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copied!<p>see ld's option <code>--wrap symbol</code>. From the man page:</p> <blockquote> <p>--wrap symbol Use a wrapper function for symbol. Any undefined reference to symbol will be resolved to "<code>__wrap_symbol</code>". Any undefined reference to "<code>__real_symbol</code>" will be resolved to symbol.</p> <p>This can be used to provide a wrapper for a system function. The wrapper function should be called "<code>__wrap_symbol</code>". If it wishes to call the system function, it should call "<code>__real_symbol</code>".</p> <p>Here is a trivial example:</p> </blockquote> <pre><code>void * __wrap_malloc (size_t c) { printf ("malloc called with %zu\n", c); return __real_malloc (c); } </code></pre> <blockquote> <p>If you link other code with this file using --wrap malloc, then all calls to "<code>malloc</code>" will call the function "<code>__wrap_malloc</code>" instead. The call to "__real_malloc" in<br> "<code>__wrap_malloc</code>" will call the real "<code>malloc</code>" function.</p> <p>You may wish to provide a "<code>__real_malloc</code>" function as well, so that links without the --wrap option will succeed. If you do this, you should not put the definition of "<code>__real_malloc</code>" in the same file as "<code>__wrap_malloc</code>"; if you do, the assembler may resolve the call before the linker has a chance to wrap it to "malloc".</p> </blockquote> <p>The other option is to possibly look at the source for ltrace, it is more or less does the same thing :-P.</p> <p>Here's an idea though. You could have your <code>LD_PRELOAD</code>'ed library change the PLT entries to point to your code. This you technically the <code>sbrk()</code> function is still callable from your code nativly.</p>

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