don't try to update /etc/mtab unless it is a regular file. #16

pipcet · Apr 18, 2015

That's what the other mount helpers appear to be doing.

Debian switched to keeping a symlink to /proc/mounts in /etc/mtab, but didn't modify setmntent(3) to handle that case gracefully, so the only way to avoid error messages on Debian systems appears to be to lstat() /etc/mtab and check it's not a symbolic link.

libmount goes further and keeps some mount data in /run/mount/utab or $LIBMOUNT_UTAB, but I don't think we need to do that.

pipcet don't try to update /etc/mtab unless it is a regular file. …
That's what the other mount helpers appear to be doing.
a03d9ee

garlick merged commit 6d2ee8c into chaos:master Apr 18, 2015

pipcet deleted the pipcet:ignore-symlinked-mtab branch Apr 18, 2015

@@ @@ -481,8 +481,21 @@ _update_mtab (char *options, char *spec, char *dir) @@
          uid_t saved_euid = geteuid ();
          FILE *f;
          int ret = 0;
+    +    struct stat st;
          struct mntent mnt;
+    +    ret = lstat(_PATH_MOUNTED, &st);
+    +
+    +    /* /etc/mtab can be a symlink to /proc/mounts or
+    +     * /proc/self/mounts, in which case we shouldn't write to it even
+    +     * if /proc isn't mounted.  Return success in that case to avoid a
+    +     * spurious error message. */
+    +    if (ret != 0)
+    +	return 0;
+    +
+    +    if (!S_ISREG(st.st_mode))
+    +	return 1;
+    +
          mnt.mnt_fsname = spec;
          mnt.mnt_dir = dir;
          mnt.mnt_type = "diod";

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don't try to update /etc/mtab unless it is a regular file. #16

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