commands/umount/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 <getopt.h>
  11 #include <errno.h>
  12 #include <limits.h>
  13 #include <minix/minlib.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <sys/mount.h>
  18 #include <stdio.h>
  19
  20 int main(int argc, char **argv);
  21 int find_mtab_entry(char *name);
  22 void update_mtab(void);
  23 void usage(void);
  24
  25 static char device[PATH_MAX+1], mountpoint[PATH_MAX+1], vs[10], rw[10];
  26
  27 int main(argc, argv)
  28 int argc;
  29 char *argv[];
  30 {
  31   int found;
  32   int flags = 0UL;
  33   int i;
  34   char c;
  35   char *name;
  36
  37   while ((c = getopt (argc, argv, "e")) != -1)
  38   {
  39         switch (c) {
  40                 case 'e': flags |= MS_EXISTING; break;
  41                 default: break;
  42         }
  43   }
  44
  45   if (argc - optind != 1) {
  46            usage();
  47   }
  48
  49   name = argv[optind];
  50
  51
  52   found = find_mtab_entry(name);
  53
  54
  55   if (umount2(name, flags) < 0) {
  56         if (errno == EINVAL)
  57                 std_err("umount: Device not mounted\n");
  58         else if (errno == ENOTBLK)
  59                 std_err("umount: Not a mountpoint\n");
  60         else
  61                 perror("umount");
  62         exit(1);
  63   }
  64   if (found) {
  65         printf("%s unmounted from %s\n", device, mountpoint);
  66         update_mtab();
  67   }
  68   else printf("%s unmounted (mtab not updated)\n", name);
  69   return(0);
  70 }
  71
  72 int find_mtab_entry(name)
  73 char *name;
  74 {
  75 /* Find a matching mtab entry for 'name' which may be a special or a path,
  76  * and generate a new mtab file without this entry on the fly. Do not write
  77  * out the result yet. Return whether we found a matching entry.
  78  */
  79   char special[PATH_MAX+1], mounted_on[PATH_MAX+1], version[10], rw_flag[10];
  80   struct stat nstat, mstat;
  81   int n, found;
  82
  83   if (load_mtab("umount") < 0) return 0;
  84
  85   if (stat(name, &nstat) != 0) return 0;
  86
  87   found = 0;
  88   while (1) {
  89         n = get_mtab_entry(special, mounted_on, version, rw_flag);
  90         if (n < 0) break;
  91         if (strcmp(name, special) == 0 || (stat(mounted_on, &mstat) == 0 &&
  92                 mstat.st_dev == nstat.st_dev && mstat.st_ino == nstat.st_ino))
  93         {
  94                 /* If we found an earlier match, keep that one. Mountpoints
  95                  * may be stacked on top of each other, and unmounting should
  96                  * take place in the reverse order of mounting.
  97                  */
  98                 if (found) {
  99                         (void) put_mtab_entry(device, mountpoint, vs, rw);
 100                 }
 101
 102                 strcpy(device, special);
 103                 strcpy(mountpoint, mounted_on);
 104                 strcpy(vs, version);
 105                 strcpy(rw, rw_flag);
 106                 found = 1;
 107                 continue;
 108         }
 109         (void) put_mtab_entry(special, mounted_on, version, rw_flag);
 110   }
 111
 112   return found;
 113 }
 114
 115 void update_mtab()
 116 {
 117 /* Write out the new mtab file. */
 118   int n;
 119
 120   n = rewrite_mtab("umount");
 121   if (n < 0) {
 122         std_err("/etc/mtab not updated.\n");
 123         exit(1);
 124   }
 125 }
 126
 127 void usage()
 128 {
 129   std_err("Usage: umount [-e] name\n");
 130   exit(1);
 131 }