2 * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file ipc.c Inter-process communication and shared memory helpers. */
19 * \return The identifier for the new mutex on success, \a -E_SEM_GET
26 int ret
= semget(IPC_PRIVATE
, 1, IPC_CREAT
| 0666);
27 return ret
< 0? -E_SEM_GET
: ret
;
33 * \param id The identifier of the mutex to be destroyed.
35 * \return Positive on success, \a -E_SEM_REMOVE on errors.
39 int mutex_destroy(int id
)
41 int ret
= semctl(id
, 0, IPC_RMID
);
42 return ret
< 0? -E_SEM_REMOVE
: 1;
45 static void para_semop(int id
, struct sembuf
*sops
, int num
)
48 if (semop(id
, sops
, num
) >= 0)
50 } while (errno
== EINTR
);
52 PARA_NOTICE_LOG("semaphore set %d was removed\n", id
);
55 PARA_EMERG_LOG("fatal semop error %s: pid %d\n", strerror(errno
),
61 * Lock the given mutex.
63 * \param id The identifier of the shared memory area to lock.
65 * This function either succeeds or aborts.
67 * \sa semop(2), struct misc_meta_data.
69 void mutex_lock(int id
)
71 struct sembuf sops
[2] = {
83 para_semop(id
, sops
, 2);
89 * \param id The identifier of the mutex.
91 * This function either succeeds or aborts.
93 * \sa semop(2), struct misc_meta_data.
95 void mutex_unlock(int id
)
97 struct sembuf sops
[1] = {
104 para_semop(id
, sops
, 1);
108 * Create a new shared memory area of given size.
110 * \param size The size of the shared memory area to create.
112 * \return The id of the shared memory areay on success, \a -E_SHM_GET on errors.
116 int shm_new(size_t size
)
118 int ret
= shmget(IPC_PRIVATE
, size
, IPC_CREAT
| IPC_EXCL
| 0600);
119 return ret
< 0 ? -E_SHM_GET
: ret
;
123 * Destroy the given shared memory area.
125 * \param id The shared memory identifier.
127 * \return The return value of the underlying shmctl() call on success,
128 * \a -E_SHM_DESTROY on errors.
132 int shm_destroy(int id
)
134 struct shmid_ds shm_desc
;
135 int ret
= shmctl(id
, IPC_RMID
, &shm_desc
);
136 return ret
< 0? -E_SHM_DESTROY
: ret
;
140 * Attach a shared memory segment.
142 * \param id The identifier of the shared memory segment to attach.
143 * \param mode either ATTACH_RO (read only) or ATTACH_RW (read/write).
144 * \param result points to the attached area just attached.
146 * \return positive on success, \a -E_SHM_ATTACH on errors.
150 int shm_attach(int id
, enum shm_attach_mode mode
, void **result
)
152 if (mode
== ATTACH_RW
) {
153 *result
= shmat(id
, NULL
, 0);
154 return *result
? 1 : -E_SHM_ATTACH
;
156 *result
= shmat(id
, NULL
, SHM_RDONLY
);
157 return *result
? 1 : -E_SHM_ATTACH
;
161 * Detach a shared memory segment.
163 * \param addr The address of the attached segment.
165 * \return Positive on success, \a -E_SHM_DETACH on errors.
169 int shm_detach(void *addr
)
171 int ret
= shmdt(addr
);
172 return ret
< 0? -E_SHM_DETACH
: 1;