xref: /netbsd-src/external/gpl3/gdb/dist/gdb/completer.c (revision 8ecbf5f02b752fcb7debe1a8fab1dc82602bc760)
1 /* Line completion stuff for GDB, the GNU debugger.
2    Copyright (C) 2000-2019 Free Software Foundation, Inc.
3 
4    This file is part of GDB.
5 
6    This program is free software; you can redistribute it and/or modify
7    it under the terms of the GNU General Public License as published by
8    the Free Software Foundation; either version 3 of the License, or
9    (at your option) any later version.
10 
11    This program is distributed in the hope that it will be useful,
12    but WITHOUT ANY WARRANTY; without even the implied warranty of
13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14    GNU General Public License for more details.
15 
16    You should have received a copy of the GNU General Public License
17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
18 
19 #include "defs.h"
20 #include "symtab.h"
21 #include "gdbtypes.h"
22 #include "expression.h"
23 #include "filenames.h"		/* For DOSish file names.  */
24 #include "language.h"
25 #include "common/gdb_signals.h"
26 #include "target.h"
27 #include "reggroups.h"
28 #include "user-regs.h"
29 #include "arch-utils.h"
30 #include "location.h"
31 #include <algorithm>
32 #include "linespec.h"
33 #include "cli/cli-decode.h"
34 
35 /* FIXME: This is needed because of lookup_cmd_1 ().  We should be
36    calling a hook instead so we eliminate the CLI dependency.  */
37 #include "gdbcmd.h"
38 
39 /* Needed for rl_completer_word_break_characters() and for
40    rl_filename_completion_function.  */
41 #include "readline/readline.h"
42 
43 /* readline defines this.  */
44 #undef savestring
45 
46 #include "completer.h"
47 
48 /* Misc state that needs to be tracked across several different
49    readline completer entry point calls, all related to a single
50    completion invocation.  */
51 
52 struct gdb_completer_state
53 {
54   /* The current completion's completion tracker.  This is a global
55      because a tracker can be shared between the handle_brkchars and
56      handle_completion phases, which involves different readline
57      callbacks.  */
58   completion_tracker *tracker = NULL;
59 
60   /* Whether the current completion was aborted.  */
61   bool aborted = false;
62 };
63 
64 /* The current completion state.  */
65 static gdb_completer_state current_completion;
66 
67 /* An enumeration of the various things a user might attempt to
68    complete for a location.  If you change this, remember to update
69    the explicit_options array below too.  */
70 
71 enum explicit_location_match_type
72 {
73     /* The filename of a source file.  */
74     MATCH_SOURCE,
75 
76     /* The name of a function or method.  */
77     MATCH_FUNCTION,
78 
79     /* The fully-qualified name of a function or method.  */
80     MATCH_QUALIFIED,
81 
82     /* A line number.  */
83     MATCH_LINE,
84 
85     /* The name of a label.  */
86     MATCH_LABEL
87 };
88 
89 /* Prototypes for local functions.  */
90 
91 /* readline uses the word breaks for two things:
92    (1) In figuring out where to point the TEXT parameter to the
93    rl_completion_entry_function.  Since we don't use TEXT for much,
94    it doesn't matter a lot what the word breaks are for this purpose,
95    but it does affect how much stuff M-? lists.
96    (2) If one of the matches contains a word break character, readline
97    will quote it.  That's why we switch between
98    current_language->la_word_break_characters() and
99    gdb_completer_command_word_break_characters.  I'm not sure when
100    we need this behavior (perhaps for funky characters in C++
101    symbols?).  */
102 
103 /* Variables which are necessary for fancy command line editing.  */
104 
105 /* When completing on command names, we remove '-' from the list of
106    word break characters, since we use it in command names.  If the
107    readline library sees one in any of the current completion strings,
108    it thinks that the string needs to be quoted and automatically
109    supplies a leading quote.  */
110 static const char gdb_completer_command_word_break_characters[] =
111 " \t\n!@#$%^&*()+=|~`}{[]\"';:?/>.<,";
112 
113 /* When completing on file names, we remove from the list of word
114    break characters any characters that are commonly used in file
115    names, such as '-', '+', '~', etc.  Otherwise, readline displays
116    incorrect completion candidates.  */
117 /* MS-DOS and MS-Windows use colon as part of the drive spec, and most
118    programs support @foo style response files.  */
119 static const char gdb_completer_file_name_break_characters[] =
120 #ifdef HAVE_DOS_BASED_FILE_SYSTEM
121   " \t\n*|\"';?><@";
122 #else
123   " \t\n*|\"';:?><";
124 #endif
125 
126 /* Characters that can be used to quote completion strings.  Note that
127    we can't include '"' because the gdb C parser treats such quoted
128    sequences as strings.  */
129 static const char gdb_completer_quote_characters[] = "'";
130 
131 /* Accessor for some completer data that may interest other files.  */
132 
133 const char *
134 get_gdb_completer_quote_characters (void)
135 {
136   return gdb_completer_quote_characters;
137 }
138 
139 /* This can be used for functions which don't want to complete on
140    symbols but don't want to complete on anything else either.  */
141 
142 void
143 noop_completer (struct cmd_list_element *ignore,
144 		completion_tracker &tracker,
145 		const char *text, const char *prefix)
146 {
147 }
148 
149 /* Complete on filenames.  */
150 
151 void
152 filename_completer (struct cmd_list_element *ignore,
153 		    completion_tracker &tracker,
154 		    const char *text, const char *word)
155 {
156   int subsequent_name;
157 
158   subsequent_name = 0;
159   while (1)
160     {
161       gdb::unique_xmalloc_ptr<char> p_rl
162 	(rl_filename_completion_function (text, subsequent_name));
163       if (p_rl == NULL)
164 	break;
165       /* We need to set subsequent_name to a non-zero value before the
166 	 continue line below, because otherwise, if the first file
167 	 seen by GDB is a backup file whose name ends in a `~', we
168 	 will loop indefinitely.  */
169       subsequent_name = 1;
170       /* Like emacs, don't complete on old versions.  Especially
171          useful in the "source" command.  */
172       const char *p = p_rl.get ();
173       if (p[strlen (p) - 1] == '~')
174 	continue;
175 
176       tracker.add_completion
177 	(make_completion_match_str (std::move (p_rl), text, word));
178     }
179 #if 0
180   /* There is no way to do this just long enough to affect quote
181      inserting without also affecting the next completion.  This
182      should be fixed in readline.  FIXME.  */
183   /* Ensure that readline does the right thing
184      with respect to inserting quotes.  */
185   rl_completer_word_break_characters = "";
186 #endif
187 }
188 
189 /* The corresponding completer_handle_brkchars
190    implementation.  */
191 
192 static void
193 filename_completer_handle_brkchars (struct cmd_list_element *ignore,
194 				    completion_tracker &tracker,
195 				    const char *text, const char *word)
196 {
197   set_rl_completer_word_break_characters
198     (gdb_completer_file_name_break_characters);
199 }
200 
201 /* Possible values for the found_quote flags word used by the completion
202    functions.  It says what kind of (shell-like) quoting we found anywhere
203    in the line. */
204 #define RL_QF_SINGLE_QUOTE      0x01
205 #define RL_QF_DOUBLE_QUOTE      0x02
206 #define RL_QF_BACKSLASH         0x04
207 #define RL_QF_OTHER_QUOTE       0x08
208 
209 /* Find the bounds of the current word for completion purposes, and
210    return a pointer to the end of the word.  This mimics (and is a
211    modified version of) readline's _rl_find_completion_word internal
212    function.
213 
214    This function skips quoted substrings (characters between matched
215    pairs of characters in rl_completer_quote_characters).  We try to
216    find an unclosed quoted substring on which to do matching.  If one
217    is not found, we use the word break characters to find the
218    boundaries of the current word.  QC, if non-null, is set to the
219    opening quote character if we found an unclosed quoted substring,
220    '\0' otherwise.  DP, if non-null, is set to the value of the
221    delimiter character that caused a word break.  */
222 
223 struct gdb_rl_completion_word_info
224 {
225   const char *word_break_characters;
226   const char *quote_characters;
227   const char *basic_quote_characters;
228 };
229 
230 static const char *
231 gdb_rl_find_completion_word (struct gdb_rl_completion_word_info *info,
232 			     int *qc, int *dp,
233 			     const char *line_buffer)
234 {
235   int scan, end, found_quote, delimiter, pass_next, isbrk;
236   char quote_char;
237   const char *brkchars;
238   int point = strlen (line_buffer);
239 
240   /* The algorithm below does '--point'.  Avoid buffer underflow with
241      the empty string.  */
242   if (point == 0)
243     {
244       if (qc != NULL)
245 	*qc = '\0';
246       if (dp != NULL)
247 	*dp = '\0';
248       return line_buffer;
249     }
250 
251   end = point;
252   found_quote = delimiter = 0;
253   quote_char = '\0';
254 
255   brkchars = info->word_break_characters;
256 
257   if (info->quote_characters != NULL)
258     {
259       /* We have a list of characters which can be used in pairs to
260 	 quote substrings for the completer.  Try to find the start of
261 	 an unclosed quoted substring.  */
262       /* FOUND_QUOTE is set so we know what kind of quotes we
263 	 found.  */
264       for (scan = pass_next = 0;
265 	   scan < end;
266 	   scan++)
267 	{
268 	  if (pass_next)
269 	    {
270 	      pass_next = 0;
271 	      continue;
272 	    }
273 
274 	  /* Shell-like semantics for single quotes -- don't allow
275 	     backslash to quote anything in single quotes, especially
276 	     not the closing quote.  If you don't like this, take out
277 	     the check on the value of quote_char.  */
278 	  if (quote_char != '\'' && line_buffer[scan] == '\\')
279 	    {
280 	      pass_next = 1;
281 	      found_quote |= RL_QF_BACKSLASH;
282 	      continue;
283 	    }
284 
285 	  if (quote_char != '\0')
286 	    {
287 	      /* Ignore everything until the matching close quote
288 		 char.  */
289 	      if (line_buffer[scan] == quote_char)
290 		{
291 		  /* Found matching close.  Abandon this
292 		     substring.  */
293 		  quote_char = '\0';
294 		  point = end;
295 		}
296 	    }
297 	  else if (strchr (info->quote_characters, line_buffer[scan]))
298 	    {
299 	      /* Found start of a quoted substring.  */
300 	      quote_char = line_buffer[scan];
301 	      point = scan + 1;
302 	      /* Shell-like quoting conventions.  */
303 	      if (quote_char == '\'')
304 		found_quote |= RL_QF_SINGLE_QUOTE;
305 	      else if (quote_char == '"')
306 		found_quote |= RL_QF_DOUBLE_QUOTE;
307 	      else
308 		found_quote |= RL_QF_OTHER_QUOTE;
309 	    }
310 	}
311     }
312 
313   if (point == end && quote_char == '\0')
314     {
315       /* We didn't find an unclosed quoted substring upon which to do
316 	 completion, so use the word break characters to find the
317 	 substring on which to complete.  */
318       while (--point)
319 	{
320 	  scan = line_buffer[point];
321 
322 	  if (strchr (brkchars, scan) != 0)
323 	    break;
324 	}
325     }
326 
327   /* If we are at an unquoted word break, then advance past it.  */
328   scan = line_buffer[point];
329 
330   if (scan)
331     {
332       isbrk = strchr (brkchars, scan) != 0;
333 
334       if (isbrk)
335 	{
336 	  /* If the character that caused the word break was a quoting
337 	     character, then remember it as the delimiter.  */
338 	  if (info->basic_quote_characters
339 	      && strchr (info->basic_quote_characters, scan)
340 	      && (end - point) > 1)
341 	    delimiter = scan;
342 
343 	  point++;
344 	}
345     }
346 
347   if (qc != NULL)
348     *qc = quote_char;
349   if (dp != NULL)
350     *dp = delimiter;
351 
352   return line_buffer + point;
353 }
354 
355 /* See completer.h.  */
356 
357 const char *
358 advance_to_expression_complete_word_point (completion_tracker &tracker,
359 					   const char *text)
360 {
361   gdb_rl_completion_word_info info;
362 
363   info.word_break_characters
364     = current_language->la_word_break_characters ();
365   info.quote_characters = gdb_completer_quote_characters;
366   info.basic_quote_characters = rl_basic_quote_characters;
367 
368   const char *start
369     = gdb_rl_find_completion_word (&info, NULL, NULL, text);
370 
371   tracker.advance_custom_word_point_by (start - text);
372 
373   return start;
374 }
375 
376 /* See completer.h.  */
377 
378 bool
379 completion_tracker::completes_to_completion_word (const char *word)
380 {
381   if (m_lowest_common_denominator_unique)
382     {
383       const char *lcd = m_lowest_common_denominator;
384 
385       if (strncmp_iw (word, lcd, strlen (lcd)) == 0)
386 	{
387 	  /* Maybe skip the function and complete on keywords.  */
388 	  size_t wordlen = strlen (word);
389 	  if (word[wordlen - 1] == ' ')
390 	    return true;
391 	}
392     }
393 
394   return false;
395 }
396 
397 /* Complete on linespecs, which might be of two possible forms:
398 
399        file:line
400    or
