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Re: [xml/sgml] xerces packages and arm: opinions sought

On Tue, Aug 10, 2004 at 07:49:17PM -0400, Jay Berkenbilt wrote:
> Responding to my own question, I talked about this on IRC and decided
> to just downgrade to icu21 rather than dropping arm support.  Someone
> on IRC volunteered to sponsor the upload.

Your decision notwithstanding, the problem with icu28 seems to be:

Program received signal SIGSEGV, Segmentation fault.
expandGroupLengths (s=0x5e4744e2 <Address 0x5e4744e2 out of bounds>, 
    offsets=0xbfffe908, lengths=0xbfffe8c4) at ../../source/common/unames.c:520
520             lengthByte=*s++;
Current language:  auto; currently c
(gdb) bt
#0  expandGroupLengths (s=0x5e4744e2 <Address 0x5e4744e2 out of bounds>, 
    offsets=0xbfffe908, lengths=0xbfffe8c4) at
#1  0x400adb30 in enumGroupNames (names=0x40420020, group=0x0, start=0, 
    end=31, fn=0x40420020, context=0x404248ec, nameChoice=U_EXTENDED_CHAR_NAME)
    at ../../source/common/unames.c:605

Which implies the problem is in the calculation of the "s" pointer:

    const uint8_t *s=(uint8_t *)names+names->groupStringOffset+
    s=expandGroupLengths(s, offsets, lengths);

I have no idea how this code is supposed to work but perhaps knowing the
values involved at the time of the call might be of use (this is right
before the call to expandGroupLengths():

(gdb) p s
$2 = (const uint8_t *) 0x5e4744e2 <Address 0x5e4744e2 out of bounds>
(gdb) p names
$3 = (UCharNames *) 0x40420020
(gdb) p names->groupStringOffset 
$4 = 17580
(gdb) p group->offsetHigh 
$5 = 7685
(gdb) p group->offsetLow 
$6 = 22
(gdb) p *names
$7 = {tokenStringOffset = 3030, groupsOffset = 14410, 
  groupStringOffset = 17580, algNamesOffset = 142956}

I'm troubled by the use of arrays are arguments in the expandGroupLengths()
function.  I'm not sure how this is meant to work; in plain C the best you 
could hope for is to pass a pointer and then dereference it in the function.
I suspect that is what is happening here, but as written it looks like the
"offsets" and "lengths" are passed uninitialized to expandGroupLengths(),
which then goes ahead and increments values therein.

Definately suspect code, on any platform, i my books anyways.


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