dbus/dbus-shell.c - manifest_repos/dbus - Git at Google

 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
 /* dbus-shell.c Shell command line utility functions.
  *
  * Copyright (C) 2002, 2003  Red Hat, Inc.
  * Copyright (C) 2003 CodeFactory AB
  *
  * Licensed under the Academic Free License version 2.1
  *
  * This program 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 of the License, or
  * (at your option) any later version.
  *
  * This program 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 this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
  */

 #include <config.h>
 #include <string.h>
 #include "dbus-internals.h"
 #include "dbus-list.h"
 #include "dbus-memory.h"
 #include "dbus-protocol.h"
 #include "dbus-shell.h"
 #include "dbus-string.h"

 /* Single quotes preserve the literal string exactly. escape
  * sequences are not allowed; not even \' - if you want a '
  * in the quoted text, you have to do something like 'foo'\''bar'
  *
  * Double quotes allow $ ` " \ and newline to be escaped with backslash.
  * Otherwise double quotes preserve things literally.
  */

 static dbus_bool_t
 unquote_string_inplace (char* str, char** end)
 {
   char* dest;
   char* s;
   char quote_char;

   dest = s = str;

   quote_char = *s;

   if (!(*s == '"' || *s == '\''))
     {
       *end = str;
       return FALSE;
     }

   /* Skip the initial quote mark */
   ++s;

   if (quote_char == '"')
     {
       while (*s)
         {
           _dbus_assert(s > dest); /* loop invariant */

           switch (*s)
             {
             case '"':
               /* End of the string, return now */
               *dest = '\0';
               ++s;
               *end = s;
               return TRUE;

             case '\\':
               /* Possible escaped quote or \ */
               ++s;
               switch (*s)
                 {
                 case '"':
                 case '\\':
                 case '`':
                 case '$':
                 case '\n':
                   *dest = *s;
                   ++s;
                   ++dest;
                   break;

                 default:
                   /* not an escaped char */
                   *dest = '\\';
                   ++dest;
                   /* ++s already done. */
                   break;
                 }
               break;

             default:
               *dest = *s;
               ++dest;
               ++s;
               break;
             }

           _dbus_assert(s > dest); /* loop invariant */
         }
     }
   else
     {
       while (*s)
         {
           _dbus_assert(s > dest); /* loop invariant */

           if (*s == '\'')
             {
               /* End of the string, return now */
               *dest = '\0';
               ++s;
               *end = s;
               return TRUE;
             }
           else
             {
               *dest = *s;
               ++dest;
               ++s;
             }

           _dbus_assert(s > dest); /* loop invariant */
         }
     }

   /* If we reach here this means the close quote was never encountered */

   *dest = '\0';

   *end = s;
   return FALSE;
 }

 /**
  * Unquotes a string as the shell (/bin/sh) would. Only handles
  * quotes; if a string contains file globs, arithmetic operators,
  * variables, backticks, redirections, or other special-to-the-shell
  * features, the result will be different from the result a real shell
  * would produce (the variables, backticks, etc. will be passed
  * through literally instead of being expanded). This function is
  * guaranteed to succeed if applied to the result of
  * _dbus_shell_quote(). If it fails, it returns %NULL.
  * The @p quoted_string need not actually contain quoted or
  * escaped text; _dbus_shell_unquote() simply goes through the string and
  * unquotes/unescapes anything that the shell would. Both single and
  * double quotes are handled, as are escapes including escaped
  * newlines. The return value must be freed with dbus_free().
  *
  * Shell quoting rules are a bit strange. Single quotes preserve the
  * literal string exactly. escape sequences are not allowed; not even
  * \' - if you want a ' in the quoted text, you have to do something
  * like 'foo'\''bar'.  Double quotes allow $, `, ", \, and newline to
  * be escaped with backslash. Otherwise double quotes preserve things
  * literally.
  *
  * @param quoted_string shell-quoted string
  **/
 char*
 _dbus_shell_unquote (const char *quoted_string)
 {
   char *unquoted;
   char *end;
   char *start;
   char *ret;
   DBusString retval;

   unquoted = _dbus_strdup (quoted_string);
   if (unquoted == NULL)
     return NULL;

   start = unquoted;
   end = unquoted;
   if (!_dbus_string_init (&retval))
     {
       dbus_free (unquoted);
       return NULL;
     }