401        symbol+offset
402 
403    This is intended to be used in commands that set breakpoints
404    etc.  */
405 
406 static void
407 complete_files_symbols (completion_tracker &tracker,
408 			const char *text, const char *word)
409 {
410   completion_list fn_list;
411   const char *p;
412   int quote_found = 0;
413   int quoted = *text == '\'' || *text == '"';
414   int quote_char = '\0';
415   const char *colon = NULL;
416   char *file_to_match = NULL;
417   const char *symbol_start = text;
418   const char *orig_text = text;
419 
420   /* Do we have an unquoted colon, as in "break foo.c:bar"?  */
421   for (p = text; *p != '\0'; ++p)
422     {
423       if (*p == '\\' && p[1] == '\'')
424 	p++;
425       else if (*p == '\'' || *p == '"')
426 	{
427 	  quote_found = *p;
428 	  quote_char = *p++;
429 	  while (*p != '\0' && *p != quote_found)
430 	    {
431 	      if (*p == '\\' && p[1] == quote_found)
432 		p++;
433 	      p++;
434 	    }
435 
436 	  if (*p == quote_found)
437 	    quote_found = 0;
438 	  else
439 	    break;		/* Hit the end of text.  */
440 	}
441 #if HAVE_DOS_BASED_FILE_SYSTEM
442       /* If we have a DOS-style absolute file name at the beginning of
443 	 TEXT, and the colon after the drive letter is the only colon
444 	 we found, pretend the colon is not there.  */
445       else if (p < text + 3 && *p == ':' && p == text + 1 + quoted)
446 	;
447 #endif
448       else if (*p == ':' && !colon)
449 	{
450 	  colon = p;
451 	  symbol_start = p + 1;
452 	}
453       else if (strchr (current_language->la_word_break_characters(), *p))
454 	symbol_start = p + 1;
455     }
456 
457   if (quoted)
458     text++;
459 
460   /* Where is the file name?  */
461   if (colon)
462     {
463       char *s;
464 
465       file_to_match = (char *) xmalloc (colon - text + 1);
466       strncpy (file_to_match, text, colon - text);
467       file_to_match[colon - text] = '\0';
468       /* Remove trailing colons and quotes from the file name.  */
469       for (s = file_to_match + (colon - text);
470 	   s > file_to_match;
471 	   s--)
472 	if (*s == ':' || *s == quote_char)
473 	  *s = '\0';
474     }
475   /* If the text includes a colon, they want completion only on a
476      symbol name after the colon.  Otherwise, we need to complete on
477      symbols as well as on files.  */
478   if (colon)
479     {
480       collect_file_symbol_completion_matches (tracker,
481 					      complete_symbol_mode::EXPRESSION,
482 					      symbol_name_match_type::EXPRESSION,
483 					      symbol_start, word,
484 					      file_to_match);
485       xfree (file_to_match);
486     }
487   else
488     {
489       size_t text_len = strlen (text);
490 
491       collect_symbol_completion_matches (tracker,
492 					 complete_symbol_mode::EXPRESSION,
493 					 symbol_name_match_type::EXPRESSION,
494 					 symbol_start, word);
495       /* If text includes characters which cannot appear in a file
496 	 name, they cannot be asking for completion on files.  */
497       if (strcspn (text,
498 		   gdb_completer_file_name_break_characters) == text_len)
499 	fn_list = make_source_files_completion_list (text, text);
500     }
501 
502   if (!fn_list.empty () && !tracker.have_completions ())
503     {
504       /* If we only have file names as possible completion, we should
505 	 bring them in sync with what rl_complete expects.  The
506 	 problem is that if the user types "break /foo/b TAB", and the
507 	 possible completions are "/foo/bar" and "/foo/baz"
508 	 rl_complete expects us to return "bar" and "baz", without the
509 	 leading directories, as possible completions, because `word'
510 	 starts at the "b".  But we ignore the value of `word' when we
511 	 call make_source_files_completion_list above (because that
512 	 would not DTRT when the completion results in both symbols
513 	 and file names), so make_source_files_completion_list returns
514 	 the full "/foo/bar" and "/foo/baz" strings.  This produces
515 	 wrong results when, e.g., there's only one possible
516 	 completion, because rl_complete will prepend "/foo/" to each
517 	 candidate completion.  The loop below removes that leading
518 	 part.  */
519       for (const auto &fn_up: fn_list)
520 	{
521 	  char *fn = fn_up.get ();
522 	  memmove (fn, fn + (word - text), strlen (fn) + 1 - (word - text));
523 	}
524     }
525 
526   tracker.add_completions (std::move (fn_list));
527 
528   if (!tracker.have_completions ())
529     {
530       /* No completions at all.  As the final resort, try completing
531 	 on the entire text as a symbol.  */
532       collect_symbol_completion_matches (tracker,
533 					 complete_symbol_mode::EXPRESSION,
534 					 symbol_name_match_type::EXPRESSION,
535 					 orig_text, word);
536     }
537 }
538 
539 /* See completer.h.  */
540 
541 completion_list
542 complete_source_filenames (const char *text)
543 {
544   size_t text_len = strlen (text);
545 
546   /* If text includes characters which cannot appear in a file name,
547      the user cannot be asking for completion on files.  */
548   if (strcspn (text,
549 	       gdb_completer_file_name_break_characters)
550       == text_len)
551     return make_source_files_completion_list (text, text);
552 
553   return {};
554 }
555 
556 /* Complete address and linespec locations.  */
557 
558 static void
559 complete_address_and_linespec_locations (completion_tracker &tracker,
560 					 const char *text,
561 					 symbol_name_match_type match_type)
562 {
563   if (*text == '*')
564     {
565       tracker.advance_custom_word_point_by (1);
566       text++;
567       const char *word
568 	= advance_to_expression_complete_word_point (tracker, text);
569       complete_expression (tracker, text, word);
570     }
571   else
572     {
573       linespec_complete (tracker, text, match_type);
574     }
575 }
576 
577 /* The explicit location options.  Note that indexes into this array
578    must match the explicit_location_match_type enumerators.  */
579 
580 static const char *const explicit_options[] =
581   {
582     "-source",
583     "-function",
584     "-qualified",
585     "-line",
586     "-label",
587     NULL
588   };
589 
590 /* The probe modifier options.  These can appear before a location in
591    breakpoint commands.  */
592 static const char *const probe_options[] =
593   {
594     "-probe",
595     "-probe-stap",
596     "-probe-dtrace",
597     NULL
598   };
599 
600 /* Returns STRING if not NULL, the empty string otherwise.  */
601 
602 static const char *
603 string_or_empty (const char *string)
604 {
605   return string != NULL ? string : "";
606 }
607 
608 /* A helper function to collect explicit location matches for the given
609    LOCATION, which is attempting to match on WORD.  */
610 
611 static void
612 collect_explicit_location_matches (completion_tracker &tracker,
613 				   struct event_location *location,
614 				   enum explicit_location_match_type what,
615 				   const char *word,
616 				   const struct language_defn *language)
617 {
618   const struct explicit_location *explicit_loc
619     = get_explicit_location (location);
620 
621   /* True if the option expects an argument.  */
622   bool needs_arg = true;
623 
624   /* Note, in the various MATCH_* below, we complete on
625      explicit_loc->foo instead of WORD, because only the former will
626      have already skipped past any quote char.  */
627   switch (what)
628     {
629     case MATCH_SOURCE:
630       {
631 	const char *source = string_or_empty (explicit_loc->source_filename);
632 	completion_list matches
633 	  = make_source_files_completion_list (source, source);
634 	tracker.add_completions (std::move (matches));
635       }
636       break;
637 
638     case MATCH_FUNCTION:
639       {
640 	const char *function = string_or_empty (explicit_loc->function_name);
641 	linespec_complete_function (tracker, function,
642 				    explicit_loc->func_name_match_type,
643 				    explicit_loc->source_filename);
644       }
645       break;
646 
647     case MATCH_QUALIFIED:
648       needs_arg = false;
649       break;
650     case MATCH_LINE:
651       /* Nothing to offer.  */
652       break;
653 
654     case MATCH_LABEL:
655       {
656 	const char *label = string_or_empty (explicit_loc->label_name);
657 	linespec_complete_label (tracker, language,
658 				 explicit_loc->source_filename,
659 				 explicit_loc->function_name,
660 				 explicit_loc->func_name_match_type,
661 				 label);
662       }
663       break;
664 
665     default:
666       gdb_assert_not_reached ("unhandled explicit_location_match_type");
667     }
668 
669   if (!needs_arg || tracker.completes_to_completion_word (word))
670     {
671       tracker.discard_completions ();
672       tracker.advance_custom_word_point_by (strlen (word));
673       complete_on_enum (tracker, explicit_options, "", "");
674       complete_on_enum (tracker, linespec_keywords, "", "");
675     }
676   else if (!tracker.have_completions ())
677     {
678       /* Maybe we have an unterminated linespec keyword at the tail of
679 	 the string.  Try completing on that.  */
680       size_t wordlen = strlen (word);
681       const char *keyword = word + wordlen;
682 
683       if (wordlen > 0 && keyword[-1] != ' ')
684 	{
685 	  while (keyword > word && *keyword != ' ')
686 	    keyword--;
687 	  /* Don't complete on keywords if we'd be completing on the
688 	     whole explicit linespec option.  E.g., "b -function
689 	     thr<tab>" should not complete to the "thread"
690 	     keyword.  */
691 	  if (keyword != word)
692 	    {
693 	      keyword = skip_spaces (keyword);
694 
695 	      tracker.advance_custom_word_point_by (keyword - word);
696 	      complete_on_enum (tracker, linespec_keywords, keyword, keyword);
697 	    }
698 	}
699       else if (wordlen > 0 && keyword[-1] == ' ')
700 	{
701 	  /* Assume that we're maybe past the explicit location
702 	     argument, and we didn't manage to find any match because
703 	     the user wants to create a pending breakpoint.  Offer the
704 	     keyword and explicit location options as possible
705 	     completions.  */
706 	  tracker.advance_custom_word_point_by (keyword - word);
707 	  complete_on_enum (tracker, linespec_keywords, keyword, keyword);
708 	  complete_on_enum (tracker, explicit_options, keyword, keyword);
709 	}
710     }
711 }
712 
713 /* If the next word in *TEXT_P is any of the keywords in KEYWORDS,
714    then advance both TEXT_P and the word point in the tracker past the
715    keyword and return the (0-based) index in the KEYWORDS array that
716    matched.  Otherwise, return -1.  */
717 
718 static int
719 skip_keyword (completion_tracker &tracker,
720 	      const char * const *keywords, const char **text_p)
721 {
722   const char *text = *text_p;
723   const char *after = skip_to_space (text);
724   size_t len = after - text;
725 
726   if (text[len] != ' ')
727     return -1;
728 
729   int found = -1;
730   for (int i = 0; keywords[i] != NULL; i++)
731     {
732       if (strncmp (keywords[i], text, len) == 0)
733 	{
734 	  if (found == -1)
735 	    found = i;
736 	  else
737 	    return -1;
738 	}
739     }
740 
741   if (found != -1)
742     {
743       tracker.advance_custom_word_point_by (len + 1);
744       text += len + 1;
745       *text_p = text;
746       return found;
747     }
748 
749   return -1;
750 }
751 
752 /* A completer function for explicit locations.  This function
753    completes both options ("-source", "-line", etc) and values.  If
754    completing a quoted string, then QUOTED_ARG_START and
755    QUOTED_ARG_END point to the quote characters.  LANGUAGE is the
756    current language.  */
757 
758 static void
759 complete_explicit_location (completion_tracker &tracker,
760 			    struct event_location *location,
761 			    const char *text,
762 			    const language_defn *language,
763 			    const char *quoted_arg_start,
764 			    const char *quoted_arg_end)
765 {
766   if (*text != '-')
767     return;
768 
769   int keyword = skip_keyword (tracker, explicit_options, &text);
770 
771   if (keyword == -1)
772     complete_on_enum (tracker, explicit_options, text, text);
773   else
774     {
775       /* Completing on value.  */
776       enum explicit_location_match_type what
777 	= (explicit_location_match_type) keyword;
778 
779       if (quoted_arg_start != NULL && quoted_arg_end != NULL)
780 	{
781 	  if (quoted_arg_end[1] == '\0')
782 	    {
783 	      /* If completing a quoted string with the cursor right
784 		 at the terminating quote char, complete the
785 		 completion word without interpretation, so that
786 		 readline advances the cursor one whitespace past the
787 		 quote, even if there's no match.  This makes these
788 		 cases behave the same:
789 
790 		   before: "b -function function()"
791 		   after:  "b -function function() "
792 
793 		   before: "b -function 'function()'"
794 		   after:  "b -function 'function()' "
795 
796 		 and trusts the user in this case:
797 
798 		   before: "b -function 'not_loaded_function_yet()'"
799 		   after:  "b -function 'not_loaded_function_yet()' "
800 	      */
801 	      gdb::unique_xmalloc_ptr<char> text_copy
802 		(xstrdup (text));
803 	      tracker.add_completion (std::move (text_copy));
804 	    }
805 	  else if (quoted_arg_end[1] == ' ')
806 	    {
807 	      /* We're maybe past the explicit location argument.
