rt/tst-cputimer3.c

   1 /* Tests for POSIX timer implementation using another process's CPU clock.  */
   2
   3 #include <unistd.h>
   4
   5 #if _POSIX_THREADS && defined _POSIX_CPUTIME
   6
   7 #include <errno.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <fcntl.h>
  12 #include <time.h>
  13 #include <signal.h>
  14 #include <sys/wait.h>
  15
  16 static clockid_t child_clock;
  17
  18 #define TEST_CLOCK child_clock
  19 #define TEST_CLOCK_MISSING(clock) \
  20   (setup_test () ? "other-process CPU clock timer support" : NULL)
  21
  22 /* This function is intended to rack up both user and system time.  */
  23 static void
  24 chew_cpu (void)
  25 {
  26   while (1)
  27     {
  28       static volatile char buf[4096];
  29       for (int i = 0; i < 100; ++i)
  30         for (size_t j = 0; j < sizeof buf; ++j)
  31           buf[j] = 0xaa;
  32       int nullfd = open ("/dev/null", O_WRONLY);
  33       for (int i = 0; i < 100; ++i)
  34         for (size_t j = 0; j < sizeof buf; ++j)
  35           buf[j] = 0xbb;
  36       write (nullfd, (char *) buf, sizeof buf);
  37       close (nullfd);
  38       if (getppid () == 1)
  39         _exit (2);
  40     }
  41 }
  42
  43 static pid_t child;
  44 static void
  45 cleanup_child (void)
  46 {
  47   if (child <= 0)
  48     return;
  49   if (kill (child, SIGKILL) < 0 && errno != ESRCH)
  50     printf ("cannot kill child %d: %m\n", child);
  51   else
  52     {
  53       int status;
  54       errno = 0;
  55       if (waitpid (child, &status, 0) != child)
  56         printf ("waitpid %d: %m\n", child);
  57     }
  58 }
  59 #define CLEANUP_HANDLER cleanup_child ()
  60
  61 static int
  62 setup_test (void)
  63 {
  64   /* Test timers on a process CPU clock by having a child process eating
  65      CPU.  First make sure we can make such timers at all.  */
  66
  67   int pipefd[2];
  68   if (pipe (pipefd) < 0)
  69     {
  70       printf ("pipe: %m\n");
  71       exit (1);
  72     }
  73
  74   child = fork ();
  75
  76   if (child == 0)
  77     {
  78       char c;
  79       close (pipefd[1]);
  80       if (read (pipefd[0], &c, 1) == 1)
  81         chew_cpu ();
  82       _exit (1);
  83     }
  84
  85   if (child < 0)
  86     {
  87       printf ("fork: %m\n");
  88       exit (1);
  89     }
  90
  91   atexit (&cleanup_child);
  92
  93   close (pipefd[0]);
  94
  95   int e = clock_getcpuclockid (child, &child_clock);
  96   if (e == EPERM)
  97     {
  98       puts ("clock_getcpuclockid does not support other processes");
  99       return 1;
 100     }
 101   if (e != 0)
 102     {
 103       printf ("clock_getcpuclockid: %s\n", strerror (e));
 104       exit (1);
 105     }
 106
 107   timer_t t;
 108   if (timer_create (TEST_CLOCK, NULL, &t) != 0)
 109     {
 110       printf ("timer_create: %m\n");
 111       return 1;
 112     }
 113   timer_delete (t);
 114
 115   /* Get the child started chewing.  */
 116   if (write (pipefd[1], "x", 1) != 1)
 117     {
 118       printf ("write to pipe: %m\n");
 119       return 1;
 120     }
 121   close (pipefd[1]);
 122
 123   return 0;
 124 }
 125
 126 #else
 127 # define TEST_CLOCK_MISSING(clock) "process clocks"
 128 #endif
 129
 130 #include "tst-timer4.c"