rld Manual

Using the rld Loader Library

RLD Manual—528857-006

2-8

dlclose()

Summary

The dlclose() function invalidates the library handle designated by the

dlopen_handle value. It unloads any DLLs that are no longer required.

Syntax for C/C++ Programmers

Parameters

dlopen_handle

specifies a currently valid library handle previously returned by a call to the

dlopen() function.

Return Values

Upon successful invalidation of the library handle, dlclose() returns 0 (zero).

Otherwise, the function returns a nonzero value, and you should call the dlerror()

or dlresultcode() function immediately to determine the problem.

Considerations

The dlclose() function invalidates the library handle designated by the

dlopen_handle value. It unloads any DLLs that are no longer required.

In the simplest case, dlclose() unloads any library loaded by the dlopen()

invocation that returned the destroyed library handle. When there are linkages between

DLLs loaded by separate dlopen() calls, a library loaded by one call might be

required by a library loaded by another call and might be unloaded by a subsequent

call to dlclose() specifying another library handle.

dlclose() does not unload the main program or DLLs that were loaded with the

main program.

When dlclose() invalidates a library handle, it decrements the usage count for the

library loaded by the dlopen() invocation that returned the destroyed handle and for

any DLLs that library required. dlclose() unloads any DLLs that are unused.

After a library has been unloaded by dlclose(), referencing addresses where the

library text and data were loaded results in undefined behavior.

The dlclose() function does not set the errno variable. For error information, call

the dlerror() or dlresultcode() function.

#include <dlfcn.h>

int dlclose (dlHandle dlopen_handle );