1  /* Tests for POSIX timer implementation using process CPU clock.  */
       2  
       3  #include <unistd.h>
       4  
       5  #if _POSIX_THREADS && defined _POSIX_CPUTIME
       6  
       7  #include <stdio.h>
       8  #include <stdlib.h>
       9  #include <string.h>
      10  #include <fcntl.h>
      11  #include <time.h>
      12  #include <pthread.h>
      13  
      14  #include <support/xunistd.h>
      15  
      16  #define TEST_CLOCK CLOCK_PROCESS_CPUTIME_ID
      17  #define TEST_CLOCK_MISSING(clock) \
      18    (setup_test () ? "process CPU clock timer support" : NULL)
      19  
      20  /* This function is intended to rack up both user and system time.  */
      21  static void *
      22  chew_cpu (void *arg)
      23  {
      24    while (1)
      25      {
      26        static volatile char buf[4096];
      27        for (int i = 0; i < 100; ++i)
      28  	for (size_t j = 0; j < sizeof buf; ++j)
      29  	  buf[j] = 0xaa;
      30        int nullfd = open ("/dev/null", O_WRONLY);
      31        for (int i = 0; i < 100; ++i)
      32  	for (size_t j = 0; j < sizeof buf; ++j)
      33  	  buf[j] = 0xbb;
      34        xwrite (nullfd, (char *) buf, sizeof buf);
      35        close (nullfd);
      36      }
      37  
      38    return NULL;
      39  }
      40  
      41  static int
      42  setup_test (void)
      43  {
      44    /* Test timers on our own process CPU clock by having a worker thread
      45       eating CPU.  First make sure we can make such timers at all.  */
      46  
      47    timer_t t;
      48    if (timer_create (TEST_CLOCK, NULL, &t) != 0)
      49      {
      50        printf ("timer_create: %m\n");
      51        return 1;
      52      }
      53    timer_delete (t);
      54  
      55    pthread_t th;
      56    int e = pthread_create (&th, NULL, chew_cpu, NULL);
      57    if (e != 0)
      58      {
      59        printf ("pthread_create: %s\n", strerror (e));
      60        exit (1);
      61      }
      62  
      63    return 0;
      64  }
      65  
      66  #else
      67  # define TEST_CLOCK_MISSING(clock) "process clocks"
      68  #endif
      69  
      70  #include "tst-timer4.c"