lib/execute.c

   1 /* Creation of autonomous subprocesses.
   2    Copyright (C) 2001-2004, 2006-2020 Free Software Foundation, Inc.
   3    Written by Bruno Haible <haible@clisp.cons.org>, 2001.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include "execute.h"
  23
  24 #include <errno.h>
  25 #include <fcntl.h>
  26 #include <stdbool.h>
  27 #include <stdlib.h>
  28 #include <signal.h>
  29 #include <unistd.h>
  30
  31 #include "error.h"
  32 #include "fatal-signal.h"
  33 #include "wait-process.h"
  34 #include "gettext.h"
  35
  36 #define _(str) gettext (str)
  37
  38 #if defined _WIN32 && ! defined __CYGWIN__
  39
  40 /* Native Windows API.  */
  41 # include <process.h>
  42 # include "w32spawn.h"
  43
  44 #else
  45
  46 /* Unix API.  */
  47 # include <spawn.h>
  48
  49 #endif
  50
  51
  52 #if defined EINTR && (defined _WIN32 && ! defined __CYGWIN__)
  53
  54 /* EINTR handling for close(), open().
  55    These functions can return -1/EINTR even though we don't have any
  56    signal handlers set up, namely when we get interrupted via SIGSTOP.  */
  57
  58 static int
  59 nonintr_close (int fd)
  60 {
  61   int retval;
  62
  63   do
  64     retval = close (fd);
  65   while (retval < 0 && errno == EINTR);
  66
  67   return retval;
  68 }
  69 #undef close /* avoid warning related to gnulib module unistd */
  70 #define close nonintr_close
  71
  72 static int
  73 nonintr_open (const char *pathname, int oflag, mode_t mode)
  74 {
  75   int retval;
  76
  77   do
  78     retval = open (pathname, oflag, mode);
  79   while (retval < 0 && errno == EINTR);
  80
  81   return retval;
  82 }
  83 #undef open /* avoid warning on VMS */
  84 #define open nonintr_open
  85
  86 #endif
  87
  88
  89 /* Execute a command, optionally redirecting any of the three standard file
  90    descriptors to /dev/null.  Return its exit code.
  91    If it didn't terminate correctly, exit if exit_on_error is true, otherwise
  92    return 127.
  93    If slave_process is true, the child process will be terminated when its
  94    creator receives a catchable fatal signal.  */
  95 int
  96 execute (const char *progname,
  97          const char *prog_path, char **prog_argv,
  98          bool ignore_sigpipe,
  99          bool null_stdin, bool null_stdout, bool null_stderr,
 100          bool slave_process, bool exit_on_error,
 101          int *termsigp)
 102 {
 103 #if defined _WIN32 && ! defined __CYGWIN__
 104
 105   /* Native Windows API.  */
 106   int orig_stdin;
 107   int orig_stdout;
 108   int orig_stderr;
 109   int exitcode;
 110   int nullinfd;
 111   int nulloutfd;
 112
 113   /* FIXME: Need to free memory allocated by prepare_spawn.  */
 114   prog_argv = prepare_spawn (prog_argv);
 115
 116   /* Save standard file handles of parent process.  */
 117   if (null_stdin)
 118     orig_stdin = dup_safer_noinherit (STDIN_FILENO);
 119   if (null_stdout)
 120     orig_stdout = dup_safer_noinherit (STDOUT_FILENO);
 121   if (null_stderr)
 122     orig_stderr = dup_safer_noinherit (STDERR_FILENO);
 123   exitcode = -1;
 124
 125   /* Create standard file handles of child process.  */
 126   nullinfd = -1;
 127   nulloutfd = -1;
 128   if ((!null_stdin
 129        || ((nullinfd = open ("NUL", O_RDONLY, 0)) >= 0
 130            && (nullinfd == STDIN_FILENO
 131                || (dup2 (nullinfd, STDIN_FILENO) >= 0
 132                    && close (nullinfd) >= 0))))
 133       && (!(null_stdout || null_stderr)
 134           || ((nulloutfd = open ("NUL", O_RDWR, 0)) >= 0
 135               && (!null_stdout
 136                   || nulloutfd == STDOUT_FILENO
 137                   || dup2 (nulloutfd, STDOUT_FILENO) >= 0)
 138               && (!null_stderr
 139                   || nulloutfd == STDERR_FILENO
 140                   || dup2 (nulloutfd, STDERR_FILENO) >= 0)
 141               && ((null_stdout && nulloutfd == STDOUT_FILENO)
 142                   || (null_stderr && nulloutfd == STDERR_FILENO)
 143                   || close (nulloutfd) >= 0))))
 144     /* Use _spawnvpe and pass the environment explicitly.  This is needed if
 145        the program has modified the environment using putenv() or [un]setenv().
