lib/dpkg/subproc.c

   1 /*
   2  * libdpkg - Debian packaging suite library routines
   3  * subproc.c - subprocess helper routines
   4  *
   5  * Copyright © 1995 Ian Jackson <ijackson@chiark.greenend.org.uk>
   6  * Copyright © 2008-2014 Guillem Jover <guillem@debian.org>
   7  *
   8  * This is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  20  */
  21
  22 #include <config.h>
  23 #include <compat.h>
  24
  25 #include <sys/types.h>
  26 #include <sys/wait.h>
  27
  28 #include <errno.h>
  29 #include <string.h>
  30 #include <signal.h>
  31 #include <unistd.h>
  32 #include <stdlib.h>
  33 #include <stdio.h>
  34
  35 #include <dpkg/i18n.h>
  36 #include <dpkg/dpkg.h>
  37 #include <dpkg/subproc.h>
  38
  39 static int signo_ignores[] = { SIGQUIT, SIGINT };
  40 static struct sigaction sa_save[array_count(signo_ignores)];
  41
  42 static void
  43 subproc_reset_signal(int sig, struct sigaction *sa_old)
  44 {
  45         if (sigaction(sig, sa_old, NULL)) {
  46                 fprintf(stderr, _("error un-catching signal %s: %s\n"),
  47                         strsignal(sig), strerror(errno));
  48                 onerr_abort++;
  49         }
  50 }
  51
  52 static void
  53 subproc_set_signal(int sig, struct sigaction *sa, struct sigaction *sa_old,
  54                    const char *name)
  55 {
  56         if (sigaction(sig, sa, sa_old))
  57                 ohshite(_("unable to ignore signal %s before running %.250s"),
  58                         strsignal(sig), name);
  59 }
  60
  61 void
  62 subproc_signals_ignore(const char *name)
  63 {
  64         struct sigaction sa;
  65         size_t i;
  66
  67         onerr_abort++;
  68         memset(&sa, 0, sizeof(sa));
  69         sigemptyset(&sa.sa_mask);
  70         sa.sa_handler = SIG_IGN;
  71         sa.sa_flags = 0;
  72
  73         for (i = 0; i < array_count(signo_ignores); i++)
  74                 subproc_set_signal(signo_ignores[i], &sa, &sa_save[i], name);
  75
  76         push_cleanup(subproc_signals_cleanup, ~0, 0);
  77         onerr_abort--;
  78 }
  79
  80 void
  81 subproc_signals_cleanup(int argc, void **argv)
  82 {
  83         size_t i;
  84
  85         for (i = 0; i < array_count(signo_ignores); i++)
  86                 subproc_reset_signal(signo_ignores[i], &sa_save[i]);
  87 }
  88
  89 void
  90 subproc_signals_restore(void)
  91 {
  92         pop_cleanup(ehflag_normaltidy);
  93 }
  94
  95 static void
  96 print_subproc_error(const char *emsg, const void *data)
  97 {
  98         fprintf(stderr, _("%s (subprocess): %s\n"), dpkg_get_progname(), emsg);
  99 }
 100
 101 pid_t
 102 subproc_fork(void)
 103 {
 104         pid_t pid;
 105
 106         pid = fork();
 107         if (pid < 0) {
 108                 onerr_abort++;
 109                 ohshite(_("fork failed"));
 110         }
 111         if (pid > 0)
 112                 return pid;
 113
 114         /* Push a new error context, so that we don't do the other cleanups,
 115          * because they'll be done by/in the parent process. */
 116         push_error_context_func(catch_fatal_error, print_subproc_error, NULL);
 117
 118         return pid;
 119 }
 120
 121 static int
 122 subproc_check(int status, const char *desc, enum subproc_flags flags)
 123 {
 124         void (*out)(const char *fmt, ...) DPKG_ATTR_PRINTF(1);
 125         int n;
 126
 127         if (flags & SUBPROC_WARN)
 128                 out = warning;
 129         else
 130                 out = ohshit;
 131
 132         if (WIFEXITED(status)) {
 133                 n = WEXITSTATUS(status);
 134                 if (!n)
 135                         return 0;
 136                 if (flags & SUBPROC_RETERROR)
 137                         return n;
 138
 139                 out(_("%s subprocess returned error exit status %d"), desc, n);
 140         } else if (WIFSIGNALED(status)) {
 141                 n = WTERMSIG(status);
 142                 if (!n)
 143                         return 0;
 144                 if ((flags & SUBPROC_NOPIPE) && n == SIGPIPE)
 145                         return 0;
 146                 if (flags & SUBPROC_RETSIGNO)
 147                         return n;
 148
 149                 if (n == SIGINT)
 150                         out(_("%s subprocess was interrupted"), desc);
 151                 else
 152                         out(_("%s subprocess was killed by signal (%s)%s"),
 153                             desc, strsignal(n),
 154                             WCOREDUMP(status) ? _(", core dumped") : "");
 155         } else {
 156                 if (flags & SUBPROC_RETERROR)
 157                         return -1;
 158
 159                 out(_("%s subprocess failed with wait status code %d"), desc,
 160                     status);
 161         }
 162
 163         return -1;
 164 }
 165
 166 static int
 167 subproc_wait(pid_t pid, const char *desc)
 168 {
 169         pid_t dead_pid;
 170         int status;
 171
 172         while ((dead_pid = waitpid(pid, &status, 0)) < 0 && errno == EINTR) ;
 173
 174         if (dead_pid != pid) {
 175                 onerr_abort++;
 176                 ohshite(_("wait for %s subprocess failed"), desc);
 177         }
 178
 179         return status;
 180 }
 181
 182 int
 183 subproc_reap(pid_t pid, const char *desc, enum subproc_flags flags)
 184 {
 185         int status, rc;
 186
 187         status = subproc_wait(pid, desc);
 188
 189         if (flags & SUBPROC_NOCHECK)
 190                 rc = status;
 191         else
 192                 rc = subproc_check(status, desc, flags);
 193
 194         return rc;
 195 }