   /* The loop allows cases such as
    * "foo"blah blah'bar'woo foo"baz"la la la\'\''foo'
    */
   while (*start)
     {
       /* Append all non-quoted chars, honoring backslash escape
        */

       while (*start && !(*start == '"' || *start == '\''))
         {
           if (*start == '\\')
             {
               /* all characters can get escaped by backslash,
                * except newline, which is removed if it follows
                * a backslash outside of quotes
                */

               ++start;
               if (*start)
                 {
                   if (*start != '\n')
 		    {
 		      if (!_dbus_string_append_byte (&retval, *start))
 			goto error;
 		    }
                   ++start;
                 }
             }
           else
             {
               if (!_dbus_string_append_byte (&retval, *start))
 		goto error;
               ++start;
             }
         }

       if (*start)
         {
           if (!unquote_string_inplace (start, &end))
 	    goto error;
           else
             {
               if (!_dbus_string_append (&retval, start))
 		goto error;
               start = end;
             }
         }
     }

   ret = _dbus_strdup (_dbus_string_get_data (&retval));
   if (!ret)
     goto error;

   dbus_free (unquoted);
   _dbus_string_free (&retval);

   return ret;

  error:
   dbus_free (unquoted);
   _dbus_string_free (&retval);
   return NULL;
 }

 /* _dbus_shell_parse_argv() does a semi-arbitrary weird subset of the way
  * the shell parses a command line. We don't do variable expansion,
  * don't understand that operators are tokens, don't do tilde expansion,
  * don't do command substitution, no arithmetic expansion, IFS gets ignored,
  * don't do filename globs, don't remove redirection stuff, etc.
  *
  * READ THE UNIX98 SPEC on "Shell Command Language" before changing
  * the behavior of this code.
  *
  * Steps to parsing the argv string:
  *
  *  - tokenize the string (but since we ignore operators,
  *    our tokenization may diverge from what the shell would do)
  *    note that tokenization ignores the internals of a quoted
  *    word and it always splits on spaces, not on IFS even
  *    if we used IFS. We also ignore "end of input indicator"
  *    (I guess this is control-D?)
  *
  *    Tokenization steps, from UNIX98 with operator stuff removed,
  *    are:
  *
  *    1) "If the current character is backslash, single-quote or
  *        double-quote (\, ' or ") and it is not quoted, it will affect
  *        quoting for subsequent characters up to the end of the quoted
  *        text. The rules for quoting are as described in Quoting
  *        . During token recognition no substitutions will be actually
  *        performed, and the result token will contain exactly the
  *        characters that appear in the input (except for newline
  *        character joining), unmodified, including any embedded or
  *        enclosing quotes or substitution operators, between the quote
  *        mark and the end of the quoted text. The token will not be
  *        delimited by the end of the quoted field."
  *
  *    2) "If the current character is an unquoted newline character,
  *        the current token will be delimited."
  *
  *    3) "If the current character is an unquoted blank character, any
  *        token containing the previous character is delimited and the
  *        current character will be discarded."
  *
  *    4) "If the previous character was part of a word, the current
  *        character will be appended to that word."
  *
  *    5) "If the current character is a "#", it and all subsequent
  *        characters up to, but excluding, the next newline character
  *        will be discarded as a comment. The newline character that
  *        ends the line is not considered part of the comment. The
  *        "#" starts a comment only when it is at the beginning of a
  *        token. Since the search for the end-of-comment does not
  *        consider an escaped newline character specially, a comment
  *        cannot be continued to the next line."
  *
  *    6) "The current character will be used as the start of a new word."
  *
  *
  *  - for each token (word), perform portions of word expansion, namely
  *    field splitting (using default whitespace IFS) and quote
  *    removal.  Field splitting may increase the number of words.
  *    Quote removal does not increase the number of words.
  *
  *   "If the complete expansion appropriate for a word results in an
  *   empty field, that empty field will be deleted from the list of
  *   fields that form the completely expanded command, unless the
  *   original word contained single-quote or double-quote characters."
  *    - UNIX98 spec
  *
  *
  */

