lib/other/fsversion.c

   1 /* This procedure examines a file system and figures out whether it is
   2  * version 1 or version 2.  It returns the result as an int.  If the
   3  * file system is neither, it returns -1.  A typical call is:
   4  *
   5  *      n = fsversion("/dev/hd1", "df");
   6  *
   7  * The first argument is the special file for the file system.
   8  * The second is the program name, which is used in error messages.
   9  */
  10
  11 #include <sys/types.h>
  12 #include <minix/config.h>
  13 #include <minix/const.h>
  14 #include <minix/minlib.h>
  15 #include <minix/type.h>
  16 #include <fcntl.h>
  17 #include <unistd.h>
  18 #include <stdio.h>
  19
  20 #include "mfs/const.h"
  21 #include "mfs/type.h"
  22 #include "mfs/super.h"
  23
  24 static struct super_block super, *sp;
  25
  26 int fsversion(dev, prog)
  27 char *dev, *prog;
  28 {
  29   int fd;
  30
  31   if ((fd = open(dev, O_RDONLY)) < 0) {
  32         std_err(prog);
  33         std_err(" cannot open ");
  34         perror(dev);
  35         return(-1);
  36   }
  37
  38   lseek(fd, (off_t) SUPER_BLOCK_BYTES, SEEK_SET);       /* skip boot block */
  39   if (read(fd, (char *) &super, (unsigned) SUPER_SIZE) != SUPER_SIZE) {
  40         std_err(prog);
  41         std_err(" cannot read super block on ");
  42         perror(dev);
  43         close(fd);
  44         return(-1);
  45   }
  46   close(fd);
  47   sp = &super;
  48   if (sp->s_magic == SUPER_MAGIC) return(1);
  49   if (sp->s_magic == SUPER_V2) return(2);
  50   if (sp->s_magic == SUPER_V3) return(3);
  51   return(-1);
  52 }