X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Fshm.c;h=79977017904308c4f5c05046f176caa7e07fb612;hb=refs%2Fheads%2Fstable-2.0;hp=d86abb98e210fadece1e35a01e55fd7d29a07f90;hpb=8da6cd6d27941d7b3b67ea1878e32a0c20206468;p=lttng-ust.git

diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index d86abb98..79977017 100644
--- 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)
 {
@@ -31,7 +84,7 @@ struct shm_object_table *shm_object_table_create(size_t max_nb_obj)
 struct shm_object *shm_object_table_append(struct shm_object_table *table,
 					   size_t memory_map_size)
 {
-	int shmfd, waitfd[2], ret, i;
+	int shmfd, waitfd[2], ret, i, sigblocked = 0;
 	struct shm_object *obj;
 	char *memory_map;
 	char tmp_name[NAME_MAX] = "ust-shm-tmp-XXXXXX";
@@ -75,6 +128,7 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
 		PERROR("pthread_sigmask");
 		goto error_pthread_sigmask;
 	}
+	sigblocked = 1;
 
 	/*
 	 * Allocate shm, and immediately unlink its shm oject, keeping
@@ -107,10 +161,16 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
 		PERROR("shm_unlink");
 		goto error_shm_release;
 	}
+	sigblocked = 0;
 	ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL);
 	if (ret == -1) {
 		PERROR("pthread_sigmask");
-		goto error_shm_release;
+		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) {
@@ -136,12 +196,20 @@ 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) {
 		PERROR("close");
 		assert(0);
 	}
 error_shm_open:
+	if (sigblocked) {
+		ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL);
+		if (ret == -1) {
+			PERROR("pthread_sigmask");
+		}
+	}
 error_pthread_sigmask:
 error_fcntl:
 	for (i = 0; i < 2; i++) {
@@ -156,22 +224,61 @@ error_pipe:
 	
 }
 
+struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table,
+			int shm_fd, int wait_fd, size_t memory_map_size)
+{
+	struct shm_object *obj;
+	char *memory_map;
+
+	if (table->allocated_len >= table->size)
+		return NULL;
+	obj = &table->objects[table->allocated_len];
+
+	/* wait_fd: set read end of the pipe. */
+	obj->wait_fd[0] = wait_fd;
+	obj->wait_fd[1] = -1;	/* write end is unset. */
+	obj->shm_fd = shm_fd;
+
+	/* memory_map: mmap */
+	memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
+			  MAP_SHARED, shm_fd, 0);
+	if (memory_map == MAP_FAILED) {
+		PERROR("mmap");
+		goto error_mmap;
+	}
+	obj->memory_map = memory_map;
+	obj->memory_map_size = memory_map_size;
+	obj->allocated_len = memory_map_size;
+	obj->index = table->allocated_len++;
+
+	return obj;
+
+error_mmap:
+	return NULL;
+}
+
 static
 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");