Re: [xml] Any outstanding bugs in closing parser contexts or running with different memory handlers?

[Daniel Veillard <veillard redhat com>]

On Thu, Sep 26, 2002 at 02:34:35PM -0700, Sean Chittenden wrote:
> ctxtClose is a blatant rip off from someplace inside of the libxml
> sources:
>
> static void ctxtClose(FILE *f) {
>   if (f != stdin) {
>     fclose(f);
>   }
> }
>
>
> ... so I'm not really sure why I'm getting the following cryptic
> error:
>
> ==19278== Invalid read of size 1
> ==19278==    at 0x40308758: (within /lib/libc-2.2.5.so)
> ==19278==    by 0x431B10BC: ctxtClose (ruby_xml_parser.c:17)

> ==19278== Invalid read of size 2
> ==19278==    at 0x40308789: (within /lib/libc-2.2.5.so)
> ==19278==    by 0x431B10BC: ctxtClose (ruby_xml_parser.c:17)
> ==19278==    by 0x432BCDAA: xmlFreeParserInputBuffer (xmlIO.c:1575)

> ==19278== Invalid read of size 4
> ==19278==    at 0x403087CB: (within /lib/libc-2.2.5.so)
> ==19278==    by 0x431B10BC: ctxtClose (ruby_xml_parser.c:17)
> ==19278==    by 0x432BCDAA: xmlFreeParserInputBuffer (xmlIO.c:1575)

> What's interesting is that the read size grows from 1 to 4.  Why I'm
> not sure, and think that there could be a stray bit being written to
> in Ruby, but I'm not 100% sure.  Since valgrind only runs on Linux,
> I'd perfectly happy to chalk this up as a linux-ism, but it crashes on
> FreeBSD too.  :-/  Anyone have any thoughts?  -sc

  Hum, how are those InputBuffer created ? The fact that the read size
changes may simply be due to buffer access informations. Note that
some optimizations from GCC can actually lead to such invalid read
warnings from valgrind, it can also be processor dependant (e.g. Athlon
vs. PIII).
Make sure you have the latest valgrind 1.0.1, if needed get in touch
with valgrind author, and get a debug version of the C library to see
exactly where this occurs *inside*.

Daniel

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