quick-read: Fix dirname(3) usage

glibc dirname() modify the string it is given and returns it.
glusterfs takes this behavior for granted, and assume that if it
gives a malloc'ed string to dirname(), then it can free()) the
return value.

Here is what SUSv2 says:
http://opengroup.org/onlinepubs/007908799/xsh/dirname.html
"The dirname() function may modify the string pointed to by path,
and may return a pointer to static storage"

At least NetBSD returns a static storage. glusterfs will return it to
a calling function that has the responsability to free it, causing
a SIGSEGV.

Thanks to: Emmanuel Dreyfus <manu@netbsd.org>

Change-Id: I8b1b946a005ee487b4b9fb23c0f85a41facfe7c4
BUG: 2923
Reviewed-on: http://review.gluster.com/52
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@gluster.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/xlators/performance/quick-read/src/quick-read.c b/xlators/performance/quick-read/src/quick-read.c
index 163285a91..1ddc4e8f7 100644
--- a/xlators/performance/quick-read/src/quick-read.c
+++ b/xlators/performance/quick-read/src/quick-read.c
@@ -83,6 +83,7 @@ qr_loc_fill (loc_t *loc, inode_t *inode, char *path)
 {
         int32_t  ret    = -1;
         char    *parent = NULL;
+	char	*path_copy = NULL;
 
         if ((loc == NULL) || (inode == NULL) || (path == NULL)
             || (inode->table == NULL)) {
@@ -95,13 +96,13 @@ qr_loc_fill (loc_t *loc, inode_t *inode, char *path)
         loc->path = gf_strdup (path);
         loc->ino = inode->ino;
 
-        parent = gf_strdup (path);
-        if (parent == NULL) {
+        path_copy = gf_strdup (path);
+        if (path_copy == NULL) {
                 ret = -1;
                 goto out;
         }
 
-        parent = dirname (parent);
+        parent = dirname (path_copy);
 
         loc->parent = inode_from_path (inode->table, parent);
         if (loc->parent == NULL) {
@@ -117,8 +118,8 @@ out:
 
         }
 
-        if (parent) {
-                GF_FREE (parent);
+        if (path_copy) {
+                GF_FREE (path_copy);
         }
 
         return ret;