support/support_process_state.c

   1 /* Wait for process state.
   2    Copyright (C) 2020-2022 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 <stdlib.h>
  20 #include <time.h>
  21 #include <string.h>
  22
  23 #include <array_length.h>
  24
  25 #include <support/process_state.h>
  26 #include <support/xstdio.h>
  27 #include <support/check.h>
  28
  29 void
  30 support_process_state_wait (pid_t pid, enum support_process_state state)
  31 {
  32 #ifdef __linux__
  33   /* For Linux it does a polling check on /proc/<pid>/status checking on
  34      third field.  */
  35
  36   /* It mimics the kernel states from fs/proc/array.c  */
  37   static const struct process_states
  38   {
  39     enum support_process_state s;
  40     char v;
  41   } process_states[] = {
  42     { support_process_state_running,      'R' },
  43     { support_process_state_sleeping,     'S' },
  44     { support_process_state_disk_sleep,   'D' },
  45     { support_process_state_stopped,      'T' },
  46     { support_process_state_tracing_stop, 't' },
  47     { support_process_state_dead,         'X' },
  48     { support_process_state_zombie,       'Z' },
  49     { support_process_state_parked,       'P' },
  50   };
  51
  52   char spath[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/status") + 1];
  53   snprintf (spath, sizeof (spath), "/proc/%i/status", pid);
  54
  55   FILE *fstatus = xfopen (spath, "r");
  56   char *line = NULL;
  57   size_t linesiz = 0;
  58
  59   for (;;)
  60     {
  61       char cur_state = -1;
  62       while (xgetline (&line, &linesiz, fstatus) > 0)
  63         if (strncmp (line, "State:", strlen ("State:")) == 0)
  64           {
  65             TEST_COMPARE (sscanf (line, "%*s %c", &cur_state), 1);
  66             break;
  67           }
  68       /* Fallback to nanosleep for invalid state.  */
  69       if (cur_state == -1)
  70         break;
  71
  72       for (size_t i = 0; i < array_length (process_states); ++i)
  73         if (state & process_states[i].s && cur_state == process_states[i].v)
  74           {
  75             free (line);
  76             xfclose (fstatus);
  77             return;
  78           }
  79
  80       rewind (fstatus);
  81       fflush (fstatus);
  82
  83       if (nanosleep (&(struct timespec) { 0, 10000000 }, NULL) != 0)
  84         FAIL_EXIT1 ("nanosleep: %m");
  85     }
  86
  87   free (line);
  88   xfclose (fstatus);
  89   /* Fallback to nanosleep if an invalid state is found.  */
  90 #endif
  91   nanosleep (&(struct timespec) { 1, 0 }, NULL);
  92 }