time/tst-cpuclock1.c

   1 /* Test program for process CPU clocks.
   2    Copyright (C) 2004-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <time.h>
  22 #include <unistd.h>
  23 #include <fcntl.h>
  24 #include <string.h>
  25 #include <errno.h>
  26 #include <signal.h>
  27 #include <stdint.h>
  28 #include <sys/wait.h>
  29
  30 #include <support/xunistd.h>
  31
  32 /* This function is intended to rack up both user and system time.  */
  33 static void
  34 chew_cpu (void)
  35 {
  36   while (1)
  37     {
  38       static volatile char buf[4096];
  39       for (int i = 0; i < 100; ++i)
  40         for (size_t j = 0; j < sizeof buf; ++j)
  41           buf[j] = 0xaa;
  42       int nullfd = open ("/dev/null", O_WRONLY);
  43       for (int i = 0; i < 100; ++i)
  44         for (size_t j = 0; j < sizeof buf; ++j)
  45           buf[j] = 0xbb;
  46       xwrite (nullfd, (char *) buf, sizeof buf);
  47       close (nullfd);
  48       if (getppid () == 1)
  49         _exit (2);
  50     }
  51 }
  52
  53 static int
  54 do_test (void)
  55 {
  56   int result = 0;
  57   clockid_t cl;
  58   int e;
  59   pid_t dead_child, child;
  60
  61   /* Fork a child and let it die, to give us a PID known not be valid
  62      (assuming PIDs don't wrap around during the test).  */
  63   {
  64     dead_child = fork ();
  65     if (dead_child == 0)
  66       _exit (0);
  67     if (dead_child < 0)
  68       {
  69         perror ("fork");
  70         return 1;
  71       }
  72     int x;
  73     if (wait (&x) != dead_child)
  74       {
  75         perror ("wait");
  76         return 2;
  77       }
  78   }
  79
  80   /* POSIX says we should get ESRCH for this.  */
  81   e = clock_getcpuclockid (dead_child, &cl);
  82   if (e != ENOSYS && e != ESRCH && e != EPERM)
  83     {
  84       printf ("clock_getcpuclockid on dead PID %d => %s\n",
  85               dead_child, strerror (e));
  86       result = 1;
  87     }
  88
  89   /* Now give us a live child eating up CPU time.  */
  90   child = fork ();
  91   if (child == 0)
  92     {
  93       chew_cpu ();
  94       _exit (1);
  95     }
  96   if (child < 0)
  97     {
  98       perror ("fork");
  99       return 1;
 100     }
 101
 102   e = clock_getcpuclockid (child, &cl);
 103   if (e == EPERM)
 104     {
 105       puts ("clock_getcpuclockid does not support other processes");
 106       goto done;
 107     }
 108   if (e != 0)
 109     {
 110       printf ("clock_getcpuclockid on live PID %d => %s\n",
 111               child, strerror (e));
 112       result = 1;
 113       goto done;
 114     }
 115
 116   const clockid_t child_clock = cl;
 117   struct timespec res;
 118   if (clock_getres (child_clock, &res) < 0)
 119     {
 120       printf ("clock_getres on live PID %d clock %lx => %s\n",
 121               child, (unsigned long int) child_clock, strerror (errno));
 122       result = 1;
 123       goto done;
 124     }
 125   printf ("live PID %d clock %lx resolution %ju.%.9ju\n",
 126           child, (unsigned long int) child_clock,
 127           (uintmax_t) res.tv_sec, (uintmax_t) res.tv_nsec);
 128
 129   struct timespec before;
 130   if (clock_gettime (child_clock, &before) < 0)
 131     {
 132       printf ("clock_gettime on live PID %d clock %lx => %s\n",
 133               child, (unsigned long int) child_clock, strerror (errno));
 134       result = 1;
 135       goto done;
 136     }
 137   /* Should be close to 0.0.  */
 138   printf ("live PID %d before sleep => %ju.%.9ju\n",
 139           child, (uintmax_t) before.tv_sec, (uintmax_t) before.tv_nsec);
 140
 141   struct timespec sleeptime = { .tv_nsec = 100000000 };
