[Cluster-devel] [PATCH] gfs2: Fix handling of mount points with spaces

[Lon Hohberger]

Mount points may contain spaces, tabs, newlines, and the
backslash character according to getmntent(3).  Unfortunately,
while scanning /proc/mounts, mount.gfs2 was not unescaping
the escape sequences, causing mount.gfs2 to not update mtab.

Utilities relying on mtab (e.g. fuser) would consequently
be unable to list processes holding references on the mount
point.

Resolves: rhbz#586100

Signed-off-by: Lon Hohberger <lhh at redhat.com>
---
 gfs2/mount/util.c |   55 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/gfs2/mount/util.c b/gfs2/mount/util.c
index 16fc382..bc26daf 100644
--- a/gfs2/mount/util.c
+++ b/gfs2/mount/util.c
@@ -201,6 +201,48 @@ void parse_opts(struct mount_options *mo)
 	log_debug("parse_opts: locktable = \"%s\"", mo->locktable);
 }
 
+/* Remove escape sequences from mount path.  Per getmntent(3), there are
+   only four escape sequences we need to handle.  Consequently, this does
+   not need to be a general-purpose unescape function */
+
+static int mnt_unescape(char *dest, size_t len, const char *src)
+{
+	unsigned i = 0, j = 0;
+	size_t srclen;
+	int ret = -1;
+
+	srclen = strlen(src);
+	while (i < srclen) {
+		if (src[i] != '\\') {
+			dest[j] = src[i];
+			++i; ++j;
+			continue;
+		}
+
+		++i;
+		if ((srclen - 3) < i)
+			return -1;
+
+		if (!strncmp(&src[i], "040", 3)) {
+			dest[j] = ' ';
+		} else if (!strncmp(&src[i], "011", 3)) {
+			dest[j] = '\t';
+		} else if (!strncmp(&src[i], "012", 3)) {
+			dest[j] = '\n';
+		} else if (!strncmp(&src[i], "134", 3)) {
+			dest[j] = '\\';
+		} else {
+			return -1;
+		}
+
+		i+=3;
+		j++;
+	}
+
+	return 0;
+}
+
+
 /* - when unmounting, we don't know the dev and need this function to set it;
    we also want to select the _last_ line with a matching dir since it will
    be the top-most fs that the umount(2) will unmount
@@ -212,6 +254,7 @@ void read_proc_mounts(struct mount_options *mo)
 	FILE *file;
 	char line[PATH_MAX];
 	char path[PATH_MAX];
+	char unescaped_path[PATH_MAX];
 	char type[PATH_MAX];
 	char opts[PATH_MAX];
 	char device[PATH_MAX];
@@ -234,8 +277,16 @@ void read_proc_mounts(struct mount_options *mo)
 	while (fgets(line, PATH_MAX, file)) {
 		if (sscanf(line, "%s %s %s %s", device, path, type, opts) != 4)
 			continue;
-		if (strcmp(path, mo->dir))
-			continue;
+		if (strcmp(path, mo->dir)) {
+			if (!strchr(path, '\\'))
+				continue;
+			/* /proc/mounts entry may have escaped spaces */
+			if (mnt_unescape(unescaped_path, sizeof(unescaped_path),
+					 path) < 0)
+				continue;
+			if (strcmp(unescaped_path, mo->dir))
+				continue;
+		}
 		if (mo->dev[0]) {
 			if (stat(device, &st_mounts_dev))
 				continue;
-- 
1.6.2.5