 static dbus_bool_t
 delimit_token (DBusString *token,
                DBusList **retval,
 	       DBusError *error)
 {
   char *str;

   str = _dbus_strdup (_dbus_string_get_data (token));
   if (!str)
     {
       _DBUS_SET_OOM (error);
       return FALSE;
     }

   if (!_dbus_list_append (retval, str))
     {
       dbus_free (str);
       _DBUS_SET_OOM (error);
       return FALSE;
     }

   return TRUE;
 }

 static DBusList*
 tokenize_command_line (const char *command_line, DBusError *error)
 {
   char current_quote;
   const char *p;
   DBusString current_token;
   DBusList *retval = NULL;
   dbus_bool_t quoted;;

   current_quote = '\0';
   quoted = FALSE;
   p = command_line;

   if (!_dbus_string_init (&current_token))
     {
       _DBUS_SET_OOM (error);
       return NULL;
     }

   while (*p)
     {
       if (current_quote == '\\')
         {
           if (*p == '\n')
             {
               /* we append nothing; backslash-newline become nothing */
             }
           else
             {
 	      if (!_dbus_string_append_byte (&current_token, '\\') ||
 	          !_dbus_string_append_byte (&current_token, *p))
 		{
 		  _DBUS_SET_OOM (error);
 		  goto error;
 		}
             }

           current_quote = '\0';
         }
       else if (current_quote == '#')
         {
           /* Discard up to and including next newline */
           while (*p && *p != '\n')
             ++p;

           current_quote = '\0';

           if (*p == '\0')
             break;
         }
       else if (current_quote)
         {
           if (*p == current_quote &&
               /* check that it isn't an escaped double quote */
               !(current_quote == '"' && quoted))
             {
               /* close the quote */
               current_quote = '\0';
             }

           /* Everything inside quotes, and the close quote,
            * gets appended literally.
            */

           if (!_dbus_string_append_byte (&current_token, *p))
 	    {
 	      _DBUS_SET_OOM (error);
 	      goto error;
 	    }
         }
       else
         {
           switch (*p)
             {
             case '\n':
               if (!delimit_token (&current_token, &retval, error))
 		goto error;

 		_dbus_string_free (&current_token);

 		if (!_dbus_string_init (&current_token))
 		  {
 		    _DBUS_SET_OOM (error);
 		    goto init_error;
 		  }

               break;

             case ' ':
             case '\t':
               /* If the current token contains the previous char, delimit
                * the current token. A nonzero length
                * token should always contain the previous char.
                */
               if (_dbus_string_get_length (&current_token) > 0)
                 {
                   if (!delimit_token (&current_token, &retval, error))
 		    goto error;

 		  _dbus_string_free (&current_token);

 		  if (!_dbus_string_init (&current_token))
 		    {
 		      _DBUS_SET_OOM (error);
 		      goto init_error;
 		    }

                 }

               /* discard all unquoted blanks (don't add them to a token) */
               break;


               /* single/double quotes are appended to the token,
                * escapes are maybe appended next time through the loop,
                * comment chars are never appended.
                */

             case '\'':
             case '"':
               if (!_dbus_string_append_byte (&current_token, *p))
 		{
 		  _DBUS_SET_OOM (error);
 		  goto error;
 		}

