[PATCH v3 02/19] Remove completion_tracker_t from the public completion API.

Keith Seitz
2015-08-06T19:58:23Z

Differences from last version:

1. Removed comments about recording an additional completion from
add_completion.
2. Removed requirement to xstrdup arg to add_completion; add_completeion
uses new function completer_strdup.
3. Consolidated (oft-repeated) partial copy code into completer_strdup.
Removed this code from all completion functions.

---

This patch removes the recently introduced "completion tracker" concept
from the public completion API. In the previous patch, the completion
tracker was added to the (new) completer_data structure that is now
used by all completion functions.

Since completion_tracker_t is now used entirely inside completer.c, there
is no need to make its type opaque, so the typedef has been removed.

This patch also fixes gdb/17960, which is easily demonstrated:

$ gdb -nx -q gdb
(gdb) b gdb.c:ma<TAB>
./../src/gdb/completer.c:837: internal-error: maybe_add_completion:
Assertion `tracker != NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)

This occurs because the code path in this case is:
complete_line
- complete_line_internal
-- location_completer

gdb/ChangeLog

PR gdb/17960
* completer.c (struct completer_data) <tracker>: Change type to
htab_t.
(enum maybe_add_completion_enum): Make private; moved from
completer.h.
[DEFAULT_MAX_COMPLETIONS]: Define.
(new_completion_tracker): Remove function.
(new_completer_data): New function.
(free_completion_tracker): Remove function.
(free_completer_data): New function.
(make_cleanup_free_completion_tracker): Remove function.
(maybe_add_completion): Make static. Update comments.
Use completer_data instead of completion_tracker_t.
(completer_strdup): New function.
(add_completion): New function.
(complete_line, gdb_completion_word_break_characters): Use
completer_data instead of completion_tracker.
* completer.h (completion_tracker_t, new_completion_tracker)
(make_cleanup_free_completion_tracker, maybe_add_completion)
(enum maybe_add_completion): Remove declarations.
(enum add_completion_status): Define.
(add_completion): Declare.
* symtab.c (completion_tracker): Remove variable.
(completion_list_add_name): Use add_completion instead of
maybe_add_completion and partial copy.
(default_make_symbol_completion_list_break_on_1): Do not use
completion_tracker.

gdb/testsuite/ChangeLog

PR gdb/17960
* gdb.base/completion.exp: Add some basic tests for the
location completer, including a regression test for
the gdb/17960 assertion failure.
---
gdb/completer.c | 231 +++++++++++++++++++++++----------
gdb/completer.h | 66 +++------
gdb/symtab.c | 62 +--------
gdb/testsuite/gdb.base/completion.exp | 78 +++++++++++
4 files changed, 260 insertions(+), 177 deletions(-)

diff --git a/gdb/completer.c b/gdb/completer.c
index 476f9f2..bf4137e 100644
--- a/gdb/completer.c
+++ b/gdb/completer.c
@@ -92,10 +92,31 @@ static char *gdb_completer_quote_characters = "'";

struct completer_data
{
- /* The completion tracker being used by the completer. */
- completion_tracker_t tracker;
+ /* A hashtable used to track completions. */
+ htab_t tracker;
};

+/* Return values for maybe_add_completion. */
+
+enum maybe_add_completion_enum
+{
+ /* NAME has been recorded and max_completions has not been reached,
+ or completion tracking is disabled (max_completions < 0). */
+ MAYBE_ADD_COMPLETION_OK,
+
+ /* NAME has been recorded and max_completions has been reached
+ (thus the caller can stop searching). */
+ MAYBE_ADD_COMPLETION_OK_MAX_REACHED,
+
+ /* max-completions entries has been reached.
+ Whether NAME is a duplicate or not is not determined. */
+ MAYBE_ADD_COMPLETION_MAX_REACHED,
+
+ /* NAME has already been recorded.
+ Note that this is never returned if completion tracking is disabled
+ (max_completions < 0). */
+ MAYBE_ADD_COMPLETION_DUPLICATE
+};
\f
/* Accessor for some completer data that may interest other files. */

