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Re: Heads up: *possible* bug in cygwin

If somebody with a debuggable cygwin kernel could look into this, I'd appreciate it. I'll try to follow up on my own, but it takes FOREVER to do a 'cvs update' on the cygwin source tree over a 28.8k modem...
Sigh. Finally built a debuggable cygwin from current CVS. Here's the stacktrace from the SIGSEGV.

#0 dlmalloc (bytes=60) at /usr/src/kernel/src/winsup/cygwin/
#1 0x6104003b in dlrealloc (oldmem=0xa041d80, bytes=808464432) at /usr/src/kernel/src/winsup/cygwin/
#2 0x610409f8 in realloc (p=0xa041d80, size=32768) at /usr/src/kernel/src/winsup/cygwin/
#3 0x00405d40 in g_realloc (mem=0xa041d80, size=32768) at gmem.c:338
#4 0x00401d4a in g_string_maybe_expand (string=0xa100d4c, len=20223) at gstring.c:202
#5 0x0040225a in g_string_append (fstring=0xa100d4c, val=0xa042588 '0' <repeats 200 times>...) at gstring.c:297
#6 0x00402c7f in g_string_sprintfa_int (string=0xa100d4c, fmt=0x401330 "%s|%0100d|%s|%s|%0*d|%*.*f|%10000.10000f", args=0x22fd38 "p\023@") at gstring.c:484
#7 0x00402cc4 in g_string_sprintf (string=0xa100d4c, fmt=0x401330 "%s|%0100d|%s|%s|%0*d|%*.*f|%10000.10000f") at gstring.c:498
#8 0x004018be in main (argc=1, argv=0xa0411e0) at string-test.c:109
#9 0x61007888 in dll_crt0_1() () at /usr/src/kernel/src/winsup/cygwin/
#10 0x61007b6d in _dll_crt0 () at /usr/src/kernel/src/winsup/cygwin/
#11 0x0040d2b2 in cygwin_crt0 (f=0x4013be <main>) at /usr/src/kernel/src/winsup/cygwin/lib/cygwin_crt0.c:32
#12 0x0040103c in mainCRTStartup ()
#13 0x77e8d326 in _system_dlls__ ()

The problem seems to occur deep in the innards of Doug Lea's malloc (in the "mALLOc()" function -- although that's hard to see from the stacktrace above since cygwin itself was compiled with -fomit-frame-pointer). There HAS been a change in this file ( since May 1, 2002...most significantly, on Sep 18 it was updated to version 2.7.2 from 2.7.1 -- but that wasn't much of a change.

Unfortunately, I'm not going to be able to look at this again until this weekend -- and the first thing I'll have to do is read the docs on Lea's site about how his malloc is *supposed* to work. Talk about your black magic...


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