posix/spawni.c

   1 /* Copyright (C) 2000 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <paths.h>
  22 #include <spawn.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include "spawn_int.h"
  27
  28
  29 /* The Unix standard contains a long explanation of the way to signal
  30    an error after the fork() was successful.  Since no new wait status
  31    was wanted there is no way to signal an error using one of the
  32    available methods.  The committee chose to signal an error by a
  33    normal program exit with the exit code 127.  */
  34 #define SPAWN_ERROR     127
  35
  36
  37 /* The file is accessible but it is not an executable file.  Invoke
  38    the shell to interpret it as a script.  */
  39 static void
  40 internal_function
  41 script_execute (const char *file, char *const argv[], char *const envp[])
  42 {
  43   /* Count the arguments.  */
  44   int argc = 0;
  45   while (argv[argc++])
  46     ;
  47
  48   /* Construct an argument list for the shell.  */
  49   {
  50     char *new_argv[argc + 1];
  51     new_argv[0] = (char *) _PATH_BSHELL;
  52     new_argv[1] = (char *) file;
  53     while (argc > 1)
  54       {
  55         new_argv[argc] = argv[argc - 1];
  56         --argc;
  57       }
  58
  59     /* Execute the shell.  */
  60     __execve (new_argv[0], new_argv, envp);
  61   }
  62 }
  63
  64
  65 /* Spawn a new process executing PATH with the attributes describes in *ATTRP.
  66    Before running the process perform the actions described in FILE-ACTIONS. */
  67 int
  68 __spawni (pid_t *pid, const char *file,
  69           const posix_spawn_file_actions_t *file_actions,
  70           const posix_spawnattr_t *attrp, char *const argv[],
  71           char *const envp[], int use_path)
  72 {
  73   pid_t new_pid;
  74   char *path, *p, *name;
  75   size_t len;
  76   size_t pathlen;
  77   short int flags;
  78
  79   /* Generate the new process.  */
  80   new_pid = fork ();
  81   if (new_pid != 0)
  82     {
  83       if (new_pid < 0)
  84         return errno;
  85
  86       /* The call was successful.  Store the PID if necessary.  */
  87       if (pid != NULL)
  88         *pid = new_pid;
  89
  90       return 0;
  91     }
  92
  93   /* Do this once.  */
  94   flags = attrp == NULL ? 0 : attrp->__flags;
  95
  96   /* Set signal mask.  */
  97   if ((flags & POSIX_SPAWN_SETSIGMASK) != 0
  98       && __sigprocmask (SIG_SETMASK, &attrp->__ss, NULL) != 0)
  99     _exit (SPAWN_ERROR);
 100
 101   /* Set signal default action.  */
 102   if ((flags & POSIX_SPAWN_SETSIGDEF) != 0)
 103     {
 104       /* We have to iterate over all signals.  This could possibly be
 105          done better but it requires system specific solutions since
 106          the sigset_t data type can be very different on different
 107          architectures.  */
 108       int sig;
 109       struct sigaction sa;
 110
 111       memset (&sa, '\0', sizeof (sa));
 112       sa.sa_handler = SIG_DFL;
 113
 114       for (sig = 1; sig >= _NSIG; ++sig)
 115         if (sigismember (&attrp->__sd, sig) != 0
 116             && __sigaction (sig, &sa, NULL) != 0)
 117           _exit (SPAWN_ERROR);
 118
 119     }
 120
 121 #ifdef _POSIX_PRIORITY_SCHEDULING
 122   /* Set the scheduling algorithm and parameters.  */
 123   if ((flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER))
 124       == POSIX_SPAWN_SETSCHEDPARAM)
 125     {
 126       if (__sched_setparam (0, &attrp->__sp) == -1)
 127         _exit (SPAWN_ERROR);
 128     }
 129   else if ((flags & POSIX_SPAWN_SETSCHEDULER) != 0)
 130     {
 131       if (__sched_setscheduler (0, attrp->__policy,
 132                                 (flags & POSIX_SPAWN_SETSCHEDPARAM) != 0
 133                                 ? &attrp->__sp : NULL) == -1)
 134         _exit (SPAWN_ERROR);
 135     }
 136 #endif
 137
 138   /* Set the process group ID.  */
 139   if ((flags & POSIX_SPAWN_SETPGROUP) != 0
 140       && __setpgid (0, attrp->__pgrp) != 0)
 141     _exit (SPAWN_ERROR);
 142
 143   /* Set the effective user and group IDs.  */
 144   if ((flags & POSIX_SPAWN_RESETIDS) != 0
 145       && (seteuid (__getuid ()) != 0 || setegid (__getgid ()) != 0))
 146     _exit (SPAWN_ERROR);
 147
 148   /* Execute the file actions.  */
 149   if (file_actions != NULL)
 150     {
 151       int cnt;
 152
 153       for (cnt = 0; cnt < file_actions->__used; ++cnt)