@@ -803,48 +824,41 @@ complete_line_internal (struct completer_data *cdata,

/* See completer.h. */

-int max_completions = 200;
+#define DEFAULT_MAX_COMPLETIONS 200
+int max_completions = DEFAULT_MAX_COMPLETIONS;

-/* See completer.h. */
+/* Allocate a new completer data structure. */

-completion_tracker_t
-new_completion_tracker (void)
+static struct completer_data *
+new_completer_data (int size)
{
- if (max_completions <= 0)
- return NULL;
+ struct completer_data *cdata = XCNEW (struct completer_data);

- return htab_create_alloc (max_completions,
- htab_hash_string, (htab_eq) streq,
- NULL, xcalloc, xfree);
+ cdata->tracker
+ = htab_create_alloc ((size < 0 ? DEFAULT_MAX_COMPLETIONS : size),
+ htab_hash_string, (htab_eq) streq, NULL,
+ xcalloc, xfree);
+ return cdata;
}

-/* Cleanup routine to free a completion tracker and reset the pointer
- to NULL. */
+/* Free the completion data represented by P. */

static void
-free_completion_tracker (void *p)
+free_completer_data (void *p)
{
- completion_tracker_t *tracker_ptr = p;
+ struct completer_data *cdata = p;

- htab_delete (*tracker_ptr);
- *tracker_ptr = NULL;
+ htab_delete (cdata->tracker);
+ xfree (cdata);
}

-/* See completer.h. */
-
-struct cleanup *
-make_cleanup_free_completion_tracker (completion_tracker_t *tracker_ptr)
-{
- if (*tracker_ptr == NULL)
- return make_cleanup (null_cleanup, NULL);
-
- return make_cleanup (free_completion_tracker, tracker_ptr);
-}
-
-/* See completer.h. */
+/* Add the completion NAME to the list of generated completions if
+ it is not there already.
+ If max_completions is negative, nothing is done, not even watching
+ for duplicates, and MAYBE_ADD_COMPLETION_OK is always returned. */

-enum maybe_add_completion_enum
-maybe_add_completion (completion_tracker_t tracker, char *name)
+static enum maybe_add_completion_enum
+maybe_add_completion (struct completer_data *cdata, char *name)
{
void **slot;

@@ -853,23 +867,82 @@ maybe_add_completion (completion_tracker_t tracker, char *name)
if (max_completions == 0)
return MAYBE_ADD_COMPLETION_MAX_REACHED;

- gdb_assert (tracker != NULL);
-
- if (htab_elements (tracker) >= max_completions)
+ if (htab_elements (cdata->tracker) >= max_completions)
return MAYBE_ADD_COMPLETION_MAX_REACHED;

- slot = htab_find_slot (tracker, name, INSERT);
+ slot = htab_find_slot (cdata->tracker, name, INSERT);

if (*slot != HTAB_EMPTY_ENTRY)
return MAYBE_ADD_COMPLETION_DUPLICATE;

*slot = name;

- return (htab_elements (tracker) < max_completions
+ return (htab_elements (cdata->tracker) < max_completions
? MAYBE_ADD_COMPLETION_OK
: MAYBE_ADD_COMPLETION_OK_MAX_REACHED);
}

