/*
* libringbuffer/shm.c
*
* 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
*/
#include "shm.h"
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h> /* For mode constants */
#include <fcntl.h> /* For O_* constants */
#include <assert.h>
#include <stdio.h>
#include <signal.h>
#include <dirent.h>
#include <lttng/align.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)
{
struct shm_object_table *table;
table = zmalloc(sizeof(struct shm_object_table) +
max_nb_obj * sizeof(table->objects[0]));
if (!table)
return NULL;
table->size = max_nb_obj;
return table;
}
static
struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table,
size_t memory_map_size,
int stream_fd)
{
int shmfd, waitfd[2], ret, i;
struct shm_object *obj;
char *memory_map;
if (stream_fd < 0)
return NULL;
if (table->allocated_len >= table->size)
return NULL;
obj = &table->objects[table->allocated_len];
/* wait_fd: create pipe */
ret = pipe(waitfd);
if (ret < 0) {
PERROR("pipe");
goto error_pipe;
}
for (i = 0; i < 2; i++) {
ret = fcntl(waitfd[i], 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(waitfd[1], F_SETFL, O_NONBLOCK);
if (ret < 0) {
PERROR("fcntl");
goto error_fcntl;
}
memcpy(obj->wait_fd, waitfd, sizeof(waitfd));
/* create shm */
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;
}
obj->shm_fd_ownership = 0;
obj->shm_fd = shmfd;
/* memory_map: mmap */
memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
MAP_SHARED, shmfd, 0);
if (memory_map == MAP_FAILED) {
PERROR("mmap");
goto error_mmap;
}
obj->type = SHM_OBJECT_SHM;
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_zero_file:
error_fcntl:
for (i = 0; i < 2; i++) {
ret = close(waitfd[i]);
if (ret) {
PERROR("close");
assert(0);
}
}
error_pipe:
return NULL;
}
static
struct shm_object *_shm_object_table_alloc_mem(struct shm_object_table *table,
size_t memory_map_size)
{
struct shm_object *obj;
void *memory_map;
int waitfd[2], i, ret;
if (table->allocated_len >= table->size)
return NULL;
obj = &table->objects[table->allocated_len];
memory_map = zmalloc(memory_map_size);
if (!memory_map)
goto alloc_error;
/* wait_fd: create pipe */
ret = pipe(waitfd);
if (ret < 0) {
PERROR("pipe");
goto error_pipe;
}
for (i = 0; i < 2; i++) {
ret = fcntl(waitfd[i], 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(waitfd[1], F_SETFL, O_NONBLOCK);
if (ret < 0) {
PERROR("fcntl");
goto error_fcntl;
}
memcpy(obj->wait_fd, waitfd, sizeof(waitfd));
/* no shm_fd */
obj->shm_fd = -1;
obj->shm_fd_ownership = 0;
obj->type = SHM_OBJECT_MEM;
obj->memory_map = memory_map;
obj->memory_map_size = memory_map_size;
obj->allocated_len = 0;
obj->index = table->allocated_len++;
return obj;
error_fcntl:
for (i = 0; i < 2; i++) {
ret = close(waitfd[i]);
if (ret) {
PERROR("close");
assert(0);
}
}
error_pipe:
free(memory_map);
alloc_error:
return NULL;
}
struct shm_object *shm_object_table_alloc(struct shm_object_table *table,
size_t memory_map_size,
enum shm_object_type type,
int stream_fd)
{
switch (type) {
case SHM_OBJECT_SHM:
return _shm_object_table_alloc_shm(table, memory_map_size,
stream_fd);
case SHM_OBJECT_MEM:
return _shm_object_table_alloc_mem(table, memory_map_size);
default:
assert(0);
}
return NULL;
}
struct shm_object *shm_object_table_append_shm(struct shm_object_table *table,
int shm_fd, int wakeup_fd, uint32_t stream_nr,
size_t memory_map_size)
{
struct shm_object *obj;
char *memory_map;
int ret;
if (table->allocated_len >= table->size)
return NULL;
/* streams _must_ be received in sequential order, else fail. */
if (stream_nr + 1 != table->allocated_len)
return NULL;
obj = &table->objects[table->allocated_len];
/* wait_fd: set write end of the pipe. */
obj->wait_fd[0] = -1; /* read end is unset */
obj->wait_fd[1] = wakeup_fd;
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) {
PERROR("fcntl");
goto error_fcntl;
}
/* 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->type = SHM_OBJECT_SHM;
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_fcntl:
error_mmap:
return NULL;
}
/*
* Passing ownership of mem to object.
*/
struct shm_object *shm_object_table_append_mem(struct shm_object_table *table,
void *mem, size_t memory_map_size, int wakeup_fd)
{
struct shm_object *obj;
int ret;
if (table->allocated_len >= table->size)
return NULL;
obj = &table->objects[table->allocated_len];
obj->wait_fd[0] = -1; /* read end is unset */
obj->wait_fd[1] = wakeup_fd;
obj->shm_fd = -1;
obj->shm_fd_ownership = 0;
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) {
PERROR("fcntl");
goto error_fcntl;
}
obj->type = SHM_OBJECT_MEM;
obj->memory_map = mem;
obj->memory_map_size = memory_map_size;
obj->allocated_len = memory_map_size;
obj->index = table->allocated_len++;
return obj;
error_fcntl:
return NULL;
}
static
void shmp_object_destroy(struct shm_object *obj)
{
switch (obj->type) {
case SHM_OBJECT_SHM:
{
int ret, i;
ret = munmap(obj->memory_map, obj->memory_map_size);
if (ret) {
PERROR("umnmap");
assert(0);
}
if (obj->shm_fd_ownership) {
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");
assert(0);
}
}
break;
}
case SHM_OBJECT_MEM:
{
int ret, i;
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);
}
}
free(obj->memory_map);
break;
}
default:
assert(0);
}
}
void shm_object_table_destroy(struct shm_object_table *table)
{
int i;
for (i = 0; i < table->allocated_len; i++)
shmp_object_destroy(&table->objects[i]);
free(table);
}
/*
* zalloc_shm - allocate memory within a shm object.
*
* Shared memory is already zeroed by shmget.
* *NOT* multithread-safe (should be protected by mutex).
* Returns a -1, -1 tuple on error.
*/
struct shm_ref zalloc_shm(struct shm_object *obj, size_t len)
{
struct shm_ref ref;
struct shm_ref shm_ref_error = { -1, -1 };
if (obj->memory_map_size - obj->allocated_len < len)
return shm_ref_error;
ref.index = obj->index;
ref.offset = obj->allocated_len;
obj->allocated_len += len;
return ref;
}
void align_shm(struct shm_object *obj, size_t align)
{
size_t offset_len = offset_align(obj->allocated_len, align);
obj->allocated_len += offset_len;
}