1/* Wait for process state.
2 Copyright (C) 2020-2021 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
29void
30support_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}
93