1/* -*- mode: C; c-file-style: "gnu" -*- */
2/* dbus-shell.c Shell command line utility functions.
3 *
4 * Copyright (C) 2002, 2003  Red Hat, Inc.
5 * Copyright (C) 2003 CodeFactory AB
6 *
7 * Licensed under the Academic Free License version 2.1
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
22 *
23 */
24
25#include <string.h>
26#include "dbus-internals.h"
27#include "dbus-list.h"
28#include "dbus-memory.h"
29#include "dbus-protocol.h"
30#include "dbus-shell.h"
31#include "dbus-string.h"
32
33/* Single quotes preserve the literal string exactly. escape
34 * sequences are not allowed; not even \' - if you want a '
35 * in the quoted text, you have to do something like 'foo'\''bar'
36 *
37 * Double quotes allow $ ` " \ and newline to be escaped with backslash.
38 * Otherwise double quotes preserve things literally.
39 */
40
41static dbus_bool_t
42unquote_string_inplace (char* str, char** end)
43{
44  char* dest;
45  char* s;
46  char quote_char;
47
48  dest = s = str;
49
50  quote_char = *s;
51
52  if (!(*s == '"' || *s == '\''))
53    {
54      *end = str;
55      return FALSE;
56    }
57
58  /* Skip the initial quote mark */
59  ++s;
60
61  if (quote_char == '"')
62    {
63      while (*s)
64        {
65          _dbus_assert(s > dest); /* loop invariant */
66
67          switch (*s)
68            {
69            case '"':
70              /* End of the string, return now */
71              *dest = '\0';
72              ++s;
73              *end = s;
74              return TRUE;
75
76            case '\\':
77              /* Possible escaped quote or \ */
78              ++s;
79              switch (*s)
80                {
81                case '"':
82                case '\\':
83                case '`':
84                case '$':
85                case '\n':
86                  *dest = *s;
87                  ++s;
88                  ++dest;
89                  break;
90
91                default:
92                  /* not an escaped char */
93                  *dest = '\\';
94                  ++dest;
95                  /* ++s already done. */
96                  break;
97                }
98              break;
99
100            default:
101              *dest = *s;
102              ++dest;
103              ++s;
104              break;
105            }
106
107          _dbus_assert(s > dest); /* loop invariant */
108        }
109    }
110  else
111    {
112      while (*s)
113        {
114          _dbus_assert(s > dest); /* loop invariant */
115
116          if (*s == '\'')
117            {
118              /* End of the string, return now */
119              *dest = '\0';
120              ++s;
121              *end = s;
122              return TRUE;
123            }
124          else
125            {
126              *dest = *s;
127              ++dest;
128              ++s;
129            }
130
131          _dbus_assert(s > dest); /* loop invariant */
132        }
133    }
134
135  /* If we reach here this means the close quote was never encountered */
136
137  *dest = '\0';
138
139  *end = s;
140  return FALSE;
141}
142
143/**
144 * Quotes a string so that the shell (/bin/sh) will interpret the
145 * quoted string to mean @unquoted_string. If you pass a filename to
146 * the shell, for example, you should first quote it with this
147 * function.  The return value must be freed with dbus_free(). The
148 * quoting style used is undefined (single or double quotes may be
149 * used).
150 *
151 * @unquoted_string: a literal string
152 **/
153char*
154_dbus_shell_quote (const char *unquoted_string)
155{
156  /* We always use single quotes, because the algorithm is cheesier.
157   * We could use double if we felt like it, that might be more
158   * human-readable.
159   */
160
161  const char *p;
162  char *ret;
163  DBusString dest;
164
165  _dbus_string_init (&dest);
166
167  p = unquoted_string;
168
169  /* could speed this up a lot by appending chunks of text at a
170   * time.
171   */
172  while (*p)
173    {
174      /* Replace literal ' with a close ', a \', and a open ' */
175      if (*p == '\'')
176	{
177	  if (!_dbus_string_append (&dest, "'\\''"))
178	    {
179	      _dbus_string_free (&dest);
180	      return NULL;
181	    }
182	}
183      else
184	{
185	  if (!_dbus_string_append_byte (&dest, *p))
186	    {
187	      _dbus_string_free (&dest);
188	      return NULL;
189	    }
190	}
191
192      ++p;
193    }
194
195  /* close the quote */
196  if (_dbus_string_append_byte (&dest, '\''))
197    {
198      ret = _dbus_strdup (_dbus_string_get_data (&dest));
199      _dbus_string_free (&dest);
200
201      return ret;
202    }
203
204  _dbus_string_free (&dest);
205
206  return NULL;
207}
208
209/**
210 * Unquotes a string as the shell (/bin/sh) would. Only handles
211 * quotes; if a string contains file globs, arithmetic operators,
212 * variables, backticks, redirections, or other special-to-the-shell
213 * features, the result will be different from the result a real shell
214 * would produce (the variables, backticks, etc. will be passed
215 * through literally instead of being expanded). This function is
216 * guaranteed to succeed if applied to the result of
217 * _dbus_shell_quote(). If it fails, it returns %NULL.
