Move to kernel style SPDX license identifiers

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

diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index 44a830af20446142f8e21177b5187e8dfd6d4af0..3dbb9f4928a6d81b43c01fc1dbd4dbd3620ebf0c 100644 (file)
--- a/libringbuffer/shm.c
+++ b/libringbuffer/shm.c
@@ -1,25 +1,10 @@
 /*
- * libringbuffer/shm.c
+ * SPDX-License-Identifier: LGPL-2.1-only
  *
  * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * 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
  */
 
 #define _LGPL_SOURCE
-#include <config.h>
 #include "shm.h"
 #include <unistd.h>
 #include <fcntl.h>
@@ -129,25 +114,35 @@ struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table,
        }
        memcpy(obj->wait_fd, waitfd, sizeof(waitfd));
 
-       /* create shm */
+       /*
+        * Set POSIX shared memory object size
+        *
+        * First, use ftruncate() to set its size, some implementations won't
+        * allow writes past the size set by ftruncate.
+        * Then, use write() to fill it with zeros, this allows us to fully
+        * allocate it and detect a shortage of shm space without dealing with
+        * a SIGBUS.
+        */
 
        shmfd = stream_fd;
-       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");
                goto error_ftruncate;
        }
+       ret = zero_file(shmfd, memory_map_size);
+       if (ret) {
+               PERROR("zero_file");
+               goto error_zero_file;
+       }
+
        /*
         * Also ensure the file metadata is synced with the storage by using
-        * fsync(2).
+        * fsync(2). Some platforms don't allow fsync on POSIX shm fds, ignore
+        * EINVAL accordingly.
         */
        ret = fsync(shmfd);
-       if (ret) {
+       if (ret && errno != EINVAL) {
                PERROR("fsync");
                goto error_fsync;
        }
@@ -329,11 +324,6 @@ struct shm_object *shm_object_table_append_shm(struct shm_object_table *table,
        obj->shm_fd = shm_fd;
        obj->shm_fd_ownership = 1;
 
-       ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC);
-       if (ret < 0) {
-               PERROR("fcntl");
-               goto error_fcntl;
-       }
        /* The write end of the pipe needs to be non-blocking */
        ret = fcntl(obj->wait_fd[1], F_SETFL, O_NONBLOCK);
        if (ret < 0) {
@@ -524,6 +514,6 @@ struct shm_ref zalloc_shm(struct shm_object *obj, size_t len)
 
 void align_shm(struct shm_object *obj, size_t align)
 {
-       size_t offset_len = offset_align(obj->allocated_len, align);
+       size_t offset_len = lttng_ust_offset_align(obj->allocated_len, align);
        obj->allocated_len += offset_len;
 }