Linux dlopen : can a library be "notified" when it is loaded?

Question

有没有办法让共享库在加载时得到“通知”？

换句话说，假设我在共享库上使用dlopen，是否有一个函数在共享库(例如main？)上自动调用(如果存在)

Answer 1

Libraries should export initialization and cleanup routines using the gcc __attribute__((constructor)) and __attribute__((destructor)) function attributes. See the gcc info pages for information on these. Constructor routines are executed before dlopen returns (or before main() is started if the library is loaded at load time). Destructor routines are executed before dlclose returns (or after exit() or completion of main() if the library is loaded at load time). The C prototypes for these functions are:

 void __attribute__ ((constructor))  my_init(void);  
 void __attribute__  ((destructor)) my_fini(void);

取自http://tldp.org/HOWTO/Program-Library-HOWTO/index.html

也就是说，您只需将 __attribute__ ((constructor)) 添加到您希望在加载共享库时调用的函数。上面的文档还指出，较旧的 _ini 和 _fini 函数被认为已过时。