D-Bus  1.16.2
dbus-shell.c
1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
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  * SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
8  *
9  * Licensed under the Academic Free License version 2.1
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24  *
25  */
26 
27 #include <config.h>
28 #include <string.h>
29 #include "dbus-internals.h"
30 #include "dbus-list.h"
31 #include "dbus-memory.h"
32 #include "dbus-protocol.h"
33 #include "dbus-shell.h"
34 #include "dbus-string.h"
35 
36 /* Single quotes preserve the literal string exactly. escape
37  * sequences are not allowed; not even \' - if you want a '
38  * in the quoted text, you have to do something like 'foo'\''bar'
39  *
40  * Double quotes allow $ ` " \ and newline to be escaped with backslash.
41  * Otherwise double quotes preserve things literally.
42  */
43 
44 static dbus_bool_t
45 unquote_string_inplace (char* str, char** end)
46 {
47  char* dest;
48  char* s;
49  char quote_char;
50 
51  dest = s = str;
52 
53  quote_char = *s;
54 
55  if (!(*s == '"' || *s == '\''))
56  {
57  *end = str;
58  return FALSE;
59  }
60 
61  /* Skip the initial quote mark */
62  ++s;
63 
64  if (quote_char == '"')
65  {
66  while (*s)
67  {
68  _dbus_assert(s > dest); /* loop invariant */
69 
70  switch (*s)
71  {
72  case '"':
73  /* End of the string, return now */
74  *dest = '\0';
75  ++s;
76  *end = s;
77  return TRUE;
78 
79  case '\\':
80  /* Possible escaped quote or \ */
81  ++s;
82  switch (*s)
83  {
84  case '"':
85  case '\\':
86  case '`':
87  case '$':
88  case '\n':
89  *dest = *s;
90  ++s;
91  ++dest;
92  break;
93 
94  default:
95  /* not an escaped char */
96  *dest = '\\';
97  ++dest;
98  /* ++s already done. */
99  break;
100  }
101  break;
102 
103  default:
104  *dest = *s;
105  ++dest;
106  ++s;
107  break;
108  }
109 
110  _dbus_assert(s > dest); /* loop invariant */
111  }
112  }
113  else
114  {
115  while (*s)
116  {
117  _dbus_assert(s > dest); /* loop invariant */
118 
119  if (*s == '\'')
120  {
121  /* End of the string, return now */
122  *dest = '\0';
123  ++s;
124  *end = s;
125  return TRUE;
126  }
127  else
128  {
129  *dest = *s;
130  ++dest;
131  ++s;
132  }
133 
134  _dbus_assert(s > dest); /* loop invariant */
135  }
136  }
137 
138  /* If we reach here this means the close quote was never encountered */
139 
140  *dest = '\0';
141 
142  *end = s;
143  return FALSE;
144 }
145 
170 char*
171 _dbus_shell_unquote (const char *quoted_string)
172 {
173  char *unquoted;
174  char *end;
175  char *start;
176  char *ret;
177  DBusString retval;
178 
179  unquoted = _dbus_strdup (quoted_string);
180  if (unquoted == NULL)
181  return NULL;
182 
183  start = unquoted;
184  end = unquoted;
185  if (!_dbus_string_init (&retval))
186  {
187  dbus_free (unquoted);
188  return NULL;
189  }
190 
191  /* The loop allows cases such as
192  * "foo"blah blah'bar'woo foo"baz"la la la\'\''foo'
193  */
194  while (*start)
195  {
196  /* Append all non-quoted chars, honoring backslash escape
197  */
198 
199  while (*start && !(*start == '"' || *start == '\''))
200  {
201  if (*start == '\\')
202  {
203  /* all characters can get escaped by backslash,
204  * except newline, which is removed if it follows
205  * a backslash outside of quotes
206  */
207 
208  ++start;
209  if (*start)
210  {
211  if (*start != '\n')
212  {
213  if (!_dbus_string_append_byte (&retval, *start))
214  goto error;
215  }
216  ++start;
217  }
218  }
219  else
220  {
221  if (!_dbus_string_append_byte (&retval, *start))
222  goto error;
223  ++start;
224  }
225  }
226 
227  if (*start)
228  {
229  if (!unquote_string_inplace (start, &end))
230  goto error;
231  else
232  {
233  if (!_dbus_string_append (&retval, start))
234  goto error;
235  start = end;
236  }
237  }
238  }
239 
240  ret = _dbus_strdup (_dbus_string_get_data (&retval));
241  if (!ret)
242  goto error;
243 
244  dbus_free (unquoted);
245  _dbus_string_free (&retval);
246 
247  return ret;
248 
249  error:
250  dbus_free (unquoted);
251  _dbus_string_free (&retval);
252  return NULL;
253 }
254 
255 /* _dbus_shell_parse_argv() does a semi-arbitrary weird subset of the way
256  * the shell parses a command line. We don't do variable expansion,
257  * don't understand that operators are tokens, don't do tilde expansion,
258  * don't do command substitution, no arithmetic expansion, IFS gets ignored,
259  * don't do filename globs, don't remove redirection stuff, etc.
