/*
* 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"
#include <unistd.h>
+#include <string.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h> /* For mode constants */
#include <fcntl.h> /* For O_* constants */
#include <assert.h>
-#include <ust/align.h>
+#include <stdio.h>
+#include <signal.h>
+#include <dirent.h>
+#include <lttng/align.h>
+#include <helper.h>
+#include <limits.h>
+#include <helper.h>
+/* FIXME: Include UUID the proper way, e.g. config.h... */
+#include <uuid/uuid.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)
{
return table;
}
+/*
+ * Generate a unique name with the desired prefix.
+ * Pattern is as follow: prefix-pid-uuid.
+ * Caller is responsible of freeing the resulting string.
+ */
+static
+char *gen_unique_name(const char *prefix)
+{
+ int written;
+ pid_t pid;
+ uuid_t uuid;
+ char uuid_str[37];
+ char tmp_name[NAME_MAX];
+ char *name;
+
+ if (!prefix)
+ return NULL;
+
+ pid = getpid();
+
+ uuid_generate(uuid);
+ uuid_unparse(uuid, uuid_str);
+
+ written = snprintf(tmp_name, NAME_MAX,
+ "%s-%d-%s", prefix, pid, uuid_str);
+
+ if (written < 0 || written >= NAME_MAX)
+ return NULL;
+
+ name = zmalloc(written + 1);
+
+ if (!name)
+ return NULL;
+
+ return strncpy(name, tmp_name, written);
+}
+
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, ret, sigblocked = 0;
struct shm_object *obj;
char *memory_map;
+ const char *base_shm = "/dev/shm/";
+ const char *base_path = "/tmp/lttng-fds/";
+ const char *waitfd_prefix = "ust-wait";
+ const char *shm_prefix = "ust-shm";
+
+ char *wait_pipe_path, *wait_pipe_file;
+ char *shm_path, *shm_symlink_path, *shm_file;
+
+ char tmp_name[NAME_MAX] = "ust-shm-tmp-XXXXXX";
+
+ sigset_t all_sigs, orig_sigs;
+
if (table->allocated_len >= table->size)
return NULL;
- obj = &table->objects[table->allocated_len++];
+ obj = &table->objects[table->allocated_len];
- /* wait_fd: create pipe */
- ret = pipe(waitfd);
- if (ret < 0) {
- PERROR("pipe");
- goto error_pipe;
+ wait_pipe_file = gen_unique_name(waitfd_prefix);
+
+ if (!wait_pipe_file) {
+ goto error_gen_unique_wait;
}
- for (i = 0; i < 2; i++) {
- ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC);
- if (ret < 0) {
- PERROR("fcntl");
- goto error_fcntl;
- }
+
+ wait_pipe_path = zmalloc(strlen(base_path)
+ + strlen(wait_pipe_file) + 1);
+
+ if (!wait_pipe_path) {
+ free(wait_pipe_file);
+ goto error_wait_alloc;
}
- /* The write end of the pipe needs to be non-blocking */
- ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK);
+
+ strncat(wait_pipe_path, base_path, strlen(base_path));
+ strncat(wait_pipe_path, wait_pipe_file, strlen(wait_pipe_file));
+
+ free(wait_pipe_file);
+
+ /* wait_fd: create named pipe */
+ ret = mkfifo(wait_pipe_path, 0777);
if (ret < 0) {
- PERROR("fcntl");
- goto error_fcntl;
+ PERROR("mkfifo");
+ goto error_mkfifo;
}
- *obj->wait_fd = *waitfd;
+
+ obj->wait_fd[0] = -1;
+ obj->wait_fd[1] = -1;
+ obj->wait_pipe_path = wait_pipe_path;
/* shm_fd: create shm */
/*
- * Allocate shm, and immediately unlink its shm oject, keeping
- * only the file descriptor as a reference to the object. If it
- * already exists (caused by short race window during which the
- * global object exists in a concurrent shm_open), simply retry.
+ * Theoretically, we could leak a shm if the application crashes
+ * between open and unlink. Disable signals on this thread for
+ * increased safety against this scenario.
+ */
+ sigfillset(&all_sigs);
+ ret = pthread_sigmask(SIG_BLOCK, &all_sigs, &orig_sigs);
+ if (ret == -1) {
+ PERROR("pthread_sigmask");
+ goto error_pthread_sigmask;
+ }
+ sigblocked = 1;
+
+ /*
* We specifically do _not_ use the / at the beginning of the
* pathname so that some OS implementations can keep it local to
* the process (POSIX leaves this implementation-defined).
