Code for malloc and free

Question

Where can I find the code for malloc my gcc compiler is using at the moment? I actually want to write my own malloc function which will be a little different from the original one. I know I can use hooks et all, but I want to see the real code.

Answer 1

Look in the appropriate release of glibc at the old release site¹ or here. For example, if you are using glib 2.9, it is in this archive. Look for the file malloc/malloc.c.

You will see that it is not a trivial piece of library code.

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¹ It looks like they changed the directory structure after glibc-2.9.

Answer 2

I am able to browse the source online here.

Answer 3

The POSIX interface of malloc is defined here.

If you want to find out how the C library in GNU/Linux (glibc) implements malloc, go and get the source code from http://ftp.gnu.org/gnu/glibc/ and look at the malloc/malloc.c file.

There is also the base documentation of the Memory Allocator by Doug Lea that describes the theory of a m(emory)alloc(ator) (read this carrefully, and then decide if you really need to implement your own malloc).

Answer 4

malloc() should be in glibc.

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