使用 ld 的 --wrap 参数替换掉库函数
--wrap=symbol Use a wrapper function for symbol.
Any undefined reference to symbol will be resolved to "__wrap_symbol".
Any undefined reference to "__real_symbol" will be resolved to symbol. Here is a trivial example: void * __wrap_malloc (size_t c) { printf ("malloc called with %zu\n", c); return __real_malloc (c); } If you link other code with this file using --wrap malloc, then all calls to "malloc" will call the function "__wrap_malloc" instead.The call to "__real_malloc" in "__wrap_malloc" will call the real "malloc" function.You may wish to provide a "__real_malloc" function as well, so that links without the --wrap option will succeed. If you do this, you should not put the definition of "__real_malloc" in the same file as "__wrap_malloc"; if you do, the assembler may resolve the call before the linker has a chance to wrap it to "malloc".Only undefined references are replaced by the linker. So, translation unit internal references to symbol are not resolved to "__wrap_symbol". In the next example, the call to "f" in "g" is not resolved to "__wrap_f". int f(void) { return 123; }int g(void) { return f(); }
