+/*
+ * Copyright (C) 2006-2011 Andre Noll <maan@systemlinux.org>
+ *
+ * Licensed under the GPL v2. For licencing details see COPYING.
+ */
+
+/** \file ipc.c Inter-process communication and shared memory helpers. */
+
#include "para.h"
#include "error.h"
#include "ipc.h"
#include <sys/ipc.h>
#include <sys/shm.h>
+#include <sys/sem.h>
-
+/**
+ * Define a new mutex.
+ *
+ * \return The identifier for the new mutex on success, a negative error code
+ * on errors.
+ *
+ * \sa semget(2).
+ */
int mutex_new(void)
{
int ret = semget(IPC_PRIVATE, 1, IPC_CREAT | 0666);
- return ret < 0? -E_SEM_GET : ret;
+ return ret < 0? -ERRNO_TO_PARA_ERROR(errno) : ret;
}
-int mutex_remove(int id)
+/**
+ * Destroy a mutex.
+ *
+ * \param id The identifier of the mutex to be destroyed.
+ *
+ * \return Standard.
+ *
+ * \sa semctl(2)
+ */
+int mutex_destroy(int id)
{
int ret = semctl(id, 0, IPC_RMID);
- return ret < 0? -E_SEM_REMOVE : 1;
+ return ret < 0? -ERRNO_TO_PARA_ERROR(errno) : 1;
}
static void para_semop(int id, struct sembuf *sops, int num)
{
- if (semop(id, sops, num) >= 0)
+ do {
+ if (semop(id, sops, num) >= 0)
+ return;
+ } while (errno == EINTR);
+ if (errno == EIDRM) {
+ PARA_CRIT_LOG("semaphore set %d was removed\n", id);
return;
- PARA_WARNING_LOG("semop failed (%s), retrying\n", strerror(errno));
- while (semop(id, sops, num) < 0)
- ; /* nothing */
+ }
+ PARA_EMERG_LOG("fatal semop error %s: pid %d\n", strerror(errno),
+ (int)getpid());
+ exit(EXIT_FAILURE);
}
/**
- * lock the given mutex
+ * Lock the given mutex.
+ *
+ * \param id The identifier of the shared memory area to lock.
*
- * \sa semop(2), struct misc_meta_data
+ * This function either succeeds or aborts.
+ *
+ * \sa semop(2), struct misc_meta_data.
*/
void mutex_lock(int id)
{
}
/**
- * unlock a mutex
+ * Unlock a mutex.
+ *
+ * \param id The identifier of the mutex.
*
- * \sa semop(2), struct misc_meta_data
+ * This function either succeeds or aborts.
+ *
+ * \sa semop(2), struct misc_meta_data.
*/
void mutex_unlock(int id)
{
}
/**
- * create a new shared memory area of given size
- *
- * \sa shmget(2)
+ * Create a new shared memory area of given size.
+ *
+ * \param size The size of the shared memory area to create.
+ *
+ * \return The id of the shared memory array on success, a negative error
+ * code on errors.
+ *
+ * \sa shmget(2).
*/
int shm_new(size_t size)
{
int ret = shmget(IPC_PRIVATE, size, IPC_CREAT | IPC_EXCL | 0600);
- return ret < 0 ? -E_SHM_GET : ret;
+ return ret < 0 ? -ERRNO_TO_PARA_ERROR(errno) : ret;
}
/**
- * destroy the given shared memory area
- * \sa shmctl(2)
- **/
+ * Destroy the given shared memory area.
+ *
+ * \param id The shared memory identifier.
+ *
+ * \return The return value of the underlying shmctl() call on success,
+ * a negative error code on errors.
+ *
+ * \sa shmctl(2).
+ */
int shm_destroy(int id)
{
struct shmid_ds shm_desc;
int ret = shmctl(id, IPC_RMID, &shm_desc);
- return ret < 0? -E_SHM_DESTROY : ret;
+ return ret < 0? -ERRNO_TO_PARA_ERROR(errno) : ret;
}
/**
- * attach a shared memory area
+ * Attach a shared memory segment.
*
- * \sa semop(2)
+ * \param id The identifier of the shared memory segment to attach.
+ * \param mode Either ATTACH_RO (read only) or ATTACH_RW (read/write).
+ * \param result Points to the attached area just attached on success.
+ *
+ * \return Standard.
+ *
+ * \sa shmat(2).
*/
-void *shm_attach(int id, enum shm_attach_mode mode)
+int shm_attach(int id, enum shm_attach_mode mode, void **result)
{
if (mode == ATTACH_RW)
- return shmat(id, NULL, 0);
- return shmat(id, NULL, SHM_RDONLY);
+ *result = shmat(id, NULL, 0);
+ else
+ *result = shmat(id, NULL, SHM_RDONLY);
+ return *result == (void *) -1? -ERRNO_TO_PARA_ERROR(errno) : 1;
}
+
+/**
+ * Detach a shared memory segment.
+ *
+ * \param addr The address of the attached segment.
+ *
+ * \return Standard.
+ *
+ * \sa shmdt(2).
+ */
int shm_detach(void *addr)
{
int ret = shmdt(addr);
- return ret < 0? -E_SHM_DETACH : 1;
+ return ret < 0? -ERRNO_TO_PARA_ERROR(errno) : 1;
}