*/
do {
- shmfd = shm_open("ust-shm-tmp",
+ /*
+ * Using mktemp filename with O_CREAT | O_EXCL open
+ * flags.
+ */
+ mktemp(tmp_name);
+ if (tmp_name[0] == '\0') {
+ PERROR("mktemp");
+ goto error_shm_open;
+ }
+ shmfd = shm_open(tmp_name,
O_CREAT | O_EXCL | O_RDWR, 0700);
- } while (shmfd < 0 && errno == EEXIST);
+ } while (shmfd < 0 && (errno == EEXIST || errno == EACCES));
if (shmfd < 0) {
PERROR("shm_open");
goto error_shm_open;
}
- ret = shm_unlink("ust-shm-tmp");
+
+ sigblocked = 0;
+ ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL);
+ if (ret == -1) {
+ PERROR("pthread_sigmask");
+ goto error_sigmask_release;
+ }
+
+ /* Create unique symlink to shm */
+ shm_path = zmalloc(strlen(base_shm) + strlen(tmp_name) + 1);
+
+ if (!shm_path) {
+ goto error_shm_alloc;
+ }
+
+ strncat(shm_path, base_shm, strlen(base_shm));
+ strncat(shm_path, tmp_name, strlen(tmp_name));
+
+ shm_file = gen_unique_name(shm_prefix);
+
+ if (!shm_file) {
+ free(shm_path);
+ goto error_gen_unique_shm;
+ }
+
+ shm_symlink_path = zmalloc(strlen(base_path) + strlen(shm_file) + 1);
+
+ if (!shm_symlink_path) {
+ free(shm_path);
+ free(shm_file);
+ goto error_symlink_alloc;
+ }
+
+ strncat(shm_symlink_path, base_path, strlen(base_path));
+ strncat(shm_symlink_path, shm_file, strlen(shm_file));
+
+ free(shm_file);
+
+ ret = symlink(shm_path, shm_symlink_path);
+ if (ret < 0) {
+ PERROR("symlink");
+ free(shm_path);
+ free(shm_symlink_path);
+ goto error_symlink_shm;
+ }
+
+ free(shm_path);
+
+ ret = zero_file(shmfd, memory_map_size);
if (ret) {
- PERROR("shm_unlink");
- goto error_unlink;
+ PERROR("zero_file");
+ goto error_zero_file;
}
ret = ftruncate(shmfd, memory_map_size);
if (ret) {
goto error_ftruncate;
}
obj->shm_fd = shmfd;
+ obj->shm_path = shm_symlink_path;
/* memory_map: mmap */
memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
obj->memory_map = memory_map;
obj->memory_map_size = memory_map_size;
obj->allocated_len = 0;
+ obj->index = table->allocated_len++;
+
return obj;
error_mmap:
error_ftruncate:
-error_unlink:
+error_zero_file:
+ free(shm_symlink_path);
+error_symlink_shm:
+error_symlink_alloc:
+error_gen_unique_shm:
+error_shm_alloc:
+error_sigmask_release:
ret = close(shmfd);
if (ret) {
PERROR("close");
assert(0);
}
error_shm_open:
-error_fcntl:
- for (i = 0; i < 2; i++) {
- ret = close(waitfd[i]);
- if (ret) {
- PERROR("close");
- assert(0);
+ if (sigblocked) {
+ ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL);
+ if (ret == -1) {
+ PERROR("pthread_sigmask");
}
}
-error_pipe:
- free(obj);
+error_pthread_sigmask:
+error_mkfifo:
+ free(wait_pipe_path);
+error_wait_alloc:
+error_gen_unique_wait:
+ return NULL;
+}
+
+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
{
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);
+ }
+ }
+
+ if (obj->shm_path) {
+ free(obj->shm_path);
+ }
+
for (i = 0; i < 2; i++) {
+ if (obj->wait_fd[i] < 0)
+ continue;
ret = close(obj->wait_fd[i]);
if (ret) {
PERROR("close");
assert(0);
}
}
+
+ if (obj->wait_pipe_path) {
+ free(obj->wait_pipe_path);
+ }
}
void shm_object_table_destroy(struct shm_object_table *table)
projects / lttng-ust.git / blobdiff