+/* A strdup-like function used by the completer to copy bits of completion
+ strings. */
+
+static char *
+completer_strdup (const char *match, const char *text, const char *word)
+{
+ char *alloc;
+
+ if (text == NULL || word == NULL || text == word)
+ return xstrdup (match);
+
+ if (word > text)
+ {
+ gdb_assert (strlen (match) > (word - text));
+
+ /* Return some portion of match. */
+ match += (word - text);
+ alloc = xmalloc (strlen (match) + 1);
+ strcpy (alloc, match);
+ }
+ else
+ {
+ /* Return some of text plus match. */
+ alloc = xmalloc (strlen (match) + (text - word) + 1);
+ strncpy (alloc, word, text - word);
+ alloc[text - word] = '\0';
+ strcat (alloc, match);
+ }
+
+ return alloc;
+}
+
+/* See completer.h. */
+
+enum add_completion_status
+add_completion (struct completer_data *cdata, VEC (char_ptr) **result,
+ const char *match, const char *text, const char *word)
+{
+ enum maybe_add_completion_enum add_status;
+ char *alloc = completer_strdup (match, text, word);
+
+ add_status = maybe_add_completion (cdata, alloc);
+ switch (add_status)
+ {
+ case MAYBE_ADD_COMPLETION_OK:
+ VEC_safe_push (char_ptr, *result, alloc);
+ break;
+ case MAYBE_ADD_COMPLETION_OK_MAX_REACHED:
+ VEC_safe_push (char_ptr, *result, alloc);
+ return ADD_COMPLETION_MAX_REACHED;
+ case MAYBE_ADD_COMPLETION_MAX_REACHED:
+ xfree (alloc);
+ return ADD_COMPLETION_MAX_REACHED;
+ case MAYBE_ADD_COMPLETION_DUPLICATE:
+ xfree (alloc);
+ break;
+ }
+
+ return ADD_COMPLETION_OK;
+}
+
void
throw_max_completions_reached_error (void)
{
@@ -894,54 +967,63 @@ complete_line (const char *text, const char *line_buffer, int point)
{
VEC (char_ptr) *list;
VEC (char_ptr) *result = NULL;
- struct cleanup *cleanups;
- completion_tracker_t tracker;
+ struct cleanup *cdata_cleanup, *list_cleanup;
char *candidate;
- int ix, max_reached;
+ int ix;
+ struct completer_data *cdata;

if (max_completions == 0)
return NULL;
- list = complete_line_internal (NULL, text, line_buffer, point,
+
+ cdata = new_completer_data (max_completions);
+ cdata_cleanup = make_cleanup (free_completer_data, cdata);
+ list = complete_line_internal (cdata, text, line_buffer, point,
handle_completions);
if (max_completions < 0)
- return list;
-
- tracker = new_completion_tracker ();
- cleanups = make_cleanup_free_completion_tracker (&tracker);
- make_cleanup_free_char_ptr_vec (list);
-
- /* Do a final test for too many completions. Individual completers may
- do some of this, but are not required to. Duplicates are also removed
- here. Otherwise the user is left scratching his/her head: readline and
- complete_command will remove duplicates, and if removal of duplicates
- there brings the total under max_completions the user may think gdb quit
- searching too early. */
-
- for (ix = 0, max_reached = 0;
- !max_reached && VEC_iterate (char_ptr, list, ix, candidate);
- ++ix)
{
- enum maybe_add_completion_enum add_status;
+ do_cleanups (cdata_cleanup);
+ return list;
+ }
+
+ list_cleanup = make_cleanup_free_char_ptr_vec (list);

- add_status = maybe_add_completion (tracker, candidate);
+ /* If complete_line_internal returned more completions than were
+ recorded by the completion tracker, then the completer function that
+ was run does not support completion tracking. In this case,
+ do a final test for too many completions.

