core: use readdir(3) with glibc, and associated cleanup

Starting with glibc-2.23 (i.e. what's in Fedora 25), readdir_r(3)
is marked as deprecated. Specifically the function decl in <dirent.h>
has the deprecated attribute, and now warnings are thrown during the
compile on Fedora 25 builds.

The readdir(_r)(3) man page (on Fedora 25 at least) and World+Dog say
that glibc's readdir(3) is, and always has been, MT-SAFE as long as
only one thread is accessing the directory object returned by opendir().
World+Dog also says there is a potential buffer overflow in readdir_r().
World+Dog suggests that it is preferable to simply use readdir(). There's
an implication that eventually readdir_r(3) will be removed from glibc.
POSIX has, apparently deprecated it in the standard, or even removed it
entirely.

Over and above that, our source near the various uses of readdir(_r)(3)
has a few unsafe uses of strcpy()+strcat().

(AFAIK nobody has looked at the readdir(3) implemenation in *BSD to see
if the same is true on those platforms, and we can't be sure of MacOS
even though we know it's based on *BSD.)

Change-Id: I5481f18ba1eebe7ee177895eecc9a80a71b60568
BUG: 1356998
Signed-off-by: Kaleb S. KEITHLEY <kkeithle@redhat.com>
Reviewed-on: http://review.gluster.org/14838
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Kotresh HR <khiremat@redhat.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>

1 files changed, 33 insertions, 33 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-volgen.c b/xlators/mgmt/glusterd/src/glusterd-volgen.c
index b56e9f26379..6a755486d7d 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volgen.c
+++ b/xlators/mgmt/glusterd/src/glusterd-volgen.c
@@ -913,58 +913,59 @@ out:
 static void
 volgen_apply_filters (char *orig_volfile)
 {
-        DIR           *filterdir = NULL;
-        struct dirent  entry = {0,};
-        struct dirent *next = NULL;
-        char          *filterpath = NULL;
-        struct stat    statbuf = {0,};
+        DIR           *filterdir  = NULL;
+        struct dirent *entry      = NULL;
+        struct dirent  scratch[2] = {{0,},};
+        struct stat    statbuf    = {0,};
+        char           filterpath[PATH_MAX] = {0,};
 
         filterdir = sys_opendir (FILTERDIR);
-        if (!filterdir) {
+
+        if (!filterdir)
                 return;
-        }
 
-        while ((readdir_r(filterdir,&entry,&next) == 0) && next) {
-                if (!strncmp(entry.d_name,".",sizeof(entry.d_name))) {
-                        continue;
-                }
-                if (!strncmp(entry.d_name,"..",sizeof(entry.d_name))) {
+        for (;;) {
+
+                errno = 0;
+
+                entry = sys_readdir (filterdir, scratch);
+
+                if (!entry || errno != 0)
+                        break;
+
+                if (strcmp (entry->d_name, ".") == 0 ||
+                    strcmp (entry->d_name, "..") == 0)
                         continue;
-                }
                 /*
                  * d_type isn't guaranteed to be present/valid on all systems,
                  * so do an explicit stat instead.
                  */
-                if (gf_asprintf(&filterpath,"%s/%.*s",FILTERDIR,
-                                sizeof(entry.d_name), entry.d_name) == (-1)) {
-                        continue;
-                }
+                (void) snprintf (filterpath, sizeof(filterpath), "%s/%s",
+                                 FILTERDIR, entry->d_name);
+
                 /* Deliberately use stat instead of lstat to allow symlinks. */
-                if (sys_stat(filterpath, &statbuf) == (-1)) {
-                        goto free_fp;
-                }
-                if (!S_ISREG(statbuf.st_mode)) {
-                        goto free_fp;
-                }
+                if (sys_stat (filterpath, &statbuf) == -1)
+                        continue;
+
+                if (!S_ISREG (statbuf.st_mode))
+                        continue;
                 /*
                  * We could check the mode in statbuf directly, or just skip
                  * this entirely and check for EPERM after exec fails, but this
                  * is cleaner.
                  */
-                if (sys_access(filterpath, X_OK) != 0) {
-                        goto free_fp;
-                }
-                if (runcmd(filterpath,orig_volfile,NULL)) {
+                if (sys_access (filterpath, X_OK) != 0)
+                        continue;
+
+                if (runcmd (filterpath, orig_volfile, NULL)) {
                         gf_msg ("glusterd", GF_LOG_ERROR, 0,
                                 GD_MSG_FILTER_RUN_FAILED,
-                                "failed to run filter %.*s",
-                                (int)sizeof(entry.d_name), entry.d_name);
+                                "failed to run filter %s",
+                                entry->d_name);
                 }
-free_fp:
-                GF_FREE(filterpath);
         }
 
-        sys_closedir (filterdir);
+        (void) sys_closedir (filterdir);
 }
 
 static int
@@ -979,7 +980,6 @@ volgen_write_volfile (volgen_graph_t *graph, char *filename)
 
         if (gf_asprintf (&ftmp, "%s.tmp", filename) == -1) {
                 ftmp = NULL;
-
                 goto error;
         }