808 		 Skip the argument without interpretion, assuming the
809 		 user may want to create pending breakpoint.  Offer
810 		 the keyword and explicit location options as possible
811 		 completions.  */
812 	      tracker.advance_custom_word_point_by (strlen (text));
813 	      complete_on_enum (tracker, linespec_keywords, "", "");
814 	      complete_on_enum (tracker, explicit_options, "", "");
815 	    }
816 	  return;
817 	}
818 
819       /* Now gather matches  */
820       collect_explicit_location_matches (tracker, location, what, text,
821 					 language);
822     }
823 }
824 
825 /* A completer for locations.  */
826 
827 void
828 location_completer (struct cmd_list_element *ignore,
829 		    completion_tracker &tracker,
830 		    const char *text, const char * /* word */)
831 {
832   int found_probe_option = -1;
833 
834   /* If we have a probe modifier, skip it.  This can only appear as
835      first argument.  Until we have a specific completer for probes,
836      falling back to the linespec completer for the remainder of the
837      line is better than nothing.  */
838   if (text[0] == '-' && text[1] == 'p')
839     found_probe_option = skip_keyword (tracker, probe_options, &text);
840 
841   const char *option_text = text;
842   int saved_word_point = tracker.custom_word_point ();
843 
844   const char *copy = text;
845 
846   explicit_completion_info completion_info;
847   event_location_up location
848     = string_to_explicit_location (&copy, current_language,
849 				   &completion_info);
850   if (completion_info.quoted_arg_start != NULL
851       && completion_info.quoted_arg_end == NULL)
852     {
853       /* Found an unbalanced quote.  */
854       tracker.set_quote_char (*completion_info.quoted_arg_start);
855       tracker.advance_custom_word_point_by (1);
856     }
857 
858   if (completion_info.saw_explicit_location_option)
859     {
860       if (*copy != '\0')
861 	{
862 	  tracker.advance_custom_word_point_by (copy - text);
863 	  text = copy;
864 
865 	  /* We found a terminator at the tail end of the string,
866 	     which means we're past the explicit location options.  We
867 	     may have a keyword to complete on.  If we have a whole
868 	     keyword, then complete whatever comes after as an
869 	     expression.  This is mainly for the "if" keyword.  If the
870 	     "thread" and "task" keywords gain their own completers,
871 	     they should be used here.  */
872 	  int keyword = skip_keyword (tracker, linespec_keywords, &text);
873 
874 	  if (keyword == -1)
875 	    {
876 	      complete_on_enum (tracker, linespec_keywords, text, text);
877 	    }
878 	  else
879 	    {
880 	      const char *word
881 		= advance_to_expression_complete_word_point (tracker, text);
882 	      complete_expression (tracker, text, word);
883 	    }
884 	}
885       else
886 	{
887 	  tracker.advance_custom_word_point_by (completion_info.last_option
888 						- text);
889 	  text = completion_info.last_option;
890 
891 	  complete_explicit_location (tracker, location.get (), text,
892 				      current_language,
893 				      completion_info.quoted_arg_start,
894 				      completion_info.quoted_arg_end);
895 
896 	}
897     }
898   /* This is an address or linespec location.  */
899   else if (location != NULL)
900     {
901       /* Handle non-explicit location options.  */
902 
903       int keyword = skip_keyword (tracker, explicit_options, &text);
904       if (keyword == -1)
905 	complete_on_enum (tracker, explicit_options, text, text);
906       else
907 	{
908 	  tracker.advance_custom_word_point_by (copy - text);
909 	  text = copy;
910 
911 	  symbol_name_match_type match_type
912 	    = get_explicit_location (location.get ())->func_name_match_type;
913 	  complete_address_and_linespec_locations (tracker, text, match_type);
914 	}
915     }
916   else
917     {
918       /* No options.  */
919       complete_address_and_linespec_locations (tracker, text,
920 					       symbol_name_match_type::WILD);
921     }
922 
923   /* Add matches for option names, if either:
924 
925      - Some completer above found some matches, but the word point did
926        not advance (e.g., "b <tab>" finds all functions, or "b -<tab>"
927        matches all objc selectors), or;
928 
929      - Some completer above advanced the word point, but found no
930        matches.
931   */
932   if ((text[0] == '-' || text[0] == '\0')
933       && (!tracker.have_completions ()
934 	  || tracker.custom_word_point () == saved_word_point))
935     {
936       tracker.set_custom_word_point (saved_word_point);
937       text = option_text;
938 
939       if (found_probe_option == -1)
940 	complete_on_enum (tracker, probe_options, text, text);
941       complete_on_enum (tracker, explicit_options, text, text);
942     }
943 }
944 
945 /* The corresponding completer_handle_brkchars
946    implementation.  */
947 
948 static void
949 location_completer_handle_brkchars (struct cmd_list_element *ignore,
950 				    completion_tracker &tracker,
951 				    const char *text,
952 				    const char *word_ignored)
953 {
954   tracker.set_use_custom_word_point (true);
955 
956   location_completer (ignore, tracker, text, NULL);
957 }
958 
959 /* Helper for expression_completer which recursively adds field and
960    method names from TYPE, a struct or union type, to the OUTPUT
961    list.  */
962 
963 static void
964 add_struct_fields (struct type *type, completion_list &output,
965 		   const char *fieldname, int namelen)
966 {
967   int i;
968   int computed_type_name = 0;
969   const char *type_name = NULL;
970 
971   type = check_typedef (type);
972   for (i = 0; i < TYPE_NFIELDS (type); ++i)
973     {
974       if (i < TYPE_N_BASECLASSES (type))
975 	add_struct_fields (TYPE_BASECLASS (type, i),
976 			   output, fieldname, namelen);
977       else if (TYPE_FIELD_NAME (type, i))
978 	{
979 	  if (TYPE_FIELD_NAME (type, i)[0] != '\0')
980 	    {
981 	      if (! strncmp (TYPE_FIELD_NAME (type, i),
982 			     fieldname, namelen))
983 		output.emplace_back (xstrdup (TYPE_FIELD_NAME (type, i)));
984 	    }
985 	  else if (TYPE_CODE (TYPE_FIELD_TYPE (type, i)) == TYPE_CODE_UNION)
986 	    {
987 	      /* Recurse into anonymous unions.  */
988 	      add_struct_fields (TYPE_FIELD_TYPE (type, i),
989 				 output, fieldname, namelen);
990 	    }
991 	}
992     }
993 
994   for (i = TYPE_NFN_FIELDS (type) - 1; i >= 0; --i)
995     {
996       const char *name = TYPE_FN_FIELDLIST_NAME (type, i);
997 
998       if (name && ! strncmp (name, fieldname, namelen))
999 	{
1000 	  if (!computed_type_name)
1001 	    {
1002 	      type_name = TYPE_NAME (type);
1003 	      computed_type_name = 1;
1004 	    }
1005 	  /* Omit constructors from the completion list.  */
1006 	  if (!type_name || strcmp (type_name, name))
1007 	    output.emplace_back (xstrdup (name));
1008 	}
1009     }
1010 }
1011 
1012 /* See completer.h.  */
1013 
1014 void
1015 complete_expression (completion_tracker &tracker,
1016 		     const char *text, const char *word)
1017 {
1018   struct type *type = NULL;
1019   gdb::unique_xmalloc_ptr<char> fieldname;
1020   enum type_code code = TYPE_CODE_UNDEF;
1021 
1022   /* Perform a tentative parse of the expression, to see whether a
1023      field completion is required.  */
1024   TRY
1025     {
1026       type = parse_expression_for_completion (text, &fieldname, &code);
1027     }
1028   CATCH (except, RETURN_MASK_ERROR)
1029     {
1030       return;
1031     }
1032   END_CATCH
1033 
1034   if (fieldname != nullptr && type)
1035     {
1036       for (;;)
1037 	{
1038 	  type = check_typedef (type);
1039 	  if (TYPE_CODE (type) != TYPE_CODE_PTR && !TYPE_IS_REFERENCE (type))
1040 	    break;
1041 	  type = TYPE_TARGET_TYPE (type);
1042 	}
1043 
1044       if (TYPE_CODE (type) == TYPE_CODE_UNION
1045 	  || TYPE_CODE (type) == TYPE_CODE_STRUCT)
1046 	{
1047 	  completion_list result;
1048 
1049 	  add_struct_fields (type, result, fieldname.get (),
1050 			     strlen (fieldname.get ()));
1051 	  tracker.add_completions (std::move (result));
1052 	  return;
1053 	}
1054     }
1055   else if (fieldname != nullptr && code != TYPE_CODE_UNDEF)
1056     {
1057       collect_symbol_completion_matches_type (tracker, fieldname.get (),
1058 					      fieldname.get (), code);
1059       return;
1060     }
1061 
1062   complete_files_symbols (tracker, text, word);
1063 }
1064 
1065 /* Complete on expressions.  Often this means completing on symbol
1066    names, but some language parsers also have support for completing
1067    field names.  */
1068 
1069 void
1070 expression_completer (struct cmd_list_element *ignore,
1071 		      completion_tracker &tracker,
1072 		      const char *text, const char *word)
1073 {
1074   complete_expression (tracker, text, word);
1075 }
1076 
1077 /* See definition in completer.h.  */
1078 
1079 void
1080 set_rl_completer_word_break_characters (const char *break_chars)
1081 {
1082   rl_completer_word_break_characters = (char *) break_chars;
1083 }
1084 
1085 /* See definition in completer.h.  */
1086 
1087 void
1088 set_gdb_completion_word_break_characters (completer_ftype *fn)
1089 {
1090   const char *break_chars;
1091 
1092   /* So far we are only interested in differentiating filename
1093      completers from everything else.  */
1094   if (fn == filename_completer)
1095     break_chars = gdb_completer_file_name_break_characters;
1096   else
1097     break_chars = gdb_completer_command_word_break_characters;
1098 
1099   set_rl_completer_word_break_characters (break_chars);
1100 }
1101 
1102 /* Complete on symbols.  */
1103 
1104 void
1105 symbol_completer (struct cmd_list_element *ignore,
1106 		  completion_tracker &tracker,
1107 		  const char *text, const char *word)
1108 {
1109   collect_symbol_completion_matches (tracker, complete_symbol_mode::EXPRESSION,
1110 				     symbol_name_match_type::EXPRESSION,
1111 				     text, word);
1112 }
1113 
1114 /* Here are some useful test cases for completion.  FIXME: These
1115    should be put in the test suite.  They should be tested with both
1116    M-? and TAB.
1117 
1118    "show output-" "radix"
1119    "show output" "-radix"
1120    "p" ambiguous (commands starting with p--path, print, printf, etc.)
