2 * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file ipc.c interprocess 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
), getpid());
60 * lock the given mutex
62 * \param id of the shared memory area to lock
64 * This function either succeeds or aborts.
66 * \sa semop(2), struct misc_meta_data
68 void mutex_lock(int id
)
70 struct sembuf sops
[2] = {
82 para_semop(id
, sops
, 2);
88 * \param id the identifier of the mutex
90 * This function either succeeds or aborts.
92 * \sa semop(2), struct misc_meta_data
94 void mutex_unlock(int id
)
96 struct sembuf sops
[1] = {
103 para_semop(id
, sops
, 1);
107 * create a new shared memory area of given size
109 * \param size the size of the shared memory area to create
111 * \return The id of the shared memory areay on success, \a -E_SHM_GET on errors.
115 int shm_new(size_t size
)
117 int ret
= shmget(IPC_PRIVATE
, size
, IPC_CREAT
| IPC_EXCL
| 0600);
118 return ret
< 0 ? -E_SHM_GET
: ret
;
122 * destroy the given shared memory area
124 * \param id the shared memory id
126 * \return The return value of the underlying shmctl() call on success,
127 * \a -E_SHM_DESTROY on errors.
131 int shm_destroy(int id
)
133 struct shmid_ds shm_desc
;
134 int ret
= shmctl(id
, IPC_RMID
, &shm_desc
);
135 return ret
< 0? -E_SHM_DESTROY
: ret
;
139 * attach a shared memory segment
141 * \param id the identifier of the shared memory segment to attach
142 * \param mode either ATTACH_RO (read only) or ATTACH_RW (read/write)
143 * \param result points to the attached area just attached
145 * \return positive on success, \a -E_SHM_ATTACH on errors.
149 int shm_attach(int id
, enum shm_attach_mode mode
, void **result
)
151 if (mode
== ATTACH_RW
) {
152 *result
= shmat(id
, NULL
, 0);
153 return *result
? 1 : -E_SHM_ATTACH
;
155 *result
= shmat(id
, NULL
, SHM_RDONLY
);
156 return *result
? 1 : -E_SHM_ATTACH
;
160 * detach a shared memory segment
162 * \param addr the address of the attached segment
164 * \return positive on success, \a -E_SHM_DETACH on errors.
168 int shm_detach(void *addr
)
170 int ret
= shmdt(addr
);
171 return ret
< 0? -E_SHM_DETACH
: 1;