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Re: [RFC][Python] gdbpy_frame_stop_reason_string bug
On Tue, Oct 25, 2011 at 2:48 PM, Kevin Pouget <kevin.pouget@gmail.com> wrote:
> On Tue, Oct 25, 2011 at 2:22 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>>> From: Kevin Pouget <kevin.pouget@gmail.com>
>>> Date: Tue, 25 Oct 2011 09:20:19 +0200
>>> Cc: pedro@codesourcery.com, pmuldoon@redhat.com, gdb-patches@sourceware.org,
>>> ? ? ? tromey@redhat.com
>>>
>>> >> +@item gdb.FRAME_UNWIND_FIRST_ERROR
>>> >> +All the conditions after this alias are considered errors;
>>> >
>>> > Hmm... ?This table is preceded by this text:
>>> >
>>> > ?@defun Frame.unwind_stop_reason ()
>>> > ?Return an integer representing the reason why it's not possible to find
>>> > ?more frames toward the outermost frame. ?Use
>>> > ?@code{gdb.frame_stop_reason_string} to convert the value returned by this
>>> > ?function to a string. The value can be one of:
>>> >
>>> > So "conditions after this alias" seems inappropriate in the list that
>>> > follows, because we are not describing conditions or aliases. ?Can you
>>> > rephrase this to be consistent with the rest of the list.
>>>
>>> I'm not sure about you see wrong with "alias". We could replace it
>>> with "reference" (like the & operator in C++, but also used in Python
>>> and Java), but it sounds more or less the same to me.
>>>
>>> What do you think about:
>>> "Stop reasons greater or equal to this value/alias/reference"
>>
>> Now that I understand the intent, I would suggest
>>
>> ?Any stop reason greater or equal to this value indicates some kind
>> ?of error. ?This special value facilitates writing code that tests
>> ?for errors in unwinding in a way that will work correctly even if
>> ?the list of the other values is modified in future @value{GDBN}
>> ?versions. ?Using it, you could write:
>
> yes, if you feel like it has to be explicited, it's better this way
>
> @smallexample
> reason = gdb.selected_frame().unwind_stop_reason ()
> reason_str = ?gdb.frame_stop_reason_string (reason)
> if reason >= ?gdb.FRAME_UNWIND_FIRST_ERROR:
> ? ?print "An error occured during the unwinding process: %s" % reason_str
>
> @end smallexample
>>
>>> > And why is it important that the value is an alias for another?
>>>
>>> it's important because it's not a distinct value as the other ones, so
>>> > frame_stop_reason_string(UNWIND_FIRST_ERROR) == frame_stop_reason_string(UNWIND_UNAVAILABLE)
>>> is True, which might be counter-intuitive if you don't know that
>>> UNWIND_FIRST_ERROR is an alias/reference
>>
>> I still don't see the importance, sorry. ?Moreover, having this text
>> means that we will need to update the manual each time the list of
>> unwind reasons is modified, **which in a way works against this very
>> feature.**
>
> You're half right with this last sentence, but this Python value is
> not here to ease *our* (GDB developers) lives, but rather for Python
> developers.
> this value is not meant to change very often (not to say almost
> never), so I think it's not a big burden to change the documentation
> as well when it happens.
> The very reason why I wrote it is that I think it's useful for the
> reader: when you look over this list, you can easily see what is a
> normal reason for unwinders to stop, and what isn't (I think that not
> so many people will actually have the chance to use it, but out of
> curiosity, some people will want to read and understand it).
>
>
> But that put aside, you're not convinced yet and I'm running short of
> arguments ... Pedro, Tom, Phil, how do you see that ?
Hello,
there was a line longer than 80char in unwind_reason.def, I've split it
I've also added the definition for FRAME_UNWIND_FIRST_ERROR that you
suggested Eli
(I've truncated the example to
> reason = gdb.selected_frame().unwind_stop_reason ()
> reason_str = gdb.frame_stop_reason_string (reason)
> if reason >= gdb.FRAME_UNWIND_FIRST_ERROR:
> print "An error occured: %s" % reason_str
because the full line was too long for the PDF.
is it your last word for not mentioning the current value of the alias?
Thanks,
Kevin
2011-10-14 Kevin Pouget <kevin.pouget@st.com>
* frame.c (frame_stop_reason_string): Rewrite using
unwind_stop_reasons.def.
* frame.h (enum unwind_stop_reason): Likewise.
* python/py-frame.c (gdbpy_initialize_frames): Likewise.
(gdbpy_frame_stop_reason_string): Use new enum unwind_stop_reason
constants for bound-checking.
* unwind_stop_reasons.def: New file.
