

    return retval;
}

    void
ml_setdirty(buf, flag)
    buf_T    *buf;
    int        flag;
{
    bhdr_T    *hp;
    ZERO_BL    *b0p;

    if (!buf->b_ml.ml_mfp)
    return;
    for (hp = buf->b_ml.ml_mfp->mf_used_last; hp != NULL; hp = hp->bh_prev)
    {
    if (hp->bh_bnum == 0)
    {
        b0p = (ZERO_BL *)(hp->bh_data);
        b0p->b0_dirty = flag ? 0x55 : 0;
        hp->bh_flags |= BH_DIRTY;
        mf_sync(buf->b_ml.ml_mfp, MFS_ZERO);
        break;
    }
    }
}

#if defined(FEAT_BYTEOFF) || defined(PROTO)

#define MLCS_MAXL 800    /* max no of lines in chunk */
#define MLCS_MINL 400   /* should be half of MLCS_MAXL */

/*
 * Keep information for finding byte offset of a line, updtytpe may be one of:
 * ML_CHNK_ADDLINE: Add len to parent chunk, possibly splitting it
 *       Careful: ML_CHNK_ADDLINE may cause ml_find_line() to be called.
 * ML_CHNK_DELLINE: Subtract len from parent chunk, possibly deleting it
 * ML_CHNK_UPDLINE: Add len to parent chunk, as a signed entity.
 */
    static void
ml_updatechunk(buf, line, len, updtype)
    buf_T    *buf;
    linenr_T    line;
    int        len;
    int        updtype;
{
    static buf_T    *ml_upd_lastbuf = NULL;
    static linenr_T    ml_upd_lastline;
    static linenr_T    ml_upd_lastcurline;
    static int        ml_upd_lastcurix;

    linenr_T        curline = ml_upd_lastcurline;
    int            curix = ml_upd_lastcurix;
    long        size;
    chunksize_T        *curchnk;
    int            rest;
    bhdr_T        *hp;
    DATA_BL        *dp;

    if (buf->b_ml.ml_usedchunks == -1 || !len)
    return;
    if (buf->b_ml.ml_chunksize == NULL)
    {
    buf->b_ml.ml_chunksize = (chunksize_T *)
                  alloc((unsigned)sizeof(chunksize_T) * 100);
    if (buf->b_ml.ml_chunksize == NULL)
    {
        buf->b_ml.ml_usedchunks = -1;
        return;
    }
    buf->b_ml.ml_numchunks = 100;
    buf->b_ml.ml_usedchunks = 1;
    buf->b_ml.ml_chunksize[0].mlcs_numlines = 1;
    buf->b_ml.ml_chunksize[0].mlcs_totalsize = 1;
    }

    if (updtype == ML_CHNK_UPDLINE && buf->b_ml.ml_line_count == 1)
    {
    /*
     * First line in empty buffer from ml_flush_line() -- reset
     */
    buf->b_ml.ml_usedchunks = 1;
    buf->b_ml.ml_chunksize[0].mlcs_numlines = 1;
    buf->b_ml.ml_chunksize[0].mlcs_totalsize =
                  (long)STRLEN(buf->b_ml.ml_line_ptr) + 1;
    return;
    }

    /*
     * Find chunk that our line belongs to, curline will be at start of the
     * chunk.
     */
    if (buf != ml_upd_lastbuf || line != ml_upd_lastline + 1
        || updtype != ML_CHNK_ADDLINE)
    {
    for (curline = 1, curix = 0;
         curix < buf->b_ml.ml_usedchunks - 1
         && line >= curline + buf->b_ml.ml_chunksize[curix].mlcs_numlines;
         curix++)
    {
        curline += buf->b_ml.ml_chunksize[curix].mlcs_numlines;
    }
    }
    else if (line >= curline + buf->b_ml.ml_chunksize[curix].mlcs_numlines
         && curix < buf->b_ml.ml_usedchunks - 1)
    {
    /* Adjust cached curix & curline */
    curline += buf->b_ml.ml_chunksize[curix].mlcs_numlines;
    curix++;
    }
    curchnk = buf->b_ml.ml_chunksize + curix;

    if (updtype == ML_CHNK_DELLINE)
    len *= -1;
    curchnk->mlcs_totalsize += len;
    if (updtype == ML_CHNK_ADDLINE)
    {
    curchnk->mlcs_numlines++;

