misc-utils/waitpid.c

   1 /*
   2  * waitpid(1) - wait for process termination
   3  *
   4  * Copyright (C) 2022 Thomas Weißschuh <thomas@t-8ch.de>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it would be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include <sys/epoll.h>
  22 #include <sys/timerfd.h>
  23 #include <assert.h>
  24 #include <stdlib.h>
  25 #include <errno.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28 #include <stdbool.h>
  29 #include <getopt.h>
  30
  31 #include "pidfd-utils.h"
  32 #include "c.h"
  33 #include "nls.h"
  34 #include "xalloc.h"
  35 #include "strutils.h"
  36 #include "exitcodes.h"
  37 #include "timeutils.h"
  38 #include "optutils.h"
  39
  40 #define EXIT_TIMEOUT_EXPIRED 3
  41
  42 #define TIMEOUT_SOCKET_IDX UINT64_MAX
  43
  44 static bool verbose = false;
  45 static struct timespec timeout;
  46 static bool allow_exited = false;
  47 static size_t count;
  48
  49 static pid_t *parse_pids(size_t n_strings, char * const *strings)
  50 {
  51         pid_t *pids = xcalloc(n_strings, sizeof(*pids));
  52
  53         for (size_t i = 0; i < n_strings; i++)
  54                 pids[i] = strtopid_or_err(strings[i], _("failed to parse pid"));
  55
  56         return pids;
  57 }
  58
  59 static int *open_pidfds(size_t n_pids, pid_t *pids)
  60 {
  61         int *pidfds = xcalloc(n_pids, sizeof(*pidfds));
  62
  63         for (size_t i = 0; i < n_pids; i++) {
  64                 pidfds[i] = pidfd_open(pids[i], 0);
  65                 if (pidfds[i] == -1) {
  66                         if (allow_exited && errno == ESRCH) {
  67                                 warnx(_("PID %d has exited, skipping"), pids[i]);
  68                                 continue;
  69                         }
  70                         err_nosys(EXIT_FAILURE, _("could not open pid %u"), pids[i]);
  71                 }
  72         }
  73
  74         return pidfds;
  75 }
  76
  77 static int open_timeoutfd(void)
  78 {
  79         int fd;
  80         struct itimerspec timer = {};
  81
  82         if (!timeout.tv_sec && !timeout.tv_nsec)
  83                 return -1;
  84
  85         timer.it_value = timeout;
  86
  87         fd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC);
  88         if (fd == -1)
  89                 err_nosys(EXIT_FAILURE, _("could not create timerfd"));
  90
  91         if (timerfd_settime(fd, 0, &timer, NULL))
  92                 err_nosys(EXIT_FAILURE, _("could not set timer"));
  93
  94         return fd;
  95
  96 }
  97
  98 static size_t add_listeners(int epll, size_t n_pids, int * const pidfds, int timeoutfd)
  99 {
 100         size_t skipped = 0;
 101         struct epoll_event evt = {
 102                 .events = EPOLLIN,
 103         };
 104
 105         if (timeoutfd != -1) {
 106                 evt.data.u64 = TIMEOUT_SOCKET_IDX;
 107                 if (epoll_ctl(epll, EPOLL_CTL_ADD, timeoutfd, &evt))
 108                         err_nosys(EXIT_FAILURE, _("could not add timerfd"));
 109         }
 110
 111         for (size_t i = 0; i < n_pids; i++) {
 112                 if (pidfds[i] == -1) {
 113                         skipped++;
 114                         continue;
 115                 }
 116                 evt.data.u64 = i;
 117                 if (epoll_ctl(epll, EPOLL_CTL_ADD, pidfds[i], &evt))
 118                         err_nosys(EXIT_FAILURE, _("could not add listener"));
 119         }
 120
 121         return n_pids - skipped;
 122 }
 123
 124 static void wait_for_exits(int epll, size_t active_pids, pid_t * const pids,
 125                            int * const pidfds)
 126 {
 127         while (active_pids) {
 128                 struct epoll_event evt;
 129                 int ret, fd;
 130
 131                 ret = epoll_wait(epll, &evt, 1, -1);
 132                 if (ret == -1) {
 133                         if (errno == EINTR)
 134                                 continue;
 135                         else
 136                                 err_nosys(EXIT_FAILURE, _("failure during wait"));
 137                 }
 138                 if (evt.data.u64 == TIMEOUT_SOCKET_IDX) {
 139                         if (verbose)
 140                                 printf(_("Timeout expired\n"));
 141                         exit(EXIT_TIMEOUT_EXPIRED);