               /* FALL THRU */

             case '#':
             case '\\':
               current_quote = *p;
               break;

             default:
               /* Combines rules 4) and 6) - if we have a token, append to it,
                * otherwise create a new token.
                */
               if (!_dbus_string_append_byte (&current_token, *p))
 		{
 		  _DBUS_SET_OOM (error);
 		  goto error;
 		}
               break;
             }
         }

       /* We need to count consecutive backslashes mod 2,
        * to detect escaped doublequotes.
        */
       if (*p != '\\')
 	quoted = FALSE;
       else
 	quoted = !quoted;

       ++p;
     }

   if (!delimit_token (&current_token, &retval, error))
     goto error;

   if (current_quote)
     {
       dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "Unclosed quotes in command line");
       goto error;
     }

   if (retval == NULL)
     {
       dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "No tokens found in command line");
       goto error;
     }

   _dbus_string_free (&current_token);

   return retval;

  error:
   _dbus_string_free (&current_token);

  init_error:
   if (retval)
     {
       _dbus_list_foreach (&retval, (DBusForeachFunction) dbus_free, NULL);
       _dbus_list_clear (&retval);
     }

   return NULL;
 }

 /**
  * _dbus_shell_parse_argv:
  *
  * Parses a command line into an argument vector, in much the same way
  * the shell would, but without many of the expansions the shell would
  * perform (variable expansion, globs, operators, filename expansion,
  * etc. are not supported). The results are defined to be the same as
  * those you would get from a UNIX98 /bin/sh, as long as the input
  * contains none of the unsupported shell expansions. If the input
  * does contain such expansions, they are passed through
  * literally. Free the returned vector with dbus_free_string_array().
  *
  * @param command_line command line to parse
  * @param argcp return location for number of args
  * @param argvp return location for array of args
  * @param error error information
  **/
 dbus_bool_t
 _dbus_shell_parse_argv (const char *command_line,
 			int        *argcp,
 			char     ***argvp,
 			DBusError  *error)
 {
   /* Code based on poptParseArgvString() from libpopt */
   int argc = 0;
   char **argv = NULL;
   DBusList *tokens = NULL;
   int i;
   DBusList *tmp_list;

   if (!command_line)
     {
       _dbus_verbose ("Command line is NULL\n");
       return FALSE;
     }

   tokens = tokenize_command_line (command_line, error);
   if (tokens == NULL)
     {
       _dbus_verbose ("No tokens for command line '%s'\n", command_line);
       return FALSE;
     }

   /* Because we can't have introduced any new blank space into the
    * tokens (we didn't do any new expansions), we don't need to
    * perform field splitting. If we were going to honor IFS or do any
    * expansions, we would have to do field splitting on each word
    * here. Also, if we were going to do any expansion we would need to
    * remove any zero-length words that didn't contain quotes
    * originally; but since there's no expansion we know all words have
    * nonzero length, unless they contain quotes.
    *
    * So, we simply remove quotes, and don't do any field splitting or
    * empty word removal, since we know there was no way to introduce
    * such things.
    */

   argc = _dbus_list_get_length (&tokens);
   argv = dbus_new (char *, argc + 1);
   if (!argv)
     {
       _DBUS_SET_OOM (error);
       goto error;
     }

   i = 0;
   tmp_list = tokens;
   while (tmp_list)
     {
       argv[i] = _dbus_shell_unquote (tmp_list->data);

       if (!argv[i])
         {
           int j;
 	  for (j = 0; j < i; j++)
 	    dbus_free(argv[j]);

           dbus_free (argv);
 	  _DBUS_SET_OOM (error);
 	  goto error;
         }

       tmp_list = _dbus_list_get_next_link (&tokens, tmp_list);
       ++i;
     }
   argv[argc] = NULL;

   _dbus_list_foreach (&tokens, (DBusForeachFunction) dbus_free, NULL);
   _dbus_list_clear (&tokens);

   if (argcp)
     *argcp = argc;

   if (argvp)
     *argvp = argv;
   else
     dbus_free_string_array (argv);

   return TRUE;

  error:
   _dbus_list_foreach (&tokens, (DBusForeachFunction) dbus_free, NULL);
   _dbus_list_clear (&tokens);

   return FALSE;

