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, 21 insertions, 20 deletions

diff --git a/tools/gfind_missing_files/gcrawler.c b/tools/gfind_missing_files/gcrawler.c
index 35772b51582..02b644a1a77 100644
--- a/tools/gfind_missing_files/gcrawler.c
+++ b/tools/gfind_missing_files/gcrawler.c
@@ -306,12 +306,12 @@ xworker_do_crawl (struct xwork *xwork, struct dirjob *job)
         int             ret = -1;
         int             boff;
         int             plen;
-        struct dirent  *result;
-        char            dbuf[512];
         char           *path = NULL;
         struct dirjob  *cjob = NULL;
         struct stat     statbuf = {0,};
-        char            gfid_path[4096] = {0,};
+        struct dirent  *entry;
+        struct dirent   scratch[2] = {{0,},};
+        char            gfid_path[PATH_MAX] = {0,};
 
 
         plen = strlen (job->dirname) + 256 + 2;
@@ -329,27 +329,29 @@ xworker_do_crawl (struct xwork *xwork, struct dirjob *job)
         boff = sprintf (path, "%s/", job->dirname);
 
         for (;;) {
-                ret = readdir_r (dirp, (struct dirent *)dbuf, &result);
-                if (ret) {
-                        err ("readdir_r(%s): %s\n", job->dirname,
-                             strerror (errno));
-                        goto out;
-                }
-
-                if (!result) /* EOF */
+                errno = 0;
+                entry = sys_readdir (dirp, scratch);
+                if (!entry || errno != 0) {
+                        if (errno != 0) {
+                                err ("readdir(%s): %s\n", job->dirname,
+                                     strerror (errno));
+                                ret = errno;
+                                goto out;
+                        }
                         break;
+                }
 
-                if (result->d_ino == 0)
+                if (entry->d_ino == 0)
                         continue;
 
-                if (skip_name (job->dirname, result->d_name))
+                if (skip_name (job->dirname, entry->d_name))
                         continue;
 
                 /* It is sure that, children and grandchildren of .glusterfs
                  * are directories, just add them to global queue.
                  */
-                if (skip_stat (job, result->d_name)) {
-                        strncpy (path + boff, result->d_name, (plen-boff));
+                if (skip_stat (job, entry->d_name)) {
+                        strncpy (path + boff, entry->d_name, (plen-boff));
                         cjob = dirjob_new (path, job);
                         if (!cjob) {
                                 err ("dirjob_new(%s): %s\n",
@@ -361,13 +363,12 @@ xworker_do_crawl (struct xwork *xwork, struct dirjob *job)
                         continue;
                 }
 
-                strcpy (gfid_path, slavemnt);
-                strcat (gfid_path, "/.gfid/");
-                strcat (gfid_path, result->d_name);
+                (void) snprintf (gfid_path, sizeof(gfid_path), "%s/.gfid/%s",
+                                 slavemnt, entry->d_name);
                 ret = sys_lstat (gfid_path, &statbuf);
 
                 if (ret && errno == ENOENT) {
-                        out ("%s\n", result->d_name);
+                        out ("%s\n", entry->d_name);
                         BUMP (skipped_gfids);
                 }
 
@@ -381,7 +382,7 @@ xworker_do_crawl (struct xwork *xwork, struct dirjob *job)
         ret = 0;
 out:
         if (dirp)
-                sys_closedir (dirp);
+                (void) sys_closedir (dirp);
 
         return ret;
 }