Usage of Valgrind on a C program

Question

I am just a beginner in the usage of valgrind.I have ubuntu opened as a part of vmWare and i just made a c program which should show valgrind errors and had run the valgrind on the a.out ,but i am unable to see the line numbers to be visible on the output: The command used is :

valgrind --leak-check=full --track-origins=yes ./a.out

for the C program as shown below:

  #include <stdlib.h>

  #define ARRAY_SIZE      (5)

  typedef char TEST_TYPE;


  void invalid_write(TEST_TYPE* array, int size)
  {
     array[size] = 5;
  }


 int main(void)
 {
    TEST_TYPE static_array[ARRAY_SIZE];
    TEST_TYPE* dynamic_array = NULL;
    TEST_TYPE* p = NULL;
    TEST_TYPE i;


    dynamic_array = (TEST_TYPE*)malloc(ARRAY_SIZE * sizeof(TEST_TYPE));
   /* ERROR 1 : Writing out of array boundaries (heap overrun) */
    invalid_write(dynamic_array, ARRAY_SIZE);
 }

with the output as shown below:

==6801== Memcheck, a memory error detector
==6801== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==6801== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==6801== Command: ./a.out
==6801== 
==6801== Invalid write of size 1
==6801==    at 0x80483ED: invalid_write (in /home/jci/a.out)
==6801==    by 0x804842E: main (in /home/jci/a.out)
==6801==  Address 0x419702d is 0 bytes after a block of size 5 alloc'd
==6801==    at 0x4026444: malloc (vg_replace_malloc.c:263)
==6801==    by 0x8048416: main (in /home/jci/a.out)
==6801== 
==6801== 
==6801== HEAP SUMMARY:
==6801==     in use at exit: 5 bytes in 1 blocks
==6801==   total heap usage: 1 allocs, 0 frees, 5 bytes allocated
==6801== 
==6801== 5 bytes in 1 blocks are definitely lost in loss record 1 of 1
==6801==    at 0x4026444: malloc (vg_replace_malloc.c:263)
==6801==    by 0x8048416: main (in /home/jci/a.out)
==6801== 
==6801== LEAK SUMMARY:
==6801==    definitely lost: 5 bytes in 1 blocks
==6801==    indirectly lost: 0 bytes in 0 blocks
==6801==      possibly lost: 0 bytes in 0 blocks
==6801==    still reachable: 0 bytes in 0 blocks
==6801==         suppressed: 0 bytes in 0 blocks
==6801== 
==6801== For counts of detected and suppressed errors, rerun with: -v
==6801== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 11 from 6)

How am i supposed to get the line numbers of these errors so that we could exactly pin point the problem? Currently the valgrind version used is 3.7.0.

Did you compile the program with debug information? Use the `-g` flag to GCC for that. — Some programmer dude, Mar 22 '13 at 11:52
cc b.c is the command and the valgrind command used was valgrind --leak-check=full --track-origins=yes ./a.out — Maddy, Mar 22 '13 at 11:52
At the risk of sounding like a broken record, [please don't cast the return value of `malloc()` and friends, in C](http://stackoverflow.com/a/605858/28169). Thanks. — unwind, Mar 22 '13 at 11:52
@unwind I wonder why stackoverflow hasn't implemented an s/\([^)]+\) *malloc/alert("There is no need to cast malloc in C");/ yet, providing the "C" tag is included in the question... — autistic, Mar 22 '13 at 13:12

harald · Answer 1 · 2013-03-22T16:10:14.170

4

You need to build the program with debugging info, for gcc you should be able to do something like this:

gcc -g -O0 -Wall sourcefile.c

Valgrind will then show you the line numbers and function names from your source.

edited Mar 22 '13 at 16:10

answered Mar 22 '13 at 11:53

harald

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I might add that it is often wise to disable compiler optimization, as well, since it can make the relationships to source lines very confusing at times... CFLAGS="-g -O0 -Wall" is a good idea when trying to debug and/or use valgrind (presuming you're using a gcc like compiler) – K Scott Piel Mar 22 '13 at 12:17

Valeri Atamaniouk · Answer 2 · 2013-03-22T13:54:30.163

0

You can use addr2line tool for that purpose.

addr2line --exe a.out 8048416

I assume you have used -g flag when building objects:

gcc -c -g my_source1.c -o mysource1.o
gcc -c -g my_source2.c -o mysource2.o
gcc mysource1.o mysource2.o -o myapp

Or:

gcc -g my_source1.c my_source2.c -o myapp

edited Mar 22 '13 at 13:54

answered Mar 22 '13 at 11:56

Valeri Atamaniouk

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"I assume you have used `-g`" -- if he had, Valgrind would have shown him line numbers without use of `addr2line`. Since Valgrind didn't, one has to assume that he had not; making `addr2line` also useless. – Employed Russian Mar 24 '13 at 18:58
@EmployedRussian addr2line can be used after getting run results. Even if the original executable had no debug symbols, the tool can be used with a new build. Not always, but in many cases it is possible – Valeri Atamaniouk Mar 24 '13 at 19:28

Usage of Valgrind on a C program

2 Answers2