    /* May resize here so we don't have to do it in both cases below */
    if (buf->b_ml.ml_usedchunks + 1 >= buf->b_ml.ml_numchunks)
    {
        buf->b_ml.ml_numchunks = buf->b_ml.ml_numchunks * 3 / 2;
        buf->b_ml.ml_chunksize = (chunksize_T *)
        vim_realloc(buf->b_ml.ml_chunksize,
                sizeof(chunksize_T) * buf->b_ml.ml_numchunks);
        if (buf->b_ml.ml_chunksize == NULL)
        {
        /* Hmmmm, Give up on offset for this buffer */
        buf->b_ml.ml_usedchunks = -1;
        return;
        }
    }

    if (buf->b_ml.ml_chunksize[curix].mlcs_numlines >= MLCS_MAXL)
    {
        int        count;        /* number of entries in block */
        int        idx;
        int        text_end;
        int        linecnt;

        mch_memmove(buf->b_ml.ml_chunksize + curix + 1,
            buf->b_ml.ml_chunksize + curix,
            (buf->b_ml.ml_usedchunks - curix) *
            sizeof(chunksize_T));
        /* Compute length of first half of lines in the splitted chunk */
        size = 0;
        linecnt = 0;
        while (curline < buf->b_ml.ml_line_count
            && linecnt < MLCS_MINL)
        {
        if ((hp = ml_find_line(buf, curline, ML_FIND)) == NULL)
        {
            buf->b_ml.ml_usedchunks = -1;
            return;
        }
        dp = (DATA_BL *)(hp->bh_data);
        count = (long)(buf->b_ml.ml_locked_high) -
            (long)(buf->b_ml.ml_locked_low) + 1;
        idx = curline - buf->b_ml.ml_locked_low;
        curline = buf->b_ml.ml_locked_high + 1;
        if (idx == 0)/* first line in block, text at the end */
            text_end = dp->db_txt_end;
        else
            text_end = ((dp->db_index[idx - 1]) & DB_INDEX_MASK);
        /* Compute index of last line to use in this MEMLINE */
        rest = count - idx;
        if (linecnt + rest > MLCS_MINL)
        {
            idx += MLCS_MINL - linecnt - 1;
            linecnt = MLCS_MINL;
        }
        else
        {
            idx = count - 1;
            linecnt += rest;
        }
        size += text_end - ((dp->db_index[idx]) & DB_INDEX_MASK);
        }
        buf->b_ml.ml_chunksize[curix].mlcs_numlines = linecnt;
        buf->b_ml.ml_chunksize[curix + 1].mlcs_numlines -= linecnt;
        buf->b_ml.ml_chunksize[curix].mlcs_totalsize = size;
        buf->b_ml.ml_chunksize[curix + 1].mlcs_totalsize -= size;
        buf->b_ml.ml_usedchunks++;
        ml_upd_lastbuf = NULL;   /* Force recalc of curix & curline */
        return;
    }
    else if (buf->b_ml.ml_chunksize[curix].mlcs_numlines >= MLCS_MINL
             && curix == buf->b_ml.ml_usedchunks - 1
             && buf->b_ml.ml_line_count - line <= 1)
    {
        /*
         * We are in the last chunk and it is cheap to crate a new one
         * after this. Do it now to avoid the loop above later on
         */
        curchnk = buf->b_ml.ml_chunksize + curix + 1;
        buf->b_ml.ml_usedchunks++;
        if (line == buf->b_ml.ml_line_count)
        {
        curchnk->mlcs_numlines = 0;
        curchnk->mlcs_totalsize = 0;
        }
        else
        {
        /*
         * Line is just prior to last, move count for last
         * This is the common case  when loading a new file
         */
        hp = ml_find_line(buf, buf->b_ml.ml_line_count, ML_FIND);
        if (hp == NULL)
        {
            buf->b_ml.ml_usedchunks = -1;
            return;
        }
        dp = (DATA_BL *)(hp->bh_data);
        if (dp->db_line_count == 1)
            rest = dp->db_txt_end - dp->db_txt_start;
        else
            rest =
            ((dp->db_index[dp->db_line_count - 2]) & DB_INDEX_MASK)
            - dp->db_txt_start;
        curchnk->mlcs_totalsize = rest;
        curchnk->mlcs_numlines = 1;
        curchnk[-1].mlcs_totalsize -= rest;
        curchnk[-1].mlcs_numlines -= 1;
        }
    }
    }
    else if (updtype == ML_CHNK_DELLINE)
    {
    curchnk->mlcs_numlines--;
    ml_upd_lastbuf = NULL;   /* Force recalc of curix & curline */
    if (curix < (buf->b_ml.ml_usedchunks - 1)
        && (curchnk->mlcs_numlines + curchnk[1].mlcs_numlines)
           <= MLCS_MINL)
    {
        curix++;
        curchnk = buf->b_ml.ml_chunksize + curix;
    }
    else if (curix == 0 && curchnk->mlcs_numlines <= 0)
    {
        buf->b_ml.ml_usedchunks--;
        mch_memmove(buf->b_ml.ml_chunksize, buf->b_ml.ml_chunksize + 1,
            buf->b_ml.ml_usedchunks * sizeof(chunksize_T));
        return;
    }
    else if (curix == 0 || (curchnk->mlcs_numlines > 10
            && (curchnk->mlcs_numlines + curchnk[-1].mlcs_numlines)
               > MLCS_MINL))
    {
        return;
    }