 }
	/* -- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -- */
	/* dbus-shell.c Shell command line utility functions.
	*
	* Copyright (C) 2002, 2003 Red Hat, Inc.
	* Copyright (C) 2003 CodeFactory AB
	*
	* Licensed under the Academic Free License version 2.1
	*
	* This program 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 of the License, or
	* (at your option) any later version.
	*
	* This program 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 this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*
	*/

	#include <config.h>
	#include <string.h>
	#include "dbus-internals.h"
	#include "dbus-list.h"
	#include "dbus-memory.h"
	#include "dbus-protocol.h"
	#include "dbus-shell.h"
	#include "dbus-string.h"

	/* Single quotes preserve the literal string exactly. escape
	* sequences are not allowed; not even \' - if you want a '
	* in the quoted text, you have to do something like 'foo'\''bar'
	*
	* Double quotes allow $ ` " \ and newline to be escaped with backslash.
	* Otherwise double quotes preserve things literally.
	*/

	static dbus_bool_t
	unquote_string_inplace (char* str, char** end)
	{
	char* dest;
	char* s;
	char quote_char;

	dest = s = str;

	quote_char = *s;

	if (!(s == '"' \|\| s == '\''))
	{
	*end = str;
	return FALSE;
	}

	/* Skip the initial quote mark */
	++s;

	if (quote_char == '"')
	{
	while (*s)
	{
	_dbus_assert(s > dest); /* loop invariant */

	switch (*s)
	{
	case '"':
	/* End of the string, return now */
	*dest = '\0';
	++s;
	*end = s;
	return TRUE;

	case '\\':
	/* Possible escaped quote or \ */
	++s;
	switch (*s)
	{
	case '"':
	case '\\':
	case '`':
	case '$':
	case '\n':
	dest = s;
	++s;
	++dest;
	break;

	default:
	/* not an escaped char */
	*dest = '\\';
	++dest;
	/* ++s already done. */
	break;
	}
	break;

	default:
	dest = s;
	++dest;
	++s;
	break;
	}

	_dbus_assert(s > dest); /* loop invariant */
	}
	}
	else
	{
	while (*s)
	{
	_dbus_assert(s > dest); /* loop invariant */

	if (*s == '\'')
	{
	/* End of the string, return now */
	*dest = '\0';
	++s;
	*end = s;
	return TRUE;
	}
	else
	{
	dest = s;
	++dest;
	++s;
	}

	_dbus_assert(s > dest); /* loop invariant */
	}
	}

	/* If we reach here this means the close quote was never encountered */

	*dest = '\0';

	*end = s;
	return FALSE;
	}

	/**
	* Unquotes a string as the shell (/bin/sh) would. Only handles
	* quotes; if a string contains file globs, arithmetic operators,
	* variables, backticks, redirections, or other special-to-the-shell
	* features, the result will be different from the result a real shell
	* would produce (the variables, backticks, etc. will be passed
	* through literally instead of being expanded). This function is
	* guaranteed to succeed if applied to the result of
	* _dbus_shell_quote(). If it fails, it returns %NULL.
	* The @p quoted_string need not actually contain quoted or
	* escaped text; _dbus_shell_unquote() simply goes through the string and
	* unquotes/unescapes anything that the shell would. Both single and
	* double quotes are handled, as are escapes including escaped
	* newlines. The return value must be freed with dbus_free().
	*
	* Shell quoting rules are a bit strange. Single quotes preserve the
	* literal string exactly. escape sequences are not allowed; not even
	* \' - if you want a ' in the quoted text, you have to do something
	* like 'foo'\''bar'. Double quotes allow $, `, ", \, and newline to
	* be escaped with backslash. Otherwise double quotes preserve things
	* literally.
	*
	* @param quoted_string shell-quoted string
	**/
	char*
	_dbus_shell_unquote (const char *quoted_string)
	{
	char *unquoted;
	char *end;
	char *start;
	char *ret;
	DBusString retval;

	unquoted = _dbus_strdup (quoted_string);
	if (unquoted == NULL)
	return NULL;

	start = unquoted;
	end = unquoted;
	if (!_dbus_string_init (&retval))
	{
	dbus_free (unquoted);
	return NULL;
	}

