[PATCH] change thread-unsafe readdir to thread-safe readdir_r calls

[Steven Dake]

From: Steven Dake <sd...@cast.broked.org>

The readdir POSIX api is not thread safe.  This presents problems in
multithreaded programs that use the libibverbs APIs.  This patch has been
tested with a libibverbs application (http://www.corosync.org) on
Mellanox MT26428 cards.

This updated version uses alloca instead of malloc.

Signed-off-by: Steven Dake <sd...@redhat.com>
---
 src/init.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/init.c b/src/init.c
index 4f0130e..11b8415 100644
--- a/src/init.c
+++ b/src/init.c
@@ -35,6 +35,9 @@
 #  include <config.h>
 #endif /* HAVE_CONFIG_H */
 
+#if HAVE_ALLOCA_H
+#include <alloca.h>
+#endif
 #include <stdlib.h>
 #include <string.h>
 #include <glob.h>
@@ -46,6 +49,7 @@
 #include <sys/time.h>
 #include <sys/resource.h>
 #include <dirent.h>
+#include <stddef.h>
 #include <errno.h>
 
 #include "ibverbs.h"
@@ -85,6 +89,7 @@ static int find_sysfs_devs(void)
        struct ibv_sysfs_dev *sysfs_dev = NULL;
        char value[8];
        int ret = 0;
+       struct dirent *buf;
 
        snprintf(class_path, sizeof class_path, "%s/class/infiniband_verbs",
                 ibv_get_sysfs_path());
@@ -93,7 +98,8 @@ static int find_sysfs_devs(void)
        if (!class_dir)
                return ENOSYS;
 
-       while ((dent = readdir(class_dir))) {
+       buf = alloca(offsetof(struct dirent, d_name) + NAME_MAX + 1);
+       while (readdir_r(class_dir, buf, &dent) == 0 && dent) {
                struct stat buf;
 
                if (dent->d_name[0] == '.')
@@ -294,6 +300,7 @@ static void read_config(void)
 {
        DIR *conf_dir;
        struct dirent *dent;
+       struct dirent *buf;
        char *path;
 
        conf_dir = opendir(IBV_CONFIG_DIR);
@@ -303,7 +310,8 @@ static void read_config(void)
                return;
        }
 
-       while ((dent = readdir(conf_dir))) {
+       buf = alloca(offsetof(struct dirent, d_name) + NAME_MAX + 1);
+       while (readdir_r(conf_dir, buf, &dent) == 0 && dent) {
                struct stat buf;
 
                if (asprintf(&path, "%s/%s", IBV_CONFIG_DIR, dent->d_name) < 0) 
{
-- 
1.6.6.1

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