dllmain-linux.c File Reference

Linux implementation of library_startup() and library_shutdown() More...

#include "logstdio.h"
#include "log.h"
#include <dlfcn.h>
#include <unistd.h>

Functions
void	library_startup (void *base_addr, void *userptr)
	Dynamic library startup. More...
void	library_shutdown (void *userptr)
	Dynamic library shutdown. More...

Detailed Description

Linux implementation of library_startup() and library_shutdown()

Function Documentation

void library_shutdown

(

void *

userptr

)

Dynamic library shutdown.

On Windows, this function will be called automatically by DllMain().

On Linux, this function needs to be invoked manually (whenever "unloading" the library is requested).

void library_startup	(	void *	base_addr,
		void *	userptr
	)

Dynamic library startup.

An important task of this function is to initialize the global variables (lcfr_globals) before the library will attempt to make any use of them.

On Windows, this function will be called automatically by DllMain() with base_addr set to the module handle (= address). The userptr parameter reflects lpReserved, which has a special meaning in this context (For details see the MSDN link from the description of DllMain).

On Linux, this function needs to be invoked manually (by the "injector" / process that loads the shared object). To help with locating the library in memory and setting up global vars as needed, the base_addr will be the address of the startup function itself (which allows us to use dladdr() on it), and userptr will receive the actual library handle. (Unlike Windows, the handle does not reflect the module/load address under Linux.)