	/* The loop allows cases such as
	* "foo"blah blah'bar'woo foo"baz"la la la\'\''foo'
	*/
	while (*start)
	{
	/* Append all non-quoted chars, honoring backslash escape
	*/

	while (start && !(start == '"' \|\| *start == '\''))
	{
	if (*start == '\\')
	{
	/* all characters can get escaped by backslash,
	* except newline, which is removed if it follows
	* a backslash outside of quotes
	*/

	++start;
	if (*start)
	{
	if (*start != '\n')
	{
	if (!_dbus_string_append_byte (&retval, *start))
	goto error;
	}
	++start;
	}
	}
	else
	{
	if (!_dbus_string_append_byte (&retval, *start))
	goto error;
	++start;
	}
	}

	if (*start)
	{
	if (!unquote_string_inplace (start, &end))
	goto error;
	else
	{
	if (!_dbus_string_append (&retval, start))
	goto error;
	start = end;
	}
	}
	}

	ret = _dbus_strdup (_dbus_string_get_data (&retval));
	if (!ret)
	goto error;

	dbus_free (unquoted);
	_dbus_string_free (&retval);

	return ret;

	error:
	dbus_free (unquoted);
	_dbus_string_free (&retval);
	return NULL;
	}

	/* _dbus_shell_parse_argv() does a semi-arbitrary weird subset of the way
	* the shell parses a command line. We don't do variable expansion,
	* don't understand that operators are tokens, don't do tilde expansion,
	* don't do command substitution, no arithmetic expansion, IFS gets ignored,
	* don't do filename globs, don't remove redirection stuff, etc.
	*
	* READ THE UNIX98 SPEC on "Shell Command Language" before changing
	* the behavior of this code.
	*
	* Steps to parsing the argv string:
	*
	* - tokenize the string (but since we ignore operators,
	* our tokenization may diverge from what the shell would do)
	* note that tokenization ignores the internals of a quoted
	* word and it always splits on spaces, not on IFS even
	* if we used IFS. We also ignore "end of input indicator"
	* (I guess this is control-D?)
	*
	* Tokenization steps, from UNIX98 with operator stuff removed,
	* are:
	*
	* 1) "If the current character is backslash, single-quote or
	* double-quote (\, ' or ") and it is not quoted, it will affect
	* quoting for subsequent characters up to the end of the quoted
	* text. The rules for quoting are as described in Quoting
	* . During token recognition no substitutions will be actually
	* performed, and the result token will contain exactly the
	* characters that appear in the input (except for newline
	* character joining), unmodified, including any embedded or
	* enclosing quotes or substitution operators, between the quote
	* mark and the end of the quoted text. The token will not be
	* delimited by the end of the quoted field."
	*
	* 2) "If the current character is an unquoted newline character,
	* the current token will be delimited."
	*
	* 3) "If the current character is an unquoted blank character, any
	* token containing the previous character is delimited and the
	* current character will be discarded."
	*
	* 4) "If the previous character was part of a word, the current
	* character will be appended to that word."
	*
	* 5) "If the current character is a "#", it and all subsequent
	* characters up to, but excluding, the next newline character
	* will be discarded as a comment. The newline character that
	* ends the line is not considered part of the comment. The
	* "#" starts a comment only when it is at the beginning of a
	* token. Since the search for the end-of-comment does not
	* consider an escaped newline character specially, a comment
	* cannot be continued to the next line."
	*
	* 6) "The current character will be used as the start of a new word."
	*
	*
	* - for each token (word), perform portions of word expansion, namely
	* field splitting (using default whitespace IFS) and quote
	* removal. Field splitting may increase the number of words.
	* Quote removal does not increase the number of words.
	*
	* "If the complete expansion appropriate for a word results in an
	* empty field, that empty field will be deleted from the list of
	* fields that form the completely expanded command, unless the
	* original word contained single-quote or double-quote characters."
	* - UNIX98 spec
	*
	*
	*/

