builtins/exec.def

   1 This file is exec.def, from which is created exec.c.
   2 It implements the builtin "exec" in Bash.
   3
   4 Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.
   5
   6 This file is part of GNU Bash, the Bourne Again SHell.
   7
   8 Bash is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 Bash is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License along
  19 with Bash; see the file COPYING.  If not, write to the Free Software
  20 Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.
  21
  22 $PRODUCES exec.c
  23
  24 $BUILTIN exec
  25 $FUNCTION exec_builtin
  26 $SHORT_DOC exec [-cl] [-a name] file [redirection ...]
  27 Exec FILE, replacing this shell with the specified program.
  28 If FILE is not specified, the redirections take effect in this
  29 shell.  If the first argument is `-l', then place a dash in the
  30 zeroth arg passed to FILE, as login does.  If the `-c' option
  31 is supplied, FILE is executed with a null environment.  The `-a'
  32 option means to make set argv[0] of the executed process to NAME.
  33 If the file cannot be executed and the shell is not interactive,
  34 then the shell exits, unless the shell option `execfail' is set.
  35 $END
  36
  37 #include <config.h>
  38
  39 #include "../bashtypes.h"
  40 #include "posixstat.h"
  41 #include <signal.h>
  42 #include <errno.h>
  43
  44 #if defined (HAVE_UNISTD_H)
  45 #  include <unistd.h>
  46 #endif
  47
  48 #include "../bashansi.h"
  49
  50 #include "../shell.h"
  51 #include "../execute_cmd.h"
  52 #include "../findcmd.h"
  53 #if defined (JOB_CONTROL)
  54 #  include "../jobs.h"
  55 #endif
  56 #include "../flags.h"
  57 #include "../trap.h"
  58 #if defined (HISTORY)
  59 #  include "../bashhist.h"
  60 #endif
  61 #include "common.h"
  62 #include "bashgetopt.h"
  63
  64 /* Not all systems declare ERRNO in errno.h... and some systems #define it! */
  65 #if !defined (errno)
  66 extern int errno;
  67 #endif /* !errno */
  68
  69 extern int interactive, interactive_shell, subshell_environment;
  70 extern REDIRECT *redirection_undo_list;
  71
  72 int no_exit_on_failed_exec;
  73
  74 /* If the user wants this to look like a login shell, then
  75    prepend a `-' onto NAME and return the new name. */
  76 static char *
  77 mkdashname (name)
  78      char *name;
  79 {
  80   char *ret;
  81
  82   ret = xmalloc (2 + strlen (name));
  83   ret[0] = '-';
  84   strcpy (ret + 1, name);
  85   return ret;
  86 }
  87
  88 int
  89 exec_builtin (list)
  90      WORD_LIST *list;
  91 {
  92   int exit_value = EXECUTION_FAILURE;
  93   int cleanenv, login, opt;
  94   char *argv0, *command, **args, **env, *newname, *com2;
  95
  96   cleanenv = login = 0;
  97   argv0 = (char *)NULL;
  98
  99   reset_internal_getopt ();
 100   while ((opt = internal_getopt (list, "cla:")) != -1)
 101     {
 102       switch (opt)
 103         {
 104         case 'c':
 105           cleanenv = 1;
 106           break;
 107         case 'l':
 108           login = 1;
 109           break;
 110         case 'a':
 111           argv0 = list_optarg;
 112           break;
 113         default:
 114           builtin_usage ();
 115           return (EX_USAGE);
 116         }
 117     }
 118   list = loptend;
 119
 120   /* First, let the redirections remain. */
 121   dispose_redirects (redirection_undo_list);
 122   redirection_undo_list = (REDIRECT *)NULL;
 123
 124   if (list == 0)
 125     return (EXECUTION_SUCCESS);
 126
 127 #if defined (RESTRICTED_SHELL)
 128   if (restricted)
 129     {
 130       builtin_error ("restricted");
 131       return (EXECUTION_FAILURE);
 132     }
 133 #endif /* RESTRICTED_SHELL */
 134
 135   args = word_list_to_argv (list, 1, 0, (int *)NULL);
 136
 137   /* A command with a slash anywhere in its name is not looked up in $PATH. */
 138   command = absolute_program (args[0]) ? args[0] : search_for_command (args[0]);
 139
 140   if (command == 0)
 141     {
 142       builtin_error ("%s: not found", args[0]);
 143       exit_value = EX_NOTFOUND; /* As per Posix.2, 3.14.6 */
 144       goto failed_exec;
 145     }
 146
 147   com2 = full_pathname (command);
 148   if (com2)
 149     {
 150       if (command != args[0])
 151         free (command);
 152       command = com2;
 153     }
 154
 155   if (argv0)
 156     {
 157       free (args[0]);
 158       args[0] = login ? mkdashname (argv0) : savestring (argv0);
 159     }
 160   else if (login)
 161     {
 162       newname = mkdashname (args[0]);
 163       free (args[0]);
 164       args[0] = newname;
 165     }
 166
 167   /* Decrement SHLVL by 1 so a new shell started here has the same value,
 168      preserving the appearance.  After we do that, we need to change the
 169      exported environment to include the new value. */
 170   if (cleanenv == 0)
 171     adjust_shell_level (-1);
 172
 173   if (cleanenv)
 174     env = (char **)NULL;
 175   else
 176     {
 177       maybe_make_export_env ();
 178       env = export_env;
 179     }
 180
 181 #if defined (HISTORY)
 182   if (interactive_shell && subshell_environment == 0)
 183     maybe_save_shell_history ();
 184 #endif /* HISTORY */
 185
 186   restore_original_signals ();
 187
 188 #if defined (JOB_CONTROL)
 189   if (subshell_environment == 0)
 190     end_job_control ();
 191 #endif /* JOB_CONTROL */
 192
 193   shell_execve (command, args, env);
 194
 195   /* We have to set this to NULL because shell_execve has called realloc()
 196      to stuff more items at the front of the array, which may have caused
 197      the memory to be freed by realloc().  We don't want to free it twice. */
 198   args = (char **)NULL;
 199   if (cleanenv == 0)
 200     adjust_shell_level (1);
 201
 202   if (executable_file (command) == 0)
 203     {
 204       builtin_error ("%s: cannot execute: %s", command, strerror (errno));
 205       exit_value = EX_NOEXEC;   /* As per Posix.2, 3.14.6 */
 206     }
 207   else
 208     file_error (command);
 209
 210 failed_exec:
 211   if (command)
 212     free (command);
 213
 214   if (subshell_environment || (interactive == 0 && no_exit_on_failed_exec == 0))
 215     exit_shell (exit_value);
 216
 217   if (args)
 218     free_array (args);
 219
 220   initialize_traps ();
 221   reinitialize_signals ();
 222
 223 #if defined (JOB_CONTROL)
 224   restart_job_control ();
 225 #endif /* JOB_CONTROL */
 226
 227   return (exit_value);
 228 }