Comment # 1 on bug 1173797 from Hans Schwab

Comment on attachment 839408 [details]
The fist c-Programm

The second c-programm:

/* y.c */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ipc.h> // IPC_NOWAIT = 0x800, SEM_UNDO = 0x1000
#include <sys/sem.h>
#include <errno.h>
enum {LOCK_SEMA=-1, UNLOCK_SEMA=1};
#define KEY  1234567L     

static int semid = -1;

static int printSemaValue(int line, const char *pStr) {

   int semVal0(0), semVal1(0);

   semVal0 = semctl (semid, 0, GETVAL);
   if (semVal0 < 0) {
      printf ("In Line %d: retcode < 0 from semctl (%d, 0, GETVAL), errno =
%d\n\n", __LINE__-2, semid, errno);
      return semVal0;
   }

   semVal1 = semctl (semid, 1, GETVAL);
   if (semVal1 < 0) {
      printf ("In Line %d: retcode < 0 from semctl (%d, 1, GETVAL), errno =
%d\n\n", __LINE__-2, semid, errno);
      return semVal1;
   }

   printf ("\n");

   printf ("semVal0 GETVAL %d\n", semVal0);

   printf ("semVal1 GETVAL %d\n%s, in Line %d\n", semVal1, pStr, line);

   return 1;

} 

static int init_semaphore (void) {

   int semVal0(0), semVal1(0);

   semid = semget (KEY, 0, IPC_PRIVATE);
   if (semid < 0) {
      printf ("\n Line %d: sema was not created\n", __LINE__-2);
      return semid;
   }

   semVal0 = semctl (semid, 0, GETVAL);
   if (semVal0 < 0) {
      printf ("In Line %d: retcode < 0 from semctl (%d, 0, GETVAL), errno =
%d\n\n", __LINE__-2, semid, errno);
      return semVal0;
   }

   semVal1 = semctl (semid, 1, GETVAL);
   if (semVal0 < 0) {
      printf ("In Line %d: retcode < 0 from semctl (%d, 1, GETVAL), errno =
%d\n\n", __LINE__-2, semid, errno);
      return semVal1;
   }

   return 1;
}

static int semaphoreOp (int op, int semNum) {
   struct sembuf semaphore [] = {(unsigned short) semNum, (short) op, (short)
SEM_UNDO};
   if( semop (semid, semaphore, 1) == -1) {
      return -1;
   }
   return 1;
}

int main (void) {
   long loop, res;
   int lineNr (-1);
   int myError(0);

   res = init_semaphore ();
   if (res < 0) {
      printf ("\nretcode < 0 from init_semaphore\n");

      semctl(semid, 1, IPC_RMID, 0);

      return res;
   }

   printSemaValue(__LINE__, "init_semaphore() was successful");

   for (loop =0; myError==0; ++loop) {

      printf ("\nloop = %ld\n", loop);

      res = semaphoreOp (LOCK_SEMA, 1);
      lineNr =__LINE__ -1;
      if (res < 0) {

         int semVal0(0), semVal1(1);
         myError = errno;

         if (myError == EIDRM) {

            printf ("In Line %d: LOCK_SEMA, sem_num 1, was not
successful;\nerrno = %d (=EIDRM, Identifier removed)\n\n", 
            lineNr, myError);
         }
         else {
            printf ("In Line %d: LOCK_SEMA, sem_num 1, was not
successful;\nerrno = %d\n\n", 
            lineNr, myError);
         }

         break;
      }

//       sleep (1);

      res = semaphoreOp (UNLOCK_SEMA, 0);
      lineNr =__LINE__ -1;

      if (res < 0) {

         int semVal0(0), semVal1(1);
         myError = errno;

         if (myError == EIDRM) {

            printf ("In Line %d: UNLOCK_SEMA, sem_num 0, was not
successful;\nerrno = %d (=EIDRM, Identifier removed)\n\n", 
            lineNr, myError);
         }
         else {
            printf ("In Line %d: UNLOCK_SEMA, sem_num 0, was not
successful;\nerrno = %d\n\n", 
            lineNr, myError);
         }

         break;
      }

      printf ("\n");

   } // for ...

   // semctl(semid, 0, IPC_RMID, 0);

   return 1;
}