mirror of https://github.com/hslam/ipc.git
104 lines
3.7 KiB
Go
104 lines
3.7 KiB
Go
// Copyright (c) 2020 Meng Huang (mhboy@outlook.com)
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// This package is licensed under a MIT license that can be found in the LICENSE file.
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package ipc
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import (
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"github.com/hslam/sem"
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"unsafe"
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)
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// Sembuf represents an operation.
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type Sembuf struct {
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SemNum uint16
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SemOp int16
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SemFlg int16
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}
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// Semget calls the semget system call.
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//
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// The semget() system call returns the System V semaphore set identifier
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// associated with the argument key.
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//
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// A new set of nsems semaphores is created if key has the value
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// IPC_PRIVATE or if no existing semaphore set is associated with key
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// and IPC_CREAT is specified in semflg.
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//
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// If semflg specifies both IPC_CREAT and IPC_EXCL and a semaphore set
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// already exists for key, then semget() fails with errno set to EEXIST.
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//
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// The argument nsems can be 0 (a don't care) when a semaphore set is
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// not being created. Otherwise, nsems must be greater than 0 and less
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// than or equal to the maximum number of semaphores per semaphore set.
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//
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// If successful, the return value will be the semaphore set identifier,
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// otherwise, -1 is returned, with errno indicating the error.
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func Semget(key int, nsems int, semflg int) (int, error) {
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return sem.Get(key, nsems, semflg)
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}
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// Semsetvalue calls the semctl SETVAL system call.
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func Semsetvalue(semid int, semnum int, semun int) (bool, error) {
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return sem.SetValue(semid, semnum, semun)
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}
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// Semgetvalue calls the semctl GETVAL system call.
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func Semgetvalue(semid int, semnum int) (int, error) {
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return sem.GetValue(semid, semnum)
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}
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// Semp calls the semop P system call.
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// Flags recognized in semflg are IPC_NOWAIT and SEM_UNDO.
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// If an operation specifies SEM_UNDO, it will be automatically undone when the
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// process terminates.
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func Semp(semid int, semnum int, semflg int) (bool, error) {
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return sem.P(semid, semnum, semflg)
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}
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// Semv calls the semop V system call.
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// Flags recognized in semflg are IPC_NOWAIT and SEM_UNDO.
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// If an operation specifies SEM_UNDO, it will be automatically undone when the
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// process terminates.
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func Semv(semid int, semnum int, semflg int) (bool, error) {
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return sem.V(semid, semnum, semflg)
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}
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// Semop calls the semop system call.
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//
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// semop() performs operations on selected semaphores in the set indi‐
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// cated by semid. Each of the nsops elements in the array pointed to
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// by sops is a structure that specifies an operation to be performed on
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// a single semaphore. The elements of this structure are of type
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// struct sembuf, containing the following members:
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//
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// unsigned short sem_num; /* semaphore number */
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// short sem_op; /* semaphore operation */
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// short sem_flg; /* operation flags */
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//
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// Flags recognized in sem_flg are IPC_NOWAIT and SEM_UNDO.
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// If an operation specifies SEM_UNDO, it will be automatically undone when the
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// process terminates.
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//
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// The set of operations contained in sops is performed in array order,
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// and atomically, that is, the operations are performed either as a
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// complete unit, or not at all. The behavior of the system call if not
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// all operations can be performed immediately depends on the presence
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// of the IPC_NOWAIT flag in the individual sem_flg fields, as noted be‐
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// low.
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func Semop(semid int, sops uintptr, nsops int) (bool, error) {
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return sem.Op(semid, sops, nsops)
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}
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// Semoperate calls the semop system call.
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// Flags recognized in SemFlg are IPC_NOWAIT and SEM_UNDO.
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// If an operation specifies SEM_UNDO, it will be automatically undone when the
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// process terminates.
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func Semoperate(semid int, sops []Sembuf) (bool, error) {
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return Semop(semid, uintptr(unsafe.Pointer(&sops[0])), len(sops))
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}
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// Semrm removes the semaphore with the given id.
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func Semrm(semid int) error {
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return sem.Remove(semid)
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}
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