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: 1383593
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/15628
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

5 files changed, 51 insertions, 10 deletions

diff --git a/api/src/gfapi.aliases b/api/src/gfapi.aliases
index b37665f0588..0dead255487 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
 
@@ -153,3 +153,5 @@ _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
diff --git a/api/src/gfapi.map b/api/src/gfapi.map
index f38ef024181..ca19baef896 100644
--- a/api/src/gfapi.map
+++ b/api/src/gfapi.map
@@ -186,3 +186,8 @@ GFAPI_3.7.16 {
 		glfs_upcall_inode_get_oldpobject;
 		glfs_upcall_inode_get_oldpstat;
 } GFAPI_3.7.15;
+
+GFAPI_3.7.17 {
+	global:
+		glfs_realpath;
+} GFAPI_3.7.16;
diff --git a/api/src/glfs-fops.c b/api/src/glfs-fops.c
index 0fbcde395ea..be1077a2760 100644
--- a/api/src/glfs-fops.c
+++ b/api/src/glfs-fops.c
@@ -4005,9 +4005,11 @@ 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;
@@ -4022,8 +4024,20 @@ 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;
@@ -4054,9 +4068,11 @@ 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);
@@ -4067,7 +4083,22 @@ 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 b53af35b158..79504e0e07e 100644
--- a/api/src/glfs.h
+++ b/api/src/glfs.h
@@ -757,9 +757,11 @@ 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).
  */