1121    "p "  ambiguous (all symbols)
1122    "info t foo" no completions
1123    "info t " no completions
1124    "info t" ambiguous ("info target", "info terminal", etc.)
1125    "info ajksdlfk" no completions
1126    "info ajksdlfk " no completions
1127    "info" " "
1128    "info " ambiguous (all info commands)
1129    "p \"a" no completions (string constant)
1130    "p 'a" ambiguous (all symbols starting with a)
1131    "p b-a" ambiguous (all symbols starting with a)
1132    "p b-" ambiguous (all symbols)
1133    "file Make" "file" (word break hard to screw up here)
1134    "file ../gdb.stabs/we" "ird" (needs to not break word at slash)
1135  */
1136 
1137 enum complete_line_internal_reason
1138 {
1139   /* Preliminary phase, called by gdb_completion_word_break_characters
1140      function, is used to either:
1141 
1142      #1 - Determine the set of chars that are word delimiters
1143 	  depending on the current command in line_buffer.
1144 
1145      #2 - Manually advance RL_POINT to the "word break" point instead
1146 	  of letting readline do it (based on too-simple character
1147 	  matching).
1148 
1149      Simpler completers that just pass a brkchars array to readline
1150      (#1 above) must defer generating the completions to the main
1151      phase (below).  No completion list should be generated in this
1152      phase.
1153 
1154      OTOH, completers that manually advance the word point(#2 above)
1155      must set "use_custom_word_point" in the tracker and generate
1156      their completion in this phase.  Note that this is the convenient
1157      thing to do since they'll be parsing the input line anyway.  */
1158   handle_brkchars,
1159 
1160   /* Main phase, called by complete_line function, is used to get the
1161      list of possible completions.  */
1162   handle_completions,
1163 
1164   /* Special case when completing a 'help' command.  In this case,
1165      once sub-command completions are exhausted, we simply return
1166      NULL.  */
1167   handle_help,
1168 };
1169 
1170 /* Helper for complete_line_internal to simplify it.  */
1171 
1172 static void
1173 complete_line_internal_normal_command (completion_tracker &tracker,
1174 				       const char *command, const char *word,
1175 				       const char *cmd_args,
1176 				       complete_line_internal_reason reason,
1177 				       struct cmd_list_element *c)
1178 {
1179   const char *p = cmd_args;
1180 
1181   if (c->completer == filename_completer)
1182     {
1183       /* Many commands which want to complete on file names accept
1184 	 several file names, as in "run foo bar >>baz".  So we don't
1185 	 want to complete the entire text after the command, just the
1186 	 last word.  To this end, we need to find the beginning of the
1187 	 file name by starting at `word' and going backwards.  */
1188       for (p = word;
1189 	   p > command
1190 	     && strchr (gdb_completer_file_name_break_characters,
1191 			p[-1]) == NULL;
1192 	   p--)
1193 	;
1194     }
1195 
1196   if (reason == handle_brkchars)
1197     {
1198       completer_handle_brkchars_ftype *brkchars_fn;
1199 
1200       if (c->completer_handle_brkchars != NULL)
1201 	brkchars_fn = c->completer_handle_brkchars;
1202       else
1203 	{
1204 	  brkchars_fn
1205 	    = (completer_handle_brkchars_func_for_completer
1206 	       (c->completer));
1207 	}
1208 
1209       brkchars_fn (c, tracker, p, word);
1210     }
1211 
1212   if (reason != handle_brkchars && c->completer != NULL)
1213     (*c->completer) (c, tracker, p, word);
1214 }
1215 
1216 /* Internal function used to handle completions.
1217 
1218 
1219    TEXT is the caller's idea of the "word" we are looking at.
1220 
1221    LINE_BUFFER is available to be looked at; it contains the entire
1222    text of the line.  POINT is the offset in that line of the cursor.
1223    You should pretend that the line ends at POINT.
1224 
1225    See complete_line_internal_reason for description of REASON.  */
1226 
1227 static void
1228 complete_line_internal_1 (completion_tracker &tracker,
1229 			  const char *text,
1230 			  const char *line_buffer, int point,
1231 			  complete_line_internal_reason reason)
1232 {
1233   char *tmp_command;
1234   const char *p;
1235   int ignore_help_classes;
1236   /* Pointer within tmp_command which corresponds to text.  */
1237   const char *word;
1238   struct cmd_list_element *c, *result_list;
1239 
1240   /* Choose the default set of word break characters to break
1241      completions.  If we later find out that we are doing completions
1242      on command strings (as opposed to strings supplied by the
1243      individual command completer functions, which can be any string)
1244      then we will switch to the special word break set for command
1245      strings, which leaves out the '-' character used in some
1246      commands.  */
1247   set_rl_completer_word_break_characters
1248     (current_language->la_word_break_characters());
1249 
1250   /* Decide whether to complete on a list of gdb commands or on
1251      symbols.  */
1252   tmp_command = (char *) alloca (point + 1);
1253   p = tmp_command;
1254 
1255   /* The help command should complete help aliases.  */
1256   ignore_help_classes = reason != handle_help;
1257 
1258   strncpy (tmp_command, line_buffer, point);
1259   tmp_command[point] = '\0';
1260   if (reason == handle_brkchars)
1261     {
1262       gdb_assert (text == NULL);
1263       word = NULL;
1264     }
1265   else
1266     {
1267       /* Since text always contains some number of characters leading up
1268 	 to point, we can find the equivalent position in tmp_command
1269 	 by subtracting that many characters from the end of tmp_command.  */
1270       word = tmp_command + point - strlen (text);
1271     }
1272 
1273   /* Move P up to the start of the command.  */
1274   p = skip_spaces (p);
1275 
1276   if (*p == '\0')
1277     {
1278       /* An empty line is ambiguous; that is, it could be any
1279 	 command.  */
1280       c = CMD_LIST_AMBIGUOUS;
1281       result_list = 0;
1282     }
1283   else
1284     {
1285       c = lookup_cmd_1 (&p, cmdlist, &result_list, ignore_help_classes);
1286     }
1287 
1288   /* Move p up to the next interesting thing.  */
1289   while (*p == ' ' || *p == '\t')
1290     {
1291       p++;
1292     }
1293 
1294   tracker.advance_custom_word_point_by (p - tmp_command);
1295 
1296   if (!c)
1297     {
1298       /* It is an unrecognized command.  So there are no
1299 	 possible completions.  */
1300     }
1301   else if (c == CMD_LIST_AMBIGUOUS)
1302     {
1303       const char *q;
1304 
1305       /* lookup_cmd_1 advances p up to the first ambiguous thing, but
1306 	 doesn't advance over that thing itself.  Do so now.  */
1307       q = p;
1308       while (*q && (isalnum (*q) || *q == '-' || *q == '_'))
1309 	++q;
1310       if (q != tmp_command + point)
1311 	{
1312 	  /* There is something beyond the ambiguous
1313 	     command, so there are no possible completions.  For
1314 	     example, "info t " or "info t foo" does not complete
1315 	     to anything, because "info t" can be "info target" or
1316 	     "info terminal".  */
1317 	}
1318       else
1319 	{
1320 	  /* We're trying to complete on the command which was ambiguous.
1321 	     This we can deal with.  */
1322 	  if (result_list)
1323 	    {
1324 	      if (reason != handle_brkchars)
1325 		complete_on_cmdlist (*result_list->prefixlist, tracker, p,
1326 				     word, ignore_help_classes);
1327 	    }
1328 	  else
1329 	    {
1330 	      if (reason != handle_brkchars)
1331 		complete_on_cmdlist (cmdlist, tracker, p, word,
1332 				     ignore_help_classes);
1333 	    }
1334 	  /* Ensure that readline does the right thing with respect to
1335 	     inserting quotes.  */
1336 	  set_rl_completer_word_break_characters
1337 	    (gdb_completer_command_word_break_characters);
1338 	}
1339     }
1340   else
1341     {
1342       /* We've recognized a full command.  */
1343 
1344       if (p == tmp_command + point)
1345 	{
1346 	  /* There is no non-whitespace in the line beyond the
1347 	     command.  */
1348 
1349 	  if (p[-1] == ' ' || p[-1] == '\t')
1350 	    {
1351 	      /* The command is followed by whitespace; we need to
1352 		 complete on whatever comes after command.  */
1353 	      if (c->prefixlist)
1354 		{
1355 		  /* It is a prefix command; what comes after it is
1356 		     a subcommand (e.g. "info ").  */
1357 		  if (reason != handle_brkchars)
1358 		    complete_on_cmdlist (*c->prefixlist, tracker, p, word,
1359 					 ignore_help_classes);
1360 
1361 		  /* Ensure that readline does the right thing
1362 		     with respect to inserting quotes.  */
1363 		  set_rl_completer_word_break_characters
1364 		    (gdb_completer_command_word_break_characters);
1365 		}
1366 	      else if (reason == handle_help)
1367 		;
1368 	      else if (c->enums)
1369 		{
1370 		  if (reason != handle_brkchars)
1371 		    complete_on_enum (tracker, c->enums, p, word);
1372 		  set_rl_completer_word_break_characters
1373 		    (gdb_completer_command_word_break_characters);
1374 		}
1375 	      else
1376 		{
1377 		  /* It is a normal command; what comes after it is
1378 		     completed by the command's completer function.  */
1379 		  complete_line_internal_normal_command (tracker,
1380 							 tmp_command, word, p,
1381 							 reason, c);
1382 		}
1383 	    }
1384 	  else
1385 	    {
1386 	      /* The command is not followed by whitespace; we need to
1387 		 complete on the command itself, e.g. "p" which is a
1388 		 command itself but also can complete to "print", "ptype"
1389 		 etc.  */
1390 	      const char *q;
1391 
1392 	      /* Find the command we are completing on.  */
1393 	      q = p;
1394 	      while (q > tmp_command)
1395 		{
1396 		  if (isalnum (q[-1]) || q[-1] == '-' || q[-1] == '_')
1397 		    --q;
1398 		  else
1399 		    break;
1400 		}
1401 
1402 	      if (reason != handle_brkchars)
1403 		complete_on_cmdlist (result_list, tracker, q, word,
1404 				     ignore_help_classes);
1405 
1406 	      /* Ensure that readline does the right thing
1407 		 with respect to inserting quotes.  */
1408 	      set_rl_completer_word_break_characters
1409 		(gdb_completer_command_word_break_characters);
1410 	    }
1411 	}
1412       else if (reason == handle_help)
1413 	;
1414       else
1415 	{
1416 	  /* There is non-whitespace beyond the command.  */
1417 
1418 	  if (c->prefixlist && !c->allow_unknown)
1419 	    {
1420 	      /* It is an unrecognized subcommand of a prefix command,
1421 		 e.g. "info adsfkdj".  */
1422 	    }
1423 	  else if (c->enums)
1424 	    {
1425 	      if (reason != handle_brkchars)
1426 		complete_on_enum (tracker, c->enums, p, word);
1427 	    }
1428 	  else
1429 	    {
1430 	      /* It is a normal command.  */
1431 	      complete_line_internal_normal_command (tracker,
1432 						     tmp_command, word, p,
1433 						     reason, c);
1434 	    }
1435 	}
1436     }
1437 }
1438 
1439 /* Wrapper around complete_line_internal_1 to handle
1440    MAX_COMPLETIONS_REACHED_ERROR.  */
1441 
1442 static void
1443 complete_line_internal (completion_tracker &tracker,
1444 			const char *text,
1445 			const char *line_buffer, int point,
1446 			complete_line_internal_reason reason)
1447 {
1448   TRY
1449     {
1450       complete_line_internal_1 (tracker, text, line_buffer, point, reason);
1451     }
1452   CATCH (except, RETURN_MASK_ERROR)
1453     {
1454       if (except.error != MAX_COMPLETIONS_REACHED_ERROR)
1455 	throw_exception (except);
1456     }
1457   END_CATCH
1458 }
1459 
1460 /* See completer.h.  */
1461 
1462 int max_completions = 200;
1463 
1464 /* Initial size of the table.  It automagically grows from here.  */
1465 #define INITIAL_COMPLETION_HTAB_SIZE 200
1466 
1467 /* See completer.h.  */
1468 
1469 completion_tracker::completion_tracker ()
1470 {
1471   m_entries_hash = htab_create_alloc (INITIAL_COMPLETION_HTAB_SIZE,