    /* Collapse chunks */
    curchnk[-1].mlcs_numlines += curchnk->mlcs_numlines;
    curchnk[-1].mlcs_totalsize += curchnk->mlcs_totalsize;
    buf->b_ml.ml_usedchunks--;
    if (curix < buf->b_ml.ml_usedchunks)
    {
        mch_memmove(buf->b_ml.ml_chunksize + curix,
            buf->b_ml.ml_chunksize + curix + 1,
            (buf->b_ml.ml_usedchunks - curix) *
            sizeof(chunksize_T));
    }
    return;
    }
    ml_upd_lastbuf = buf;
    ml_upd_lastline = line;
    ml_upd_lastcurline = curline;
    ml_upd_lastcurix = curix;
}

/*
 * Find offset for line or line with offset.
 * Find line with offset if line is 0; return remaining offset in offp
 * Find offset of line if line > 0
 * return -1 if information is not available
 */
    long
ml_find_line_or_offset(buf, line, offp)
    buf_T    *buf;
    linenr_T    line;
    long    *offp;
{
    linenr_T    curline;
    int        curix;
    long    size;
    bhdr_T    *hp;
    DATA_BL    *dp;
    int        count;        /* number of entries in block */
    int        idx;
    int        start_idx;
    int        text_end;
    long    offset;
    int        len;
    int        ffdos = (get_fileformat(buf) == EOL_DOS);

    if (buf->b_ml.ml_usedchunks == -1
        || buf->b_ml.ml_chunksize == NULL
        || line < 0)
    return -1;

    if (offp == NULL)
    offset = 0;
    else
    offset = *offp;
    if (line == 0 && offset <= 0)
    return 1;   /* Not a "find offset" and offset 0 _must_ be in line 1 */
    /*
     * Find the last chunk before the one containing our line. Last chunk is
     * special because it will never qualify
     */
    curline = 1;
    curix = size = 0;
    while (curix < buf->b_ml.ml_usedchunks - 1
        && ((line
         && line >= curline + buf->b_ml.ml_chunksize[curix].mlcs_numlines)
        || (offset
       && offset >= size + buf->b_ml.ml_chunksize[curix].mlcs_totalsize
              + ffdos * buf->b_ml.ml_chunksize[curix].mlcs_numlines)))
    {
    curline += buf->b_ml.ml_chunksize[curix].mlcs_numlines;
    size += buf->b_ml.ml_chunksize[curix].mlcs_totalsize;
    if (offset && ffdos)
        size += buf->b_ml.ml_chunksize[curix].mlcs_numlines;
    curix++;
    }

    while ((line && curline < line) || (offset && size < offset))
    {
    if (curline > buf->b_ml.ml_line_count
        || (hp = ml_find_line(buf, curline, ML_FIND)) == NULL)
    {
        return -1;
    }
    dp = (DATA_BL *)(hp->bh_data);
    count = (long)(buf->b_ml.ml_locked_high) -
        (long)(buf->b_ml.ml_locked_low) + 1;
    start_idx = idx = curline - buf->b_ml.ml_locked_low;
    if (idx == 0)/* first line in block, text at the end */
        text_end = dp->db_txt_end;
    else
        text_end = ((dp->db_index[idx - 1]) & DB_INDEX_MASK);
    /* Compute index of last line to use in this MEMLINE */
    if (line)
    {
        if (curline + (count - idx) >= line)
        idx += line - curline - 1;
        else
        idx = count - 1;
    }
    else
    {
        while (offset >= size
               + text_end - (int)((dp->db_index[idx]) & DB_INDEX_MASK)
                                      + ffdos)
        {
        if (ffdos)
            size++;
        if (idx == count - 1)
            break;
        idx++;
        }
    }
    len = text_end - ((dp->db_index[idx]) & DB_INDEX_MASK);
    size += len;
    if (offp != NULL && size >= offset)
    {
        if (size + ffdos == offset)
        *offp = 0;
        else if (idx == start_idx)
        *offp = offset - size + len;
        else
        *offp = offset - size + len
             - (text_end - ((dp->db_index[idx - 1]) & DB_INDEX_MASK));
        return curline + idx - start_idx;
    }
    curline = buf->b_ml.ml_locked_high + 1;
    }

    if (ffdos)
    size += line - 1;
    return size;
}

/*
 * Goto byte in buffer with offset 'cnt'.
 */
    void
goto_byte(cnt)
    long    cnt;
{
    long    boff = cnt;
    linenr_T    lnum;

    ml_flush_line(curbuf);    /* cached line may be dirty */
    setpcmark();
    if (boff)
    --boff;
    lnum = ml_find_line_or_offset(curbuf, (linenr_T)0, &boff);
    if (lnum < 1)    /* past the end */
    {
    curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
    curwin->w_curswant = MAXCOL;
    coladvance((colnr_T)MAXCOL);
    }
    else
    {
    curwin->w_cursor.lnum = lnum;
    curwin->w_cursor.col = (colnr_T)boff;
    curwin->w_set_curswant = TRUE;
    }
    check_cursor();

# ifdef FEAT_MBYTE
    /* prevent cursor from moving on the trail byte */
    if (has_mbyte)
    mb_adjust_cursor();
# endif
}
#endif