260  *
261  * READ THE UNIX98 SPEC on "Shell Command Language" before changing
262  * the behavior of this code.
263  *
264  * Steps to parsing the argv string:
265  *
266  * - tokenize the string (but since we ignore operators,
267  * our tokenization may diverge from what the shell would do)
268  * note that tokenization ignores the internals of a quoted
269  * word and it always splits on spaces, not on IFS even
270  * if we used IFS. We also ignore "end of input indicator"
271  * (I guess this is control-D?)
272  *
273  * Tokenization steps, from UNIX98 with operator stuff removed,
274  * are:
275  *
276  * 1) "If the current character is backslash, single-quote or
277  * double-quote (\, ' or ") and it is not quoted, it will affect
278  * quoting for subsequent characters up to the end of the quoted
279  * text. The rules for quoting are as described in Quoting
280  * . During token recognition no substitutions will be actually
281  * performed, and the result token will contain exactly the
282  * characters that appear in the input (except for newline
283  * character joining), unmodified, including any embedded or
284  * enclosing quotes or substitution operators, between the quote
285  * mark and the end of the quoted text. The token will not be
286  * delimited by the end of the quoted field."
287  *
288  * 2) "If the current character is an unquoted newline character,
289  * the current token will be delimited."
290  *
291  * 3) "If the current character is an unquoted blank character, any
292  * token containing the previous character is delimited and the
293  * current character will be discarded."
294  *
295  * 4) "If the previous character was part of a word, the current
296  * character will be appended to that word."
297  *
298  * 5) "If the current character is a "#", it and all subsequent
299  * characters up to, but excluding, the next newline character
300  * will be discarded as a comment. The newline character that
301  * ends the line is not considered part of the comment. The
302  * "#" starts a comment only when it is at the beginning of a
303  * token. Since the search for the end-of-comment does not
304  * consider an escaped newline character specially, a comment
305  * cannot be continued to the next line."
306  *
307  * 6) "The current character will be used as the start of a new word."
308  *
309  *
310  * - for each token (word), perform portions of word expansion, namely
311  * field splitting (using default whitespace IFS) and quote
312  * removal. Field splitting may increase the number of words.
313  * Quote removal does not increase the number of words.
314  *
315  * "If the complete expansion appropriate for a word results in an
316  * empty field, that empty field will be deleted from the list of
317  * fields that form the completely expanded command, unless the
318  * original word contained single-quote or double-quote characters."
319  * - UNIX98 spec
320  *
321  *
322  */
323 
324 static dbus_bool_t
325 delimit_token (DBusString *token,
326  DBusList **retval,
327  DBusError *error)
328 {
329  char *str;
330 
331  str = _dbus_strdup (_dbus_string_get_data (token));
332  if (!str)
333  {
334  _DBUS_SET_OOM (error);
335  return FALSE;
336  }
337 
338  if (!_dbus_list_append (retval, str))
339  {
340  dbus_free (str);
341  _DBUS_SET_OOM (error);
342  return FALSE;
343  }
344 
345  return TRUE;
346 }
347 
348 static DBusList*
349 tokenize_command_line (const char *command_line, DBusError *error)
350 {
351  char current_quote;
352  const char *p;
353  DBusString current_token;
354  DBusList *retval = NULL;
355  dbus_bool_t quoted;;
356 
357  current_quote = '\0';
358  quoted = FALSE;
359  p = command_line;
360 
361  if (!_dbus_string_init (&current_token))
362  {
363  _DBUS_SET_OOM (error);
364  return NULL;
365  }
366 
367  while (*p)
368  {
369  if (current_quote == '\\')
370  {
371  if (*p == '\n')
372  {
373  /* we append nothing; backslash-newline become nothing */
374  }
375  else
376  {
377  if (!_dbus_string_append_byte (&current_token, '\\') ||
378  !_dbus_string_append_byte (&current_token, *p))
379  {
380  _DBUS_SET_OOM (error);
381  goto error;
382  }
383  }
384 
385  current_quote = '\0';
386  }
387  else if (current_quote == '#')
388  {
389  /* Discard up to and including next newline */
390  while (*p && *p != '\n')
391  ++p;
392 
393  current_quote = '\0';
394 
395  if (*p == '\0')
396  break;
397  }
398  else if (current_quote)
399  {
400  if (*p == current_quote &&
401  /* check that it isn't an escaped double quote */
402  !(current_quote == '"' && quoted))
403  {
404  /* close the quote */
405  current_quote = '\0';
406  }
407 
408  /* Everything inside quotes, and the close quote,
409  * gets appended literally.
