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 #include <intprops.h>
  25
  26 #include <support/process_state.h>
  27 #include <support/xstdio.h>
  28 #include <support/check.h>
  29
  30 void
  31 support_process_state_wait (pid_t pid, enum support_process_state state)
  32 {
  33 #ifdef __linux__
  34   /* For Linux it does a polling check on /proc/<pid>/status checking on
  35      third field.  */
  36
  37   /* It mimics the kernel states from fs/proc/array.c  */
  38   static const struct process_states
  39   {
  40     enum support_process_state s;
  41     char v;
  42   } process_states[] = {
  43     { support_process_state_running,      'R' },
  44     { support_process_state_sleeping,     'S' },
  45     { support_process_state_disk_sleep,   'D' },
  46     { support_process_state_stopped,      'T' },
  47     { support_process_state_tracing_stop, 't' },
  48     { support_process_state_dead,         'X' },
  49     { support_process_state_zombie,       'Z' },
  50     { support_process_state_parked,       'P' },
  51   };
  52
  53   char spath[sizeof ("/proc/") + INT_STRLEN_BOUND (pid_t) + sizeof ("/status") + 1];
  54   snprintf (spath, sizeof (spath), "/proc/%i/status", pid);
  55
  56   FILE *fstatus = xfopen (spath, "r");
  57   char *line = NULL;
  58   size_t linesiz = 0;
  59
  60   for (;;)
  61     {
  62       char cur_state = -1;
  63       while (xgetline (&line, &linesiz, fstatus) > 0)
  64         if (strncmp (line, "State:", strlen ("State:")) == 0)
  65           {
  66             TEST_COMPARE (sscanf (line, "%*s %c", &cur_state), 1);
  67             break;
  68           }
  69       /* Fallback to nanosleep for invalid state.  */
  70       if (cur_state == -1)
  71         break;
  72
  73       for (size_t i = 0; i < array_length (process_states); ++i)
  74         if (state & process_states[i].s && cur_state == process_states[i].v)
  75           {
  76             free (line);
  77             xfclose (fstatus);
  78             return;
  79           }
  80
  81       rewind (fstatus);
  82       fflush (fstatus);
  83
  84       if (nanosleep (&(struct timespec) { 0, 10000000 }, NULL) != 0)
  85         FAIL_EXIT1 ("nanosleep: %m");
  86     }
  87
  88   free (line);
  89   xfclose (fstatus);
  90   /* Fallback to nanosleep if an invalid state is found.  */
  91 #endif
  92   nanosleep (&(struct timespec) { 1, 0 }, NULL);
  93 }