1472 				      htab_hash_string, streq_hash,
1473 				      NULL, xcalloc, xfree);
1474 }
1475 
1476 /* See completer.h.  */
1477 
1478 void
1479 completion_tracker::discard_completions ()
1480 {
1481   xfree (m_lowest_common_denominator);
1482   m_lowest_common_denominator = NULL;
1483 
1484   m_lowest_common_denominator_unique = false;
1485 
1486   m_entries_vec.clear ();
1487 
1488   htab_delete (m_entries_hash);
1489   m_entries_hash = htab_create_alloc (INITIAL_COMPLETION_HTAB_SIZE,
1490 				      htab_hash_string, streq_hash,
1491 				      NULL, xcalloc, xfree);
1492 }
1493 
1494 /* See completer.h.  */
1495 
1496 completion_tracker::~completion_tracker ()
1497 {
1498   xfree (m_lowest_common_denominator);
1499   htab_delete (m_entries_hash);
1500 }
1501 
1502 /* See completer.h.  */
1503 
1504 bool
1505 completion_tracker::maybe_add_completion
1506   (gdb::unique_xmalloc_ptr<char> name,
1507    completion_match_for_lcd *match_for_lcd,
1508    const char *text, const char *word)
1509 {
1510   void **slot;
1511 
1512   if (max_completions == 0)
1513     return false;
1514 
1515   if (htab_elements (m_entries_hash) >= max_completions)
1516     return false;
1517 
1518   slot = htab_find_slot (m_entries_hash, name.get (), INSERT);
1519   if (*slot == HTAB_EMPTY_ENTRY)
1520     {
1521       const char *match_for_lcd_str = NULL;
1522 
1523       if (match_for_lcd != NULL)
1524 	match_for_lcd_str = match_for_lcd->finish ();
1525 
1526       if (match_for_lcd_str == NULL)
1527 	match_for_lcd_str = name.get ();
1528 
1529       gdb::unique_xmalloc_ptr<char> lcd
1530 	= make_completion_match_str (match_for_lcd_str, text, word);
1531 
1532       recompute_lowest_common_denominator (std::move (lcd));
1533 
1534       *slot = name.get ();
1535       m_entries_vec.push_back (std::move (name));
1536     }
1537 
1538   return true;
1539 }
1540 
1541 /* See completer.h.  */
1542 
1543 void
1544 completion_tracker::add_completion (gdb::unique_xmalloc_ptr<char> name,
1545 				    completion_match_for_lcd *match_for_lcd,
1546 				    const char *text, const char *word)
1547 {
1548   if (!maybe_add_completion (std::move (name), match_for_lcd, text, word))
1549     throw_error (MAX_COMPLETIONS_REACHED_ERROR, _("Max completions reached."));
1550 }
1551 
1552 /* See completer.h.  */
1553 
1554 void
1555 completion_tracker::add_completions (completion_list &&list)
1556 {
1557   for (auto &candidate : list)
1558     add_completion (std::move (candidate));
1559 }
1560 
1561 /* Helper for the make_completion_match_str overloads.  Returns NULL
1562    as an indication that we want MATCH_NAME exactly.  It is up to the
1563    caller to xstrdup that string if desired.  */
1564 
1565 static char *
1566 make_completion_match_str_1 (const char *match_name,
1567 			     const char *text, const char *word)
1568 {
1569   char *newobj;
1570 
1571   if (word == text)
1572     {
1573       /* Return NULL as an indication that we want MATCH_NAME
1574 	 exactly.  */
1575       return NULL;
1576     }
1577   else if (word > text)
1578     {
1579       /* Return some portion of MATCH_NAME.  */
1580       newobj = xstrdup (match_name + (word - text));
1581     }
1582   else
1583     {
1584       /* Return some of WORD plus MATCH_NAME.  */
1585       size_t len = strlen (match_name);
1586       newobj = (char *) xmalloc (text - word + len + 1);
1587       memcpy (newobj, word, text - word);
1588       memcpy (newobj + (text - word), match_name, len + 1);
1589     }
1590 
1591   return newobj;
1592 }
1593 
1594 /* See completer.h.  */
1595 
1596 gdb::unique_xmalloc_ptr<char>
1597 make_completion_match_str (const char *match_name,
1598 			   const char *text, const char *word)
1599 {
1600   char *newobj = make_completion_match_str_1 (match_name, text, word);
1601   if (newobj == NULL)
1602     newobj = xstrdup (match_name);
1603   return gdb::unique_xmalloc_ptr<char> (newobj);
1604 }
1605 
1606 /* See completer.h.  */
1607 
1608 gdb::unique_xmalloc_ptr<char>
1609 make_completion_match_str (gdb::unique_xmalloc_ptr<char> &&match_name,
1610 			   const char *text, const char *word)
1611 {
1612   char *newobj = make_completion_match_str_1 (match_name.get (), text, word);
1613   if (newobj == NULL)
1614     return std::move (match_name);
1615   return gdb::unique_xmalloc_ptr<char> (newobj);
1616 }
1617 
1618 /* Generate completions all at once.  Does nothing if max_completions
1619    is 0.  If max_completions is non-negative, this will collect at
1620    most max_completions strings.
1621 
1622    TEXT is the caller's idea of the "word" we are looking at.
1623 
1624    LINE_BUFFER is available to be looked at; it contains the entire
1625    text of the line.
1626 
1627    POINT is the offset in that line of the cursor.  You
1628    should pretend that the line ends at POINT.  */
1629 
1630 void
1631 complete_line (completion_tracker &tracker,
1632 	       const char *text, const char *line_buffer, int point)
1633 {
1634   if (max_completions == 0)
1635     return;
1636   complete_line_internal (tracker, text, line_buffer, point,
1637 			  handle_completions);
1638 }
1639 
1640 /* Complete on command names.  Used by "help".  */
1641 
1642 void
1643 command_completer (struct cmd_list_element *ignore,
1644 		   completion_tracker &tracker,
1645 		   const char *text, const char *word)
1646 {
1647   complete_line_internal (tracker, word, text,
1648 			  strlen (text), handle_help);
1649 }
1650 
1651 /* The corresponding completer_handle_brkchars implementation.  */
1652 
1653 static void
1654 command_completer_handle_brkchars (struct cmd_list_element *ignore,
1655 				   completion_tracker &tracker,
1656 				   const char *text, const char *word)
1657 {
1658   set_rl_completer_word_break_characters
1659     (gdb_completer_command_word_break_characters);
1660 }
1661 
1662 /* Complete on signals.  */
1663 
1664 void
1665 signal_completer (struct cmd_list_element *ignore,
1666 		  completion_tracker &tracker,
1667 		  const char *text, const char *word)
1668 {
1669   size_t len = strlen (word);
1670   int signum;
1671   const char *signame;
1672 
1673   for (signum = GDB_SIGNAL_FIRST; signum != GDB_SIGNAL_LAST; ++signum)
1674     {
1675       /* Can't handle this, so skip it.  */
1676       if (signum == GDB_SIGNAL_0)
1677 	continue;
1678 
1679       signame = gdb_signal_to_name ((enum gdb_signal) signum);
1680 
1681       /* Ignore the unknown signal case.  */
1682       if (!signame || strcmp (signame, "?") == 0)
1683 	continue;
1684 
1685       if (strncasecmp (signame, word, len) == 0)
1686 	{
1687 	  gdb::unique_xmalloc_ptr<char> copy (xstrdup (signame));
1688 	  tracker.add_completion (std::move (copy));
1689 	}
1690     }
1691 }
1692 
1693 /* Bit-flags for selecting what the register and/or register-group
1694    completer should complete on.  */
1695 
1696 enum reg_completer_target
1697   {
1698     complete_register_names = 0x1,
1699     complete_reggroup_names = 0x2
1700   };
1701 DEF_ENUM_FLAGS_TYPE (enum reg_completer_target, reg_completer_targets);
1702 
1703 /* Complete register names and/or reggroup names based on the value passed
1704    in TARGETS.  At least one bit in TARGETS must be set.  */
1705 
1706 static void
1707 reg_or_group_completer_1 (completion_tracker &tracker,
1708 			  const char *text, const char *word,
1709 			  reg_completer_targets targets)
1710 {
1711   size_t len = strlen (word);
1712   struct gdbarch *gdbarch;
1713   const char *name;
1714 
1715   gdb_assert ((targets & (complete_register_names
1716 			  | complete_reggroup_names)) != 0);
1717   gdbarch = get_current_arch ();
1718 
1719   if ((targets & complete_register_names) != 0)
1720     {
1721       int i;
1722 
1723       for (i = 0;
1724 	   (name = user_reg_map_regnum_to_name (gdbarch, i)) != NULL;
1725 	   i++)
1726 	{
1727 	  if (*name != '\0' && strncmp (word, name, len) == 0)
1728 	    {
1729 	      gdb::unique_xmalloc_ptr<char> copy (xstrdup (name));
1730 	      tracker.add_completion (std::move (copy));
1731 	    }
1732 	}
1733     }
1734 
1735   if ((targets & complete_reggroup_names) != 0)
1736     {
1737       struct reggroup *group;
1738 
1739       for (group = reggroup_next (gdbarch, NULL);
1740 	   group != NULL;
1741 	   group = reggroup_next (gdbarch, group))
1742 	{
1743 	  name = reggroup_name (group);
1744 	  if (strncmp (word, name, len) == 0)
1745 	    {
1746 	      gdb::unique_xmalloc_ptr<char> copy (xstrdup (name));
1747 	      tracker.add_completion (std::move (copy));
1748 	    }
1749 	}
1750     }
1751 }
1752 
1753 /* Perform completion on register and reggroup names.  */
1754 
1755 void
1756 reg_or_group_completer (struct cmd_list_element *ignore,
1757 			completion_tracker &tracker,
1758 			const char *text, const char *word)
1759 {
1760   reg_or_group_completer_1 (tracker, text, word,
1761 			    (complete_register_names
1762 			     | complete_reggroup_names));
1763 }
1764 
1765 /* Perform completion on reggroup names.  */
1766 
1767 void
1768 reggroup_completer (struct cmd_list_element *ignore,
1769 		    completion_tracker &tracker,
1770 		    const char *text, const char *word)
1771 {
1772   reg_or_group_completer_1 (tracker, text, word,
1773 			    complete_reggroup_names);
1774 }
1775 
1776 /* The default completer_handle_brkchars implementation.  */
1777 
1778 static void
1779 default_completer_handle_brkchars (struct cmd_list_element *ignore,
1780 				   completion_tracker &tracker,
1781 				   const char *text, const char *word)
1782 {
1783   set_rl_completer_word_break_characters
1784     (current_language->la_word_break_characters ());
1785 }
1786 
1787 /* See definition in completer.h.  */
1788 
1789 completer_handle_brkchars_ftype *
1790 completer_handle_brkchars_func_for_completer (completer_ftype *fn)
1791 {
1792   if (fn == filename_completer)
1793     return filename_completer_handle_brkchars;
1794 
1795   if (fn == location_completer)
1796     return location_completer_handle_brkchars;
1797 
1798   if (fn == command_completer)
1799     return command_completer_handle_brkchars;
1800 
1801   return default_completer_handle_brkchars;
1802 }
1803 
1804 /* Used as brkchars when we want to tell readline we have a custom
1805    word point.  We do that by making our rl_completion_word_break_hook
1806    set RL_POINT to the desired word point, and return the character at
1807    the word break point as the break char.  This is two bytes in order
1808    to fit one break character plus the terminating null.  */
1809 static char gdb_custom_word_point_brkchars[2];
1810 
1811 /* Since rl_basic_quote_characters is not completer-specific, we save
1812    its original value here, in order to be able to restore it in
1813    gdb_rl_attempted_completion_function.  */
1814 static const char *gdb_org_rl_basic_quote_characters = rl_basic_quote_characters;
1815 
1816 /* Get the list of chars that are considered as word breaks
1817    for the current command.  */
1818 
1819 static char *
1820 gdb_completion_word_break_characters_throw ()
1821 {
1822   /* New completion starting.  Get rid of the previous tracker and
1823      start afresh.  */
1824   delete current_completion.tracker;
1825   current_completion.tracker = new completion_tracker ();
1826 
1827   completion_tracker &tracker = *current_completion.tracker;
1828 
1829   complete_line_internal (tracker, NULL, rl_line_buffer,
1830 			  rl_point, handle_brkchars);
1831 
1832   if (tracker.use_custom_word_point ())
1833     {
1834       gdb_assert (tracker.custom_word_point () > 0);
1835       rl_point = tracker.custom_word_point () - 1;
1836       gdb_custom_word_point_brkchars[0] = rl_line_buffer[rl_point];
1837       rl_completer_word_break_characters = gdb_custom_word_point_brkchars;
1838       rl_completer_quote_characters = NULL;
1839 
1840       /* Clear this too, so that if we're completing a quoted string,
1841 	 readline doesn't consider the quote character a delimiter.
