gfapi: warn when glfs_realpath() returned malloc'd memory

glfs_realpath() may return memory allocated with malloc(). Depending on
the memory allocator that the application uses, calling free() on the
returned string can cause segmentation faults or other problems.

Functions that allocate memory, need to match the free'ing of the same
memory allocator and memory accounting. glibc/malloc and jemalloc/free
do not match together (other allocators could probably trigger these
problems as well).

Applications need to provide a pre-allocated buffer, or in case
glfs_realpath() allocates the memory, glfs_free() should be used to free
it.

Cherry picked from commit 85e959052148ec481823d55c8b91cdee36da2b43:
> Change-Id: I5d721a7425674aa700db8a7a436cbedb95a5927f
> BUG: 1370931
> Signed-off-by: Niels de Vos <ndevos@redhat.com>
> Reviewed-on: http://review.gluster.org/15332
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

Change-Id: I5d721a7425674aa700db8a7a436cbedb95a5927f
BUG: 1383591
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/15621
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

5 files changed, 50 insertions, 10 deletions

diff --git a/api/src/gfapi.aliases b/api/src/gfapi.aliases
index ac89d35df6b..74ef4d3442d 100644
--- a/api/src/gfapi.aliases
+++ b/api/src/gfapi.aliases
@@ -82,7 +82,7 @@ _pub_glfs_fremovexattr _glfs_fremovexattr$GFAPI_3.4.0
 _pub_glfs_getcwd _glfs_getcwd$GFAPI_3.4.0
 _pub_glfs_chdir _glfs_chdir$GFAPI_3.4.0
 _pub_glfs_fchdir _glfs_fchdir$GFAPI_3.4.0
-_pub_glfs_realpath _glfs_realpath$GFAPI_3.4.0
+_pub_glfs_realpath34 _glfs_realpath$GFAPI_3.4.0
 _pub_glfs_posix_lock _glfs_posix_lock$GFAPI_3.4.0
 _pub_glfs_dup _glfs_dup$GFAPI_3.4.0
 
@@ -153,5 +153,6 @@ _pub_glfs_upcall_inode_get_pobject _glfs_upcall_inode_get_pobject$GFAPI_3.7.16
 _pub_glfs_upcall_inode_get_pstat _glfs_upcall_inode_get_pstat$GFAPI_3.7.16
 _pub_glfs_upcall_inode_get_oldpobject _glfs_upcall_inode_get_oldpobject$GFAPI_3.7.16
 _pub_glfs_upcall_inode_get_oldpstat _glfs_upcall_inode_get_oldpstat$GFAPI_3.7.16
+_pub_glfs_realpath _glfs_realpath$GFAPI_3.7.17
 
 _pub_glfs_ipc _glfs_ipc$GFAPI_4.0.0
diff --git a/api/src/gfapi.map b/api/src/gfapi.map
index bd7ff13fe41..1ae6d4665fc 100644
--- a/api/src/gfapi.map
+++ b/api/src/gfapi.map
@@ -188,6 +188,11 @@ GFAPI_3.7.16 {
 		glfs_upcall_inode_get_oldpstat;
 } GFAPI_3.7.15;
 
+GFAPI_3.7.17 {
+	global:
+		glfs_realpath;
+} GFAPI_3.7.16;
+
 GFAPI_4.0.0 {
 	global:
 		glfs_ipc;
diff --git a/api/src/glfs-fops.c b/api/src/glfs-fops.c
index 9c31502d725..d0bc9b6effa 100644
--- a/api/src/glfs-fops.c
+++ b/api/src/glfs-fops.c
@@ -4050,9 +4050,11 @@ invalid_fs:
 
 GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_fchdir, 3.4.0);
 
+static gf_boolean_t warn_realpath = _gf_true; /* log once */
 
-char *
-pub_glfs_realpath (struct glfs *fs, const char *path, char *resolved_path)
+static char *
+glfs_realpath_common (struct glfs *fs, const char *path, char *resolved_path,
+                      gf_boolean_t warn_deprecated)
 {
 	int              ret = -1;
 	char            *retpath = NULL;
@@ -4067,8 +4069,20 @@ pub_glfs_realpath (struct glfs *fs, const char *path, char *resolved_path)
 
 	if (resolved_path)
 		retpath = resolved_path;
-	else
-		retpath = allocpath = malloc (PATH_MAX + 1);
+        else if (warn_deprecated) {
+                retpath = allocpath = malloc (PATH_MAX + 1);
+                if (warn_realpath) {
+                        warn_realpath = _gf_false;
+                        gf_log (THIS->name, GF_LOG_WARNING, "this application "
+                                "is compiled against an old version of "
+                                "libgfapi, it should use glfs_free() to "
+                                "release the path returned by "
+                                "glfs_realpath()");
+                }
+        } else {
+                retpath = allocpath = GF_CALLOC (1, PATH_MAX + 1,
+                                                 glfs_mt_realpath_t);
+        }
 
 	if (!retpath) {
 		ret = -1;
@@ -4099,9 +4113,11 @@ out:
 	loc_wipe (&loc);
 
 	if (ret == -1) {
-		if (allocpath)
-			free (allocpath);
-		retpath = NULL;
+                if (warn_deprecated && allocpath)
+                        free (allocpath);
+                else if (allocpath)
+                        GF_FREE (allocpath);
+                retpath = NULL;
 	}
 
 	glfs_subvol_done (fs, subvol);
@@ -4112,7 +4128,22 @@ invalid_fs:
 	return retpath;
 }
 
-GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_realpath, 3.4.0);
+
+char *
+pub_glfs_realpath34 (struct glfs *fs, const char *path, char *resolved_path)
+{
+        return glfs_realpath_common (fs, path, resolved_path, _gf_true);
+}
+
+GFAPI_SYMVER_PUBLIC(glfs_realpath34, glfs_realpath, 3.4.0);
+
+char *
+pub_glfs_realpath (struct glfs *fs, const char *path, char *resolved_path)
+{
+        return glfs_realpath_common (fs, path, resolved_path, _gf_false);
+}
+
+GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_realpath, 3.7.17);
 
 
 char *
diff --git a/api/src/glfs-mem-types.h b/api/src/glfs-mem-types.h
index d32d63f0f13..52033360853 100644
--- a/api/src/glfs-mem-types.h
+++ b/api/src/glfs-mem-types.h
@@ -28,6 +28,7 @@ enum glfs_mem_types_ {
         glfs_mt_upcall_entry_t,
 	glfs_mt_acl_t,
         glfs_mt_upcall_inode_t,
+        glfs_mt_realpath_t,
 	glfs_mt_end
 };
 #endif
diff --git a/api/src/glfs.h b/api/src/glfs.h
index 30600a79c32..c81b7cc5d0b 100644
--- a/api/src/glfs.h
+++ b/api/src/glfs.h
@@ -755,9 +755,11 @@ int glfs_chdir (glfs_t *fs, const char *path) __THROW
 int glfs_fchdir (glfs_fd_t *fd) __THROW
         GFAPI_PUBLIC(glfs_fchdir, 3.4.0);
 
-char *glfs_realpath (glfs_t *fs, const char *path, char *resolved_path) __THROW
+char *glfs_realpath34 (glfs_t *fs, const char *path, char *resolved_path) __THROW
         GFAPI_PUBLIC(glfs_realpath, 3.4.0);
 
+char *glfs_realpath (glfs_t *fs, const char *path, char *resolved_path) __THROW
+        GFAPI_PUBLIC(glfs_realpath, 3.7.17);
 /*
  * @cmd and @flock are as specified in man fcntl(2).
  */