PC-Online 1998 February/PCOnline_02_1998.iso/filesbbs/win95/ext2tool.exe/SRC/PART.C

C/C++ Source or Header | 1995-07-20 | 4KB | 171 lines

/***************************************************************************
 * part.c - Routines for handling disk partitions
 *
 * Copyright (C) 1995 Claus Tondering, [e-mail]
 * This file may be redistributed under the terms of the GNU Public License.
 ***************************************************************************/

#include <string.h>
#include <sys/types.h>
#include "genhd.h"
#include "part.h"
#include "diskio.h"
#include "ext2_fs.h"
#include "e2err.h"


struct firstsector fs, fs2;

#if 0
void dump_sector(struct firstsector *);
#endif

/**********************************************************************
 * get_part() fetches 16 partition descriptors from the disk.
 *
 * Returns error code.
 **********************************************************************/

int
get_part(int disk, struct part_desc *pl)
{
    int i, next, err;
    long startsect, offset;

#if 0
    printf("Reading sector 0\n");
#endif
    err=readdisk(disk, 0, 1, &fs);
    if (err) return err;

#if 0
    dump_sector (&fs);
#endif

    if (fs.magic!=FIRST_SECT_MAGIC)
        return E2E_BADPART;

    memset(pl,0,sizeof(*pl)*16);
    for (i=0; i<4; i++) {
        if (fs.part[i].sys_ind) {
            pl[i].is_extended = fs.part[i].sys_ind==EXTENDED_PARTITION;
            pl[i].start = fs.part[i].start_sectlo+(fs.part[i].start_secthi<<16);
            pl[i].length = fs.part[i].nr_sectslo+(fs.part[i].nr_sectshi<<16);
            pl[i].parttype = fs.part[i].sys_ind;
        }
    }
    next=4;

    for (i=0; i<4; i++) {
        if (fs.part[i].sys_ind==EXTENDED_PARTITION) {
            startsect = pl[i].start;
            offset = 0;
            while (1) {
                if (next==16)
                    return 0;

#if 0
                printf("Reading sector 0x%x\n", startsect+offset);
#endif
                err=readdisk(disk, startsect+offset, 1, &fs2);
                if (err) return err;

#if 0
                dump_sector (&fs2);
#endif

                if (fs2.magic!=FIRST_SECT_MAGIC)
                    return E2E_BADPART;

                pl[next].start = startsect + offset + fs2.part[0].start_sectlo+(fs2.part[0].start_secthi<<16);
                pl[next].length = fs2.part[0].nr_sectslo+(fs2.part[0].nr_sectshi<<16);
                next++;
                if (fs2.part[1].sys_ind!=EXTENDED_PARTITION)
                    break;
                offset = fs2.part[1].start_sectlo+(fs2.part[1].start_secthi<<16);
            }
        }
    }
    return 0;
}


/**********************************************************************
 * getfstype finds the type of the file system on the partition.
 * It is not very good at it, but it identifies ext2 file systems,
 * which is the important thing.
 *
 * Returns the file system type or a negative error code.
 **********************************************************************/

int
getfstype(int disk, unsigned short parttype, unsigned long start)
{
    static union {
        u_char    bytes[512];
        u_short shorts[256];
        u_long    longs[128];
    } testblock;
    int err;

    if (parttype == PART_SWAP)
        return SWAP;

    if (parttype == PART_DOS32)
        return MSDOSFS;

    err=readdisk(disk, start, 1, &testblock);
    if (err) return -err;

#if 0
    if (strncmp(testblock.bytes+3,"MSDOS",5)==0) /* There must be a better way to do this */
        return MSDOSFS;
#endif

    err=readdisk(disk, start+2, 1, &testblock);
    if (err) return -err;

    if (testblock.shorts[28]==EXT2_SUPER_MAGIC)
        return EXT2FS;

    err=readdisk(disk, start+7, 1, &testblock);
    if (err) return -err;

    if (memcmp(testblock.bytes+0x1f6, "SWAP-SPACE", 10)==0)
        return SWAP;

    return 0;
}

#if 0
void dump_sector(struct firstsector *f)
{
    int i;

    printf("Initial 0x1be bytes:");
    for (i=0; i<0x1be; i++) {
        if ((i&0xf)==0) printf("\n");
        printf("%02x ",f->fill[i]);
    }

    for (i=0; i<4; i++) {
        printf("\nPartition descriptor %i:\n",i);
        printf("    boot_ind: %02x\n",f->part[i].boot_ind);
        printf("    head: %02x\n",f->part[i].head);
        printf("    sector: %02x\n",f->part[i].sector);
        printf("    cyl: %02x\n",f->part[i].cyl);
        printf("    sys_ind: %02x\n",f->part[i].sys_ind);
        printf("    end_head: %02x\n",f->part[i].end_head);
        printf("    end_sector: %02x\n",f->part[i].end_sector);
        printf("    end_cyl: %02x\n",f->part[i].end_cyl);
        printf("    start_sectlo: %04x\n",f->part[i].start_sectlo);
        printf("    start_secthi: %04x\n",f->part[i].start_secthi);
        printf("    nr_sectslo: %04x\n",f->part[i].nr_sectslo);
        printf("    nr_sectshi: %04x\n",f->part[i].nr_sectshi);
    }

    printf("Magic: %04x\n",f->magic);
    printf("----------------------------------------\n");
}
#endif