1842 	 If we didn't do this, readline would auto-complete {b
1843 	 'fun<tab>} to {'b 'function()'}, i.e., add the terminating
1844 	 \', but, it wouldn't append the separator space either, which
1845 	 is not desirable.  So instead we take care of appending the
1846 	 quote character to the LCD ourselves, in
1847 	 gdb_rl_attempted_completion_function.  Since this global is
1848 	 not just completer-specific, we'll restore it back to the
1849 	 default in gdb_rl_attempted_completion_function.  */
1850       rl_basic_quote_characters = NULL;
1851     }
1852 
1853   return rl_completer_word_break_characters;
1854 }
1855 
1856 char *
1857 gdb_completion_word_break_characters ()
1858 {
1859   /* New completion starting.  */
1860   current_completion.aborted = false;
1861 
1862   TRY
1863     {
1864       return gdb_completion_word_break_characters_throw ();
1865     }
1866   CATCH (ex, RETURN_MASK_ALL)
1867     {
1868       /* Set this to that gdb_rl_attempted_completion_function knows
1869 	 to abort early.  */
1870       current_completion.aborted = true;
1871     }
1872   END_CATCH
1873 
1874   return NULL;
1875 }
1876 
1877 /* See completer.h.  */
1878 
1879 const char *
1880 completion_find_completion_word (completion_tracker &tracker, const char *text,
1881 				 int *quote_char)
1882 {
1883   size_t point = strlen (text);
1884 
1885   complete_line_internal (tracker, NULL, text, point, handle_brkchars);
1886 
1887   if (tracker.use_custom_word_point ())
1888     {
1889       gdb_assert (tracker.custom_word_point () > 0);
1890       *quote_char = tracker.quote_char ();
1891       return text + tracker.custom_word_point ();
1892     }
1893 
1894   gdb_rl_completion_word_info info;
1895 
1896   info.word_break_characters = rl_completer_word_break_characters;
1897   info.quote_characters = gdb_completer_quote_characters;
1898   info.basic_quote_characters = rl_basic_quote_characters;
1899 
1900   return gdb_rl_find_completion_word (&info, quote_char, NULL, text);
1901 }
1902 
1903 /* See completer.h.  */
1904 
1905 void
1906 completion_tracker::recompute_lowest_common_denominator
1907   (gdb::unique_xmalloc_ptr<char> &&new_match_up)
1908 {
1909   if (m_lowest_common_denominator == NULL)
1910     {
1911       /* We don't have a lowest common denominator yet, so simply take
1912 	 the whole NEW_MATCH_UP as being it.  */
1913       m_lowest_common_denominator = new_match_up.release ();
1914       m_lowest_common_denominator_unique = true;
1915     }
1916   else
1917     {
1918       /* Find the common denominator between the currently-known
1919 	 lowest common denominator and NEW_MATCH_UP.  That becomes the
1920 	 new lowest common denominator.  */
1921       size_t i;
1922       const char *new_match = new_match_up.get ();
1923 
1924       for (i = 0;
1925 	   (new_match[i] != '\0'
1926 	    && new_match[i] == m_lowest_common_denominator[i]);
1927 	   i++)
1928 	;
1929       if (m_lowest_common_denominator[i] != new_match[i])
1930 	{
1931 	  m_lowest_common_denominator[i] = '\0';
1932 	  m_lowest_common_denominator_unique = false;
1933 	}
1934     }
1935 }
1936 
1937 /* See completer.h.  */
1938 
1939 void
1940 completion_tracker::advance_custom_word_point_by (size_t len)
1941 {
1942   m_custom_word_point += len;
1943 }
1944 
1945 /* Build a new C string that is a copy of LCD with the whitespace of
1946    ORIG/ORIG_LEN preserved.
1947 
1948    Say the user is completing a symbol name, with spaces, like:
1949 
1950      "foo ( i"
1951 
1952    and the resulting completion match is:
1953 
1954      "foo(int)"
1955 
1956    we want to end up with an input line like:
1957 
1958      "foo ( int)"
1959       ^^^^^^^      => text from LCD [1], whitespace from ORIG preserved.
1960 	     ^^	   => new text from LCD
1961 
1962    [1] - We must take characters from the LCD instead of the original
1963    text, since some completions want to change upper/lowercase.  E.g.:
1964 
1965      "handle sig<>"
1966 
1967    completes to:
1968 
1969      "handle SIG[QUIT|etc.]"
1970 */
1971 
1972 static char *
1973 expand_preserving_ws (const char *orig, size_t orig_len,
1974 		      const char *lcd)
1975 {
1976   const char *p_orig = orig;
1977   const char *orig_end = orig + orig_len;
1978   const char *p_lcd = lcd;
1979   std::string res;
1980 
1981   while (p_orig < orig_end)
1982     {
1983       if (*p_orig == ' ')
1984 	{
1985 	  while (p_orig < orig_end && *p_orig == ' ')
1986 	    res += *p_orig++;
1987 	  p_lcd = skip_spaces (p_lcd);
1988 	}
1989       else
1990 	{
1991 	  /* Take characters from the LCD instead of the original
1992 	     text, since some completions change upper/lowercase.
1993 	     E.g.:
1994 	       "handle sig<>"
1995 	     completes to:
1996 	       "handle SIG[QUIT|etc.]"
1997 	  */
1998 	  res += *p_lcd;
1999 	  p_orig++;
2000 	  p_lcd++;
2001 	}
2002     }
2003 
2004   while (*p_lcd != '\0')
2005     res += *p_lcd++;
2006 
2007   return xstrdup (res.c_str ());
2008 }
2009 
2010 /* See completer.h.  */
2011 
2012 completion_result
2013 completion_tracker::build_completion_result (const char *text,
2014 					     int start, int end)
2015 {
2016   completion_list &list = m_entries_vec;	/* The completions.  */
2017 
2018   if (list.empty ())
2019     return {};
2020 
2021   /* +1 for the LCD, and +1 for NULL termination.  */
2022   char **match_list = XNEWVEC (char *, 1 + list.size () + 1);
2023 
2024   /* Build replacement word, based on the LCD.  */
2025 
2026   match_list[0]
2027     = expand_preserving_ws (text, end - start,
2028 			    m_lowest_common_denominator);
2029 
2030   if (m_lowest_common_denominator_unique)
2031     {
2032       /* We don't rely on readline appending the quote char as
2033 	 delimiter as then readline wouldn't append the ' ' after the
2034 	 completion.  */
2035       char buf[2] = { (char) quote_char () };
2036 
2037       match_list[0] = reconcat (match_list[0], match_list[0],
2038 				buf, (char *) NULL);
2039       match_list[1] = NULL;
2040 
2041       /* If the tracker wants to, or we already have a space at the
2042 	 end of the match, tell readline to skip appending
2043 	 another.  */
2044       bool completion_suppress_append
2045 	= (suppress_append_ws ()
2046 	   || match_list[0][strlen (match_list[0]) - 1] == ' ');
2047 
2048       return completion_result (match_list, 1, completion_suppress_append);
2049     }
2050   else
2051     {
2052       int ix;
2053 
2054       for (ix = 0; ix < list.size (); ++ix)
2055 	match_list[ix + 1] = list[ix].release ();
2056       match_list[ix + 1] = NULL;
2057 
2058       return completion_result (match_list, list.size (), false);
2059     }
2060 }
2061 
2062 /* See completer.h  */
2063 
2064 completion_result::completion_result ()
2065   : match_list (NULL), number_matches (0),
2066     completion_suppress_append (false)
2067 {}
2068 
2069 /* See completer.h  */
2070 
2071 completion_result::completion_result (char **match_list_,
2072 				      size_t number_matches_,
2073 				      bool completion_suppress_append_)
2074   : match_list (match_list_),
2075     number_matches (number_matches_),
2076     completion_suppress_append (completion_suppress_append_)
2077 {}
2078 
2079 /* See completer.h  */
2080 
2081 completion_result::~completion_result ()
2082 {
2083   reset_match_list ();
2084 }
2085 
2086 /* See completer.h  */
2087 
2088 completion_result::completion_result (completion_result &&rhs)
2089 {
2090   if (this == &rhs)
2091     return;
2092 
2093   reset_match_list ();
2094   match_list = rhs.match_list;
2095   rhs.match_list = NULL;
2096   number_matches = rhs.number_matches;
2097   rhs.number_matches = 0;
2098 }
2099 
2100 /* See completer.h  */
2101 
2102 char **
2103 completion_result::release_match_list ()
2104 {
2105   char **ret = match_list;
2106   match_list = NULL;
2107   return ret;
2108 }
2109 
2110 /* See completer.h  */
2111 
2112 void
2113 completion_result::sort_match_list ()
2114 {
2115   if (number_matches > 1)
2116     {
2117       /* Element 0 is special (it's the common prefix), leave it
2118 	 be.  */
2119       std::sort (&match_list[1],
2120 		 &match_list[number_matches + 1],
2121 		 compare_cstrings);
2122     }
2123 }
2124 
2125 /* See completer.h  */
2126 
2127 void
2128 completion_result::reset_match_list ()
2129 {
2130   if (match_list != NULL)
2131     {
2132       for (char **p = match_list; *p != NULL; p++)
2133 	xfree (*p);
2134       xfree (match_list);
2135       match_list = NULL;
2136     }
2137 }
2138 
2139 /* Helper for gdb_rl_attempted_completion_function, which does most of
2140    the work.  This is called by readline to build the match list array
2141    and to determine the lowest common denominator.  The real matches
2142    list starts at match[1], while match[0] is the slot holding
2143    readline's idea of the lowest common denominator of all matches,
2144    which is what readline replaces the completion "word" with.
2145 
2146    TEXT is the caller's idea of the "word" we are looking at, as
2147    computed in the handle_brkchars phase.
2148 
2149    START is the offset from RL_LINE_BUFFER where TEXT starts.  END is
2150    the offset from RL_LINE_BUFFER where TEXT ends (i.e., where
2151    rl_point is).
2152 
2153    You should thus pretend that the line ends at END (relative to
2154    RL_LINE_BUFFER).
2155 
2156    RL_LINE_BUFFER contains the entire text of the line.  RL_POINT is
2157    the offset in that line of the cursor.  You should pretend that the
2158    line ends at POINT.
2159 
2160    Returns NULL if there are no completions.  */
2161 
2162 static char **
2163 gdb_rl_attempted_completion_function_throw (const char *text, int start, int end)
2164 {
2165   /* Completers that provide a custom word point in the
2166      handle_brkchars phase also compute their completions then.
2167      Completers that leave the completion word handling to readline
2168      must be called twice.  If rl_point (i.e., END) is at column 0,
2169      then readline skips the handle_brkchars phase, and so we create a
2170      tracker now in that case too.  */
2171   if (end == 0 || !current_completion.tracker->use_custom_word_point ())
2172     {
2173       delete current_completion.tracker;
2174       current_completion.tracker = new completion_tracker ();
2175 
2176       complete_line (*current_completion.tracker, text,
2177 		     rl_line_buffer, rl_point);
2178     }
2179 
2180   completion_tracker &tracker = *current_completion.tracker;
2181 
2182   completion_result result
2183     = tracker.build_completion_result (text, start, end);
2184 
2185   rl_completion_suppress_append = result.completion_suppress_append;
2186   return result.release_match_list ();
2187 }
2188 
2189 /* Function installed as "rl_attempted_completion_function" readline
2190    hook.  Wrapper around gdb_rl_attempted_completion_function_throw
2191    that catches C++ exceptions, which can't cross readline.  */
2192 
2193 char **
2194 gdb_rl_attempted_completion_function (const char *text, int start, int end)
2195 {
2196   /* Restore globals that might have been tweaked in
2197      gdb_completion_word_break_characters.  */
2198   rl_basic_quote_characters = gdb_org_rl_basic_quote_characters;
2199 
2200   /* If we end up returning NULL, either on error, or simple because
2201      there are no matches, inhibit readline's default filename
2202      completer.  */
2203   rl_attempted_completion_over = 1;
2204 
2205   /* If the handle_brkchars phase was aborted, don't try
2206      completing.  */
2207   if (current_completion.aborted)
2208     return NULL;
2209 
2210   TRY
2211     {
2212       return gdb_rl_attempted_completion_function_throw (text, start, end);
2213     }
2214   CATCH (ex, RETURN_MASK_ALL)
2215     {
2216     }
2217   END_CATCH
2218 
2219   return NULL;
2220 }
2221 
2222 /* Skip over the possibly quoted word STR (as defined by the quote
2223    characters QUOTECHARS and the word break characters BREAKCHARS).
