dlfcn.h File Reference

Dynamic shared library loading. More...

Functions
void *	dlopen (const char *path, int mode)
	Open a shared library symbol table handle.
void *	dlsym (void *image, const char *symbolName)
	get the address of a symbol from a shared library.

Detailed Description

Dynamic shared library loading.

Function Documentation

dlopen()

void * dlopen	(	const char *	file,
		int	flags
	)

Open a shared library symbol table handle.

Refer to the POSIX specification for the full specification. This page only documents Haiku specific behavior.

The following are left implementation defined by POSIX:

• If the "file" argument does not contain a slash character, it will be handled as a file name to be searched in a list of directories set by the LIBRARY_PATH environment variable. That variable is a list of path separated by colon characters. If one of the paths contains the sequence A, that is replaced with the directory where the currently running executable is stored.
• If neither RTLD_LOCAL or RTLD_GLOBAL is defined, RTLD_LOCAL is the default.

In addition to the POSIX standard flags, dlopen supports the following extended flags:

• RTLD_NOLOAD: do not load the shared object if it is not already loaded in the current program address space. Only return a valid handle if the library is already loaded by other means such as a previous call to dlopen or the runtime_loader symbol resolution at program startup.
• RTLD_GROUP: do not use existing symbols from already loaded libraries to resolve dependencies from the loaded library. The library must explicitly link to all other libraries it needs. These may provide symbols with the same name as other symbols from already loaded libraries without interfering.

dlsym()

void * dlsym	(	void *	image,
		const char *	symbolName
	)

get the address of a symbol from a shared library.

Refer to the POSIX specification for the full specification. This page only documents Haiku specific behavior.

The following values are accepted for the image parameter in addition to handles obtained through calls to dlopen (these are currently "reserved for future use" in POSIX):

• RTLD_DEFAULT: find the symbol in the global scope
• RTLD_NEXT: find the next definition of the symbol