- switch (add_status)
+ Duplicates are also removed here. Otherwise the user is left
+ scratching his/her head: readline and complete_command will remove
+ duplicates, and if removal of duplicates there brings the total under
+ max_completions the user may think gdb quit searching too early. */
+
+ if (VEC_length (char_ptr, list) > htab_elements (cdata->tracker))
+ {
+ enum add_completion_status max_reached = ADD_COMPLETION_OK;
+
+ /* Clear the tracker so that we can re-use it to count the number
+ of returned completions. */
+ htab_empty (cdata->tracker);
+
+ for (ix = 0; (max_reached == ADD_COMPLETION_OK
+ && VEC_iterate (char_ptr, list, ix, candidate)); ++ix)
{
- case MAYBE_ADD_COMPLETION_OK:
- VEC_safe_push (char_ptr, result, xstrdup (candidate));
- break;
- case MAYBE_ADD_COMPLETION_OK_MAX_REACHED:
- VEC_safe_push (char_ptr, result, xstrdup (candidate));
- max_reached = 1;
- break;
- case MAYBE_ADD_COMPLETION_MAX_REACHED:
- gdb_assert_not_reached ("more than max completions reached");
- case MAYBE_ADD_COMPLETION_DUPLICATE:
- break;
+ max_reached = add_completion (cdata, &result, candidate, NULL, NULL);
}
+
+ /* The return result has been assembled and the original list from
+ complete_line_internal is no longer needed. Free it. */
+ do_cleanups (list_cleanup);
+ }
+ else
+ {
+ /* There is a valid tracker for the completion -- simply return
+ the completed list. */
+ discard_cleanups (list_cleanup);
+ result = list;
}

- do_cleanups (cleanups);
+ do_cleanups (cdata_cleanup);

return result;
}
@@ -1074,9 +1156,14 @@ char *
gdb_completion_word_break_characters (void)
{
VEC (char_ptr) *list;
+ struct completer_data *cdata;
+ struct cleanup *cleanup;

- list = complete_line_internal (NULL, rl_line_buffer, rl_line_buffer,
+ cdata = new_completer_data (max_completions);
+ cleanup = make_cleanup (free_completer_data, cdata);
+ list = complete_line_internal (cdata, rl_line_buffer, rl_line_buffer,
rl_point, handle_brkchars);
+ do_cleanups (cleanup);
gdb_assert (list == NULL);
return rl_completer_word_break_characters;
}
diff --git a/gdb/completer.h b/gdb/completer.h
index 7139c0a..43d1321 100644
--- a/gdb/completer.h
+++ b/gdb/completer.h
@@ -132,59 +132,31 @@ extern const char *skip_quoted (const char *);

extern int max_completions;

-/* Object to track how many unique completions have been generated.
- Used to limit the size of generated completion lists. */
+/* Return values for add_completion. */

-typedef htab_t completion_tracker_t;
-
-/* Create a new completion tracker.
- The result is a hash table to track added completions, or NULL
- if max_completions <= 0. If max_completions < 0, tracking is disabled.
- If max_completions == 0, the max is indeed zero. */
-
-extern completion_tracker_t new_completion_tracker (void);
-
-/* Make a cleanup to free a completion tracker, and reset its pointer
- to NULL. */
-
-extern struct cleanup *make_cleanup_free_completion_tracker
- (completion_tracker_t *tracker_ptr);
-
-/* Return values for maybe_add_completion. */
-
-enum maybe_add_completion_enum
+enum add_completion_status
{
- /* NAME has been recorded and max_completions has not been reached,
- or completion tracking is disabled (max_completions < 0). */
- MAYBE_ADD_COMPLETION_OK,
-
- /* NAME has been recorded and max_completions has been reached
- (thus the caller can stop searching). */
- MAYBE_ADD_COMPLETION_OK_MAX_REACHED,
-
- /* max-completions entries has been reached.
- Whether NAME is a duplicate or not is not determined. */
- MAYBE_ADD_COMPLETION_MAX_REACHED,
-
- /* NAME has already been recorded.
- Note that this is never returned if completion tracking is disabled
- (max_completions < 0). */
- MAYBE_ADD_COMPLETION_DUPLICATE
+ /* Completion was added -- keep looking for more. */
+ ADD_COMPLETION_OK,
+
+ /* Maximum number of completions has been reached or the maximum
+ has already been reached by a previous call to add_completion.
+ Callers can make no assumptions about whether the completion was
+ added or not. */
+ ADD_COMPLETION_MAX_REACHED
};

-/* Add the completion NAME to the list of generated completions if
- it is not there already.
- If max_completions is negative, nothing is done, not even watching
- for duplicates, and MAYBE_ADD_COMPLETION_OK is always returned.
+/* Add the given MATCH to the completer result in CDATA.
+ Returns one of the above enum add_completion_status codes to indicate
+ whether the caller should continue to look for/compute more completions.

