[Valgrind-users] "uninitialised value": cannot find the leak

[Mila R. <mi...@ru...>]

Hello,

I am currently working on a project to port some C-code from SGI to other 
platforms. The program now runs on Linux and produces the same results as 
on SGI. I would like to use valgrind to see if there are any undetected 
memory leaks. There are plenty but since I cannot find the source I would 
like to as for hints how to proceed and spot the errors.
The code (with lines) causing the error message:
--------------------------------------------------------------------------
1403	printf("-------DEBUG: %d, %d----\n", *atomCount, *maxAtomCount);
1404	printf("-------DEBUG: %p, %p----\n", atomCount, maxAtomCount);
1405    if (*atomCount < *maxAtomCount)
1406       {
1407        atomPtr = *atomList + *atomCount;
1408        (*atomCount)++;
1409
1410        return( atomPtr );
1411       }
--------------------------------------------------------------------------
The program is run with
 	valgrind -v <progname> <prog-options> > valgrind.log 2>&1
An extract from valgrind.log reads:
-------DEBUG: 7, 32----
-------DEBUG: 0x41d6b7c, 0x41d6b80----
-------DEBUG: 8, 32----
-------DEBUG: 0x41d6b7c, 0x41d6b80----
-------DEB==7810== Use of uninitialised value of size 4
==7810==    at 0x40B74B9: (within /lib/tls/i686/cmov/libc-2.3.6.so)
==7810==    by 0x40BB5EC: vfprintf (in /lib/tls/i686/cmov/libc-2.3.6.so)
==7810==    by 0x40C11A2: printf (in /lib/tls/i686/cmov/libc-2.3.6.so)
==7810==    by 0x8143AA1: getNextAtomPtr (pdb.c:1403)
==7810==    by 0x8144632: setSegAtomInfo (pdb.c:1887)
==7810==    by 0x81432C3: indexPDB (pdb.c:1050)
==7810==    by 0x8142F28: readPDB (pdb.c:908)
==7810==    by 0x805B48D: main (pales.c:705)
==7810==
==7810== Conditional jump or move depends on uninitialised value(s)
==7810==    at 0x40B74C1: (within /lib/tls/i686/cmov/libc-2.3.6.so)
==7810==    by 0x40BB5EC: vfprintf (in /lib/tls/i686/cmov/libc-2.3.6.so)
==7810==    by 0x40C11A2: printf (in /lib/tls/i686/cmov/libc-2.3.6.so)
==7810==    by 0x8143AA1: getNextAtomPtr (pdb.c:1403)
==7810==    by 0x8144632: setSegAtomInfo (pdb.c:1887)
==7810==    by 0x81432C3: indexPDB (pdb.c:1050)
==7810==    by 0x8142F28: readPDB (pdb.c:908)
==7810==    by 0x805B48D: main (pales.c:705)
 	... 12 more reports on "
UG: 9, 32----
-------DEBUG: 0x41d6b7c, 0x41d6b80----
-------DEBUG: 10, 32----
-------DEBUG: 0x41d6b7c, 0x41d6b80----
-------DEBUG: 11, 32----
-------DEBUG: 0x41d6b7c, 0x41d6b80----


My questions:
Do the messages from valgrind refer to when the variable *atomCount has 
the value 9, or can it refer to a later stage of that loop?

If it does refer to when *atomCount==9, how can one of the two variables 
be uninitialised? Since they are very regular (*atomCount properly 
counting up), doesn't that indicate that it is properly initialised?

I have been searching the code to figure out at what stage one of the two 
pointers used in line 1405 might be uninitialised, but without success. 
Are there other tips that might help me find out what causes valgrind to 
issue this message, i.e., trace back where the uninitialised variable stem 
from?

valgring version
 	valgrind-3.2.1-Debian (i686),
code compiled with
 	gcc version 4.1.2 20061028 (prerelease) (Debian 4.1.1-19)
and options
 	-O0 -g -Wall

I hope I provided all necessary information and would be very grateful for 
any hints as to how to proceed.

Mila.