Enrico Fraccaroli (Galfurian)
136 lines
4.5 KiB
C
136 lines
4.5 KiB
C
/// @file sem.h
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/// @brief Definition of structure for managing semaphores.
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/// @copyright (c) 2014-2024 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#pragma once
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#include "sys/types.h"
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#include "stddef.h"
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#include "sys/ipc.h"
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#include "time.h"
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#define SEM_UNDO 0x1000 ///< Undo the operation on exit.
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/// @defgroup SemaphoreCommands semctl commands
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/// @brief List of commands for semctl function.
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/// @{
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#define GETPID 11 ///< Get sempid.
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#define GETVAL 12 ///< Get semval.
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#define GETALL 13 ///< Get all semval's.
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#define GETNCNT 14 ///< Get semncnt.
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#define GETZCNT 15 ///< Get semzcnt.
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#define SETVAL 16 ///< Set semval.
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#define SETALL 17 ///< Set all semval's.
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#define SEM_STAT 18 ///< Return a semid_ds structure.
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#define SEM_INFO 19 ///< Return a seminfo structure.
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/// }@
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#define SEM_SET_MAX 256
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/// @brief Optional argument for semctl() function
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union semun {
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/// @brief Value for SETVAL.
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int val;
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/// @brief Buffer for IPC_STAT & IPC_SET.
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struct semid_ds *buf;
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/// @brief Array for GETALL & SETALL.
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unsigned short *array;
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/// @brief Buffer for IPC_INFO.
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struct seminfo *__buf;
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};
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/// @brief Single Semaphore.
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struct sem {
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/// @brief Process ID of the last operation.
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pid_t sem_pid;
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/// @brief Semaphore Value.
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unsigned short sem_val;
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/// @brief Number of processes waiting for the semaphore.
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unsigned short sem_ncnt;
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/// @brief Number of processes waiting for the value to become 0.
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unsigned short sem_zcnt;
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};
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/// @brief Semaphore set
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struct semid_ds {
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/// @brief Ownership and permissions.
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struct ipc_perm sem_perm;
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/// @brief Last semop time.
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time_t sem_otime;
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/// @brief Last change time.
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time_t sem_ctime;
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/// @brief Number of semaphores in set.
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unsigned short sem_nsems;
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};
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/// @brief Buffer to use with the semaphore IPC.
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struct sembuf {
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/// @brief Semaphore index in array.
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unsigned short sem_num;
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/// @brief Semaphore operation.
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short sem_op;
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/// @brief Operation flags.
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short sem_flg;
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};
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#ifdef __KERNEL__
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/// @brief Initializes the semaphore system.
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/// @return 0 on success, 1 on failure.
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int sem_init(void);
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/// @brief Get a System V semaphore set identifier.
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/// @param key can be used either to obtain the identifier of a previously
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/// created semaphore set, or to create a new set.
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/// @param nsems number of semaphores.
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/// @param semflg controls the behaviour of the function.
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/// @return the semaphore set identifier, -1 on failure, and errno is set to
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/// indicate the error.
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long sys_semget(key_t key, int nsems, int semflg);
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/// @brief Performs operations on selected semaphores in the set.
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/// @param semid the semaphore set identifier.
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/// @param sops specifies operations to be performed on single semaphores.
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/// @param nsops number of operations.
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/// @return 0 on success, -1 on failure and errno is set to indicate the error.
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long sys_semop(int semid, struct sembuf *sops, unsigned nsops);
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/// @brief Performs control operations on a semaphore set.
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/// @param semid the semaphore set identifier.
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/// @param semnum the n-th semaphore of the set on which we perform the operations.
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/// @param cmd the command to perform.
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/// @param arg
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/// @return 0 on success, -1 on failure and errno is set to indicate the error.
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long sys_semctl(int semid, int semnum, int cmd, union semun *arg);
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#else
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/// @brief Get a System V semaphore set identifier.
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/// @param key can be used either to obtain the identifier of a previously
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/// created semaphore set, or to create a new set.
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/// @param nsems number of semaphores.
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/// @param semflg controls the behaviour of the function.
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/// @return the semaphore set identifier, -1 on failure, and errno is set to
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/// indicate the error.
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long semget(key_t key, int nsems, int semflg);
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/// @brief Performs operations on selected semaphores in the set.
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/// @param semid the semaphore set identifier.
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/// @param sops specifies operations to be performed on single semaphores.
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/// @param nsops number of operations.
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/// @return 0 on success, -1 on failure and errno is set to indicate the error.
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long semop(int semid, struct sembuf *sops, unsigned nsops);
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/// @brief Performs control operations on a semaphore set.
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/// @param semid the semaphore set identifier.
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/// @param semnum the n-th semaphore of the set on which we perform the operations.
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/// @param cmd the command to perform.
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/// @param arg
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/// @return 0 on success, -1 on failure and errno is set to indicate the error.
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long semctl(int semid, int semnum, int cmd, union semun *arg);
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#endif
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