- If MAYBE_ADD_COMPLETION_MAX_REACHED is returned, callers are required to
- record at least one more completion. The final list will be pruned to
- max_completions, but recording at least one more than max_completions is
- the signal to the completion machinery that too many completions were
- found. */
+ If TEXT and WORD are non-NULL, then portions of the strings will be
+ saved into the completion list. See completer_strdup for more. */

-extern enum maybe_add_completion_enum
- maybe_add_completion (completion_tracker_t tracker, char *name);
+extern enum add_completion_status
+ add_completion (struct completer_data *cdata,
+ VEC (char_ptr) **result, const char *match,
+ const char *text, const char *word);

/* Wrapper to throw MAX_COMPLETIONS_REACHED_ERROR. */

diff --git a/gdb/symtab.c b/gdb/symtab.c
index f4407a0..34eb6d7 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -5046,15 +5046,6 @@ static VEC (char_ptr) *return_val;
completion_list_add_name \
(cdata, MSYMBOL_NATURAL_NAME (symbol), (sym_text), (len), (text), (word))

-/* Tracker for how many unique completions have been generated. Used
- to terminate completion list generation early if the list has grown
- to a size so large as to be useless. This helps avoid GDB seeming
- to lock up in the event the user requests to complete on something
- vague that necessitates the time consuming expansion of many symbol
- tables. */
-
-static completion_tracker_t completion_tracker;
-
/* Test to see if the symbol specified by SYMNAME (which is already
demangled for C++ symbols) matches SYM_TEXT in the first SYM_TEXT_LEN
characters. If so, add it to the current completion list. */
@@ -5070,50 +5061,11 @@ completion_list_add_name (struct completer_data *cdata,
return;

/* We have a match for a completion, so add SYMNAME to the current list
- of matches. Note that the name is moved to freshly malloc'd space. */
-
- {
- char *newobj;
- enum maybe_add_completion_enum add_status;
-
- if (word == sym_text)
- {
- newobj = xmalloc (strlen (symname) + 5);
- strcpy (newobj, symname);
- }
- else if (word > sym_text)
- {
- /* Return some portion of symname. */
- newobj = xmalloc (strlen (symname) + 5);
- strcpy (newobj, symname + (word - sym_text));
- }
- else
- {
- /* Return some of SYM_TEXT plus symname. */
- newobj = xmalloc (strlen (symname) + (sym_text - word) + 5);
- strncpy (newobj, word, sym_text - word);
- newobj[sym_text - word] = '\0';
- strcat (newobj, symname);
- }
-
- add_status = maybe_add_completion (completion_tracker, newobj);
+ of matches. */

- switch (add_status)
- {
- case MAYBE_ADD_COMPLETION_OK:
- VEC_safe_push (char_ptr, return_val, newobj);
- break;
- case MAYBE_ADD_COMPLETION_OK_MAX_REACHED:
- VEC_safe_push (char_ptr, return_val, newobj);
- throw_max_completions_reached_error ();
- case MAYBE_ADD_COMPLETION_MAX_REACHED:
- xfree (newobj);
- throw_max_completions_reached_error ();
- case MAYBE_ADD_COMPLETION_DUPLICATE:
- xfree (newobj);
- break;
- }
- }
+ if (add_completion (cdata, &return_val, symname, sym_text, word)
+ == ADD_COMPLETION_MAX_REACHED)
+ throw_max_completions_reached_error ();
}

