Problem about C semaphore functions

[zemon]

Hello,

I am studying on semaphores in C about 5-6 days. I found a java code piece and wanted to turn that to C language but couldn't find one function in C.

I wanna find what should I use in C for that or is there anything for this function.

In Java: semap.availablePermits() In C : ?

Is it true ?

In Java: semap.acquire() In C: WaitForSingleObject(semap, INFINITE) ?


Thanks.

[leont58]

I'm on Sun Solaris, but most of this should be the same regardless of OS. I hope this helps.
- LT

semaphore research in the MAN pages:
man semop
man semctl
man semget
man ipcs
man ipcrm

the include files:

    #include <sys/types.h>
    #include <sys/ipc.h>
    #include <sys/sem.h>

A unique key and semaphore struct:

     key_t semkey = 2012;

     union semun {
        int val;
        struct semid_ds *buf;
        ushort *array;
     } arg;

get semaphore id for use:

     int  semflg = IPC_CREAT | 0666;  /* create with full access */
     int  nsems = 1;  /* number of concurrent processes to allow */
     id = semget(semkey, nsems, semflg); /* "id" is used in the semctl() and semop() functions */

create a semaphore:

     id = semget(semkey, nsems, semflg);
     arg.val = 1;
     if (semctl(id, 0, SETVAL, arg) < 0)
                fprintf(stderr, "semctl create() failed\n");

delete a semaphore:

     id = semget(semkey, nsems, semflg);
      if ( semctl(id, 0, IPC_RMID, arg) == -1)
                fprintf(stderr, "semctl delete() failed\n");

lock semaphore:

      struct sembuf sbuf;
      sbuf.sem_num = 0;
      sbuf.sem_op  = -1;  /* lock it */
      sbuf.sem_flg = SEM_UNDO;
      if ( semop(id, &sbuf, 1) == -1)
                fprintf(stderr, "semop lock() failed\n");

unlock semaphore:

      struct sembuf sbuf;
      sbuf.sem_num = 0;
      sbuf.sem_op  = 1;  /* UNLOCK IT */
      sbuf.sem_flg = SEM_UNDO;
      if ( semop(id, &sbuf, 1) == -1)
                fprintf(stderr, "semop unlock() failed\n");