Fix for re-reading /etc/mtab in zfs_is_mounted()

[zfs.git] / lib / libzfs / libzfs_dataset.c

diff --git a/lib/libzfs/libzfs_dataset.c b/lib/libzfs/libzfs_dataset.c
index 554b0ea..244b687 100644 (file)
--- a/lib/libzfs/libzfs_dataset.c
+++ b/lib/libzfs/libzfs_dataset.c
@@ -629,12 +629,15 @@ libzfs_mnttab_init(libzfs_handle_t *hdl)
            sizeof (mnttab_node_t), offsetof(mnttab_node_t, mtn_node));
 }
 
-void
+int
 libzfs_mnttab_update(libzfs_handle_t *hdl)
 {
        struct mnttab entry;
 
-       rewind(hdl->libzfs_mnttab);
+       /* Reopen MNTTAB to prevent reading stale data from open file */
+       if (freopen(MNTTAB, "r", hdl->libzfs_mnttab) == NULL)
+               return (ENOENT);
+
        while (getmntent(hdl->libzfs_mnttab, &entry) == 0) {
                mnttab_node_t *mtn;
 
@@ -647,6 +650,8 @@ libzfs_mnttab_update(libzfs_handle_t *hdl)
                mtn->mtn_mt.mnt_mntopts = zfs_strdup(hdl, entry.mnt_mntopts);
                avl_add(&hdl->libzfs_mnttab_cache, mtn);
        }
+
+       return (0);
 }
 
 void
@@ -677,13 +682,18 @@ libzfs_mnttab_find(libzfs_handle_t *hdl, const char *fsname,
 {
        mnttab_node_t find;
        mnttab_node_t *mtn;
+       int error;
 
        if (!hdl->libzfs_mnttab_enable) {
                struct mnttab srch = { 0 };
 
                if (avl_numnodes(&hdl->libzfs_mnttab_cache))
                        libzfs_mnttab_fini(hdl);
-               rewind(hdl->libzfs_mnttab);
+
+               /* Reopen MNTTAB to prevent reading stale data from open file */
+               if (freopen(MNTTAB, "r", hdl->libzfs_mnttab) == NULL)
+                       return (ENOENT);
+
                srch.mnt_special = (char *)fsname;
                srch.mnt_fstype = MNTTYPE_ZFS;
                if (getmntany(hdl->libzfs_mnttab, entry, &srch) == 0)
@@ -693,7 +703,8 @@ libzfs_mnttab_find(libzfs_handle_t *hdl, const char *fsname,
        }
 
        if (avl_numnodes(&hdl->libzfs_mnttab_cache) == 0)
-               libzfs_mnttab_update(hdl);
+               if ((error = libzfs_mnttab_update(hdl)) != 0)
+                       return (error);
 
        find.mtn_mt.mnt_special = (char *)fsname;
        mtn = avl_find(&hdl->libzfs_mnttab_cache, &find, NULL);