minix/lib/other/fsversion.c

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2005-04-21 16:53:53 +02:00
/* This procedure examines a file system and figures out whether it is
* version 1 or version 2. It returns the result as an int. If the
* file system is neither, it returns -1. A typical call is:
*
* n = fsversion("/dev/hd1", "df");
*
* The first argument is the special file for the file system.
* The second is the program name, which is used in error messages.
*/
#include <sys/types.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include "mfs/const.h"
#include "mfs/type.h"
#include "mfs/super.h"
2005-04-21 16:53:53 +02:00
static struct super_block super, *sp;
int fsversion(dev, prog)
char *dev, *prog;
{
int fd;
if ((fd = open(dev, O_RDONLY)) < 0) {
std_err(prog);
std_err(" cannot open ");
perror(dev);
return(-1);
}
lseek(fd, (off_t) SUPER_BLOCK_BYTES, SEEK_SET); /* skip boot block */
if (read(fd, (char *) &super, (unsigned) SUPER_SIZE) != SUPER_SIZE) {
std_err(prog);
std_err(" cannot read super block on ");
perror(dev);
close(fd);
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);
return(-1);
}