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Auto-detect ext2 partitions in mount

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This commit is contained in:
Erik van der Kouwe
2010-08-03 06:28:58 +00:00
parent 453be3b530
commit a719ab7780
4 changed files with 49 additions and 25 deletions
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27
lib/libc/other/fsversion.c
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@@ -16,12 +16,20 @@
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include "mfs/const.h"
#include "mfs/type.h"
#include "mfs/super.h"
static struct super_block super, *sp;
static char super[SUPER_BLOCK_BYTES];
#define MAGIC_OFFSET_MFS 0x18
#define MAGIC_OFFSET_EXT 0x38
#define MAGIC_VALUE_EXT2 0xef53
static int check_super(off_t offset, unsigned short magic)
{
return (memcmp(super + offset, &magic, sizeof(magic)) == 0) ? 1 : 0;
}
int fsversion(dev, prog)
char *dev, *prog;
@@ -36,7 +44,7 @@ char *dev, *prog;
}
lseek(fd, (off_t) SUPER_BLOCK_BYTES, SEEK_SET); /* skip boot block */
if (read(fd, (char *) &super, (unsigned) SUPER_SIZE) != SUPER_SIZE) {
if (read(fd, (char *) &super, sizeof(super)) != sizeof(super)) {
std_err(prog);
std_err(" cannot read super block on ");
perror(dev);
@@ -44,9 +52,12 @@ char *dev, *prog;
return(-1);
}
close(fd);
sp = &super;
if (sp->s_magic == SUPER_MAGIC) return(1);
if (sp->s_magic == SUPER_V2) return(2);
if (sp->s_magic == SUPER_V3) return(3);
/* first check MFS, a valid MFS may look like EXT but not vice versa */
if (check_super(MAGIC_OFFSET_MFS, SUPER_MAGIC)) return FSVERSION_MFS1;
if (check_super(MAGIC_OFFSET_MFS, SUPER_V2)) return FSVERSION_MFS2;
if (check_super(MAGIC_OFFSET_MFS, SUPER_V3)) return FSVERSION_MFS3;
if (check_super(MAGIC_OFFSET_EXT, MAGIC_VALUE_EXT2)) return FSVERSION_EXT2;
return(-1);
}