sysdeps/posix/spawni.c

   1 /* Guts of POSIX spawn interface.  Generic POSIX.1 version.
   2    Copyright (C) 2000, 2001, 2002, 2003, 2004 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <paths.h>
  23 #include <spawn.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include "spawn_int.h"
  28 #include <not-cancel.h>
  29
  30
  31 /* The Unix standard contains a long explanation of the way to signal
  32    an error after the fork() was successful.  Since no new wait status
  33    was wanted there is no way to signal an error using one of the
  34    available methods.  The committee chose to signal an error by a
  35    normal program exit with the exit code 127.  */
  36 #define SPAWN_ERROR     127
  37
  38
  39 /* The file is accessible but it is not an executable file.  Invoke
  40    the shell to interpret it as a script.  */
  41 static void
  42 internal_function
  43 script_execute (const char *file, char *const argv[], char *const envp[])
  44 {
  45   /* Count the arguments.  */
  46   int argc = 0;
  47   while (argv[argc++])
  48     ;
  49
  50   /* Construct an argument list for the shell.  */
  51   {
  52     char *new_argv[argc + 1];
  53     new_argv[0] = (char *) _PATH_BSHELL;
  54     new_argv[1] = (char *) file;
  55     while (argc > 1)
  56       {
  57         new_argv[argc] = argv[argc - 1];
  58         --argc;
  59       }
  60
  61     /* Execute the shell.  */
  62     __execve (new_argv[0], new_argv, envp);
  63   }
  64 }
  65
  66
  67 /* Spawn a new process executing PATH with the attributes describes in *ATTRP.
  68    Before running the process perform the actions described in FILE-ACTIONS. */
  69 int
  70 __spawni (pid_t *pid, const char *file,
  71           const posix_spawn_file_actions_t *file_actions,
  72           const posix_spawnattr_t *attrp, char *const argv[],
  73           char *const envp[], int use_path)
  74 {
  75   pid_t new_pid;
  76   char *path, *p, *name;
  77   size_t len;
  78   size_t pathlen;
  79
  80   /* Do this once.  */
  81   short int flags = attrp == NULL ? 0 : attrp->__flags;
  82
  83   /* Generate the new process.  */
  84   if (flags & POSIX_SPAWN_USEVFORK)
  85     new_pid = __vfork ();
  86   else
  87     new_pid = __fork ();
  88
  89   if (new_pid != 0)
  90     {
  91       if (new_pid < 0)
  92         return errno;
  93
  94       /* The call was successful.  Store the PID if necessary.  */
  95       if (pid != NULL)
  96         *pid = new_pid;
  97
  98       return 0;
  99     }
 100
 101   /* Set signal mask.  */
 102   if ((flags & POSIX_SPAWN_SETSIGMASK) != 0
 103       && __sigprocmask (SIG_SETMASK, &attrp->__ss, NULL) != 0)
 104     _exit (SPAWN_ERROR);
 105
 106   /* Set signal default action.  */
 107   if ((flags & POSIX_SPAWN_SETSIGDEF) != 0)
 108     {
 109       /* We have to iterate over all signals.  This could possibly be
 110          done better but it requires system specific solutions since
 111          the sigset_t data type can be very different on different
 112          architectures.  */
 113       int sig;
 114       struct sigaction sa;
 115
 116       memset (&sa, '\0', sizeof (sa));
 117       sa.sa_handler = SIG_DFL;
 118
 119       for (sig = 1; sig <= _NSIG; ++sig)
 120         if (__sigismember (&attrp->__sd, sig) != 0
 121             && __sigaction (sig, &sa, NULL) != 0)
 122           _exit (SPAWN_ERROR);
 123
 124     }
 125
 126 #ifdef _POSIX_PRIORITY_SCHEDULING
 127   /* Set the scheduling algorithm and parameters.  */
 128   if ((flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER))
 129       == POSIX_SPAWN_SETSCHEDPARAM)
 130     {
 131       if (__sched_setparam (0, &attrp->__sp) == -1)
 132         _exit (SPAWN_ERROR);
 133     }
 134   else if ((flags & POSIX_SPAWN_SETSCHEDULER) != 0)
 135     {
 136       if (__sched_setscheduler (0, attrp->__policy,
 137                                 (flags & POSIX_SPAWN_SETSCHEDPARAM) != 0
 138                                 ? &attrp->__sp : NULL) == -1)
 139         _exit (SPAWN_ERROR);
 140     }
 141 #endif
 142
 143   /* Set the process group ID.  */
 144   if ((flags & POSIX_SPAWN_SETPGROUP) != 0
 145       && __setpgid (0, attrp->__pgrp) != 0)
 146     _exit (SPAWN_ERROR);
 147
 148   /* Set the effective user and group IDs.  */
 149   if ((flags & POSIX_SPAWN_RESETIDS) != 0
 150       && (seteuid (__getuid ()) != 0 || setegid (__getgid ()) != 0))
 151     _exit (SPAWN_ERROR);
 152
 153   /* Execute the file actions.  */