From d310b0e18b3b6aaf029b16bfcfa9ba9e056e4348 Mon Sep 17 00:00:00 2001
From: Kevin Pouget <kevin.pouget@st.com>
Date: Mon, 17 Oct 2011 09:42:44 +0200
Subject: [PATCH] Move unwind reasons to an external .def file
---
gdb/doc/gdb.texinfo | 13 +++++++
gdb/frame.c | 20 ++--------
gdb/frame.h | 51 +++++----------------------
gdb/python/py-frame.c | 21 ++++-------
gdb/stack.c | 2 +-
gdb/unwind_stop_reasons.def | 80 +++++++++++++++++++++++++++++++++++++++++++
6 files changed, 116 insertions(+), 71 deletions(-)
create mode 100644 gdb/unwind_stop_reasons.def
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 69e2bda..f99fd4a4 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -23445,6 +23445,19 @@ stack corruption.
@item gdb.FRAME_UNWIND_NO_SAVED_PC
The frame unwinder did not find any saved PC, but we needed
one to unwind further.
+
+@item gdb.FRAME_UNWIND_FIRST_ERROR
+Any stop reason greater or equal to this value indicates some kind
+of error. This special value facilitates writing code that tests
+for errors in unwinding in a way that will work correctly even if
+the list of the other values is modified in future @value{GDBN}
+versions. Using it, you could write:
+@smallexample
+reason = gdb.selected_frame().unwind_stop_reason ()
+reason_str = gdb.frame_stop_reason_string (reason)
+if reason >= gdb.FRAME_UNWIND_FIRST_ERROR:
+ print "An error occured: %s" % reason_str
+@end smallexample
@end table
@end defun
diff --git a/gdb/frame.c b/gdb/frame.c
index 5824020..e5e442a 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -2351,23 +2351,11 @@ frame_stop_reason_string (enum unwind_stop_reason reason)
{
switch (reason)
{
- case UNWIND_NULL_ID:
- return _("unwinder did not report frame ID");
+#define SET(name, description) \
+ case name: return _(description);
+#include "unwind_stop_reasons.def"
+#undef SET
- case UNWIND_UNAVAILABLE:
- return _("Not enough registers or memory available to unwind further");
-
- case UNWIND_INNER_ID:
- return _("previous frame inner to this frame (corrupt stack?)");
-
- case UNWIND_SAME_ID:
- return _("previous frame identical to this frame (corrupt stack?)");
-
- case UNWIND_NO_SAVED_PC:
- return _("frame did not save the PC");
-
- case UNWIND_NO_REASON:
- case UNWIND_FIRST_ERROR:
default:
internal_error (__FILE__, __LINE__,
"Invalid frame stop reason");
diff --git a/gdb/frame.h b/gdb/frame.h
index a261a91..55972de 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -446,47 +446,16 @@ extern struct address_space *get_frame_address_space (struct frame_info *);
enum unwind_stop_reason
{
- /* No particular reason; either we haven't tried unwinding yet,
- or we didn't fail. */
- UNWIND_NO_REASON,
-
- /* The previous frame's analyzer returns an invalid result
- from this_id.
-
- FIXME drow/2006-08-16: This is how GDB used to indicate end of
- stack. We should migrate to a model where frames always have a
- valid ID, and this becomes not just an error but an internal
- error. But that's a project for another day. */
- UNWIND_NULL_ID,
-
- /* This frame is the outermost. */
- UNWIND_OUTERMOST,
-
- /* All the conditions after this point are considered errors;
- abnormal stack termination. If a backtrace stops for one
- of these reasons, we'll let the user know. This marker
- is not a valid stop reason. */
- UNWIND_FIRST_ERROR,
-
- /* Can't unwind further, because that would require knowing the
- values of registers or memory that haven't been collected. */
- UNWIND_UNAVAILABLE,
-
- /* This frame ID looks like it ought to belong to a NEXT frame,
- but we got it for a PREV frame. Normally, this is a sign of
- unwinder failure. It could also indicate stack corruption. */
- UNWIND_INNER_ID,
-
- /* This frame has the same ID as the previous one. That means
- that unwinding further would almost certainly give us another
- frame with exactly the same ID, so break the chain. Normally,
- this is a sign of unwinder failure. It could also indicate
- stack corruption. */
- UNWIND_SAME_ID,
-
- /* The frame unwinder didn't find any saved PC, but we needed
- one to unwind further. */
- UNWIND_NO_SAVED_PC,
+#define SET(name, description) name,
+#define FIRST_ENTRY(name) UNWIND_FIRST = name,
+#define LAST_ENTRY(name) UNWIND_LAST = name,
+#define FIRST_ERROR(name) UNWIND_FIRST_ERROR = name,
+
+#include "unwind_stop_reasons.def"
+#undef SET
+#undef FIRST_ENTRY
+#undef LAST_ENTRY
+#undef FIRST_ERROR
};
/* Return the reason why we can't unwind past this frame. */
diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index 398ce84..5ed4347 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -542,7 +542,7 @@ gdbpy_frame_stop_reason_string (PyObject *self, PyObject *args)
if (!PyArg_ParseTuple (args, "i", &reason))
return NULL;
- if (reason < 0 || reason > UNWIND_NO_SAVED_PC)
+ if (reason < UNWIND_FIRST || reason > UNWIND_LAST)
{
PyErr_SetString (PyExc_ValueError,
_("Invalid frame stop reason."));
@@ -599,18 +599,13 @@ gdbpy_initialize_frames (void)
PyModule_AddIntConstant (gdb_module, "SIGTRAMP_FRAME", SIGTRAMP_FRAME);
PyModule_AddIntConstant (gdb_module, "ARCH_FRAME", ARCH_FRAME);
PyModule_AddIntConstant (gdb_module, "SENTINEL_FRAME", SENTINEL_FRAME);
- PyModule_AddIntConstant (gdb_module,
- "FRAME_UNWIND_NO_REASON", UNWIND_NO_REASON);
- PyModule_AddIntConstant (gdb_module,
- "FRAME_UNWIND_NULL_ID", UNWIND_NULL_ID);
- PyModule_AddIntConstant (gdb_module,
- "FRAME_UNWIND_FIRST_ERROR", UNWIND_FIRST_ERROR);
- PyModule_AddIntConstant (gdb_module,
- "FRAME_UNWIND_INNER_ID", UNWIND_INNER_ID);
- PyModule_AddIntConstant (gdb_module,
- "FRAME_UNWIND_SAME_ID", UNWIND_SAME_ID);
- PyModule_AddIntConstant (gdb_module,
- "FRAME_UNWIND_NO_SAVED_PC", UNWIND_NO_SAVED_PC);
+
+#define SET(name, description) \
+ PyModule_AddIntConstant (gdb_module, "FRAME_"#name, name);
+#define FIRST_ERROR(name) \
+ PyModule_AddIntConstant (gdb_module, "FRAME_"#name, name);
+#include "unwind_stop_reasons.def"
+#undef SET
Py_INCREF (&frame_object_type);
PyModule_AddObject (gdb_module, "Frame", (PyObject *) &frame_object_type);
diff --git a/gdb/stack.c b/gdb/stack.c
index 953d3bd..003725a 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -1625,7 +1625,7 @@ backtrace_command_1 (char *count_exp, int show_locals, int from_tty)
enum unwind_stop_reason reason;
reason = get_frame_unwind_stop_reason (trailing);
- if (reason > UNWIND_FIRST_ERROR)
+ if (reason >= UNWIND_FIRST_ERROR)
printf_filtered (_("Backtrace stopped: %s\n"),
frame_stop_reason_string (reason));
}
diff --git a/gdb/unwind_stop_reasons.def b/gdb/unwind_stop_reasons.def
new file mode 100644
index 0000000..9a34feb
--- /dev/null
+++ b/gdb/unwind_stop_reasons.def
@@ -0,0 +1,80 @@
+/* Copyright 2011 Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ 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/>. */
+
+/* Reasons why frames could not be further unwound
+ SET (name, description)
+
+ After this reason name, all reasons should be considered errors;
+ i.e.: abnormal stack termination.
+ FIRST_ERROR (name)
+
+ First and Last reason defined
+ FIRST_ENTRY (name)
+ LAST_ENTRY (name) */
+
+#ifdef SET
+/* No particular reason; either we haven't tried unwinding yet,
+ or we didn't fail. */
+SET (UNWIND_NO_REASON, "no reason")
+
+/* The previous frame's analyzer returns an invalid result
+ from this_id.
+
+ FIXME drow/2006-08-16: This is how GDB used to indicate end of
+ stack. We should migrate to a model where frames always have a
+ valid ID, and this becomes not just an error but an internal
+ error. But that's a project for another day. */
+SET (UNWIND_NULL_ID, "unwinder did not report frame ID")
+
+/* This frame is the outermost. */
+SET (UNWIND_OUTERMOST, "outermost")
+
+/* Can't unwind further, because that would require knowing the
+ values of registers or memory that haven't been collected. */
+SET (UNWIND_UNAVAILABLE, \
+ "not enough registers or memory available to unwind further")
+
+/* This frame ID looks like it ought to belong to a NEXT frame,
+ but we got it for a PREV frame. Normally, this is a sign of
+ unwinder failure. It could also indicate stack corruption. */
+SET (UNWIND_INNER_ID, "previous frame inner to this frame (corrupt stack?)")
+
+/* This frame has the same ID as the previous one. That means
+ that unwinding further would almost certainly give us another
+ frame with exactly the same ID, so break the chain. Normally,
+ this is a sign of unwinder failure. It could also indicate
+ stack corruption. */
+SET (UNWIND_SAME_ID, "previous frame identical to this frame (corrupt stack?)")
+
+/* The frame unwinder didn't find any saved PC, but we needed
+ one to unwind further. */
+SET (UNWIND_NO_SAVED_PC, "frame did not save the PC")
+
+#endif /* SET */
+
+
+#ifdef FIRST_ERROR
+FIRST_ERROR (UNWIND_UNAVAILABLE)
+#endif
+
+#ifdef FIRST_ENTRY
+FIRST_ENTRY (UNWIND_NO_REASON)
+#endif
+
+#ifdef LAST_ENTRY
+LAST_ENTRY (UNWIND_NO_SAVED_PC)
+#endif
--
1.7.6.4