From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Problem with Ctor/Dtor.
Date:	Mon, 13 Sep 1999 13:45:30 +0200
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On Sat, 11 Sep 1999, Christo Fogelberg wrote:

> 1) When the class is destructed, the program crashes.
> 2) If, for some bizarre reason, a string with an extension (.dat) is
> entered, then the program crashes on constructing the database.

Please tell what version of the compiler and Binutils are you using.

If you use Binutils 2.9.1, did you patch the sources in any way,
before building Binutils?  If so, please tell what patches did you
apply.

> Exiting due to signal SIGILL
> Invalid Opcode at eip=00000018
> eax=00000009 ebx=000b2dbc ecx=00000008 edx=00032a2a esi=00000056
> edi=00032b25
> ebp=000b2afd esp=000b2af1 program=C:\DJGPP\DATABASE\DATABA~1.EXE
> cs: sel=00af  base=835c4000  limit=000bffff
> ds: sel=00b7  base=835c4000  limit=000bffff
> es: sel=00b7  base=835c4000  limit=000bffff
> fs: sel=0087  base=0000ef60  limit=0000ffff
> gs: sel=00c7  base=00000000  limit=0010ffff
> ss: sel=00b7  base=835c4000  limit=000bffff
> App stack: [000b2b24..00032b24]  Exceptn stack: [00032a00..00030ac0]
> 
> Call frame traceback EIPs:
>   0x00000018   0x18
>   0x00000140   0x140
> 
> ##############################################
> 
> Exiting due to signal SIGSEGV
> General Protection Fault at eip=00000014
> eax=00000009 ebx=000b2dbc ecx=00000006 edx=00032a28 esi=00000054
> edi=00032b24
> ebp=000b2afc esp=000b2ae4 program=C:\DJGPP\DATABASE\DATABA~1.EXE
> cs: sel=00af  base=835c4000  limit=000bffff
> ds: sel=00b7  base=835c4000  limit=000bffff
> es: sel=00b7  base=835c4000  limit=000bffff
> fs: sel=0087  base=0000ef60  limit=0000ffff
> gs: sel=00c7  base=00000000  limit=0010ffff
> ss: sel=00b7  base=835c4000  limit=000bffff
> App stack: [000b2b24..00032b24]  Exceptn stack: [00032a00..00030ac0]
> 
> Call frame traceback EIPs:
>   0x00000014   0x14
>   0x00014020   ___djgpp_exception_table

These two crashes seem to indicate that something is very wrong with
your static constructors and destructors.  It could be a result of
some patch to Binutils.

> Exiting due to signal SIGSEGV
> General Protection Fault at eip=00008366
> eax=5e5be465 ebx=00000000 ecx=00014456 edx=fe040800 esi=00000011
> edi=00000020
> ebp=00014476 esp=000b2af8 program=C:\DJGPP\DATABASE\DATABA~1.EXE
> cs: sel=00af  base=835dc000  limit=000bffff
> ds: sel=00b7  base=835dc000  limit=000bffff
> es: sel=00b7  base=835dc000  limit=000bffff
> fs: sel=0087  base=0000ef60  limit=0000ffff
> gs: sel=00c7  base=00000000  limit=0010ffff
> ss: sel=00b7  base=835dc000  limit=000bffff
> App stack: [000b2b24..00032b24]  Exceptn stack: [00032a00..00030ac0]
> 
> Call frame traceback EIPs:
>   0x00008366   ___8ofstreamiPCcii+226

EBP is trashed here (it's outside the valid limits for the stack,
which are printed under "App stack").  I suggest running under a
debugger to see what overwrites EBP.  It's possible that some code
overwrites a local array or something.

> Exiting due to signal SIGSEGV
> General Protection Fault at eip=000147bc
> eax=746164fe ebx=000b2db0 ecx=000b2db0 edx=00032d48 esi=000b2db8
> edi=000000c8
> ebp=000b29d4 esp=000b29c8 program=C:\DJGPP\DATABASE\DATABA~1.EXE
> cs: sel=00a7  base=835f6000  limit=000bffff
> ds: sel=00af  base=835f6000  limit=000bffff
> es: sel=00af  base=835f6000  limit=000bffff
> fs: sel=0087  base=0000ef60  limit=0000ffff
> gs: sel=00c7  base=00000000  limit=0010ffff
> ss: sel=00af  base=835f6000  limit=000bffff
> App stack: [000b2b24..00032b24]  Exceptn stack: [00032a00..00030ac0]
> 
> Call frame traceback EIPs:
>   0x000147bc   _free+172
>   0x00004339   _deallocate__t23__malloc_alloc_template1i0PvUl+17, line 158
> of da
> tabase2.cppd
>   0x000042a1
> _deallocate__t12simple_alloc2Z8TestDataZt24__default_alloc_templa
> te2b0i0P8TestDataUl+29, line 224 of database2.cpp
>   0x00004238   __$_t6vector2Z8TestDataZt24__default_alloc_template2b0i0+32,
> line
>  126 of database2.cpp
>   0x000020d9   _main+653, line 98 of database2.cpp
>   0x0001401a   ___crt1_startup+174

This seems to tell that you overwrite an allocated buffer, and thus
trashing the hidden info maintained by malloc and free beyond the end
of the buffer returned by malloc.  Or it could be that you tried to
free a buffer that wasn't result of malloc.

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