218 * The @quoted_string need not actually contain quoted or
219 * escaped text; _dbus_shell_unquote() simply goes through the string and
220 * unquotes/unescapes anything that the shell would. Both single and
221 * double quotes are handled, as are escapes including escaped
222 * newlines. The return value must be freed with dbus_free().
223 *
224 * Shell quoting rules are a bit strange. Single quotes preserve the
225 * literal string exactly. escape sequences are not allowed; not even
226 * \' - if you want a ' in the quoted text, you have to do something
227 * like 'foo'\''bar'.  Double quotes allow $, `, ", \, and newline to
228 * be escaped with backslash. Otherwise double quotes preserve things
229 * literally.
230 *
231 * @quoted_string: shell-quoted string
232 **/
233char*
234_dbus_shell_unquote (const char *quoted_string)
235{
236  char *unquoted;
237  char *end;
238  char *start;
239  char *ret;
240  DBusString retval;
241
242  unquoted = _dbus_strdup (quoted_string);
243  if (unquoted == NULL)
244    return NULL;
245
246  start = unquoted;
247  end = unquoted;
248  if (!_dbus_string_init (&retval))
249    {
250      dbus_free (unquoted);
251      return NULL;
252    }
253
254  /* The loop allows cases such as
255   * "foo"blah blah'bar'woo foo"baz"la la la\'\''foo'
256   */
257  while (*start)
258    {
259      /* Append all non-quoted chars, honoring backslash escape
260       */
261
262      while (*start && !(*start == '"' || *start == '\''))
263        {
264          if (*start == '\\')
265            {
266              /* all characters can get escaped by backslash,
267               * except newline, which is removed if it follows
268               * a backslash outside of quotes
269               */
270
271              ++start;
272              if (*start)
273                {
274                  if (*start != '\n')
275		    {
276		      if (!_dbus_string_append_byte (&retval, *start))
277			goto error;
278		    }
279                  ++start;
280                }
281            }
282          else
283            {
284              if (!_dbus_string_append_byte (&retval, *start))
285		goto error;
286              ++start;
287            }
288        }
289
290      if (*start)
291        {
292          if (!unquote_string_inplace (start, &end))
293	    goto error;
294          else
295            {
296              if (!_dbus_string_append (&retval, start))
297		goto error;
298              start = end;
299            }
300        }
301    }
302
303  ret = _dbus_strdup (_dbus_string_get_data (&retval));
304  if (!ret)
305    goto error;
306
307  dbus_free (unquoted);
308  _dbus_string_free (&retval);
309
310  return ret;
311
312 error:
313  dbus_free (unquoted);
314  _dbus_string_free (&retval);
315  return NULL;
316}
317
318/* _dbus_shell_parse_argv() does a semi-arbitrary weird subset of the way
319 * the shell parses a command line. We don't do variable expansion,
320 * don't understand that operators are tokens, don't do tilde expansion,
321 * don't do command substitution, no arithmetic expansion, IFS gets ignored,
322 * don't do filename globs, don't remove redirection stuff, etc.
323 *
324 * READ THE UNIX98 SPEC on "Shell Command Language" before changing
325 * the behavior of this code.
326 *
327 * Steps to parsing the argv string:
328 *
329 *  - tokenize the string (but since we ignore operators,
330 *    our tokenization may diverge from what the shell would do)
331 *    note that tokenization ignores the internals of a quoted
332 *    word and it always splits on spaces, not on IFS even
333 *    if we used IFS. We also ignore "end of input indicator"
334 *    (I guess this is control-D?)
335 *
336 *    Tokenization steps, from UNIX98 with operator stuff removed,
337 *    are:
338 *
339 *    1) "If the current character is backslash, single-quote or
340 *        double-quote (\, ' or ") and it is not quoted, it will affect
341 *        quoting for subsequent characters up to the end of the quoted
342 *        text. The rules for quoting are as described in Quoting
343 *        . During token recognition no substitutions will be actually
344 *        performed, and the result token will contain exactly the
345 *        characters that appear in the input (except for newline
346 *        character joining), unmodified, including any embedded or
347 *        enclosing quotes or substitution operators, between the quote
348 *        mark and the end of the quoted text. The token will not be
349 *        delimited by the end of the quoted field."
350 *
351 *    2) "If the current character is an unquoted newline character,
352 *        the current token will be delimited."
