This file is source.def, from which is created source.c.
It implements the builtins "." and  "source" in Bash.

Copyright (C) 1987-2003 Free Software Foundation, Inc.

This file is part of GNU Bash, the Bourne Again SHell.

Bash is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

Bash is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with Bash; see the file COPYING.  If not, write to the Free Software
Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.

$PRODUCES source.c

$BUILTIN source
$FUNCTION source_builtin
$SHORT_DOC source filename [arguments]
Read and execute commands from FILENAME and return.  The pathnames
in $PATH are used to find the directory containing FILENAME.  If any
ARGUMENTS are supplied, they become the positional parameters when
FILENAME is executed.
$END
$BUILTIN .
$DOCNAME dot
$FUNCTION source_builtin
$SHORT_DOC . filename [arguments]
Read and execute commands from FILENAME and return.  The pathnames
in $PATH are used to find the directory containing FILENAME.  If any
ARGUMENTS are supplied, they become the positional parameters when
FILENAME is executed.
$END
/* source.c - Implements the `.' and `source' builtins. */

#include <config.h>

#include "../bashtypes.h"
#include "posixstat.h"
#include "filecntl.h"
#if ! defined(_MINIX) && defined (HAVE_SYS_FILE_H)
#  include <sys/file.h>
#endif
#include <errno.h>

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif

#include "../bashansi.h"
#include "../bashintl.h"

#include "../shell.h"
#include "../flags.h"
#include "../findcmd.h"
#include "common.h"
#include "bashgetopt.h"
#include "../trap.h"

#if !defined (errno)
extern int errno;
#endif /* !errno */

static void maybe_pop_dollar_vars __P((void));

/* If non-zero, `.' uses $PATH to look up the script to be sourced. */
int source_uses_path = 1;

/* If non-zero, `.' looks in the current directory if the filename argument
   is not found in the $PATH. */
int source_searches_cwd = 1;

/* If this . script is supplied arguments, we save the dollar vars and
   replace them with the script arguments for the duration of the script's
   execution.  If the script does not change the dollar vars, we restore
   what we saved.  If the dollar vars are changed in the script, and we are
   not executing a shell function, we leave the new values alone and free
   the saved values. */
static void
maybe_pop_dollar_vars ()
{
  if (variable_context == 0 && (dollar_vars_changed () & ARGS_SETBLTIN))
    dispose_saved_dollar_vars ();
  else
    pop_dollar_vars ();
  if (debugging_mode)
    pop_args ();	/* restore BASH_ARGC and BASH_ARGV */
  set_dollar_vars_unchanged ();
}

/* Read and execute commands from the file passed as argument.  Guess what.
   This cannot be done in a subshell, since things like variable assignments
   take place in there.  So, I open the file, place it into a large string,
   close the file, and then execute the string. */
int
source_builtin (list)
     WORD_LIST *list;
{
  int result;
  char *filename, *debug_trap;

  if (no_options (list))
    return (EX_USAGE);
  list = loptend;

  if (list == 0)
    {
      builtin_error (_("filename argument required"));
      builtin_usage ();
      return (EX_USAGE);
    }

#if defined (RESTRICTED_SHELL)
  if (restricted && strchr (list->word->word, '/'))
    {
      sh_restricted (list->word->word);
      return (EXECUTION_FAILURE);
    }
#endif

  filename = (char *)NULL;
  if (source_uses_path)
    filename = find_path_file (list->word->word);
  if (filename == 0)
    {
      if (source_searches_cwd == 0)
	{
	  builtin_error (_("%s: file not found"), list->word->word);
	  return (EXECUTION_FAILURE);
	}
      else
	filename = savestring (list->word->word);
    }

  begin_unwind_frame ("source");
  add_unwind_protect ((Function *)xfree, filename);

  if (list->next)
    {
      push_dollar_vars ();
      add_unwind_protect ((Function *)maybe_pop_dollar_vars, (char *)NULL);
      remember_args (list->next, 1);
      if (debugging_mode)
	push_args (list->next);	/* Update BASH_ARGV and BASH_ARGC */
    }
  set_dollar_vars_unchanged ();

  /* Don't inherit the DEBUG trap unless function_trace_mode (overloaded)
     is set.  XXX - should sourced files inherit the RETURN trap?  Functions
     don't. */
  debug_trap = TRAP_STRING (DEBUG_TRAP);
  if (debug_trap && function_trace_mode == 0)
    {
      debug_trap = savestring (debug_trap);
      add_unwind_protect (xfree, debug_trap);
      add_unwind_protect (set_debug_trap, debug_trap);
      restore_default_signal (DEBUG_TRAP);
    }

  result = source_file (filename, (list && list->next));

  run_unwind_frame ("source");

  return (result);
}