2224    Returns pointer to the location after the "word".  If either
2225    QUOTECHARS or BREAKCHARS is NULL, use the same values used by the
2226    completer.  */
2227 
2228 const char *
2229 skip_quoted_chars (const char *str, const char *quotechars,
2230 		   const char *breakchars)
2231 {
2232   char quote_char = '\0';
2233   const char *scan;
2234 
2235   if (quotechars == NULL)
2236     quotechars = gdb_completer_quote_characters;
2237 
2238   if (breakchars == NULL)
2239     breakchars = current_language->la_word_break_characters();
2240 
2241   for (scan = str; *scan != '\0'; scan++)
2242     {
2243       if (quote_char != '\0')
2244 	{
2245 	  /* Ignore everything until the matching close quote char.  */
2246 	  if (*scan == quote_char)
2247 	    {
2248 	      /* Found matching close quote.  */
2249 	      scan++;
2250 	      break;
2251 	    }
2252 	}
2253       else if (strchr (quotechars, *scan))
2254 	{
2255 	  /* Found start of a quoted string.  */
2256 	  quote_char = *scan;
2257 	}
2258       else if (strchr (breakchars, *scan))
2259 	{
2260 	  break;
2261 	}
2262     }
2263 
2264   return (scan);
2265 }
2266 
2267 /* Skip over the possibly quoted word STR (as defined by the quote
2268    characters and word break characters used by the completer).
2269    Returns pointer to the location after the "word".  */
2270 
2271 const char *
2272 skip_quoted (const char *str)
2273 {
2274   return skip_quoted_chars (str, NULL, NULL);
2275 }
2276 
2277 /* Return a message indicating that the maximum number of completions
2278    has been reached and that there may be more.  */
2279 
2280 const char *
2281 get_max_completions_reached_message (void)
2282 {
2283   return _("*** List may be truncated, max-completions reached. ***");
2284 }
2285 
2286 /* GDB replacement for rl_display_match_list.
2287    Readline doesn't provide a clean interface for TUI(curses).
2288    A hack previously used was to send readline's rl_outstream through a pipe
2289    and read it from the event loop.  Bleah.  IWBN if readline abstracted
2290    away all the necessary bits, and this is what this code does.  It
2291    replicates the parts of readline we need and then adds an abstraction
2292    layer, currently implemented as struct match_list_displayer, so that both
2293    CLI and TUI can use it.  We copy all this readline code to minimize
2294    GDB-specific mods to readline.  Once this code performs as desired then
2295    we can submit it to the readline maintainers.
2296 
2297    N.B. A lot of the code is the way it is in order to minimize differences
2298    from readline's copy.  */
2299 
2300 /* Not supported here.  */
2301 #undef VISIBLE_STATS
2302 
2303 #if defined (HANDLE_MULTIBYTE)
2304 #define MB_INVALIDCH(x) ((x) == (size_t)-1 || (x) == (size_t)-2)
2305 #define MB_NULLWCH(x)   ((x) == 0)
2306 #endif
2307 
2308 #define ELLIPSIS_LEN	3
2309 
2310 /* gdb version of readline/complete.c:get_y_or_n.
2311    'y' -> returns 1, and 'n' -> returns 0.
2312    Also supported: space == 'y', RUBOUT == 'n', ctrl-g == start over.
2313    If FOR_PAGER is non-zero, then also supported are:
2314    NEWLINE or RETURN -> returns 2, and 'q' -> returns 0.  */
2315 
2316 static int
2317 gdb_get_y_or_n (int for_pager, const struct match_list_displayer *displayer)
2318 {
2319   int c;
2320 
2321   for (;;)
2322     {
2323       RL_SETSTATE (RL_STATE_MOREINPUT);
2324       c = displayer->read_key (displayer);
2325       RL_UNSETSTATE (RL_STATE_MOREINPUT);
2326 
2327       if (c == 'y' || c == 'Y' || c == ' ')
2328 	return 1;
2329       if (c == 'n' || c == 'N' || c == RUBOUT)
2330 	return 0;
2331       if (c == ABORT_CHAR || c < 0)
2332 	{
2333 	  /* Readline doesn't erase_entire_line here, but without it the
2334 	     --More-- prompt isn't erased and neither is the text entered
2335 	     thus far redisplayed.  */
2336 	  displayer->erase_entire_line (displayer);
2337 	  /* Note: The arguments to rl_abort are ignored.  */
2338 	  rl_abort (0, 0);
2339 	}
2340       if (for_pager && (c == NEWLINE || c == RETURN))
2341 	return 2;
2342       if (for_pager && (c == 'q' || c == 'Q'))
2343 	return 0;
2344       displayer->beep (displayer);
2345     }
2346 }
2347 
2348 /* Pager function for tab-completion.
2349    This is based on readline/complete.c:_rl_internal_pager.
2350    LINES is the number of lines of output displayed thus far.
2351    Returns:
2352    -1 -> user pressed 'n' or equivalent,
2353    0 -> user pressed 'y' or equivalent,
2354    N -> user pressed NEWLINE or equivalent and N is LINES - 1.  */
2355 
2356 static int
2357 gdb_display_match_list_pager (int lines,
2358 			      const struct match_list_displayer *displayer)
2359 {
2360   int i;
2361 
2362   displayer->puts (displayer, "--More--");
2363   displayer->flush (displayer);
2364   i = gdb_get_y_or_n (1, displayer);
2365   displayer->erase_entire_line (displayer);
2366   if (i == 0)
2367     return -1;
2368   else if (i == 2)
2369     return (lines - 1);
2370   else
2371     return 0;
2372 }
2373 
2374 /* Return non-zero if FILENAME is a directory.
2375    Based on readline/complete.c:path_isdir.  */
2376 
2377 static int
2378 gdb_path_isdir (const char *filename)
2379 {
2380   struct stat finfo;
2381 
2382   return (stat (filename, &finfo) == 0 && S_ISDIR (finfo.st_mode));
2383 }
2384 
2385 /* Return the portion of PATHNAME that should be output when listing
2386    possible completions.  If we are hacking filename completion, we
2387    are only interested in the basename, the portion following the
2388    final slash.  Otherwise, we return what we were passed.  Since
2389    printing empty strings is not very informative, if we're doing
2390    filename completion, and the basename is the empty string, we look
2391    for the previous slash and return the portion following that.  If
2392    there's no previous slash, we just return what we were passed.
2393 
2394    Based on readline/complete.c:printable_part.  */
2395 
2396 static char *
2397 gdb_printable_part (char *pathname)
2398 {
2399   char *temp, *x;
2400 
2401   if (rl_filename_completion_desired == 0)	/* don't need to do anything */
2402     return (pathname);
2403 
2404   temp = strrchr (pathname, '/');
2405 #if defined (__MSDOS__)
2406   if (temp == 0 && ISALPHA ((unsigned char)pathname[0]) && pathname[1] == ':')
2407     temp = pathname + 1;
2408 #endif
2409 
2410   if (temp == 0 || *temp == '\0')
2411     return (pathname);
2412   /* If the basename is NULL, we might have a pathname like '/usr/src/'.
2413      Look for a previous slash and, if one is found, return the portion
2414      following that slash.  If there's no previous slash, just return the
2415      pathname we were passed. */
2416   else if (temp[1] == '\0')
2417     {
2418       for (x = temp - 1; x > pathname; x--)
2419         if (*x == '/')
2420           break;
2421       return ((*x == '/') ? x + 1 : pathname);
2422     }
2423   else
2424     return ++temp;
2425 }
2426 
2427 /* Compute width of STRING when displayed on screen by print_filename.
2428    Based on readline/complete.c:fnwidth.  */
2429 
2430 static int
2431 gdb_fnwidth (const char *string)
2432 {
2433   int width, pos;
2434 #if defined (HANDLE_MULTIBYTE)
2435   mbstate_t ps;
2436   int left, w;
2437   size_t clen;
2438   wchar_t wc;
2439 
2440   left = strlen (string) + 1;
2441   memset (&ps, 0, sizeof (mbstate_t));
2442 #endif
2443 
2444   width = pos = 0;
2445   while (string[pos])
2446     {
2447       if (CTRL_CHAR (string[pos]) || string[pos] == RUBOUT)
2448 	{
2449 	  width += 2;
2450 	  pos++;
2451 	}
2452       else
2453 	{
2454 #if defined (HANDLE_MULTIBYTE)
2455 	  clen = mbrtowc (&wc, string + pos, left - pos, &ps);
2456 	  if (MB_INVALIDCH (clen))
2457 	    {
2458 	      width++;
2459 	      pos++;
2460 	      memset (&ps, 0, sizeof (mbstate_t));
2461 	    }
2462 	  else if (MB_NULLWCH (clen))
2463 	    break;
2464 	  else
2465 	    {
2466 	      pos += clen;
2467 	      w = wcwidth (wc);
2468 	      width += (w >= 0) ? w : 1;
2469 	    }
2470 #else
2471 	  width++;
2472 	  pos++;
2473 #endif
2474 	}
2475     }
2476 
2477   return width;
2478 }
2479 
2480 /* Print TO_PRINT, one matching completion.
2481    PREFIX_BYTES is number of common prefix bytes.
2482    Based on readline/complete.c:fnprint.  */
2483 
2484 static int
2485 gdb_fnprint (const char *to_print, int prefix_bytes,
2486 	     const struct match_list_displayer *displayer)
2487 {
2488   int printed_len, w;
2489   const char *s;
2490 #if defined (HANDLE_MULTIBYTE)
2491   mbstate_t ps;
2492   const char *end;
2493   size_t tlen;
2494   int width;
2495   wchar_t wc;
2496 
2497   end = to_print + strlen (to_print) + 1;
2498   memset (&ps, 0, sizeof (mbstate_t));
2499 #endif
2500 
2501   printed_len = 0;
2502 
2503   /* Don't print only the ellipsis if the common prefix is one of the
2504      possible completions */
2505   if (to_print[prefix_bytes] == '\0')
2506     prefix_bytes = 0;
2507 
2508   if (prefix_bytes)
2509     {
2510       char ellipsis;
2511 
2512       ellipsis = (to_print[prefix_bytes] == '.') ? '_' : '.';
2513       for (w = 0; w < ELLIPSIS_LEN; w++)
2514 	displayer->putch (displayer, ellipsis);
2515       printed_len = ELLIPSIS_LEN;
2516     }
2517 
2518   s = to_print + prefix_bytes;
2519   while (*s)
2520     {
2521       if (CTRL_CHAR (*s))
2522         {
2523           displayer->putch (displayer, '^');
2524           displayer->putch (displayer, UNCTRL (*s));
2525           printed_len += 2;
2526           s++;
2527 #if defined (HANDLE_MULTIBYTE)
2528 	  memset (&ps, 0, sizeof (mbstate_t));
2529 #endif
2530         }
2531       else if (*s == RUBOUT)
2532 	{
2533 	  displayer->putch (displayer, '^');
2534 	  displayer->putch (displayer, '?');
2535 	  printed_len += 2;
2536 	  s++;
2537 #if defined (HANDLE_MULTIBYTE)
2538 	  memset (&ps, 0, sizeof (mbstate_t));
2539 #endif
2540 	}
2541       else
2542 	{
2543 #if defined (HANDLE_MULTIBYTE)
2544 	  tlen = mbrtowc (&wc, s, end - s, &ps);
2545 	  if (MB_INVALIDCH (tlen))
2546 	    {
2547 	      tlen = 1;
2548 	      width = 1;
2549 	      memset (&ps, 0, sizeof (mbstate_t));
2550 	    }
2551 	  else if (MB_NULLWCH (tlen))
2552 	    break;
2553 	  else
2554 	    {
2555 	      w = wcwidth (wc);
2556 	      width = (w >= 0) ? w : 1;
2557 	    }
2558 	  for (w = 0; w < tlen; ++w)
2559 	    displayer->putch (displayer, s[w]);
2560 	  s += tlen;
2561 	  printed_len += width;
2562 #else
2563 	  displayer->putch (displayer, *s);
2564 	  s++;
2565 	  printed_len++;
2566 #endif
2567 	}
2568     }
2569 
2570   return printed_len;
2571 }
2572 
2573 /* Output TO_PRINT to rl_outstream.  If VISIBLE_STATS is defined and we
2574    are using it, check for and output a single character for `special'
2575    filenames.  Return the number of characters we output.
