+/*
+ * Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>
+ *
+ * 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/types.h>
+#include <sys/param.h>
+#include <sys/sysctl.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;
}
+/**
+ * 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.
+ *
+ * This function either succeeds or aborts.
*
- * \sa semop(2), struct misc_meta_data
+ * \sa semop(2), struct misc_meta_data.
*/
void mutex_lock(int id)
{
}
/**
- * unlock a mutex
+ * Unlock a mutex.
*
- * \sa semop(2), struct misc_meta_data
+ * \param id The identifier of the mutex.
+ *
+ * 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).
*/
int shm_attach(int id, enum shm_attach_mode mode, void **result)
{
- if (mode == ATTACH_RW) {
+ if (mode == ATTACH_RW)
*result = shmat(id, NULL, 0);
- return *result? 1 : -E_SHM_ATTACH;
- }
- *result = shmat(id, NULL, SHM_RDONLY);
- return *result? 1 : -E_SHM_ATTACH;
+ 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;
+}
+
+# if defined __FreeBSD__ || defined __NetBSD__
+# define SYSCTL_SHMMAX_VARIABLE "kern.ipc.shmmax"
+# elif defined __APPLE__
+# define SYSCTL_SHMMAX_VARIABLE "kern.sysv.shmmax"
+# else
+# undef SYSCTL_SHMMAX_VARIABLE
+# endif
+
+/**
+ * Get the maximal size of a shared memory area.
+ *
+ * The value is only computed once when the function is called for the first
+ * time. Subsequent calls return the number which was computed during the
+ * first call.
+ *
+ * \return A number suitable as an argument to \ref shm_new().
+ */
+size_t shm_get_shmmax(void)
+{
+ static size_t shmmax;
+
+ if (shmmax > 0) /* only dance once */
+ return shmmax;
+#ifdef __linux__ /* get it from proc fs */
+ {
+ int fd = open("/proc/sys/kernel/shmmax", O_RDONLY);
+ if (fd >= 0) {
+ char buf[100] = "";
+ int ret = read(fd, buf, sizeof(buf) - 1);
+ if (ret > 0) {
+ buf[ret] = '\0';
+ shmmax = strtoul(buf, NULL, 10);
+ }
+ close(fd);
+ }
+ }
+#elif defined SYSCTL_SHMMAX_VARIABLE
+ {
+ size_t len = sizeof(shmmax);
+ sysctlbyname(SYSCTL_SHMMAX_VARIABLE, &shmmax, &len, NULL, 0);
+ }
+#elif defined SHMMAX
+ shmmax = SHMMAX;
+#endif
+ if (shmmax == 0) {
+ PARA_WARNING_LOG("unable to determine shmmax\n");
+ shmmax = 65535; /* last resort */
+ }
+ PARA_INFO_LOG("shmmax: %zu\n", shmmax);
+ return shmmax;
}
projects / paraslash.git / blobdiff