[KinoSearch] Seg fault on trunk r3834

[Marvin Humphrey]

On Sep 7, 2008, at 11:39 AM, Dan wrote:

> ==414== Invalid read of size 4
> ==414==    at 0x457AB6C: kino_DocReader_fetch_doc (DocReader.c:54)

Thanks to the Valgrind output, this was easy to track down.   
DocReader, recently refactored, was freaking when it encountered a  
field value of "".  Somehow the test suite had managed to avoid  
presenting DocReader with such a value up till now.

The segfault occurred at the SvPVX(value_sv) directive in the  
following code from xs/KinoSearch/DocReader.c.  SvPVX is a macro for  
accessing an SV's string pointer directly -- it doesn't check first  
whether the SV holds a valid string.

          /* Read the field value. */
          value_len = Kino_InStream_Read_C32(ds_in);
-        value_sv  = newSV(value_len);
+        value_sv  = newSV((value_len ? value_len : 1));
          Kino_InStream_Read_Bytes(ds_in, SvPVX(value_sv), value_len);

The solution was to guarantee that the SV contains a string by always  
providing newSV() with a non-zero length.

Repository revision 3841 should resolve your issue.

Thanks for the report,

Marvin Humphrey
Rectangular Research
http://www.rectangular.com/