	static dbus_bool_t
	delimit_token (DBusString *token,
	DBusList **retval,
	DBusError *error)
	{
	char *str;

	str = _dbus_strdup (_dbus_string_get_data (token));
	if (!str)
	{
	_DBUS_SET_OOM (error);
	return FALSE;
	}

	if (!_dbus_list_append (retval, str))
	{
	dbus_free (str);
	_DBUS_SET_OOM (error);
	return FALSE;
	}

	return TRUE;
	}

	static DBusList*
	tokenize_command_line (const char command_line, DBusError error)
	{
	char current_quote;
	const char *p;
	DBusString current_token;
	DBusList *retval = NULL;
	dbus_bool_t quoted;;

	current_quote = '\0';
	quoted = FALSE;
	p = command_line;

	if (!_dbus_string_init (&current_token))
	{
	_DBUS_SET_OOM (error);
	return NULL;
	}

	while (*p)
	{
	if (current_quote == '\\')
	{
	if (*p == '\n')
	{
	/* we append nothing; backslash-newline become nothing */
	}
	else
	{
	if (!_dbus_string_append_byte (&current_token, '\\') \|\|
	!_dbus_string_append_byte (&current_token, *p))
	{
	_DBUS_SET_OOM (error);
	goto error;
	}
	}

	current_quote = '\0';
	}
	else if (current_quote == '#')
	{
	/* Discard up to and including next newline */
	while (p && p != '\n')
	++p;

	current_quote = '\0';

	if (*p == '\0')
	break;
	}
	else if (current_quote)
	{
	if (*p == current_quote &&
	/* check that it isn't an escaped double quote */
	!(current_quote == '"' && quoted))
	{
	/* close the quote */
	current_quote = '\0';
	}

	/* Everything inside quotes, and the close quote,
	* gets appended literally.
	*/

	if (!_dbus_string_append_byte (&current_token, *p))
	{
	_DBUS_SET_OOM (error);
	goto error;
	}
	}
	else
	{
	switch (*p)
	{
	case '\n':
	if (!delimit_token (&current_token, &retval, error))
	goto error;

	_dbus_string_free (&current_token);

	if (!_dbus_string_init (&current_token))
	{
	_DBUS_SET_OOM (error);
	goto init_error;
	}

	break;

	case ' ':
	case '\t':
	/* If the current token contains the previous char, delimit
	* the current token. A nonzero length
	* token should always contain the previous char.
	*/
	if (_dbus_string_get_length (&current_token) > 0)
	{
	if (!delimit_token (&current_token, &retval, error))
	goto error;

	_dbus_string_free (&current_token);

	if (!_dbus_string_init (&current_token))
	{
	_DBUS_SET_OOM (error);
	goto init_error;
	}

	}

	/* discard all unquoted blanks (don't add them to a token) */
	break;


	/* single/double quotes are appended to the token,
	* escapes are maybe appended next time through the loop,
	* comment chars are never appended.
	*/

	case '\'':
	case '"':
	if (!_dbus_string_append_byte (&current_token, *p))
	{
	_DBUS_SET_OOM (error);
	goto error;
	}

	/* FALL THRU */

	case '#':
	case '\\':
	current_quote = *p;
	break;

	default:
	/* Combines rules 4) and 6) - if we have a token, append to it,
	* otherwise create a new token.
	*/
	if (!_dbus_string_append_byte (&current_token, *p))
	{
	_DBUS_SET_OOM (error);
	goto error;
	}
	break;
	}
	}

