commands/simple/umount.c

   1 /* umount - unmount a file system               Author: Andy Tanenbaum */
   2
   3 #define _MINIX 1                /* for proto of the non-POSIX umount() */
   4 #define _POSIX_SOURCE 1         /* for PATH_MAX from limits.h */
   5
   6 #include <minix/type.h>
   7 #include <sys/types.h>
   8 #include <sys/stat.h>
   9 #include <fcntl.h>
  10 #include <errno.h>
  11 #include <limits.h>
  12 #include <minix/minlib.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include <unistd.h>
  16 #include <sys/mount.h>
  17 #include <stdio.h>
  18
  19 _PROTOTYPE(int main, (int argc, char **argv));
  20 _PROTOTYPE(int find_mtab_entry, (char *name));
  21 _PROTOTYPE(void update_mtab, (void));
  22 _PROTOTYPE(void usage, (void));
  23
  24 static char device[PATH_MAX+1], mountpoint[PATH_MAX+1], vs[10], rw[10];
  25
  26 int main(argc, argv)
  27 int argc;
  28 char *argv[];
  29 {
  30   int found;
  31
  32   if (argc != 2) usage();
  33   found = find_mtab_entry(argv[1]);
  34   if (umount(argv[1]) < 0) {
  35         if (errno == EINVAL)
  36                 std_err("umount: Device not mounted\n");
  37         else if (errno == ENOTBLK)
  38                 std_err("unount: Not a mountpoint\n");
  39         else
  40                 perror("umount");
  41         exit(1);
  42   }
  43   if (found) {
  44         printf("%s unmounted from %s\n", device, mountpoint);
  45         update_mtab();
  46   }
  47   else printf("%s unmounted (mtab not updated)\n", argv[1]);
  48   return(0);
  49 }
  50
  51 int find_mtab_entry(name)
  52 char *name;
  53 {
  54 /* Find a matching mtab entry for 'name' which may be a special or a path,
  55  * and generate a new mtab file without this entry on the fly. Do not write
  56  * out the result yet. Return whether we found a matching entry.
  57  */
  58   char special[PATH_MAX+1], mounted_on[PATH_MAX+1], version[10], rw_flag[10];
  59   struct stat nstat, mstat;
  60   int n, found;
  61
  62   if (load_mtab("umount") < 0) return 0;
  63
  64   if (stat(name, &nstat) != 0) return 0;
  65
  66   found = 0;
  67   while (1) {
  68         n = get_mtab_entry(special, mounted_on, version, rw_flag);
  69         if (n < 0) break;
  70         if (strcmp(name, special) == 0 || (stat(mounted_on, &mstat) == 0 &&
  71                 mstat.st_dev == nstat.st_dev && mstat.st_ino == nstat.st_ino))
  72         {
  73                 /* If we found an earlier match, keep that one. Mountpoints
  74                  * may be stacked on top of each other, and unmounting should
  75                  * take place in the reverse order of mounting.
  76                  */
  77                 if (found) {
  78                         (void) put_mtab_entry(device, mountpoint, vs, rw);
  79                 }
  80
  81                 strcpy(device, special);
  82                 strcpy(mountpoint, mounted_on);
  83                 strcpy(vs, version);
  84                 strcpy(rw, rw_flag);
  85                 found = 1;
  86                 continue;
  87         }
  88         (void) put_mtab_entry(special, mounted_on, version, rw_flag);
  89   }
  90
  91   return found;
  92 }
  93
  94 void update_mtab()
  95 {
  96 /* Write out the new mtab file. */
  97   int n;
  98
  99   n = rewrite_mtab("umount");
 100   if (n < 0) {
 101         std_err("/etc/mtab not updated.\n");
 102         exit(1);
 103   }
 104 }
 105
 106 void usage()
 107 {
 108   std_err("Usage: umount name\n");
 109   exit(1);
 110 }