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, 12 insertions, 14 deletions

diff --git a/xlators/features/bit-rot/src/stub/bit-rot-stub-helpers.c b/xlators/features/bit-rot/src/stub/bit-rot-stub-helpers.c
index 7bd270d1513..09f556db10b 100644
--- a/xlators/features/bit-rot/src/stub/bit-rot-stub-helpers.c
+++ b/xlators/features/bit-rot/src/stub/bit-rot-stub-helpers.c
@@ -465,15 +465,15 @@ static int
 br_stub_fill_readdir (fd_t *fd, br_stub_fd_t *fctx, DIR *dir, off_t off,
                       size_t size, gf_dirent_t *entries)
 {
-        off_t     in_case = -1;
-        off_t     last_off = 0;
-        size_t    filled = 0;
-        int       count = 0;
-        char      entrybuf[sizeof(struct dirent) + 256 + 8];
-        struct dirent  *entry          = NULL;
-        int32_t              this_size      = -1;
-        gf_dirent_t          *this_entry     = NULL;
-        xlator_t             *this = NULL;
+        off_t          in_case = -1;
+        off_t          last_off = 0;
+        size_t         filled = 0;
+        int            count = 0;
+        int32_t        this_size      = -1;
+        gf_dirent_t   *this_entry     = NULL;
+        xlator_t      *this           = NULL;
+        struct dirent *entry          = NULL;
+        struct dirent  scratch[2]     = {{0,},};
 
         this = THIS;
         if (!off) {
@@ -507,10 +507,8 @@ br_stub_fill_readdir (fd_t *fd, br_stub_fd_t *fctx, DIR *dir, off_t off,
                 }
 
                 errno = 0;
-                entry = NULL;
-                readdir_r (dir, (struct dirent *)entrybuf, &entry);
-
-                if (!entry) {
+                entry = sys_readdir (dir, scratch);
+                if (!entry || errno != 0) {
                         if (errno == EBADF) {
                                 gf_msg (THIS->name, GF_LOG_WARNING, 0,
                                         BRS_MSG_BAD_OBJECT_DIR_READ_FAIL,
@@ -579,7 +577,7 @@ br_stub_fill_readdir (fd_t *fd, br_stub_fd_t *fctx, DIR *dir, off_t off,
                 count++;
         }
 
-        if ((!sys_readdir (dir) && (errno == 0))) {
+        if ((!sys_readdir (dir, scratch) && (errno == 0))) {
                 /* Indicate EOF */
                 errno = ENOENT;
                 /* Remember EOF offset for later detection */