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/*
* Ouroboros - Copyright (C) 2016
*
* Ring buffer for application processes
*
* Dimitri Staessens <dimitri.staessens@intec.ugent.be>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <ouroboros/shm_ap_rbuff.h>
#define OUROBOROS_PREFIX "shm_ap_rbuff"
#include <ouroboros/logs.h>
#include <pthread.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>
#include <stdbool.h>
#include <errno.h>
#define SHM_RBUFF_FILE_SIZE (SHM_RBUFF_SIZE * sizeof(struct rb_entry) \
+ 2 * sizeof(size_t) + sizeof(pthread_mutex_t))
#define shm_rbuff_used(rb)((*rb->ptr_head + SHM_RBUFF_SIZE - *rb->ptr_tail) \
& (SHM_RBUFF_SIZE - 1))
#define shm_rbuff_free(rb)(shm_rbuff_used(rb) + 1 < SHM_RBUFF_SIZE)
struct shm_ap_rbuff {
struct rb_entry * shm_base; /* start of entry */
size_t * ptr_head; /* start of ringbuffer head */
size_t * ptr_tail; /* start of ringbuffer tail */
pthread_mutex_t * shm_mutex; /* lock all free space in shm */
pid_t pid; /* pid to which this rb belongs */
int fd;
};
struct shm_ap_rbuff * shm_ap_rbuff_create()
{
struct shm_ap_rbuff * rb;
int shm_fd;
struct rb_entry * shm_base;
pthread_mutexattr_t attr;
char fn[25];
sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", getpid());
rb = malloc(sizeof(*rb));
if (rb == NULL) {
LOG_DBGF("Could not allocate struct.");
return NULL;
}
shm_fd = shm_open(fn, O_CREAT | O_EXCL | O_RDWR, 0666);
if (shm_fd == -1) {
LOG_DBGF("Failed creating ring buffer.");
free(rb);
return NULL;
}
if (lseek(shm_fd, SHM_RBUFF_FILE_SIZE - 1, SEEK_SET) < 0) {
LOG_DBGF("Failed to extend ringbuffer.");
free(rb);
return NULL;
}
if (write(shm_fd, "", 1) != 1) {
LOG_DBGF("Failed to finalise extension of ringbuffer.");
free(rb);
return NULL;
}
shm_base = mmap(NULL,
SHM_RBUFF_FILE_SIZE,
PROT_READ | PROT_WRITE,
MAP_SHARED,
shm_fd,
0);
if (shm_base == MAP_FAILED) {
LOG_DBGF("Failed to map shared memory.");
if (close(shm_fd) == -1)
LOG_DBGF("Failed to close invalid shm.");
if (shm_unlink(fn) == -1)
LOG_DBGF("Failed to remove invalid shm.");
free(rb);
return NULL;
}
rb->shm_base = shm_base;
rb->ptr_head = (size_t *) (rb->shm_base + SHM_RBUFF_SIZE);
rb->ptr_tail = rb->ptr_head + 1;
rb->shm_mutex = (pthread_mutex_t *) (rb->ptr_tail + 1);
pthread_mutexattr_init(&attr);
pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
pthread_mutex_init(rb->shm_mutex, &attr);
*rb->ptr_head = 0;
*rb->ptr_tail = 0;
rb->fd = shm_fd;
rb->pid = getpid();
return rb;
}
struct shm_ap_rbuff * shm_ap_rbuff_open(pid_t pid)
{
struct shm_ap_rbuff * rb;
int shm_fd;
struct rb_entry * shm_base;
char fn[25];
sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", pid);
rb = malloc(sizeof(*rb));
if (rb == NULL) {
LOG_DBGF("Could not allocate struct.");
return NULL;
}
shm_fd = shm_open(fn, O_RDWR, 0666);
if (shm_fd == -1) {
LOG_DBGF("Failed opening shared memory %s.", fn);
return NULL;
}
shm_base = mmap(NULL,
SHM_RBUFF_FILE_SIZE,
PROT_READ | PROT_WRITE,
MAP_SHARED,
shm_fd,
0);
if (shm_base == MAP_FAILED) {
LOG_DBGF("Failed to map shared memory.");
if (close(shm_fd) == -1)
LOG_DBGF("Failed to close invalid shm.");
if (shm_unlink(fn) == -1)
LOG_DBGF("Failed to remove invalid shm.");
free(rb);
return NULL;
}
rb->shm_base = shm_base;
rb->ptr_head = (size_t *) (rb->shm_base + SHM_RBUFF_SIZE);
rb->ptr_tail = rb->ptr_head + 1;
rb->shm_mutex = (pthread_mutex_t *) (rb->ptr_tail + 1);
rb->fd = shm_fd;
rb->pid = pid;
return rb;
}
void shm_ap_rbuff_close(struct shm_ap_rbuff * rb)
{
if (rb == NULL) {
LOG_DBGF("Bogus input. Bugging out.");
return;
}
if (munmap(rb->shm_base, SHM_RBUFF_FILE_SIZE) == -1)
LOG_DBGF("Couldn't unmap shared memory.");
free(rb);
}
void shm_ap_rbuff_destroy(struct shm_ap_rbuff * rb)
{
char fn[25];
if (rb == NULL) {
LOG_DBGF("Bogus input. Bugging out.");
return;
}
if (rb->pid != getpid()) {
LOG_ERR("Tried to destroy other AP's rbuff.");
return;
}
sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", rb->pid);
if (munmap(rb->shm_base, SHM_RBUFF_FILE_SIZE) == -1)
LOG_DBGF("Couldn't unmap shared memory.");
if (shm_unlink(fn) == -1)
LOG_DBGF("Failed to unlink shm.");
free(rb);
}
int shm_ap_rbuff_write(struct shm_ap_rbuff * rb, struct rb_entry * e)
{
struct rb_entry * pos;
if (rb == NULL || e == NULL)
return -1;
pthread_mutex_lock(rb->shm_mutex);
if (!shm_rbuff_free(rb)) {
pthread_mutex_unlock(rb->shm_mutex);
return -1;
}
pos = rb->shm_base + *rb->ptr_head;
*pos = *e;
*rb->ptr_head = (*rb->ptr_head + 1) & (SHM_RBUFF_SIZE -1);
pthread_mutex_unlock(rb->shm_mutex);
return 0;
}
struct rb_entry * shm_ap_rbuff_read(struct shm_ap_rbuff * rb)
{
struct rb_entry * e = NULL;
if (rb == NULL)
return NULL;
pthread_mutex_lock(rb->shm_mutex);
if (shm_rbuff_used(rb) == 0) {
pthread_mutex_unlock(rb->shm_mutex);
return NULL;
}
e = malloc(sizeof(*e));
if (e == NULL) {
pthread_mutex_unlock(rb->shm_mutex);
return NULL;
}
*e = *(rb->shm_base + *rb->ptr_tail);
*rb->ptr_tail = (*rb->ptr_tail + 1) & (SHM_RBUFF_SIZE -1);
pthread_mutex_unlock(rb->shm_mutex);
return e;
}
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