 142                 }
 143                 if (verbose)
 144                         printf(_("PID %d finished\n"), pids[evt.data.u64]);
 145                 assert((size_t) ret <= active_pids);
 146                 fd = pidfds[evt.data.u64];
 147                 epoll_ctl(epll, EPOLL_CTL_DEL, fd, NULL);
 148                 active_pids -= ret;
 149         }
 150 }
 151
 152 static void __attribute__((__noreturn__)) usage(void)
 153 {
 154         FILE *out = stdout;
 155
 156         fputs(USAGE_HEADER, out);
 157         fprintf(out, _(" %s [options] pid...\n"), program_invocation_short_name);
 158
 159         fputs(USAGE_OPTIONS, out);
 160         fputs(_(" -v, --verbose           be more verbose\n"), out);
 161         fputs(_(" -t, --timeout=<timeout> wait at most timeout seconds\n"), out);
 162         fputs(_(" -e, --exited            allow exited PIDs\n"), out);
 163         fputs(_(" -c, --count=<count>     number of process exits to wait for\n"), out);
 164
 165         fputs(USAGE_SEPARATOR, out);
 166         fprintf(out, USAGE_HELP_OPTIONS(25));
 167
 168         fprintf(out, USAGE_MAN_TAIL("waitpid(1)"));
 169
 170         exit(EXIT_SUCCESS);
 171 }
 172
 173 static int parse_options(int argc, char **argv)
 174 {
 175         int c;
 176         static const struct option longopts[] = {
 177                 { "verbose", no_argument,       NULL, 'v' },
 178                 { "timeout", required_argument, NULL, 't' },
 179                 { "exited",  no_argument,       NULL, 'e' },
 180                 { "count",   required_argument, NULL, 'c' },
 181                 { "version", no_argument,       NULL, 'V' },
 182                 { "help",    no_argument,       NULL, 'h' },
 183                 { 0 }
 184         };
 185         static const ul_excl_t excl[] = {       /* rows and cols in ASCII order */
 186                 { 'c', 'e' },
 187                 { 0 }
 188         };
 189         int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
 190
 191         while ((c = getopt_long (argc, argv, "vVht:c:e", longopts, NULL)) != -1) {
 192
 193                 err_exclusive_options(c, longopts, excl, excl_st);
 194
 195                 switch (c) {
 196                 case 'v':
 197                         verbose = true;
 198                         break;
 199                 case 't':
 200                         strtotimespec_or_err(optarg, &timeout,
 201                                              _("Could not parse timeout"));
 202                         break;
 203                 case 'e':
 204                         allow_exited = true;
 205                         break;
 206                 case 'c':
 207                         count = str2num_or_err(optarg, 10, _("Invalid count"),
 208                                                1, INT64_MAX);
 209                         break;
 210                 case 'V':
 211                         print_version(EXIT_SUCCESS);
 212                 case 'h':
 213                         usage();
 214                 default:
 215                         errtryhelp(EXIT_FAILURE);
 216                 }
 217         }
 218
 219         return optind;
 220 }
 221
 222 int main(int argc, char **argv)
 223 {
 224         int pid_idx, epoll, timeoutfd, *pidfds;
 225         size_t n_pids, active_pids;
 226
 227         setlocale(LC_ALL, "");
 228         bindtextdomain(PACKAGE, LOCALEDIR);
 229         textdomain(PACKAGE);
 230
 231         pid_idx = parse_options(argc, argv);
 232         n_pids = argc - pid_idx;
 233         if (!n_pids)
 234                 errx(EXIT_FAILURE, _("no PIDs specified"));
 235
 236         if (count && count > n_pids)
 237                 errx(EXIT_FAILURE,
 238                      _("can't want for %zu of %zu PIDs"), count, n_pids);
 239
 240         pid_t *pids = parse_pids(argc - pid_idx, argv + pid_idx);
 241
 242         pidfds = open_pidfds(n_pids, pids);
 243         timeoutfd = open_timeoutfd();
 244         epoll = epoll_create(n_pids);
 245         if (epoll == -1)
 246                 err_nosys(EXIT_FAILURE, _("could not create epoll"));
 247
 248         active_pids = add_listeners(epoll, n_pids, pidfds, timeoutfd);
 249         if (count)
 250                 active_pids = min(active_pids, count);
 251         wait_for_exits(epoll, active_pids, pids, pidfds);
 252 }