410  */
411 
412  if (!_dbus_string_append_byte (&current_token, *p))
413  {
414  _DBUS_SET_OOM (error);
415  goto error;
416  }
417  }
418  else
419  {
420  switch (*p)
421  {
422  case '\n':
423  if (!delimit_token (&current_token, &retval, error))
424  goto error;
425 
426  _dbus_string_free (&current_token);
427 
428  if (!_dbus_string_init (&current_token))
429  {
430  _DBUS_SET_OOM (error);
431  goto init_error;
432  }
433 
434  break;
435 
436  case ' ':
437  case '\t':
438  /* If the current token contains the previous char, delimit
439  * the current token. A nonzero length
440  * token should always contain the previous char.
441  */
442  if (_dbus_string_get_length (&current_token) > 0)
443  {
444  if (!delimit_token (&current_token, &retval, error))
445  goto error;
446 
447  _dbus_string_free (&current_token);
448 
449  if (!_dbus_string_init (&current_token))
450  {
451  _DBUS_SET_OOM (error);
452  goto init_error;
453  }
454 
455  }
456 
457  /* discard all unquoted blanks (don't add them to a token) */
458  break;
459 
460 
461  /* single/double quotes are appended to the token,
462  * escapes are maybe appended next time through the loop,
463  * comment chars are never appended.
464  */
465 
466  case '\'':
467  case '"':
468  if (!_dbus_string_append_byte (&current_token, *p))
469  {
470  _DBUS_SET_OOM (error);
471  goto error;
472  }
473 
474  /* FALL THRU */
475 
476  case '#':
477  case '\\':
478  current_quote = *p;
479  break;
480 
481  default:
482  /* Combines rules 4) and 6) - if we have a token, append to it,
483  * otherwise create a new token.
484  */
485  if (!_dbus_string_append_byte (&current_token, *p))
486  {
487  _DBUS_SET_OOM (error);
488  goto error;
489  }
490  break;
491  }
492  }
493 
494  /* We need to count consecutive backslashes mod 2,
495  * to detect escaped doublequotes.
496  */
497  if (*p != '\\')
498  quoted = FALSE;
499  else
500  quoted = !quoted;
501 
502  ++p;
503  }
504 
505  if (!delimit_token (&current_token, &retval, error))
506  goto error;
507 
508  if (current_quote)
509  {
510  dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "Unclosed quotes in command line");
511  goto error;
512  }
513 
514  if (retval == NULL)
515  {
516  dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "No tokens found in command line");
517  goto error;
518  }
519 
520  _dbus_string_free (&current_token);
521 
522  return retval;
523 
524  error:
525  _dbus_string_free (&current_token);
526 
527  init_error:
528  _dbus_list_clear_full (&retval, dbus_free);
529  return NULL;
530 }
531 
550 _dbus_shell_parse_argv (const char *command_line,
551  int *argcp,
552  char ***argvp,
553  DBusError *error)
554 {
555  /* Code based on poptParseArgvString() from libpopt */
556  int argc = 0;
557  char **argv = NULL;
558  DBusList *tokens = NULL;
559  int i;
560  DBusList *tmp_list;
561 
562  if (!command_line)
563  {
564  _dbus_verbose ("Command line is NULL\n");
565  return FALSE;
566  }
567 
568  tokens = tokenize_command_line (command_line, error);
569  if (tokens == NULL)
570  {
571  _dbus_verbose ("No tokens for command line '%s'\n", command_line);
572  return FALSE;
573  }
574 
575  /* Because we can't have introduced any new blank space into the
576  * tokens (we didn't do any new expansions), we don't need to
577  * perform field splitting. If we were going to honor IFS or do any
578  * expansions, we would have to do field splitting on each word
579  * here. Also, if we were going to do any expansion we would need to
580  * remove any zero-length words that didn't contain quotes
581  * originally; but since there's no expansion we know all words have
582  * nonzero length, unless they contain quotes.