 146        On Windows, programs have two environments, one in the "environment
 147        block" of the process and managed through SetEnvironmentVariable(), and
 148        one inside the process, in the location retrieved by the 'environ'
 149        macro.  When using _spawnvp() without 'e', the child process inherits a
 150        copy of the environment block - ignoring the effects of putenv() and
 151        [un]setenv().  */
 152     {
 153       exitcode = _spawnvpe (P_WAIT, prog_path, (const char **) prog_argv,
 154                             (const char **) environ);
 155       if (exitcode < 0 && errno == ENOEXEC)
 156         {
 157           /* prog is not a native executable.  Try to execute it as a
 158              shell script.  Note that prepare_spawn() has already prepended
 159              a hidden element "sh.exe" to prog_argv.  */
 160           --prog_argv;
 161           exitcode = _spawnvpe (P_WAIT, prog_argv[0], (const char **) prog_argv,
 162                                 (const char **) environ);
 163         }
 164     }
 165   if (nulloutfd >= 0)
 166     close (nulloutfd);
 167   if (nullinfd >= 0)
 168     close (nullinfd);
 169
 170   /* Restore standard file handles of parent process.  */
 171   if (null_stderr)
 172     undup_safer_noinherit (orig_stderr, STDERR_FILENO);
 173   if (null_stdout)
 174     undup_safer_noinherit (orig_stdout, STDOUT_FILENO);
 175   if (null_stdin)
 176     undup_safer_noinherit (orig_stdin, STDIN_FILENO);
 177
 178   if (termsigp != NULL)
 179     *termsigp = 0;
 180
 181   if (exitcode == -1)
 182     {
 183       if (exit_on_error || !null_stderr)
 184         error (exit_on_error ? EXIT_FAILURE : 0, errno,
 185                _("%s subprocess failed"), progname);
 186       return 127;
 187     }
 188
 189   return exitcode;
 190
 191 #else
 192
 193   /* Unix API.  */
 194   /* Note about 127: Some errors during posix_spawnp() cause the function
 195      posix_spawnp() to return an error code; some other errors cause the
 196      subprocess to exit with return code 127.  It is implementation
 197      dependent which error is reported which way.  We treat both cases as
 198      equivalent.  */
 199   sigset_t blocked_signals;
 200   posix_spawn_file_actions_t actions;
 201   bool actions_allocated;
 202   posix_spawnattr_t attrs;
 203   bool attrs_allocated;
 204   int err;
 205   pid_t child;
 206
 207   if (slave_process)
 208     {
 209       sigprocmask (SIG_SETMASK, NULL, &blocked_signals);
 210       block_fatal_signals ();
 211     }
 212   actions_allocated = false;
 213   attrs_allocated = false;
 214   if ((err = posix_spawn_file_actions_init (&actions)) != 0
 215       || (actions_allocated = true,
 216           (null_stdin
 217             && (err = posix_spawn_file_actions_addopen (&actions,
 218                                                         STDIN_FILENO,
 219                                                         "/dev/null", O_RDONLY,
 220                                                         0))
 221                != 0)
 222           || (null_stdout
 223               && (err = posix_spawn_file_actions_addopen (&actions,
 224                                                           STDOUT_FILENO,
 225                                                           "/dev/null", O_RDWR,
 226                                                           0))
 227                  != 0)
 228           || (null_stderr
 229               && (err = posix_spawn_file_actions_addopen (&actions,
 230                                                           STDERR_FILENO,
 231                                                           "/dev/null", O_RDWR,
 232                                                           0))
 233                  != 0)
 234           || (slave_process
 235               && ((err = posix_spawnattr_init (&attrs)) != 0
 236                   || (attrs_allocated = true,
 237                       (err = posix_spawnattr_setsigmask (&attrs,
 238                                                          &blocked_signals))
 239                       != 0
 240                       || (err = posix_spawnattr_setflags (&attrs,
 241                                                         POSIX_SPAWN_SETSIGMASK))
 242                          != 0)))
 243           || (err = posix_spawnp (&child, prog_path, &actions,
 244                                   attrs_allocated ? &attrs : NULL, prog_argv,
 245                                   environ))
 246              != 0))
 247     {
 248       if (actions_allocated)
 249         posix_spawn_file_actions_destroy (&actions);
 250       if (attrs_allocated)
 251         posix_spawnattr_destroy (&attrs);
 252       if (slave_process)
 253         unblock_fatal_signals ();
 254       if (termsigp != NULL)
 255         *termsigp = 0;
 256       if (exit_on_error || !null_stderr)
 257         error (exit_on_error ? EXIT_FAILURE : 0, err,
 258                _("%s subprocess failed"), progname);
 259       return 127;
 260     }
 261   posix_spawn_file_actions_destroy (&actions);
 262   if (attrs_allocated)
 263     posix_spawnattr_destroy (&attrs);
 264   if (slave_process)
 265     {
 266       register_slave_subprocess (child);
 267       unblock_fatal_signals ();
 268     }
 269
 270   return wait_subprocess (child, progname, ignore_sigpipe, null_stderr,
 271                           slave_process, exit_on_error, termsigp);
 272
 273 #endif
 274 }