X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fshm.c;h=a6328d5f618fb4474d70b5d5966cf45d5ff4a121;hp=432d07ecea5eb4462d36a6a4727737532e97791f;hb=87597c2c3bbaa1502ad2025cbf16704829f3b464;hpb=ca2eb7f43cf00d12f563905d741a6789c3d130ee

diff --git a/src/bin/lttng-sessiond/shm.c b/src/bin/lttng-sessiond/shm.c
index 432d07ece..a6328d5f6 100644
--- a/src/bin/lttng-sessiond/shm.c
+++ b/src/bin/lttng-sessiond/shm.c
@@ -2,21 +2,21 @@
  * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
  *                       Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License as published by the Free
- * Software Foundation; only version 2 of the License.
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2 only,
+ * as published by the Free Software Foundation.
  *
- * This program 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 General Public License for
- * more details.
+ * This program 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 General Public License for more details.
  *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
- * Place - Suite 330, Boston, MA  02111-1307, USA.
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <fcntl.h>
 #include <limits.h>
 #include <sys/mman.h>
@@ -43,43 +43,22 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
 	int wait_shm_fd, ret;
 	mode_t mode;
 
+	assert(shm_path);
+
 	/* Default permissions */
 	mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
 
-	/* Change owner of the shm path */
+	/*
+	 * Change owner of the shm path.
+	 */
 	if (global) {
-		ret = chown(shm_path, 0, 0);
-		if (ret < 0) {
-			if (errno != ENOENT) {
-				PERROR("chown wait shm");
-				goto error;
-			}
-		}
-
 		/*
-		 * If global session daemon, any application can register so the shm
-		 * needs to be set in read-only mode for others.
+		 * If global session daemon, any application can
+		 * register. Make it initially writeable so applications
+		 * registering concurrently can do ftruncate() by
+		 * themselves.
 		 */
-		mode |= S_IROTH;
-	} else {
-		ret = chown(shm_path, getuid(), getgid());
-		if (ret < 0) {
-			if (errno != ENOENT) {
-				PERROR("chown wait shm");
-				goto error;
-			}
-		}
-	}
-
-	/*
-	 * Set permissions to the shm even if we did not create the shm.
-	 */
-	ret = chmod(shm_path, mode);
-	if (ret < 0) {
-		if (errno != ENOENT) {
-			PERROR("chmod wait shm");
-			goto error;
-		}
+		mode |= S_IROTH | S_IWOTH;
 	}
 
 	/*
@@ -105,13 +84,32 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
 	}
 
 #ifndef __FreeBSD__
-	ret = fchmod(wait_shm_fd, mode);
-	if (ret < 0) {
-		PERROR("fchmod");
-		exit(EXIT_FAILURE);
+	if (global) {
+		ret = fchown(wait_shm_fd, 0, 0);
+		if (ret < 0) {
+			PERROR("fchown");
+			exit(EXIT_FAILURE);
+		}
+		/*
+		 * If global session daemon, any application can
+		 * register so the shm needs to be set in read-only mode
+		 * for others.
+		 */
+		mode &= ~S_IWOTH;
+		ret = fchmod(wait_shm_fd, mode);
+		if (ret < 0) {
+			PERROR("fchmod");
+			exit(EXIT_FAILURE);
+		}
+	} else {
+		ret = fchown(wait_shm_fd, getuid(), getgid());
+		if (ret < 0) {
+			PERROR("fchown");
+			exit(EXIT_FAILURE);
+		}
 	}
 #else
-#warning "FreeBSD does not support setting file mode on shm FD. Remember that for secure use, lttng-sessiond should be started before applications linked on lttng-ust."
+#warning "FreeBSD does not support setting file mode on shm FD."
 #endif
 
 	DBG("Got the wait shm fd %d", wait_shm_fd);
@@ -134,9 +132,19 @@ error:
  */
 char *shm_ust_get_mmap(char *shm_path, int global)
 {
-	size_t mmap_size = sysconf(_SC_PAGE_SIZE);
+	size_t mmap_size;
 	int wait_shm_fd, ret;
 	char *wait_shm_mmap;
+	long sys_page_size;
+
+	assert(shm_path);
+
+	sys_page_size = sysconf(_SC_PAGE_SIZE);
+	if (sys_page_size < 0) {
+		PERROR("sysconf PAGE_SIZE");
+		goto error;
+	}
+	mmap_size = sys_page_size;
 
 	wait_shm_fd = get_wait_shm(shm_path, mmap_size, global);
 	if (wait_shm_fd < 0) {