ipc/shm_semaph_test.c

   1 /***************************************************************************
   2  * Copyright 1995, Technion, Israel Institute of Technology
   3  * Electrical Eng, Software Lab.
   4  * Author:    Michael Veksler.
   5  ***************************************************************************
   6  * File:      shm_semaph_test.c
   7  * Purpose:   Test semaphores handleingr shared memory operations.
   8  ***************************************************************************
   9  */
  10 #include <time.h>
  11 #include <stdio.h>
  12 #include <unistd.h>
  13 #include <errno.h>
  14 #include <stdlib.h>
  15 #include <sys/wait.h>
  16 #include "shm_semaph.h"
  17 #include <sys/shm.h>
  18 #define DEBUG_DEFINE_VARIABLES
  19 #include <stddebug.h>
  20 #include <debug.h>
  21
  22 static volatile int * volatile data;
  23 static int isparent=0;
  24 #define DELAY (rand()%10)
  25 shm_sem sem;
  26
  27 static void read_write(int num)
  28 {
  29   int i,j ;
  30   volatile float dummy=0;
  31   int val;
  32
  33   srand(num+time(NULL));
  34   for (i=0x3fff;i>=0;i--) {
  35      if((i&0x7ff)==0 && isparent)
  36         fprintf(stderr,"0x%06x\r",i);
  37      shm_write_wait(sem);
  38      *data= num;
  39      for (j=DELAY ; j>=0;j--)
  40         dummy*=2;
  41      if (*data!=num) {
  42         fprintf(stderr,"\nbad shm_write_wait(), num=%d\n",num);
  43         shm_write_signal(sem);
  44         return;
  45      }
  46      shm_write_signal(sem);
  47      for (j=DELAY ; j>=0 ;j--)
  48         dummy*=2;
  49      shm_read_wait(sem);
  50      val=*data;
  51      for (j=DELAY; j>=0 ;j--)
  52         dummy*=0.5;
  53      if (*data!=val) {
  54         fprintf(stderr,"\nbad shm_read_wait(), num=%d,val=%d,*data=%d\n",
  55                 num,val,*data);
  56         shm_read_signal(sem);
  57         return;
  58      }
  59      shm_read_signal(sem);
  60   }
  61   if (isparent)
  62      fputc('\n',stderr);
  63 }
  64 static void child1()
  65 {
  66   read_write(2);
  67 }
  68 static void child2()
  69 {
  70   read_write(10);
  71 }
  72 static void parent()
  73 {
  74   isparent=1;
  75   read_write(60);
  76 }
  77
  78 int main()
  79 {
  80   int shmid;
  81   int ret1, ret2;
  82   int pid1, pid2;
  83   int stat=0;
  84
  85   shm_sem_init(&sem);
  86   shmid=shmget(IPC_PRIVATE, 0x100, IPC_CREAT | 0700);
  87   data= (int *)shmat ( shmid, NULL, 0);
  88   *data=0;
  89
  90   switch (pid1=fork()) {
  91     case -1:
  92       perror("fork 1");
  93       return 1;
  94     case 0:
  95       fprintf(stderr,"child1\n");
  96       child1();
  97       fprintf(stderr,"child1 done\n");
  98       return 0;
  99     default :
 100   }
 101   switch (pid2=fork()) {
 102     case -1:
 103       perror("fork 2");
 104       stat|=1;
 105       break;
 106     case 0:
 107       fprintf(stderr,"child2\n");
 108       child2();
 109       fprintf(stderr,"child2 done\n");
 110       return 0;
 111     default :
 112   }
 113   fprintf(stderr,"parent\n");
 114   if (pid2>0) {                    /* if second fork did not fail */
 115      parent();
 116      fprintf(stderr,"parent done, waiting for child2\n");
 117      waitpid(pid2,&ret2,WUNTRACED);
 118      stat|=ret2;
 119   }
 120   fprintf(stderr,"parent done, waiting for child1\n");
 121   waitpid(pid1,&ret1,WUNTRACED);
 122   stat|=ret1;
 123   fprintf(stderr,"all done\n");
 124
 125   shmctl(shmid, IPC_RMID,NULL);
 126   shm_sem_done(&sem);
 127   return stat;
 128 }