Fix: don't SIGBUS when filesystem is full

[lttng-ust.git] / libringbuffer / shm.c

diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index ae63b004fd50723cd9c73511049bb8d042928f59..79977017904308c4f5c05046f176caa7e07fb612 100644 (file)
--- a/libringbuffer/shm.c
+++ b/libringbuffer/shm.c
@@ -1,9 +1,21 @@
 /*
  * libringbuffer/shm.c
  *
- * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
- * Dual LGPL v2.1/GPL v2 license.
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "shm.h"
@@ -16,7 +28,48 @@
 #include <stdio.h>
 #include <signal.h>
 #include <dirent.h>
-#include <ust/align.h>
+#include <lttng/align.h>
+#include <helper.h>
+#include <limits.h>
+#include <helper.h>
+
+/*
+ * Ensure we have the required amount of space available by writing 0
+ * into the entire buffer. Not doing so can trigger SIGBUS when going
+ * beyond the available shm space.
+ */
+static
+int zero_file(int fd, size_t len)
+{
+       ssize_t retlen;
+       size_t written = 0;
+       char *zeropage;
+       long pagelen;
+       int ret;
+
+       pagelen = sysconf(_SC_PAGESIZE);
+       if (pagelen < 0)
+               return (int) pagelen;
+       zeropage = calloc(pagelen, 1);
+       if (!zeropage)
+               return -ENOMEM;
+
+       while (len > written) {
+               do {
+                       retlen = write(fd, zeropage,
+                               min_t(size_t, pagelen, len - written));
+               } while (retlen == -1UL && errno == EINTR);
+               if (retlen < 0) {
+                       ret = (int) retlen;
+                       goto error;
+               }
+               written += retlen;
+       }
+       ret = 0;
+error:
+       free(zeropage);
+       return ret;
+}
 
 struct shm_object_table *shm_object_table_create(size_t max_nb_obj)
 {
@@ -114,6 +167,11 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
                PERROR("pthread_sigmask");
                goto error_sigmask_release;
        }
+       ret = zero_file(shmfd, memory_map_size);
+       if (ret) {
+               PERROR("zero_file");
+               goto error_zero_file;
+       }
        ret = ftruncate(shmfd, memory_map_size);
        if (ret) {
                PERROR("ftruncate");
@@ -138,6 +196,7 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
 error_mmap:
 error_ftruncate:
 error_shm_release:
+error_zero_file:
 error_sigmask_release:
        ret = close(shmfd);
        if (ret) {
@@ -203,17 +262,23 @@ void shmp_object_destroy(struct shm_object *obj)
 {
        int ret, i;
 
-        ret = munmap(obj->memory_map, obj->memory_map_size);
-        if (ret) {
-                PERROR("umnmap");
-                assert(0);
-        }
-       ret = close(obj->shm_fd);
-       if (ret) {
-               PERROR("close");
-               assert(0);
+       if (!obj->is_shadow) {
+               ret = munmap(obj->memory_map, obj->memory_map_size);
+               if (ret) {
+                       PERROR("umnmap");
+                       assert(0);
+               }
+       }
+       if (obj->shm_fd >= 0) {
+               ret = close(obj->shm_fd);
+               if (ret) {
+                       PERROR("close");
+                       assert(0);
+               }
        }
        for (i = 0; i < 2; i++) {
+               if (obj->wait_fd[i] < 0)
+                       continue;
                ret = close(obj->wait_fd[i]);
                if (ret) {
                        PERROR("close");