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I'm trying to find out where I made invalid writes to a piece of memory using Valgrind. It tells there is such an issue, also in what function, but not in what line. Although the function is quite small, I'd like to have the line-number shown in Valgrind. I've seen this on some outputs of Valgrind, but currently they are not shown, and I wonder why.

The output is the following:

niklas@emerald:~/Arbeitsfläche/spyr/bin/Debug$ valgrind --tool=memcheck --leak-check=full --show-reachable=yes ./spyr
[...]
==4404== Invalid write of size 4
==4404==    at 0x8048849: sp_ParticleBuffer_init (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404==    by 0x8048BFC: sp_ParticleSystem_createParticle (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404==    by 0x8048691: main (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404==  Address 0x422a0a0 is 4 bytes after a block of size 4 alloc'd
==4404==    at 0x402BE68: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==4404==    by 0x8048BC1: sp_ParticleSystem_createParticle (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404==    by 0x8048691: main (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404== 
==4404== Invalid write of size 4
==4404==    at 0x8048865: sp_ParticleBuffer_init (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404==    by 0x8048BFC: sp_ParticleSystem_createParticle (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404==    by 0x8048691: main (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404==  Address 0x422a09c is 0 bytes after a block of size 4 alloc'd
==4404==    at 0x402BE68: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==4404==    by 0x8048BC1: sp_ParticleSystem_createParticle (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
==4404==    by 0x8048691: main (in /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr)
[...]

I saw outputs where the line number is shown after a double-colon behind the file-name. I.e. /home/niklas/Arbeitsfläche/spyr/bin/Debug/spyr:23 or similar.

How can I enable this?

FYI, this is the sp_ParticleBuffer_init function.

int sp_ParticleBuffer_init(sp_ParticleBuffer* buffer, sp_Uint32 buffer_size, int init_zero) {
    size_t size   = sizeof(sp_Particle) * buffer_size;
    buffer->next  = null;
    buffer->array = (sp_Particle*) malloc(size);
    buffer->alive_count = 0;

    if (!buffer->array) return SPYR_ALLOCFAILED;
    if (init_zero) memset((void*) buffer->array, 0, size);
    return SPYR_NOERR;
}
Niklas R
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1 Answers1

19

You need to include debug information in your binaries. Pass the -g flag if you're using gcc.

cnicutar
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  • OMG. Thanks man. :o I was compiling using the Code::Blocks IDE and ran compilation in Debug mode. Thought it would use `-g`, but it didn't. Maybe I somehow deactivated it some day.. I also thought they were enabled as I didn't recognize that valgrind only shows me the executeable-name, not the filename. xD BUt how did valgrind know the name of the function without debugging symbols? – Niklas R Aug 26 '12 at 12:52
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    Yes, enabling the `-g` option in the settings did it. :) – Niklas R Aug 26 '12 at 12:54
  • @NiklasR Good to know. To your second question, the binaries still retain some info unless they're stripped. That info is enough to unroll the stack. – cnicutar Aug 26 '12 at 12:55
  • Thank you. (; [some fill chars...] – Niklas R Aug 26 '12 at 13:43