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Make "bt N" print correct number of frames when using a frame filter

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PR python/16497 notes that using "bt" with a positive argument prints
the wrong number of frames when a frame filter is in use.  Also, in this
case, the non-frame-filter path will print a message about "More stack
frames" when there are more; but this is not done in the frame-filter
case.

The first problem is that backtrace_command_1 passes the wrong value
to apply_ext_lang_frame_filter -- that function takes the final
frame's number as an argument, but backtrace_command_1 passes the
count, which is off by one.

The solution to the second problem is to have the C stack-printing
code stop at the correct number of frames and then print the message.

Tested using the buildbot.

ChangeLog
2018-02-26  Tom Tromey  <tom@tromey.com>

	PR python/16497:
	* stack.c (backtrace_command_1): Set PRINT_MORE_FRAMES flag.  Fix
	off-by-one in py_end computation.
	* python/py-framefilter.c (gdbpy_apply_frame_filter): Handle
	PRINT_MORE_FRAMES.
	* extension.h (enum frame_filter_flags) <PRINT_MORE_FRAMES>: New
	constant.

2018-02-26  Tom Tromey  <tom@tromey.com>

	PR python/16497:
	* gdb.python/py-framefilter.exp: Update test.
This commit is contained in:
Tom Tromey 2016-06-20 10:36:29 -06:00
parent 2ddeaf8a7d
commit 6893c19a8b
6 changed files with 49 additions and 2 deletions
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25
gdb/python/py-framefilter.c
View file

@ -1355,6 +1355,18 @@ gdbpy_apply_frame_filter (const struct extension_language_defn *extlang,
gdbpy_enter enter_py (gdbarch, current_language);
/* When we're limiting the number of frames, be careful to request
one extra frame, so that we can print a message if there are more
frames. */
int frame_countdown = -1;
if ((flags & PRINT_MORE_FRAMES) != 0 && frame_low >= 0 && frame_high >= 0)
{
++frame_high;
/* This has an extra +1 because it is checked before a frame is
printed. */
frame_countdown = frame_high - frame_low + 1;
}
gdbpy_ref<> iterable (bootstrap_python_frame_filters (frame, frame_low,
frame_high));
@ -1402,6 +1414,19 @@ gdbpy_apply_frame_filter (const struct extension_language_defn *extlang,
break;
}
if (frame_countdown != -1)
{
gdb_assert ((flags & PRINT_MORE_FRAMES) != 0);
--frame_countdown;
if (frame_countdown == 0)
{
/* We've printed all the frames we were asked to
print, but more frames existed. */
printf_filtered (_("(More stack frames follow...)\n"));
break;
}
}
success = py_print_frame (item.get (), flags, args_type, out, 0,
levels_printed.get ());