-/*
- * Copyright (C) 2006-2011 Andre Noll <maan@systemlinux.org>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
/** \file ipc.c Inter-process communication and shared memory helpers. */
#include "ipc.h"
#include <sys/types.h>
#include <sys/param.h>
-#include <sys/sysctl.h>
#include <sys/ipc.h>
#include <sys/shm.h>
*
* 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)
{
*
* 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)
{
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.
*
}
# if defined __FreeBSD__ || defined __NetBSD__
+#include <sys/sysctl.h>
# 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;
buf[ret] = '\0';
shmmax = strtoul(buf, NULL, 10);
}
+ close(fd);
}
}
#elif defined SYSCTL_SHMMAX_VARIABLE
#endif
if (shmmax == 0) {
PARA_WARNING_LOG("unable to determine shmmax\n");
- shmmax = 65535; /* last ressort */
+ shmmax = 65535; /* last resort */
}
PARA_INFO_LOG("shmmax: %zu\n", shmmax);
return shmmax;