/* ObjC: In case we are completing on a selector, look as the msymbol
@@ -5358,7 +5310,6 @@ default_make_symbol_completion_list_break_on_1 (struct completer_data *cdata,
/* Length of sym_text. */
int sym_text_len;
struct add_name_data datum;
- struct cleanup *cleanups;

/* Now look for the symbol we are supposed to complete on. */
{
@@ -5429,9 +5380,6 @@ default_make_symbol_completion_list_break_on_1 (struct completer_data *cdata,
}
gdb_assert (sym_text[sym_text_len] == '\0' || sym_text[sym_text_len] == '(');

- completion_tracker = new_completion_tracker ();
- cleanups = make_cleanup_free_completion_tracker (&completion_tracker);
-
datum.sym_text = sym_text;
datum.sym_text_len = sym_text_len;
datum.text = text;
@@ -5549,8 +5497,6 @@ default_make_symbol_completion_list_break_on_1 (struct completer_data *cdata,
/* User-defined macros are always visible. */
macro_for_each (macro_user_macros, add_macro_name, &datum);
}
-
- do_cleanups (cleanups);
}

VEC (char_ptr) *
diff --git a/gdb/testsuite/gdb.base/completion.exp b/gdb/testsuite/gdb.base/completion.exp
index 1eb0fd8..710aac0 100644
--- a/gdb/testsuite/gdb.base/completion.exp
+++ b/gdb/testsuite/gdb.base/completion.exp
@@ -777,6 +777,84 @@ gdb_test_multiple "" "$test" {
}

#
+# Tests for the location completer
+#
+
+# Turn off pending breakpoint support so that we don't get queried
+# all the time.
+gdb_test_no_output "set breakpoint pending off"
+
+set subsrc [string range $srcfile 0 [expr {[string length $srcfile] - 3}]]
+set test "tab complete break $subsrc"
+send_gdb "break $subsrc\t\t"
+gdb_test_multiple "" $test {
+ -re "break\.c.*break1\.c.*$gdb_prompt " {
+ send_gdb "1\t\n"
+ gdb_test_multiple "" $test {
+ -re ".*Function \"$srcfile2\" not defined\..*$gdb_prompt " {
+ pass $test
+ }
+ -re "$gdb_prompt p$" {
+ fail $test
+ }
+ }
+ }
+
+ -re "$gdb_prompt p$" {
+ fail $test
+ }
+}
+
+gdb_test "complete break $subsrc" "break\.c.*break1\.c"
+
+# gdb/17960
+set test "tab complete break $srcfile:ma"
+send_gdb "break $srcfile:ma\t"
+gdb_test_multiple "" $test {
+ -re "break $srcfile:main " {
+ send_gdb "\n"
+ gdb_test_multiple "" $test {
+ -re ".*Breakpoint.*at .*/$srcfile, line .*$gdb_prompt " {
+ pass $test
+ gdb_test_no_output "delete breakpoint \$bpnum" \
+ "delete breakpoint for $test"
+ }
+ -re "$gdb_prompt p$" {
+ fail $test
+ }
+ }
+ }
+ -re "$gdb_prompt p$" {
+ fail $test
+ }
+}
+
+gdb_test "complete break $srcfile:ma" "break\.c:main"
+
+set test "tab complete break need"
+send_gdb "break need\t"
+gdb_test_multiple "" $test {
+ -re "break need_malloc " {
+ send_gdb "\n"
+ gdb_test_multiple "" $test {
+ -re ".*Breakpoint.*at .*/$srcfile, line .*$gdb_prompt " {
+ pass $test
+ gdb_test_no_output "delete breakpoint \$bpnum" \
+ "delete breakpoint for $test"
+ }
+ -re "$gdb_prompt p$" {
+ fail $test
+ }
+ }
+ }
+ -re "$gdb_prompt p$" {
+ fail $test
+ }
+}
+
+gdb_test "complete break need" "need_malloc"
+
+#
# Completion limiting.
#