[RFA] stop parsing breakpoint command if invalid keyword found

[Joel Brobecker <brobecker at adacore dot com>]

With an Ada program, trying to break on a specific Ada task, but
with the wrong capitalization of the `task' keyword, we currently
get only pieces of the "garbage" that caused the error:

    (gdb) b *rendez_vous'address TASK 2
    Garbage 2 at end of command

Pushing this a little further:

    (gdb) b *rendez_vous'address TASK Task TaSK 2
    Garbage 2 at end of command

Another interesting failure mode:

    (gdb) b *rendez_vous'address TASK if
    Argument required (expression to compute).

The parser skipped `TASK', then found the `if' keyword, and thus
started looking for a condition.

This patch fixes the problem by aborting the parsing as soon as
an invalid keyword is found.  This makes it consistent with the
case where the REST parameter is passed as NULL (where an error
is raised immediately after seeing the first invalid keyword).

It also introduces a new testcase that reproduces all above scenarios.
Note the kfail for one of the tests. It's a different issue, and
I won'thave time to investigate in the next couple of weeks. Since
it is not a regression, I created PR gdb/14111 for it.

gdb/ChangeLog:

        * breakpoint.c (find_condition_and_thread): Stop parsing
        as soon as the first invalid keyword is found.

gdb/testsuite/ChangeLog:

        * gdb.ada/bad-task-bp-keyword: New testcase.

Tested on x86_64-linux, no regression.

---
 gdb/breakpoint.c                                  |    2 +-
 gdb/testsuite/gdb.ada/bad-task-bp-keyword.exp     |   52 ++++++++++++++++
 gdb/testsuite/gdb.ada/bad-task-bp-keyword/foo.adb |   68 +++++++++++++++++++++
 3 files changed, 121 insertions(+), 1 deletions(-)
 create mode 100644 gdb/testsuite/gdb.ada/bad-task-bp-keyword.exp
 create mode 100644 gdb/testsuite/gdb.ada/bad-task-bp-keyword/foo.adb

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 9557430..4d1f95a 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -8939,7 +8939,7 @@ find_condition_and_thread (char *tok, CORE_ADDR pc,
       else if (rest)
 	{
 	  *rest = savestring (tok, strlen (tok));
-	  tok += toklen;
+	  return;
 	}
       else
 	error (_("Junk at end of arguments."));
diff --git a/gdb/testsuite/gdb.ada/bad-task-bp-keyword.exp b/gdb/testsuite/gdb.ada/bad-task-bp-keyword.exp
new file mode 100644
index 0000000..41e334d
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/bad-task-bp-keyword.exp
@@ -0,0 +1,52 @@
+# Copyright 2012 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib "ada.exp"
+
+set testdir "bad-task-bp-keyword"
+set testfile "${testdir}/foo"
+set srcfile ${srcdir}/${subdir}/${testfile}.adb
+set binfile ${objdir}/${subdir}/${testfile}
+
+file mkdir ${objdir}/${subdir}/${testdir}
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug ]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+# Star the program in order to have some tasks running...
+set bp_location [gdb_get_line_number "STOP_HERE" ${testdir}/foo.adb]
+runto "foo.adb:$bp_location"
+
+# Try inserting a breakpoint on task 2, but using the wrong capitalization
+# on the 'task' keyword ("TASK" instead of "task").  The debugger should
+# report an error.  Try various weird combinations too.
+
+gdb_test "break *break_me'address TASK 2" \
+         "Garbage `TASK 2' at end of command"
+
+set test "break *break_me'address TASK Task TaSK 2"
+gdb_test_multiple "$test" $test {
+    -re "Garbage `TASK Task TaSK 2' at end of command\[\r\n\]+$gdb_prompt $" {
+        pass $test
+        }
+    -re "Garbage `TaSK 2' at end of command\[\r\n\]+$gdb_prompt $" {
+        kfail gdb/14111 "$test"
+        }
+}
+
+gdb_test "break *break_me'address TASK if" \
+         "Garbage `TASK if' at end of command"
diff --git a/gdb/testsuite/gdb.ada/bad-task-bp-keyword/foo.adb b/gdb/testsuite/gdb.ada/bad-task-bp-keyword/foo.adb
new file mode 100644
index 0000000..76ed98b
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/bad-task-bp-keyword/foo.adb
@@ -0,0 +1,68 @@
+--  Copyright 2009-2012 Free Software Foundation, Inc.
+--
+--  This program is free software; you can redistribute it and/or modify
+--  it under the terms of the GNU General Public License as published by
+--  the Free Software Foundation; either version 3 of the License, or
+--  (at your option) any later version.
+--
+--  This program is distributed in the hope that it will be useful,
+--  but WITHOUT ANY WARRANTY; without even the implied warranty of
+--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--  GNU General Public License for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+procedure Foo is
+
+   task type Caller is
+      entry Initialize;
+      entry Call_Break_Me;
+      entry Finalize;
+   end Caller;
+   type Caller_Ptr is access Caller;
+
+   procedure Break_Me is
+   begin
+      null;
+   end Break_Me;
+
+   task body Caller is
+   begin
+      accept Initialize do
+         null;
+      end Initialize;
+      accept Call_Break_Me do
+         Break_Me;
+      end Call_Break_Me;
+      accept Finalize do
+         null;
+      end Finalize;
+   end Caller;
+
+   Task_List : array (1 .. 3) of Caller_Ptr;
+
+begin
+
+   --  Start all our tasks, and call the "Initialize" entry to make
+   --  sure all of them have now been started.  We call that entry
+   --  immediately after having created the task in order to make sure
+   --  that we wait for that task to be created before we try to create
+   --  another one.  That way, we know that the order in our Task_List
+   --  corresponds to the order in the GNAT runtime.
+   for J in Task_List'Range loop
+      Task_List (J) := new Caller;
+      Task_List (J).Initialize;
+   end loop;
+
+   --  Next, call their Call_Break_Me entry of each task, using the same
+   --  order as the order used to create them.
+   for J in Task_List'Range loop  -- STOP_HERE
+      Task_List (J).Call_Break_Me;
+   end loop;
+
+   --  And finally, let all the tasks die...
+   for J in Task_List'Range loop
+      Task_List (J).Finalize;
+   end loop;
+end Foo;
-- 
1.7.1