 154   if (file_actions != NULL)
 155     {
 156       int cnt;
 157
 158       for (cnt = 0; cnt < file_actions->__used; ++cnt)
 159         {
 160           struct __spawn_action *action = &file_actions->__actions[cnt];
 161
 162           switch (action->tag)
 163             {
 164             case spawn_do_close:
 165               if (close_not_cancel (action->action.close_action.fd) != 0)
 166                 /* Signal the error.  */
 167                 _exit (SPAWN_ERROR);
 168               break;
 169
 170             case spawn_do_open:
 171               {
 172                 int new_fd = __open64 (action->action.open_action.path,
 173                                        action->action.open_action.oflag,
 174                                        action->action.open_action.mode);
 175
 176                 if (new_fd == -1)
 177                   /* The `open' call failed.  */
 178                   _exit (SPAWN_ERROR);
 179
 180                 /* Make sure the desired file descriptor is used.  */
 181                 if (new_fd != action->action.open_action.fd)
 182                   {
 183                     if (__dup2 (new_fd, action->action.open_action.fd)
 184                         != action->action.open_action.fd)
 185                       /* The `dup2' call failed.  */
 186                       _exit (SPAWN_ERROR);
 187
 188                     if (__close (new_fd) != 0)
 189                       /* The `close' call failed.  */
 190                       _exit (SPAWN_ERROR);
 191                   }
 192               }
 193               break;
 194
 195             case spawn_do_dup2:
 196               if (__dup2 (action->action.dup2_action.fd,
 197                           action->action.dup2_action.newfd)
 198                   != action->action.dup2_action.newfd)
 199                 /* The `dup2' call failed.  */
 200                 _exit (SPAWN_ERROR);
 201               break;
 202             }
 203         }
 204     }
 205
 206   if (! use_path || strchr (file, '/') != NULL)
 207     {
 208       /* The FILE parameter is actually a path.  */
 209       __execve (file, argv, envp);
 210
 211       if (errno == ENOEXEC)
 212         script_execute (file, argv, envp);
 213
 214       /* Oh, oh.  `execve' returns.  This is bad.  */
 215       _exit (SPAWN_ERROR);
 216     }
 217
 218   /* We have to search for FILE on the path.  */
 219   path = getenv ("PATH");
 220   if (path == NULL)
 221     {
 222       /* There is no `PATH' in the environment.
 223          The default search path is the current directory
 224          followed by the path `confstr' returns for `_CS_PATH'.  */
 225       len = confstr (_CS_PATH, (char *) NULL, 0);
 226       path = (char *) __alloca (1 + len);
 227       path[0] = ':';
 228       (void) confstr (_CS_PATH, path + 1, len);
 229     }
 230
 231   len = strlen (file) + 1;
 232   pathlen = strlen (path);
 233   name = __alloca (pathlen + len + 1);
 234   /* Copy the file name at the top.  */
 235   name = (char *) memcpy (name + pathlen + 1, file, len);
 236   /* And add the slash.  */
 237   *--name = '/';
 238
 239   p = path;
 240   do
 241     {
 242       char *startp;
 243
 244       path = p;
 245       p = __strchrnul (path, ':');
 246
 247       if (p == path)
 248         /* Two adjacent colons, or a colon at the beginning or the end
 249            of `PATH' means to search the current directory.  */
 250         startp = name + 1;
 251       else
 252         startp = (char *) memcpy (name - (p - path), path, p - path);
 253
 254       /* Try to execute this name.  If it works, execv will not return.  */
 255       __execve (startp, argv, envp);
 256
 257       if (errno == ENOEXEC)
 258         script_execute (startp, argv, envp);
 259
 260       switch (errno)
 261         {
 262         case EACCES:
 263         case ENOENT:
 264         case ESTALE:
 265         case ENOTDIR:
 266           /* Those errors indicate the file is missing or not executable
 267              by us, in which case we want to just try the next path
 268              directory.  */
 269           break;
 270
 271         default:
 272           /* Some other error means we found an executable file, but
 273              something went wrong executing it; return the error to our
 274              caller.  */
 275           _exit (SPAWN_ERROR);
 276             }
 277     }
 278   while (*p++ != '\0');
 279
 280   /* Return with an error.  */
 281   _exit (SPAWN_ERROR);
 282 }