ipc.c File Reference

Inter-process communication and shared memory helpers. More...

#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>

Functions
int	mutex_new (void)
	Define a new mutex. More...
int	mutex_destroy (int id)
	Destroy a mutex. More...
void	mutex_lock (int id)
	Lock the given mutex. More...
void	mutex_unlock (int id)
	Unlock a mutex. More...
int	shm_new (size_t size)
	Create a new shared memory area of given size. More...
int	shm_destroy (int id)
	Destroy the given shared memory area. More...
int	shm_attach (int id, enum shm_attach_mode mode, void **result)
	Attach a shared memory segment. More...
int	shm_size (int id, size_t *result)
	Get the size of a shared memory segment. More...
int	shm_detach (void *addr)
	Detach a shared memory segment. More...
size_t	shm_get_shmmax (void)
	Get the maximal size of a shared memory area. More...

Detailed Description

Inter-process communication and shared memory helpers.

Function Documentation

mutex_new()

int mutex_new

(

void

)

Define a new mutex.

Returns

The identifier for the new mutex on success, a negative error code on errors.

See also

semget(2).

References ERRNO_TO_PARA_ERROR.

mutex_destroy()

int mutex_destroy

(

int

id

)

Destroy a mutex.

Parameters

id	The identifier of the mutex to be destroyed.

Returns

Standard.

See also

semctl(2)

References ERRNO_TO_PARA_ERROR.

mutex_lock()

void mutex_lock

(

int

id

)

Lock the given mutex.

Parameters

id	The identifier of the shared memory area to lock.

This function either succeeds or aborts.

See also

semop(2), struct misc_meta_data.

mutex_unlock()

void mutex_unlock

(

int

id

)

Unlock a mutex.

Parameters

id	The identifier of the mutex.

This function either succeeds or aborts.

See also

semop(2), struct misc_meta_data.

shm_new()

int shm_new

(

size_t

size

)

Create a new shared memory area of given size.

Parameters

size	The size of the shared memory area to create.

Returns

The id of the shared memory array on success, a negative error code on errors.

See also

shmget(2).

References ERRNO_TO_PARA_ERROR.

Referenced by pass_buffer_as_shm(), and send_callback_request().

shm_destroy()

int shm_destroy

(

int

id

)

Destroy the given shared memory area.

Parameters

id	The shared memory identifier.

Returns

The return value of the underlying shmctl() call on success, a negative error code on errors.

See also

shmctl(2).

References ERRNO_TO_PARA_ERROR.

Referenced by pass_buffer_as_shm().

shm_attach()

int shm_attach	(	int	id,
		enum shm_attach_mode	mode,
		void **	result
	)

Attach a shared memory segment.

Parameters

id	The identifier of the shared memory segment to attach.
mode	Either ATTACH_RO (read only) or ATTACH_RW (read/write).
result	Points to the attached area just attached on success.

Returns

Standard.

See also

shmat(2).

References ATTACH_RW, and ERRNO_TO_PARA_ERROR.

Referenced by load_afd(), pass_buffer_as_shm(), and send_callback_request().

shm_size()

int shm_size	(	int	id,
		size_t *	result
	)

Get the size of a shared memory segment.

Parameters

id	The shared memory segment identifier.
result	Size in bytes is returned here, zero on errors.

Returns

Standard.

See also

shmctl(2).

References ERRNO_TO_PARA_ERROR.

Referenced by load_afd().

shm_detach()

int shm_detach

(

void *

addr

)

Detach a shared memory segment.

Parameters

addr	The address of the attached segment.

Returns

Standard.

See also

shmdt(2).

References ERRNO_TO_PARA_ERROR.

Referenced by pass_buffer_as_shm(), and send_callback_request().

shm_get_shmmax()

size_t shm_get_shmmax

(

void

)

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.

Returns

A number suitable as an argument to shm_new().

References PARA_INFO_LOG, and PARA_WARNING_LOG.