353 *
354 *    3) "If the current character is an unquoted blank character, any
355 *        token containing the previous character is delimited and the
356 *        current character will be discarded."
357 *
358 *    4) "If the previous character was part of a word, the current
359 *        character will be appended to that word."
360 *
361 *    5) "If the current character is a "#", it and all subsequent
362 *        characters up to, but excluding, the next newline character
363 *        will be discarded as a comment. The newline character that
364 *        ends the line is not considered part of the comment. The
365 *        "#" starts a comment only when it is at the beginning of a
366 *        token. Since the search for the end-of-comment does not
367 *        consider an escaped newline character specially, a comment
368 *        cannot be continued to the next line."
369 *
370 *    6) "The current character will be used as the start of a new word."
371 *
372 *
373 *  - for each token (word), perform portions of word expansion, namely
374 *    field splitting (using default whitespace IFS) and quote
375 *    removal.  Field splitting may increase the number of words.
376 *    Quote removal does not increase the number of words.
377 *
378 *   "If the complete expansion appropriate for a word results in an
379 *   empty field, that empty field will be deleted from the list of
380 *   fields that form the completely expanded command, unless the
381 *   original word contained single-quote or double-quote characters."
382 *    - UNIX98 spec
383 *
384 *
385 */
386
387static dbus_bool_t
388delimit_token (DBusString *token,
389               DBusList **retval,
390	       DBusError *error)
391{
392  char *str;
393
394  str = _dbus_strdup (_dbus_string_get_data (token));
395  if (!str)
396    {
397      _DBUS_SET_OOM (error);
398      return FALSE;
399    }
400
401  if (!_dbus_list_append (retval, str))
402    {
403      dbus_free (str);
404      _DBUS_SET_OOM (error);
405      return FALSE;
406    }
407
408  return TRUE;
409}
410
411static DBusList*
412tokenize_command_line (const char *command_line, DBusError *error)
413{
414  char current_quote;
415  const char *p;
416  DBusString current_token;
417  DBusList *retval = NULL;
418  dbus_bool_t quoted;;
419
420  current_quote = '\0';
421  quoted = FALSE;
422  p = command_line;
423
424  if (!_dbus_string_init (&current_token))
425    {
426      _DBUS_SET_OOM (error);
427      return NULL;
428    }
429
430  while (*p)
431    {
432      if (current_quote == '\\')
433        {
434          if (*p == '\n')
435            {
436              /* we append nothing; backslash-newline become nothing */
437            }
438          else
439            {
440	      if (!_dbus_string_append_byte (&current_token, '\\') ||
441	          !_dbus_string_append_byte (&current_token, *p))
442		{
443		  _DBUS_SET_OOM (error);
444		  goto error;
445		}
446            }
447
448          current_quote = '\0';
449        }
450      else if (current_quote == '#')
451        {
452          /* Discard up to and including next newline */
453          while (*p && *p != '\n')
454            ++p;
455
456          current_quote = '\0';
457
458          if (*p == '\0')
459            break;
460        }
461      else if (current_quote)
462        {
463          if (*p == current_quote &&
464              /* check that it isn't an escaped double quote */
465              !(current_quote == '"' && quoted))
466            {
467              /* close the quote */
468              current_quote = '\0';
469            }
470
471          /* Everything inside quotes, and the close quote,
472           * gets appended literally.
473           */
474
475          if (!_dbus_string_append_byte (&current_token, *p))
476	    {
477	      _DBUS_SET_OOM (error);
478	      goto error;
479	    }
480        }
481      else
482        {
483          switch (*p)
484            {
485            case '\n':
486              if (!delimit_token (&current_token, &retval, error))
487		goto error;
488
489		_dbus_string_free (&current_token);
490
491		if (!_dbus_string_init (&current_token))
492		  {
493		    _DBUS_SET_OOM (error);
494		    goto init_error;
495		  }
496
497              break;
498
499            case ' ':
500            case '\t':
501              /* If the current token contains the previous char, delimit
502               * the current token. A nonzero length
503               * token should always contain the previous char.
504               */
505              if (_dbus_string_get_length (&current_token) > 0)
506                {
507                  if (!delimit_token (&current_token, &retval, error))
508		    goto error;
509
510		  _dbus_string_free (&current_token);
511
512		  if (!_dbus_string_init (&current_token))
513		    {
514		      _DBUS_SET_OOM (error);
515		      goto init_error;
516		    }
517
518                }
519
520              /* discard all unquoted blanks (don't add them to a token) */
521              break;
522
523
524              /* single/double quotes are appended to the token,
525               * escapes are maybe appended next time through the loop,
526               * comment chars are never appended.
