summaryrefslogtreecommitdiff
path: root/rt/tst-cputimer3.c
blob: 056766a3774ce36a3a7029f200bde76bb96acb72 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
/* Tests for POSIX timer implementation using another process's CPU clock.  */

#include <unistd.h>

#if _POSIX_THREADS && defined _POSIX_CPUTIME

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <signal.h>
#include <sys/wait.h>

static clockid_t child_clock;

#define TEST_CLOCK child_clock
#define TEST_CLOCK_MISSING(clock) \
  (setup_test () ? "other-process CPU clock timer support" : NULL)

/* This function is intended to rack up both user and system time.  */
static void
chew_cpu (void)
{
  while (1)
    {
      static volatile char buf[4096];
      for (int i = 0; i < 100; ++i)
	for (size_t j = 0; j < sizeof buf; ++j)
	  buf[j] = 0xaa;
      int nullfd = open ("/dev/null", O_WRONLY);
      for (int i = 0; i < 100; ++i)
	for (size_t j = 0; j < sizeof buf; ++j)
	  buf[j] = 0xbb;
      write (nullfd, (char *) buf, sizeof buf);
      close (nullfd);
      if (getppid () == 1)
	_exit (2);
    }
}

static pid_t child;
static void
cleanup_child (void)
{
  if (child <= 0)
    return;
  if (kill (child, SIGKILL) < 0 && errno != ESRCH)
    printf ("cannot kill child %d: %m\n", child);
  else
    {
      int status;
      errno = 0;
      if (waitpid (child, &status, 0) != child)
	printf ("waitpid %d: %m\n", child);
    }
}
#define CLEANUP_HANDLER cleanup_child ()

static int
setup_test (void)
{
  /* Test timers on a process CPU clock by having a child process eating
     CPU.  First make sure we can make such timers at all.  */

  int pipefd[2];
  if (pipe (pipefd) < 0)
    {
      printf ("pipe: %m\n");
      exit (1);
    }

  child = fork ();

  if (child == 0)
    {
      char c;
      close (pipefd[1]);
      if (read (pipefd[0], &c, 1) == 1)
	chew_cpu ();
      _exit (1);
    }

  if (child < 0)
    {
      printf ("fork: %m\n");
      exit (1);
    }

  atexit (&cleanup_child);

  close (pipefd[0]);

  int e = clock_getcpuclockid (child, &child_clock);
  if (e == EPERM)
    {
      puts ("clock_getcpuclockid does not support other processes");
      return 1;
    }
  if (e != 0)
    {
      printf ("clock_getcpuclockid: %s\n", strerror (e));
      exit (1);
    }

  timer_t t;
  if (timer_create (TEST_CLOCK, NULL, &t) != 0)
    {
      printf ("timer_create: %m\n");
      return 1;
    }
  timer_delete (t);

  /* Get the child started chewing.  */
  if (write (pipefd[1], "x", 1) != 1)
    {
      printf ("write to pipe: %m\n");
      return 1;
    }
  close (pipefd[1]);

  return 0;
}

#else
# define TEST_CLOCK_MISSING(clock) "process clocks"
#endif

#include "tst-timer4.c"