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, 25 insertions, 28 deletions

diff --git a/xlators/experimental/jbr-server/src/jbr.c b/xlators/experimental/jbr-server/src/jbr.c
index e07c511f4a9..68badb85079 100644
--- a/xlators/experimental/jbr-server/src/jbr.c
+++ b/xlators/experimental/jbr-server/src/jbr.c
@@ -989,17 +989,17 @@ jbr_get_changelog_dir (xlator_t *this, char **cl_dir_p)
 void
 jbr_get_terms (call_frame_t *frame, xlator_t *this)
 {
-        int32_t         op_errno;
-        char            *cl_dir;
-        DIR             *fp             = NULL;
-        struct dirent   *rd_entry;
-        struct dirent   *rd_result;
-        int32_t         term_first      = -1;
-        int32_t         term_contig     = -1;
-        int32_t         term_last       = -1;
-        int             term_num;
-        char            *probe_str;
-        dict_t          *my_xdata       = NULL;
+        int32_t        op_errno      = 0;
+        char          *cl_dir        = NULL;
+        int32_t        term_first    = -1;
+        int32_t        term_contig   = -1;
+        int32_t        term_last     = -1;
+        int            term_num      = 0;
+        char          *probe_str     = NULL;
+        dict_t        *my_xdata      = NULL;
+        DIR           *fp            = NULL;
+        struct dirent *entry         = NULL;
+        struct dirent  scratch[2]    = {{0,},};
 
         op_errno = jbr_get_changelog_dir(this, &cl_dir);
         if (op_errno) {
@@ -1007,12 +1007,6 @@ jbr_get_terms (call_frame_t *frame, xlator_t *this)
         }
         op_errno = ENODATA;     /* Most common error after this. */
 
-        rd_entry = alloca (offsetof(struct dirent, d_name) +
-                           pathconf(cl_dir, _PC_NAME_MAX) + 1);
-        if (!rd_entry) {
-                goto err;
-        }
-
         fp = sys_opendir (cl_dir);
         if (!fp) {
                 op_errno = errno;
@@ -1021,25 +1015,28 @@ jbr_get_terms (call_frame_t *frame, xlator_t *this)
 
         /* Find first and last terms. */
         for (;;) {
-                if (readdir_r(fp, rd_entry, &rd_result) != 0) {
-                        op_errno = errno;
-                        goto err;
-                }
-                if (!rd_result) {
+                errno = 0;
+                entry = sys_readdir (fp, scratch);
+                if (!entry || errno != 0) {
+                        if (errno != 0) {
+                                op_errno = errno;
+                                goto err;
+                        }
                         break;
                 }
-                if (fnmatch("TERM.*", rd_entry->d_name, FNM_PATHNAME) != 0) {
+
+                if (fnmatch("TERM.*", entry->d_name, FNM_PATHNAME) != 0) {
                         continue;
                 }
                 /* +5 points to the character after the period */
-                term_num = atoi(rd_entry->d_name+5);
+                term_num = atoi(entry->d_name+5);
                 gf_msg (this->name, GF_LOG_INFO, 0,
                         J_MSG_GENERIC,
-                        "%s => %d", rd_entry->d_name, term_num);
+                        "%s => %d", entry->d_name, term_num);
                 if (term_num < 0) {
                         gf_msg (this->name, GF_LOG_ERROR, 0,
                                 J_MSG_INVALID,
-                                "invalid term file name %s", rd_entry->d_name);
+                                "invalid term file name %s", entry->d_name);
                         op_errno = EINVAL;
                         goto err;
                 }
@@ -1058,7 +1055,7 @@ jbr_get_terms (call_frame_t *frame, xlator_t *this)
                 goto err;
         }
 
-        sys_closedir (fp);
+        (void) sys_closedir (fp);
         fp = NULL;
 
         /*
@@ -1119,7 +1116,7 @@ jbr_get_terms (call_frame_t *frame, xlator_t *this)
 
 err:
         if (fp) {
-                sys_closedir (fp);
+                (void) sys_closedir (fp);
         }
         if (my_xdata) {
                 dict_unref(my_xdata);