-/*
- * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
- *
- * 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., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
- */
+/* Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
-/** \file ipc.c interprocess communication and shared memory helpers */
+/** \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/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>
-/** abort if semget() failed that many times */
-#define MAX_SEMOP_RETRIES 500
-
/**
- * define a new mutex
+ * Define a new mutex.
*
- * \return the identifier for the new mutex on success, \a -E_SEM_GET
+ * \return The identifier for the new mutex on success, a negative error code
* on errors.
*
- * \sa semget(2)
+ * \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
+ * Destroy a mutex.
*
- * \param id the identifier of the mutex to be destroyed
+ * \param id The identifier of the mutex to be destroyed.
*
- * \return Positive on success, \a -E_SEM_REMOVE on errors.
+ * \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)
{
- int i;
-
- for (i = 0; i < MAX_SEMOP_RETRIES; i++)
+ do {
if (semop(id, sops, num) >= 0)
return;
- PARA_EMERG_LOG("semop failed %d times, aborting\n", MAX_SEMOP_RETRIES);
+ } while (errno == EINTR);
+ if (errno == EIDRM) {
+ PARA_CRIT_LOG("semaphore set %d was removed\n", id);
+ return;
+ }
+ 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 of the shared memory area to lock
+ * \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 \ref misc_meta_data.
*/
void mutex_lock(int id)
{
}
/**
- * unlock a mutex
+ * Unlock a mutex.
*
- * \param id the identifier of the mutex
+ * \param id The identifier of the mutex.
*
* This function either succeeds or aborts.
*
- * \sa semop(2), struct misc_meta_data
+ * \sa semop(2), struct \ref misc_meta_data.
*/
void mutex_unlock(int id)
{
}
/**
- * create a new shared memory area of given size
+ * Create a new shared memory area of given size.
*
- * \param size the size of the shared memory area to create
+ * \param size The size of the shared memory area to create.
*
- * \return The id of the shared memory areay on success, \a -E_SHM_GET on errors.
+ * \return The id of the shared memory array on success, a negative error
+ * code on errors.
*
- * \sa shmget(2)
+ * \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
+ * Destroy the given shared memory area.
*
- * \param id the shared memory id
+ * \param id The shared memory identifier.
*
* \return The return value of the underlying shmctl() call on success,
- * \a -E_SHM_DESTROY on errors.
+ * a negative error code on errors.
*
- * \sa shmctl(2)
+ * \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 segment
+ * Attach a shared memory segment.
*
- * \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
+ * \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 positive on success, \a -E_SHM_ATTACH on errors.
+ * \return Standard.
*
- * \sa shmat(2)
+ * \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;
+}
+
+/**
+ * Get the size of a shared memory segment.
+ *
+ * \param id The shared memory segment identifier.
+ * \param result Size in bytes is returned here, zero on errors.
+ *
+ * \return Standard.
+ *
+ * \sa shmctl(2).
+ */
+int shm_size(int id, size_t *result)
+{
+ struct shmid_ds ds; /* data structure */
+
+ *result = 0;
+ if (shmctl(id, IPC_STAT, &ds) < 0)
+ return -ERRNO_TO_PARA_ERROR(errno);
+ *result = ds.shm_segsz;
+ return 1;
}
/**
- * detach a shared memory segment
+ * Detach a shared memory segment.
*
- * \param addr the address of the attached segment
+ * \param addr The address of the attached segment.
*
- * \return positive on success, \a -E_SHM_DETACH on errors.
+ * \return Standard.
*
- * \sa shmdt(2)
+ * \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__
+#include <sys/sysctl.h>
+# define SYSCTL_SHMMAX_VARIABLE "kern.ipc.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;
}
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