sysdeps/posix/spawni.c

   1 /* Guts of POSIX spawn interface.  Generic POSIX.1 version.
   2    Copyright (C) 2000, 2001 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 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
  29
  30 /* The Unix standard contains a long explanation of the way to signal
  31    an error after the fork() was successful.  Since no new wait status
  32    was wanted there is no way to signal an error using one of the
  33    available methods.  The committee chose to signal an error by a
  34    normal program exit with the exit code 127.  */
  35 #define SPAWN_ERROR     127
  36
  37
  38 /* The file is accessible but it is not an executable file.  Invoke
  39    the shell to interpret it as a script.  */
  40 static void
  41 internal_function
  42 script_execute (const char *file, char *const argv[], char *const envp[])
  43 {
  44   /* Count the arguments.  */
  45   int argc = 0;
  46   while (argv[argc++])
  47     ;
  48
  49   /* Construct an argument list for the shell.  */
  50   {
  51     char *new_argv[argc + 1];
  52     new_argv[0] = (char *) _PATH_BSHELL;
  53     new_argv[1] = (char *) file;
  54     while (argc > 1)
  55       {
  56         new_argv[argc] = argv[argc - 1];
  57         --argc;
  58       }
  59
  60     /* Execute the shell.  */
  61     __execve (new_argv[0], new_argv, envp);
  62   }
  63 }
  64
  65
  66 /* Spawn a new process executing PATH with the attributes describes in *ATTRP.
  67    Before running the process perform the actions described in FILE-ACTIONS. */
  68 int
  69 __spawni (pid_t *pid, const char *file,
  70           const posix_spawn_file_actions_t *file_actions,
  71           const posix_spawnattr_t *attrp, char *const argv[],
  72           char *const envp[], int use_path)
  73 {
  74   pid_t new_pid;
  75   char *path, *p, *name;
  76   size_t len;
  77   size_t pathlen;
  78   short int flags;
  79
  80   /* Generate the new process.  */
  81   new_pid = __fork ();
  82   if (new_pid != 0)
  83     {
  84       if (new_pid < 0)
  85         return errno;
  86
  87       /* The call was successful.  Store the PID if necessary.  */
  88       if (pid != NULL)
  89         *pid = new_pid;
  90
  91       return 0;
  92     }
  93
  94   /* Do this once.  */
  95   flags = attrp == NULL ? 0 : attrp->__flags;
  96
  97   /* Set signal mask.  */
  98   if ((flags & POSIX_SPAWN_SETSIGMASK) != 0
  99       && __sigprocmask (SIG_SETMASK, &attrp->__ss, NULL) != 0)
 100     _exit (SPAWN_ERROR);
 101
 102   /* Set signal default action.  */
 103   if ((flags & POSIX_SPAWN_SETSIGDEF) != 0)
 104     {
 105       /* We have to iterate over all signals.  This could possibly be
 106          done better but it requires system specific solutions since
 107          the sigset_t data type can be very different on different
 108          architectures.  */
 109       int sig;
 110       struct sigaction sa;
 111
 112       memset (&sa, '\0', sizeof (sa));
 113       sa.sa_handler = SIG_DFL;
 114
 115       for (sig = 1; sig >= _NSIG; ++sig)
 116         if (sigismember (&attrp->__sd, sig) != 0
 117             && __sigaction (sig, &sa, NULL) != 0)
 118           _exit (SPAWN_ERROR);
 119
 120     }
 121
 122 #ifdef _POSIX_PRIORITY_SCHEDULING
 123   /* Set the scheduling algorithm and parameters.  */
 124   if ((flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER))
 125       == POSIX_SPAWN_SETSCHEDPARAM)
 126     {
 127       if (__sched_setparam (0, &attrp->__sp) == -1)
 128         _exit (SPAWN_ERROR);
 129     }
 130   else if ((flags & POSIX_SPAWN_SETSCHEDULER) != 0)
 131     {
 132       if (__sched_setscheduler (0, attrp->__policy,
 133                                 (flags & POSIX_SPAWN_SETSCHEDPARAM) != 0
 134                                 ? &attrp->__sp : NULL) == -1)
 135         _exit (SPAWN_ERROR);
 136     }
 137 #endif
 138
 139   /* Set the process group ID.  */
 140   if ((flags & POSIX_SPAWN_SETPGROUP) != 0
 141       && __setpgid (0, attrp->__pgrp) != 0)
 142     _exit (SPAWN_ERROR);
 143
 144   /* Set the effective user and group IDs.  */
 145   if ((flags & POSIX_SPAWN_RESETIDS) != 0
 146       && (seteuid (__getuid ()) != 0 || setegid (__getgid ()) != 0))
 147     _exit (SPAWN_ERROR);
 148
 149   /* Execute the file actions.  */
 150   if (file_actions != NULL)
 151     {
 152       int cnt;
 153
 154       for (cnt = 0; cnt < file_actions->__used; ++cnt)