	/* We need to count consecutive backslashes mod 2,
	* to detect escaped doublequotes.
	*/
	if (*p != '\\')
	quoted = FALSE;
	else
	quoted = !quoted;

	++p;
	}

	if (!delimit_token (&current_token, &retval, error))
	goto error;

	if (current_quote)
	{
	dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "Unclosed quotes in command line");
	goto error;
	}

	if (retval == NULL)
	{
	dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "No tokens found in command line");
	goto error;
	}

	_dbus_string_free (&current_token);

	return retval;

	error:
	_dbus_string_free (&current_token);

	init_error:
	if (retval)
	{
	_dbus_list_foreach (&retval, (DBusForeachFunction) dbus_free, NULL);
	_dbus_list_clear (&retval);
	}

	return NULL;
	}

	/**
	* _dbus_shell_parse_argv:
	*
	* Parses a command line into an argument vector, in much the same way
	* the shell would, but without many of the expansions the shell would
	* perform (variable expansion, globs, operators, filename expansion,
	* etc. are not supported). The results are defined to be the same as
	* those you would get from a UNIX98 /bin/sh, as long as the input
	* contains none of the unsupported shell expansions. If the input
	* does contain such expansions, they are passed through
	* literally. Free the returned vector with dbus_free_string_array().
	*
	* @param command_line command line to parse
	* @param argcp return location for number of args
	* @param argvp return location for array of args
	* @param error error information
	**/
	dbus_bool_t
	_dbus_shell_parse_argv (const char *command_line,
	int *argcp,
	char ***argvp,
	DBusError *error)
	{
	/* Code based on poptParseArgvString() from libpopt */
	int argc = 0;
	char **argv = NULL;
	DBusList *tokens = NULL;
	int i;
	DBusList *tmp_list;

	if (!command_line)
	{
	_dbus_verbose ("Command line is NULL\n");
	return FALSE;
	}

	tokens = tokenize_command_line (command_line, error);
	if (tokens == NULL)
	{
	_dbus_verbose ("No tokens for command line '%s'\n", command_line);
	return FALSE;
	}

	/* Because we can't have introduced any new blank space into the
	* tokens (we didn't do any new expansions), we don't need to
	* perform field splitting. If we were going to honor IFS or do any
	* expansions, we would have to do field splitting on each word
	* here. Also, if we were going to do any expansion we would need to
	* remove any zero-length words that didn't contain quotes
	* originally; but since there's no expansion we know all words have
	* nonzero length, unless they contain quotes.
	*
	* So, we simply remove quotes, and don't do any field splitting or
	* empty word removal, since we know there was no way to introduce
	* such things.
	*/

	argc = _dbus_list_get_length (&tokens);
	argv = dbus_new (char *, argc + 1);
	if (!argv)
	{
	_DBUS_SET_OOM (error);
	goto error;
	}

	i = 0;
	tmp_list = tokens;
	while (tmp_list)
	{
	argv[i] = _dbus_shell_unquote (tmp_list->data);

	if (!argv[i])
	{
	int j;
	for (j = 0; j < i; j++)
	dbus_free(argv[j]);

	dbus_free (argv);
	_DBUS_SET_OOM (error);
	goto error;
	}

	tmp_list = _dbus_list_get_next_link (&tokens, tmp_list);
	++i;
	}
	argv[argc] = NULL;

	_dbus_list_foreach (&tokens, (DBusForeachFunction) dbus_free, NULL);
	_dbus_list_clear (&tokens);

	if (argcp)
	*argcp = argc;

	if (argvp)
	*argvp = argv;
	else
	dbus_free_string_array (argv);

	return TRUE;

	error:
	_dbus_list_foreach (&tokens, (DBusForeachFunction) dbus_free, NULL);
	_dbus_list_clear (&tokens);

	return FALSE;

	}