583  *
584  * So, we simply remove quotes, and don't do any field splitting or
585  * empty word removal, since we know there was no way to introduce
586  * such things.
587  */
588 
589  argc = _dbus_list_get_length (&tokens);
590  argv = dbus_new (char *, argc + 1);
591  if (!argv)
592  {
593  _DBUS_SET_OOM (error);
594  goto error;
595  }
596 
597  i = 0;
598  tmp_list = tokens;
599  while (tmp_list)
600  {
601  argv[i] = _dbus_shell_unquote (tmp_list->data);
602 
603  if (!argv[i])
604  {
605  int j;
606  for (j = 0; j < i; j++)
607  dbus_free(argv[j]);
608 
609  dbus_free (argv);
610  _DBUS_SET_OOM (error);
611  goto error;
612  }
613 
614  tmp_list = _dbus_list_get_next_link (&tokens, tmp_list);
615  ++i;
616  }
617  argv[argc] = NULL;
618 
619  _dbus_list_clear_full (&tokens, dbus_free);
620 
621  if (argcp)
622  *argcp = argc;
623 
624  if (argvp)
625  *argvp = argv;
626  else
627  dbus_free_string_array (argv);
628 
629  return TRUE;
630 
631  error:
632  _dbus_list_clear_full (&tokens, dbus_free);
633 
634  return FALSE;
635 
636 }
dbus_bool_t _dbus_string_append(DBusString *str, const char *buffer)
Appends a nul-terminated C-style string to a DBusString.
Definition: dbus-string.c:980
#define NULL
A null pointer, defined appropriately for C or C++.
void dbus_free(void *memory)
Frees a block of memory previously allocated by dbus_malloc() or dbus_malloc0().
Definition: dbus-memory.c:710
#define dbus_new(type, count)
Safe macro for using dbus_malloc().
Definition: dbus-memory.h:59
void * data
Data stored at this element.
Definition: dbus-list.h:40
void _dbus_list_clear_full(DBusList **list, DBusFreeFunction function)
Free every link and every element in the list.
Definition: dbus-list.c:570
dbus_bool_t _dbus_string_init(DBusString *str)
Initializes a string.
Definition: dbus-string.c:182
#define _dbus_list_get_next_link(list, link)
Gets the next link in the list, or NULL if there are no more links.
Definition: dbus-list.h:121
dbus_uint32_t dbus_bool_t
A boolean, valid values are TRUE and FALSE.
Definition: dbus-types.h:37
dbus_bool_t _dbus_list_append(DBusList **list, void *data)
Appends a value to the list.
Definition: dbus-list.c:273
Object representing an exception.
Definition: dbus-errors.h:50
dbus_bool_t _dbus_string_append_byte(DBusString *str, unsigned char byte)
Appends a single byte to the string, returning FALSE if not enough memory.
Definition: dbus-string.c:1190
void _dbus_string_free(DBusString *str)
Frees a string created by _dbus_string_init(), and fills it with the same contents as #_DBUS_STRING_I...
Definition: dbus-string.c:278
#define TRUE
Expands to "1".
#define _dbus_assert(condition)
Aborts with an error message if the condition is false.
A node in a linked list.
Definition: dbus-list.h:36
void dbus_free_string_array(char **str_array)
Frees a NULL-terminated array of strings.
Definition: dbus-memory.c:758
int _dbus_list_get_length(DBusList **list)
Gets the length of a list.
Definition: dbus-list.c:760
#define FALSE
Expands to "0".
void dbus_set_error_const(DBusError *error, const char *name, const char *message)
Assigns an error name and message to a DBusError.
Definition: dbus-errors.c:245
char * _dbus_strdup(const char *str)
Duplicates a string.
#define DBUS_ERROR_INVALID_ARGS
Invalid arguments passed to a method call.