mount: prevent second mount -a from mounting everything again

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 58 insertions, 19 deletions

diff --git a/util-linux/mount.c b/util-linux/mount.c
index d7ca7da37..c2b508e5b 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -1829,7 +1829,8 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
         llist_t *lst_o = NULL;
         const char *fstabname;
         FILE *fstab;
-        int i, j, rc = 0;
+        int i, j;
+        int rc = EXIT_SUCCESS;
         unsigned opt;
         struct mntent mtpair[2], *mtcur = mtpair;
         IF_NOT_DESKTOP(const int nonroot = 0;)
@@ -1893,7 +1894,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                         mtpair->mnt_type = fstype;
                         mtpair->mnt_opts = cmdopts;
                         resolve_mount_spec(&mtpair->mnt_fsname);
-                        rc = singlemount(mtpair, 0);
+                        rc = singlemount(mtpair, /*ignore_busy:*/ 0);
                         return rc;
                 }
                 storage_path = bb_simplify_path(argv[0]); // malloced
@@ -1949,10 +1950,13 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                 if (argv[0]) {
 
                         // Is this what we're looking for?
-                        if (strcmp(argv[0], mtcur->mnt_fsname) &&
-                           strcmp(storage_path, mtcur->mnt_fsname) &&
-                           strcmp(argv[0], mtcur->mnt_dir) &&
-                           strcmp(storage_path, mtcur->mnt_dir)) continue;
+                        if (strcmp(argv[0], mtcur->mnt_fsname) != 0
+                         && strcmp(storage_path, mtcur->mnt_fsname) != 0
+                         && strcmp(argv[0], mtcur->mnt_dir) != 0
+                         && strcmp(storage_path, mtcur->mnt_dir) != 0
+                        ) {
+                                continue; // no
+                        }
 
                         // Remember this entry.  Something later may have
                         // overmounted it, and we want the _last_ match.
@@ -1960,6 +1964,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
 
                 // If we're mounting all
                 } else {
+                        struct mntent *mp;
                         // No, mount -a won't mount anything,
                         // even user mounts, for mere humans
                         if (nonroot)
@@ -1969,7 +1974,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                         if (!match_fstype(mtcur, fstype))
                                 continue;
 
-                        // Skip noauto and swap anyway.
+                        // Skip noauto and swap anyway
                         if ((parse_mount_options(mtcur->mnt_opts, NULL) & (MOUNT_NOAUTO | MOUNT_SWAP))
                         // swap is bogus "fstype", parse_mount_options can't check fstypes
                          || strcasecmp(mtcur->mnt_type, "swap") == 0
@@ -1987,10 +1992,23 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                         // NFS mounts want this to be xrealloc-able
                         mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);
 
-                        // Mount this thing
-                        if (singlemount(mtcur, 1)) {
-                                // Count number of failed mounts
-                                rc++;
+                        // If nothing is mounted on this directory...
+                        // (otherwise repeated "mount -a" mounts everything again)
+                        mp = find_mount_point(mtcur->mnt_dir, /*subdir_too:*/ 0);
+                        // We do not check fsname match of found mount point -
+                        // "/" may have fsname of "/dev/root" while fstab
+                        // says "/dev/something_else".
+                        if (mp) {
+                                bb_error_msg("according to %s, "
+                                        "%s is already mounted on %s",
+                                        bb_path_mtab_file,
+                                        mp->mnt_fsname, mp->mnt_dir);
+                        } else {
+                                // ...mount this thing
+                                if (singlemount(mtcur, /*ignore_busy:*/ 1)) {
+                                        // Count number of failed mounts
+                                        rc++;
+                                }
                         }
                         free(mtcur->mnt_opts);
                 }
@@ -1998,7 +2016,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
 
         // End of fstab/mtab is reached.
         // Were we looking for something specific?
-        if (argv[0]) {
+        if (argv[0]) { // yes
                 long l;
 
                 // If we didn't find anything, complain
@@ -2031,13 +2049,24 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                                 bb_error_msg_and_die(bb_msg_you_must_be_root);
                 }
 
-                // Mount the last thing we found
-                mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);
-                append_mount_options(&(mtcur->mnt_opts), cmdopts);
-                resolve_mount_spec(&mtpair->mnt_fsname);
-                rc = singlemount(mtcur, 0);
-                if (ENABLE_FEATURE_CLEAN_UP)
-                        free(mtcur->mnt_opts);
+                //util-linux-2.12 does not do this check.
+                //// If nothing is mounted on this directory...
+                //// (otherwise repeated "mount FOO" mounts FOO again)
+                //mp = find_mount_point(mtcur->mnt_dir, /*subdir_too:*/ 0);
+                //if (mp) {
+                //      bb_error_msg("according to %s, "
+                //              "%s is already mounted on %s",
+                //              bb_path_mtab_file,
+                //              mp->mnt_fsname, mp->mnt_dir);
+                //} else {
+                        // ...mount the last thing we found
+                        mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);
+                        append_mount_options(&(mtcur->mnt_opts), cmdopts);
+                        resolve_mount_spec(&mtpair->mnt_fsname);
+                        rc = singlemount(mtcur, /*ignore_busy:*/ 0);
+                        if (ENABLE_FEATURE_CLEAN_UP)
+                                free(mtcur->mnt_opts);
+                //}
         }
 
  //ret:
@@ -2047,5 +2076,15 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                 free(storage_path);
                 free(cmdopts);
         }
+
+//TODO: exitcode should be ORed mask of (from "man mount"):
+// 0 success
+// 1 incorrect invocation or permissions
+// 2 system error (out of memory, cannot fork, no more loop devices)
+// 4 internal mount bug or missing nfs support in mount
+// 8 user interrupt
+//16 problems writing or locking /etc/mtab
+//32 mount failure
+//64 some mount succeeded
         return rc;
 }