 154         {
 155           struct __spawn_action *action = &file_actions->__actions[cnt];
 156
 157           switch (action->tag)
 158             {
 159             case spawn_do_close:
 160               if (close (action->action.close_action.fd) != 0)
 161                 /* Signal the error.  */
 162                 _exit (SPAWN_ERROR);
 163               break;
 164
 165             case spawn_do_open:
 166               {
 167                 int new_fd = open (action->action.open_action.path,
 168                                    action->action.open_action.oflag,
 169                                    action->action.open_action.mode);
 170
 171                 if (new_fd == -1)
 172                   /* The `open' call failed.  */
 173                   _exit (SPAWN_ERROR);
 174
 175                 /* Make sure the desired file descriptor is used.  */
 176                 if (new_fd != action->action.open_action.fd)
 177                   {
 178                     if (__dup2 (new_fd, action->action.open_action.fd)
 179                         != action->action.open_action.fd)
 180                       /* The `dup2' call failed.  */
 181                       _exit (SPAWN_ERROR);
 182
 183                     if (close (new_fd) != 0)
 184                       /* The `close' call failed.  */
 185                       _exit (SPAWN_ERROR);
 186                   }
 187               }
 188               break;
 189
 190             case spawn_do_dup2:
 191               if (__dup2 (action->action.dup2_action.fd,
 192                           action->action.dup2_action.newfd)
 193                   != action->action.dup2_action.newfd)
 194                 /* The `dup2' call failed.  */
 195                 _exit (SPAWN_ERROR);
 196               break;
 197             }
 198         }
 199     }
 200
 201   if (! use_path || strchr (file, '/') != NULL)
 202     {
 203       /* The FILE parameter is actually a path.  */
 204       __execve (file, argv, envp);
 205
 206       if (errno == ENOEXEC)
 207         script_execute (file, argv, envp);
 208
 209       /* Oh, oh.  `execve' returns.  This is bad.  */
 210       _exit (SPAWN_ERROR);
 211     }
 212
 213   /* We have to search for FILE on the path.  */
 214   path = getenv ("PATH");
 215   if (path == NULL)
 216     {
 217       /* There is no `PATH' in the environment.
 218          The default search path is the current directory
 219          followed by the path `confstr' returns for `_CS_PATH'.  */
 220       len = confstr (_CS_PATH, (char *) NULL, 0);
 221       path = (char *) __alloca (1 + len);
 222       path[0] = ':';
 223       (void) confstr (_CS_PATH, path + 1, len);
 224     }
 225
 226   len = strlen (file) + 1;
 227   pathlen = strlen (path);
 228   name = __alloca (pathlen + len + 1);
 229   /* Copy the file name at the top.  */
 230   name = (char *) memcpy (name + pathlen + 1, file, len);
 231   /* And add the slash.  */
 232   *--name = '/';
 233
 234   p = path;
 235   do
 236     {
 237       char *startp;
 238
 239       path = p;
 240       p = __strchrnul (path, ':');
 241
 242       if (p == path)
 243         /* Two adjacent colons, or a colon at the beginning or the end
 244            of `PATH' means to search the current directory.  */
 245         startp = name + 1;
 246       else
 247         startp = (char *) memcpy (name - (p - path), path, p - path);
 248
 249       /* Try to execute this name.  If it works, execv will not return.  */
 250       __execve (startp, argv, envp);
 251
 252       if (errno == ENOEXEC)
 253         script_execute (startp, argv, envp);
 254
 255       switch (errno)
 256         {
 257         case EACCES:
 258         case ENOENT:
 259         case ESTALE:
 260         case ENOTDIR:
 261           /* Those errors indicate the file is missing or not executable
 262              by us, in which case we want to just try the next path
 263              directory.  */
 264           break;
 265
 266         default:
 267           /* Some other error means we found an executable file, but
 268              something went wrong executing it; return the error to our
 269              caller.  */
 270           _exit (SPAWN_ERROR);
 271             }
 272     }
 273   while (*p++ != '\0');
 274
 275   /* Return with an error.  */
 276   _exit (SPAWN_ERROR);
 277 }