2576    Based on readline/complete.c:print_filename.  */
2577 
2578 static int
2579 gdb_print_filename (char *to_print, char *full_pathname, int prefix_bytes,
2580 		    const struct match_list_displayer *displayer)
2581 {
2582   int printed_len, extension_char, slen, tlen;
2583   char *s, c, *new_full_pathname;
2584   const char *dn;
2585   extern int _rl_complete_mark_directories;
2586 
2587   extension_char = 0;
2588   printed_len = gdb_fnprint (to_print, prefix_bytes, displayer);
2589 
2590 #if defined (VISIBLE_STATS)
2591  if (rl_filename_completion_desired && (rl_visible_stats || _rl_complete_mark_directories))
2592 #else
2593  if (rl_filename_completion_desired && _rl_complete_mark_directories)
2594 #endif
2595     {
2596       /* If to_print != full_pathname, to_print is the basename of the
2597 	 path passed.  In this case, we try to expand the directory
2598 	 name before checking for the stat character. */
2599       if (to_print != full_pathname)
2600 	{
2601 	  /* Terminate the directory name. */
2602 	  c = to_print[-1];
2603 	  to_print[-1] = '\0';
2604 
2605 	  /* If setting the last slash in full_pathname to a NUL results in
2606 	     full_pathname being the empty string, we are trying to complete
2607 	     files in the root directory.  If we pass a null string to the
2608 	     bash directory completion hook, for example, it will expand it
2609 	     to the current directory.  We just want the `/'. */
2610 	  if (full_pathname == 0 || *full_pathname == 0)
2611 	    dn = "/";
2612 	  else if (full_pathname[0] != '/')
2613 	    dn = full_pathname;
2614 	  else if (full_pathname[1] == 0)
2615 	    dn = "//";		/* restore trailing slash to `//' */
2616 	  else if (full_pathname[1] == '/' && full_pathname[2] == 0)
2617 	    dn = "/";		/* don't turn /// into // */
2618 	  else
2619 	    dn = full_pathname;
2620 	  s = tilde_expand (dn);
2621 	  if (rl_directory_completion_hook)
2622 	    (*rl_directory_completion_hook) (&s);
2623 
2624 	  slen = strlen (s);
2625 	  tlen = strlen (to_print);
2626 	  new_full_pathname = (char *)xmalloc (slen + tlen + 2);
2627 	  strcpy (new_full_pathname, s);
2628 	  if (s[slen - 1] == '/')
2629 	    slen--;
2630 	  else
2631 	    new_full_pathname[slen] = '/';
2632 	  new_full_pathname[slen] = '/';
2633 	  strcpy (new_full_pathname + slen + 1, to_print);
2634 
2635 #if defined (VISIBLE_STATS)
2636 	  if (rl_visible_stats)
2637 	    extension_char = stat_char (new_full_pathname);
2638 	  else
2639 #endif
2640 	  if (gdb_path_isdir (new_full_pathname))
2641 	    extension_char = '/';
2642 
2643 	  xfree (new_full_pathname);
2644 	  to_print[-1] = c;
2645 	}
2646       else
2647 	{
2648 	  s = tilde_expand (full_pathname);
2649 #if defined (VISIBLE_STATS)
2650 	  if (rl_visible_stats)
2651 	    extension_char = stat_char (s);
2652 	  else
2653 #endif
2654 	    if (gdb_path_isdir (s))
2655 	      extension_char = '/';
2656 	}
2657 
2658       xfree (s);
2659       if (extension_char)
2660 	{
2661 	  displayer->putch (displayer, extension_char);
2662 	  printed_len++;
2663 	}
2664     }
2665 
2666   return printed_len;
2667 }
2668 
2669 /* GDB version of readline/complete.c:complete_get_screenwidth.  */
2670 
2671 static int
2672 gdb_complete_get_screenwidth (const struct match_list_displayer *displayer)
2673 {
2674   /* Readline has other stuff here which it's not clear we need.  */
2675   return displayer->width;
2676 }
2677 
2678 extern int _rl_completion_prefix_display_length;
2679 extern int _rl_print_completions_horizontally;
2680 
2681 EXTERN_C int _rl_qsort_string_compare (const void *, const void *);
2682 typedef int QSFUNC (const void *, const void *);
2683 
2684 /* GDB version of readline/complete.c:rl_display_match_list.
2685    See gdb_display_match_list for a description of MATCHES, LEN, MAX.
2686    Returns non-zero if all matches are displayed.  */
2687 
2688 static int
2689 gdb_display_match_list_1 (char **matches, int len, int max,
2690 			  const struct match_list_displayer *displayer)
2691 {
2692   int count, limit, printed_len, lines, cols;
2693   int i, j, k, l, common_length, sind;
2694   char *temp, *t;
2695   int page_completions = displayer->height != INT_MAX && pagination_enabled;
2696 
2697   /* Find the length of the prefix common to all items: length as displayed
2698      characters (common_length) and as a byte index into the matches (sind) */
2699   common_length = sind = 0;
2700   if (_rl_completion_prefix_display_length > 0)
2701     {
2702       t = gdb_printable_part (matches[0]);
2703       temp = strrchr (t, '/');
2704       common_length = temp ? gdb_fnwidth (temp) : gdb_fnwidth (t);
2705       sind = temp ? strlen (temp) : strlen (t);
2706 
2707       if (common_length > _rl_completion_prefix_display_length && common_length > ELLIPSIS_LEN)
2708 	max -= common_length - ELLIPSIS_LEN;
2709       else
2710 	common_length = sind = 0;
2711     }
2712 
2713   /* How many items of MAX length can we fit in the screen window? */
2714   cols = gdb_complete_get_screenwidth (displayer);
2715   max += 2;
2716   limit = cols / max;
2717   if (limit != 1 && (limit * max == cols))
2718     limit--;
2719 
2720   /* If cols == 0, limit will end up -1 */
2721   if (cols < displayer->width && limit < 0)
2722     limit = 1;
2723 
2724   /* Avoid a possible floating exception.  If max > cols,
2725      limit will be 0 and a divide-by-zero fault will result. */
2726   if (limit == 0)
2727     limit = 1;
2728 
2729   /* How many iterations of the printing loop? */
2730   count = (len + (limit - 1)) / limit;
2731 
2732   /* Watch out for special case.  If LEN is less than LIMIT, then
2733      just do the inner printing loop.
2734 	   0 < len <= limit  implies  count = 1. */
2735 
2736   /* Sort the items if they are not already sorted. */
2737   if (rl_ignore_completion_duplicates == 0 && rl_sort_completion_matches)
2738     qsort (matches + 1, len, sizeof (char *), (QSFUNC *)_rl_qsort_string_compare);
2739 
2740   displayer->crlf (displayer);
2741 
2742   lines = 0;
2743   if (_rl_print_completions_horizontally == 0)
2744     {
2745       /* Print the sorted items, up-and-down alphabetically, like ls. */
2746       for (i = 1; i <= count; i++)
2747 	{
2748 	  for (j = 0, l = i; j < limit; j++)
2749 	    {
2750 	      if (l > len || matches[l] == 0)
2751 		break;
2752 	      else
2753 		{
2754 		  temp = gdb_printable_part (matches[l]);
2755 		  printed_len = gdb_print_filename (temp, matches[l], sind,
2756 						    displayer);
2757 
2758 		  if (j + 1 < limit)
2759 		    for (k = 0; k < max - printed_len; k++)
2760 		      displayer->putch (displayer, ' ');
2761 		}
2762 	      l += count;
2763 	    }
2764 	  displayer->crlf (displayer);
2765 	  lines++;
2766 	  if (page_completions && lines >= (displayer->height - 1) && i < count)
2767 	    {
2768 	      lines = gdb_display_match_list_pager (lines, displayer);
2769 	      if (lines < 0)
2770 		return 0;
2771 	    }
2772 	}
2773     }
2774   else
2775     {
2776       /* Print the sorted items, across alphabetically, like ls -x. */
2777       for (i = 1; matches[i]; i++)
2778 	{
2779 	  temp = gdb_printable_part (matches[i]);
2780 	  printed_len = gdb_print_filename (temp, matches[i], sind, displayer);
2781 	  /* Have we reached the end of this line? */
2782 	  if (matches[i+1])
2783 	    {
2784 	      if (i && (limit > 1) && (i % limit) == 0)
2785 		{
2786 		  displayer->crlf (displayer);
2787 		  lines++;
2788 		  if (page_completions && lines >= displayer->height - 1)
2789 		    {
2790 		      lines = gdb_display_match_list_pager (lines, displayer);
2791 		      if (lines < 0)
2792 			return 0;
2793 		    }
2794 		}
2795 	      else
2796 		for (k = 0; k < max - printed_len; k++)
2797 		  displayer->putch (displayer, ' ');
2798 	    }
2799 	}
2800       displayer->crlf (displayer);
2801     }
2802 
2803   return 1;
2804 }
2805 
2806 /* Utility for displaying completion list matches, used by both CLI and TUI.
2807 
2808    MATCHES is the list of strings, in argv format, LEN is the number of
2809    strings in MATCHES, and MAX is the length of the longest string in
2810    MATCHES.  */
2811 
2812 void
2813 gdb_display_match_list (char **matches, int len, int max,
2814 			const struct match_list_displayer *displayer)
2815 {
2816   /* Readline will never call this if complete_line returned NULL.  */
2817   gdb_assert (max_completions != 0);
2818 
2819   /* complete_line will never return more than this.  */
2820   if (max_completions > 0)
2821     gdb_assert (len <= max_completions);
2822 
2823   if (rl_completion_query_items > 0 && len >= rl_completion_query_items)
2824     {
2825       char msg[100];
2826 
2827       /* We can't use *query here because they wait for <RET> which is
2828 	 wrong here.  This follows the readline version as closely as possible
2829 	 for compatibility's sake.  See readline/complete.c.  */
2830 
2831       displayer->crlf (displayer);
2832 
2833       xsnprintf (msg, sizeof (msg),
2834 		 "Display all %d possibilities? (y or n)", len);
2835       displayer->puts (displayer, msg);
2836       displayer->flush (displayer);
2837 
2838       if (gdb_get_y_or_n (0, displayer) == 0)
2839 	{
2840 	  displayer->crlf (displayer);
2841 	  return;
2842 	}
2843     }
2844 
2845   if (gdb_display_match_list_1 (matches, len, max, displayer))
2846     {
2847       /* Note: MAX_COMPLETIONS may be -1 or zero, but LEN is always > 0.  */
2848       if (len == max_completions)
2849 	{
2850 	  /* The maximum number of completions has been reached.  Warn the user
2851 	     that there may be more.  */
2852 	  const char *message = get_max_completions_reached_message ();
2853 
2854 	  displayer->puts (displayer, message);
2855 	  displayer->crlf (displayer);
2856 	}
2857     }
2858 }
2859 
2860 void
2861 _initialize_completer (void)
2862 {
2863   add_setshow_zuinteger_unlimited_cmd ("max-completions", no_class,
2864 				       &max_completions, _("\
2865 Set maximum number of completion candidates."), _("\
2866 Show maximum number of completion candidates."), _("\
2867 Use this to limit the number of candidates considered\n\
2868 during completion.  Specifying \"unlimited\" or -1\n\
2869 disables limiting.  Note that setting either no limit or\n\
2870 a very large limit can make completion slow."),
2871 				       NULL, NULL, &setlist, &showlist);
2872 }
2873