artGenerator/binary_sem.c at main · jadethomp/artGenerator · GitHub

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#include <sys/types.h>
#include <sys/sem.h>
#include "semun.h"
#include "binary_sem.h"

int bsUseSemUndo = 0;
int bsRetryOnEintr = 1;

//initializers
int initSemAvailable(int semId, int semNum){
  union semun arg;
  arg.val = 1;
  return semctl(semId, semNum, SETVAL, arg);
}

int initSemInUse(int semId, int semNum){
  union semun arg;
  arg.val = 0;
  return semctl(semId, semNum, SETVAL, arg);
}

int reserveSem(int semId, int semNum){
  struct sembuf sops;

  sops.sem_num = semNum;
  sops.sem_op = -1;
  sops.sem_flg = bsUseSemUndo ? SEM_UNDO : 0;

  while (semop(semId, &sops, 1) == -1){
    if (errno != EINTR || !bsRetryOnEintr){
      return -1;
    }
    return 0;
  }
}

int releaseSem(int semId, int semNum){
  struct sembuf sops;

  sops.sem_num = semNum;
  sops.sem_op = 1;
  sops.sem_flg = bsUseSemUndo ? SEM_UNDO : 0;

  return semop(semId, &sops, 1);
}