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Created on 2002-07-30 09:13 by mwh, last changed 2002-07-30 18:40 by gvanrossum. This issue is now closed.
| Files | ||||
|---|---|---|---|---|
| File name | Uploaded | Description | Edit | |
| marshal.c.diff | theller, 2002-07-30 11:03 | Patch for Python/marshal.c | ||
| Messages (6) | |||
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| msg11747 - (view) | Author: Michael Hudson (mwh)  |
Date: 2002-07-30 09:13 | |
I have no idea how long this bug has existed for. I could well be a long time. I noticed it while trying to kill off SET_LINENO. To reproduce, build a debug python, cd to Tools/freeze/ and run $ /path/to/python -O freeze.py hello.py I get a wodge ot modulefinder (I presume) output, and then: freezing BaseHTTPServer ... freezing FixTk ... freezing SocketServer ... freezing StringIO ... freezing Tkconstants ... freezing Tkinter ... python: ../Python/marshal.c:66: w_more: Assertion `(int)(char)(c) == (c)' failed. Aborted (core dumped) This is on x86; on my PPC laptop where I discovered this, it gets quite a bit further before dying. So maybe some endianness fun. The assert that fails is in a Py_SAFEDOWNCAST macro. I have *no* idea where to start with this one; assigning to Thomas because I have a vague recollection he knows something about how freeze works <evil cackle> -- feel free to reassign! |
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| msg11748 - (view) | Author: Thomas Heller (theller) * |
Date: 2002-07-30 10:09 | |
Logged In: YES user_id=11105 Fails for me too (Win2k, python debug build). But it is a marshal issue! Here's a script to reproduce it when running with a debug build: import marshal; marshal.dumps([128] * 1000) (anything between 128 and 255 will trigger the error, and the list must be large enough. The debugger shows that w_long is called with x = 128, and than w_more() is called with c = 128, and the Py_SAFEDOWNCAST macro fails, maybe because char is signed on this platform. |
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| msg11749 - (view) | Author: Thomas Heller (theller) * |
Date: 2002-07-30 11:03 | |
Logged In: YES
user_id=11105
As I can see, the proper fix is to replace
static void
w_long(long x, WFILE *p)
{
w_byte((int)( x & 0xff), p);
w_byte((int)((x>> 8) & 0xff), p);
w_byte((int)((x>>16) & 0xff), p);
w_byte((int)((x>>24) & 0xff), p);
}
with
static void
w_long(long x, WFILE *p)
{
w_byte((char)( x & 0xff), p);
w_byte((char)((x>> 8) & 0xff), p);
w_byte((char)((x>>16) & 0xff), p);
w_byte((char)((x>>24) & 0xff), p);
}
and similar for the w_short() function.
Even safer would be to use the Py_SAFE_DOWNCAST
macro also in the w_byte macro.
Attached a patch for marshal.c.
|
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| msg11750 - (view) | Author: Michael Hudson (mwh) |
Date: 2002-07-30 11:15 | |
Logged In: YES user_id=6656 That fixes both my initial problem and your test case. Nice work! Check it in and add a test case? It would be nice to have w_byte as an inline function with sensible declaration... |
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| msg11751 - (view) | Author: Thomas Heller (theller) * |
Date: 2002-07-30 11:42 | |
Logged In: YES user_id=11105 Check in and added test case: committed * Up-To-Date 1.3 Lib/test/test_marshal.py committed * Up-To-Date 1.73 Python/marshal.c |
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| msg11752 - (view) | Author: Guido van Rossum (gvanrossum) * |
Date: 2002-07-30 18:40 | |
Logged In: YES user_id=6380 Nice work guys! (Now I wonder where Py_SAFE_DOWNCAST comes from. :-) |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2002-07-30 09:13:48 | mwh | create | |