1  /* Wait for process state.
       2     Copyright (C) 2020-2023 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  }