[PATCH 02/18] Remove completion_tracker_t from the public completion API.

[Keith Seitz <keiths at redhat dot com>]

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
--- make_file_symbol_completion_list
(...)
---- completion_list_add_name
----- maybe_add_completion
----> gdb_assert (tracker != NULL);

The tracker in maybe_add_completion is a static global in symtab.c called
completion_tracker.  It is initialized by
default_make_symbol_completion_list_break_on_1 (which is a defaulted
language vector method).  In this case, this function is never called
and completion_tracker is left NULL/uninitialized.

gdb/ChangeLog

	PR gdb/17960
	* completer.c (struct completer_data) <tracker>: Change type
	to htab_t.
	(DEFAULT_MAX_COMPLETIONS): Define.
	(max_completions): Initialize global to above value.
	(new_completion_tracker): Delete.
	(new_completer_data): New function.
	(make_cleanup_free_completion_tracker): Delete.
	(free_completer_data): New function.
	(maybe_add_completion): Change argument `tracker' to struct
	completer_data and use the tracker in that structure to
	do completion limiting.
	(complete_line): Remove completion_tracker code.
	Allocate a completer_data and pass that to complete_line_internal.
	Remove now unused cleanup.
	When complete_line_internal returns more completions than are
	in the tracker, reset the tracker and use maybe_add_completion
	to implement completion tracking.
	(gdb_completion_word_break_characters): Use completer_data.
	* completer.h (completion_tracker_t): Remove.
	(new_completion_tracker): Remove.
	(make_cleanup_free_completion_tracker): Remove.
	(maybe_add_completion): Replace `completion_tracker_t tracker'
	with `struct completer_data *cdata'.
	* symtab.c (completion_tracker): Remove global variable.
	(completion_list_add_name): Pass completer_data to
	maybe_add_completion instead of completion_tracker_t.
	(default_make_symbol_completion_list_break_on_1): Remove now
	unused cleanup.
	Do not allocate a completion tracker.  Use the supplied
	completer_data instead.

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                       |  157 ++++++++++++++++++---------------
 gdb/completer.h                       |   20 ----
 gdb/symtab.c                          |   17 ----
 gdb/testsuite/gdb.base/completion.exp |   78 ++++++++++++++++
 4 files changed, 168 insertions(+), 104 deletions(-)

diff --git a/gdb/completer.c b/gdb/completer.c
index f2b31e9..6708bb1 100644
--- a/gdb/completer.c
+++ b/gdb/completer.c
@@ -91,8 +91,8 @@ 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;
 };
 
 
@@ -802,47 +802,38 @@ 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.  */
-
-completion_tracker_t
-new_completion_tracker (void)
-{
-  if (max_completions <= 0)
-    return NULL;
+/* Allocate a new completer data structure.  */
 
-  return htab_create_alloc (max_completions,
-			    htab_hash_string, (htab_eq) streq,
-			    NULL, xcalloc, xfree);
-}
-
-/* Cleanup routine to free a completion tracker and reset the pointer
-   to NULL.  */
-static void
-free_completion_tracker (void *p)
+static struct completer_data *
+new_completer_data (int size)
 {
-  completion_tracker_t *tracker_ptr = p;
+  struct completer_data *cdata = XCNEW (struct completer_data);
 
-  htab_delete (*tracker_ptr);
-  *tracker_ptr = NULL;
+  cdata->tracker
+    = htab_create_alloc ((size < 0 ? DEFAULT_MAX_COMPLETIONS : size),
+			 htab_hash_string, (htab_eq) streq, NULL,
+			 xcalloc, xfree);
+  return cdata;
 }
 
-/* See completer.h.  */
+/* Free the completion data represented by P.  */
 
-struct cleanup *
-make_cleanup_free_completion_tracker (completion_tracker_t *tracker_ptr)
+static void
+free_completer_data (void *p)
 {
-  if (*tracker_ptr == NULL)
-    return make_cleanup (null_cleanup, NULL);
+  struct completer_data *cdata = p;
 
-  return make_cleanup (free_completion_tracker, tracker_ptr);
+  htab_delete (cdata->tracker);
+  xfree (cdata);
 }
 
 /* See completer.h.  */
 
 enum maybe_add_completion_enum
-maybe_add_completion (completion_tracker_t tracker, char *name)
+maybe_add_completion (struct completer_data *cdata, char *name)
 {
   void **slot;
 
@@ -851,19 +842,17 @@ 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);
 }
@@ -892,54 +881,79 @@ 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;
+  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);
+
+  /* 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.
+
+     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.  */
 
-      add_status = maybe_add_completion (tracker, candidate);
+  if (VEC_length (char_ptr, list) > htab_elements (cdata->tracker))
+    {
+      /* Clear the tracker so that we can re-use it to count the number
+	 of returned completions.  */
+      htab_empty (cdata->tracker);
 
-      switch (add_status)
+      for (ix = 0, max_reached = 0;
+	   !max_reached && 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;
+	  enum maybe_add_completion_enum add_status;
+
+	  add_status = maybe_add_completion (cdata, candidate);
+
+	  switch (add_status)
+	    {
+	    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;
+	    }
 	}
+
+      /* 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;
 }
@@ -1032,9 +1046,14 @@ 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 f32c696..003c66c 100644
--- a/gdb/completer.h
+++ b/gdb/completer.h
@@ -128,24 +128,6 @@ 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.  */
-
-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
@@ -180,7 +162,7 @@ enum maybe_add_completion_enum
    found.  */
 
 extern enum maybe_add_completion_enum
-  maybe_add_completion (completion_tracker_t tracker, char *name);
+  maybe_add_completion (struct completer_data *cdata, char *name);
 
 /* Wrapper to throw MAX_COMPLETIONS_REACHED_ERROR.  */ 
 
diff --git a/gdb/symtab.c b/gdb/symtab.c
index c0562e1..0736582 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -5017,15 +5017,6 @@ 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.  */
@@ -5067,7 +5058,7 @@ completion_list_add_name (struct completer_data *cdata,
 	strcat (newobj, symname);
       }
 
-    add_status = maybe_add_completion (completion_tracker, newobj);
+    add_status = maybe_add_completion (cdata, newobj);
 
     switch (add_status)
       {
@@ -5329,7 +5320,6 @@ 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.  */
   {
@@ -5400,9 +5390,6 @@ 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;
@@ -5520,8 +5507,6 @@ 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 f77bfe2..5afd851 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.
 #