527               */
528
529            case '\'':
530            case '"':
531              if (!_dbus_string_append_byte (&current_token, *p))
532		{
533		  _DBUS_SET_OOM (error);
534		  goto error;
535		}
536
537              /* FALL THRU */
538
539            case '#':
540            case '\\':
541              current_quote = *p;
542              break;
543
544            default:
545              /* Combines rules 4) and 6) - if we have a token, append to it,
546               * otherwise create a new token.
547               */
548              if (!_dbus_string_append_byte (&current_token, *p))
549		{
550		  _DBUS_SET_OOM (error);
551		  goto error;
552		}
553              break;
554            }
555        }
556
557      /* We need to count consecutive backslashes mod 2,
558       * to detect escaped doublequotes.
559       */
560      if (*p != '\\')
561	quoted = FALSE;
562      else
563	quoted = !quoted;
564
565      ++p;
566    }
567
568  if (!delimit_token (&current_token, &retval, error))
569    goto error;
570
571  if (current_quote)
572    {
573      dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "Unclosed quotes in command line");
574      goto error;
575    }
576
577  if (retval == NULL)
578    {
579      dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "No tokens found in command line");
580      goto error;
581    }
582
583  _dbus_string_free (&current_token);
584
585  return retval;
586
587 error:
588  _dbus_string_free (&current_token);
589
590 init_error:
591  if (retval)
592    {
593      _dbus_list_foreach (&retval, (DBusForeachFunction) dbus_free, NULL);
594      _dbus_list_clear (&retval);
595    }
596
597  return NULL;
598}
599
600/**
601 * _dbus_shell_parse_argv:
602 *
603 * Parses a command line into an argument vector, in much the same way
604 * the shell would, but without many of the expansions the shell would
605 * perform (variable expansion, globs, operators, filename expansion,
606 * etc. are not supported). The results are defined to be the same as
607 * those you would get from a UNIX98 /bin/sh, as long as the input
608 * contains none of the unsupported shell expansions. If the input
609 * does contain such expansions, they are passed through
610 * literally. Free the returned vector with dbus_free_string_array().
611 *
612 * @command_line: command line to parse
613 * @argcp: return location for number of args
614 * @argvp: return location for array of args
615 * @error: error information
616 **/
617dbus_bool_t
618_dbus_shell_parse_argv (const char *command_line,
619			int        *argcp,
620			char     ***argvp,
621			DBusError  *error)
622{
623  /* Code based on poptParseArgvString() from libpopt */
624  int argc = 0;
625  char **argv = NULL;
626  DBusList *tokens = NULL;
627  int i;
628  DBusList *tmp_list;
629
630  if (!command_line)
631    {
632      _dbus_verbose ("Command line is NULL\n");
633      return FALSE;
634    }
635
636  tokens = tokenize_command_line (command_line, error);
637  if (tokens == NULL)
638    {
639      _dbus_verbose ("No tokens for command line '%s'\n", command_line);
640      return FALSE;
641    }
642
643  /* Because we can't have introduced any new blank space into the
644   * tokens (we didn't do any new expansions), we don't need to
645   * perform field splitting. If we were going to honor IFS or do any
646   * expansions, we would have to do field splitting on each word
647   * here. Also, if we were going to do any expansion we would need to
648   * remove any zero-length words that didn't contain quotes
649   * originally; but since there's no expansion we know all words have
650   * nonzero length, unless they contain quotes.
651   *
652   * So, we simply remove quotes, and don't do any field splitting or
653   * empty word removal, since we know there was no way to introduce
654   * such things.
655   */
656
657  argc = _dbus_list_get_length (&tokens);
658  argv = dbus_new (char *, argc + 1);
659  if (!argv)
660    {
661      _DBUS_SET_OOM (error);
662      goto error;
663    }
664
665  i = 0;
666  tmp_list = tokens;
667  while (tmp_list)
668    {
669      argv[i] = _dbus_shell_unquote (tmp_list->data);
670
671      if (!argv[i])
672        {
673          int j;
674	  for (j = 0; j < i; j++)
675	    dbus_free(argv[j]);
676
677          dbus_free (argv);
678	  _DBUS_SET_OOM (error);
679	  goto error;
680        }
681
682      tmp_list = _dbus_list_get_next_link (&tokens, tmp_list);
683      ++i;
684    }
685  argv[argc] = NULL;
686
687  _dbus_list_foreach (&tokens, (DBusForeachFunction) dbus_free, NULL);
688  _dbus_list_clear (&tokens);
689
690  if (argcp)
691    *argcp = argc;
692
693  if (argvp)
694    *argvp = argv;
695  else
696    dbus_free_string_array (argv);
697
698  return TRUE;
699
700 error:
701  _dbus_list_foreach (&tokens, (DBusForeachFunction) dbus_free, NULL);
702  _dbus_list_clear (&tokens);
703
704  return FALSE;
705
706}
707