 155         {
 156           struct __spawn_action *action = &file_actions->__actions[cnt];
 157
 158           switch (action->tag)
 159             {
 160             case spawn_do_close:
 161               if (__close (action->action.close_action.fd) != 0)
 162                 /* Signal the error.  */
 163                 _exit (SPAWN_ERROR);
 164               break;
 165
 166             case spawn_do_open:
 167               {
 168                 int new_fd = __open64 (action->action.open_action.path,
 169                                        action->action.open_action.oflag,
 170                                        action->action.open_action.mode);
 171
 172                 if (new_fd == -1)
 173                   /* The `open' call failed.  */
 174                   _exit (SPAWN_ERROR);
 175
 176                 /* Make sure the desired file descriptor is used.  */
 177                 if (new_fd != action->action.open_action.fd)
 178                   {
 179                     if (__dup2 (new_fd, action->action.open_action.fd)
 180                         != action->action.open_action.fd)
 181                       /* The `dup2' call failed.  */
 182                       _exit (SPAWN_ERROR);
 183
 184                     if (__close (new_fd) != 0)
 185                       /* The `close' call failed.  */
 186                       _exit (SPAWN_ERROR);
 187                   }
 188               }
 189               break;
 190
 191             case spawn_do_dup2:
 192               if (__dup2 (action->action.dup2_action.fd,
 193                           action->action.dup2_action.newfd)
 194                   != action->action.dup2_action.newfd)
 195                 /* The `dup2' call failed.  */
 196                 _exit (SPAWN_ERROR);
 197               break;
 198             }
 199         }
 200     }
 201
 202   if (! use_path || strchr (file, '/') != NULL)
 203     {
 204       /* The FILE parameter is actually a path.  */
 205       __execve (file, argv, envp);
 206
 207       if (errno == ENOEXEC)
 208         script_execute (file, argv, envp);
 209
 210       /* Oh, oh.  `execve' returns.  This is bad.  */
 211       _exit (SPAWN_ERROR);
 212     }
 213
 214   /* We have to search for FILE on the path.  */
 215   path = getenv ("PATH");
 216   if (path == NULL)
 217     {
 218       /* There is no `PATH' in the environment.
 219          The default search path is the current directory
 220          followed by the path `confstr' returns for `_CS_PATH'.  */
 221       len = confstr (_CS_PATH, (char *) NULL, 0);
 222       path = (char *) __alloca (1 + len);
 223       path[0] = ':';
 224       (void) confstr (_CS_PATH, path + 1, len);
 225     }
 226
 227   len = strlen (file) + 1;
 228   pathlen = strlen (path);
 229   name = __alloca (pathlen + len + 1);
 230   /* Copy the file name at the top.  */
 231   name = (char *) memcpy (name + pathlen + 1, file, len);
 232   /* And add the slash.  */
 233   *--name = '/';
 234
 235   p = path;
 236   do
 237     {
 238       char *startp;
 239
 240       path = p;
 241       p = __strchrnul (path, ':');
 242
 243       if (p == path)
 244         /* Two adjacent colons, or a colon at the beginning or the end
 245            of `PATH' means to search the current directory.  */
 246         startp = name + 1;
 247       else
 248         startp = (char *) memcpy (name - (p - path), path, p - path);
 249
 250       /* Try to execute this name.  If it works, execv will not return.  */
 251       __execve (startp, argv, envp);
 252
 253       if (errno == ENOEXEC)
 254         script_execute (startp, argv, envp);
 255
 256       switch (errno)
 257         {
 258         case EACCES:
 259         case ENOENT:
 260         case ESTALE:
 261         case ENOTDIR:
 262           /* Those errors indicate the file is missing or not executable
 263              by us, in which case we want to just try the next path
 264              directory.  */
 265           break;
 266
 267         default:
 268           /* Some other error means we found an executable file, but
 269              something went wrong executing it; return the error to our
 270              caller.  */
 271           _exit (SPAWN_ERROR);
 272             }
 273     }
 274   while (*p++ != '\0');
 275
 276   /* Return with an error.  */
 277   _exit (SPAWN_ERROR);
 278 }