The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group


dlclose - close a dlopen() object


#include <dlfcn.h>

int dlclose(void *handle);


dlclose() is used to inform the system that the object referenced by a handle returned from a previous dlopen() invocation is no longer needed by the application.

The use of dlclose() reflects a statement of intent on the part of the process, but does not create any requirement upon the implementation, such as removal of the code or symbols referenced by handle. Once an object has been closed using dlclose() an application should assume that its symbols are no longer available to dlsym(). All objects loaded automatically as a result of invoking dlopen() on the referenced object are also closed.

Although a dlclose() operation is not required to remove structures from an address space, neither is an implementation prohibited from doing so. The only restriction on such a removal is that no object will be removed to which references have been relocated, until or unless all such references are removed. For instance, an object that had been loaded with a dlopen() operation specifying the RTLD_GLOBAL flag might provide a target for dynamic relocations performed in the processing of other objects - in such environments, an application may assume that no relocation, once made, will be undone or remade unless the object requiring the relocation has itself been removed.


If the referenced object was successfully closed, dlclose() returns 0. If the object could not be closed, or if handle does not refer to an open object, dlclose() returns a non-zero value. More detailed diagnostic information will be available through dlerror().


No errors are defined.




A portable application will employ a handle returned from a dlopen() invocation only within a given scope bracketed by the dlopen() and dlclose() operations. Implementations are free to use reference counting or other techniques such that multiple calls to dlopen() referencing the same object may return the same object for handle. Implementations are also free to re-use a handle. For these reasons, the value of a handle must be treated as an opaque object by the application, used only in calls to dlsym() and dlclose().




dlerror(), dlopen(), dlsym().

UNIX ® is a registered Trademark of The Open Group.
Copyright © 1997 The Open Group
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