 142   e = clock_nanosleep (child_clock, 0, &sleeptime, NULL);
 143   if (e == EINVAL || e == ENOTSUP || e == ENOSYS)
 144     {
 145       printf ("clock_nanosleep not supported for other process clock: %s\n",
 146               strerror (e));
 147     }
 148   else if (e != 0)
 149     {
 150       printf ("clock_nanosleep on other process clock: %s\n", strerror (e));
 151       result = 1;
 152     }
 153   else
 154     {
 155       struct timespec afterns;
 156       if (clock_gettime (child_clock, &afterns) < 0)
 157         {
 158           printf ("clock_gettime on live PID %d clock %lx => %s\n",
 159                   child, (unsigned long int) child_clock, strerror (errno));
 160           result = 1;
 161         }
 162       else
 163         {
 164           printf ("live PID %d after sleep => %ju.%.9ju\n",
 165                   child, (uintmax_t) afterns.tv_sec,
 166                   (uintmax_t) afterns.tv_nsec);
 167         }
 168     }
 169
 170   if (kill (child, SIGKILL) != 0)
 171     {
 172       perror ("kill");
 173       result = 2;
 174       goto done;
 175     }
 176
 177   /* Wait long enough to let the child finish dying.  */
 178
 179   sleeptime.tv_nsec = 200000000;
 180   if (nanosleep (&sleeptime, NULL) != 0)
 181     {
 182       perror ("nanosleep");
 183       result = 1;
 184       goto done;
 185     }
 186
 187   struct timespec dead;
 188   if (clock_gettime (child_clock, &dead) < 0)
 189     {
 190       printf ("clock_gettime on dead PID %d clock %lx => %s\n",
 191               child, (unsigned long int) child_clock, strerror (errno));
 192       result = 1;
 193       goto done;
 194     }
 195   /* Should be close to 0.1.  */
 196   printf ("dead PID %d => %ju.%.9ju\n",
 197           child, (uintmax_t) dead.tv_sec, (uintmax_t) dead.tv_nsec);
 198
 199   /* Now reap the child and verify that its clock is no longer valid.  */
 200   {
 201     int x;
 202     if (waitpid (child, &x, 0) != child)
 203       {
 204         perror ("waitpid");
 205         result = 1;
 206       }
 207   }
 208
 209   if (clock_gettime (child_clock, &dead) == 0)
 210     {
 211       printf ("clock_gettime on reaped PID %d clock %lx => %ju%.9ju\n",
 212               child, (unsigned long int) child_clock,
 213               (uintmax_t) dead.tv_sec, (uintmax_t) dead.tv_nsec);
 214       result = 1;
 215     }
 216   else
 217     {
 218       if (errno != EINVAL)
 219         result = 1;
 220       printf ("clock_gettime on reaped PID %d clock %lx => %s\n",
 221               child, (unsigned long int) child_clock, strerror (errno));
 222     }
 223
 224   if (clock_getres (child_clock, &dead) == 0)
 225     {
 226       printf ("clock_getres on reaped PID %d clock %lx => %ju%.9ju\n",
 227               child, (unsigned long int) child_clock,
 228               (uintmax_t) dead.tv_sec, (uintmax_t) dead.tv_nsec);
 229       result = 1;
 230     }
 231   else
 232     {
 233       if (errno != EINVAL)
 234         result = 1;
 235       printf ("clock_getres on reaped PID %d clock %lx => %s\n",
 236               child, (unsigned long int) child_clock, strerror (errno));
 237     }
 238
 239   return result;
 240
 241  done:
 242   {
 243     if (kill (child, SIGKILL) != 0 && errno != ESRCH)
 244       {
 245         perror ("kill");
 246         return 2;
 247       }
 248     int x;
 249     if (waitpid (child, &x, 0) != child && errno != ECHILD)
 250       {
 251         perror ("waitpid");
 252         return 2;
 253       }
 254   }
 255
 256   return result;
 257 }
 258
 259
 260 #define TEST_FUNCTION do_test ()
 261 #include "../test-skeleton.c"