DLCLOSE(3C)DLCLOSE(3C)NAMEdlclose - close a shared object
int dlclose(void *handle);
The dlclose() function decrements the reference count of the supplied
handle. This handle represents an executable object file and its depen‐
dencies, acquired from a previous call to dlopen(). A handle that is no
longer referenced is processed in an attempt to unload any objects that
are associated with the handle from the current process. An unrefer‐
enced handle is no longer available to dlsym().
Any finalization code within an object is executed prior to that object
being unloaded. Any routines registered by an object using atexit(3C)
are called prior to that object being unloaded. See NOTES.
If the handle was successfully unreferenced, dlclose() returns 0. If
the handle is invalid, or an error occurred as a result of unloading an
object, dlclose() returns a non-zero value. Additional diagnostic
information is available through dlerror().
The dlclose() function is one of a family of functions that give the
user direct access to the dynamic linking facilities. These facilities
are available to dynamically-linked processes only. See the Linker and
See attributes(5) for descriptions of the following attributes:
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
│Interface Stability │ Standard │
│MT-Level │ MT-Safe │
SEE ALSOld(1), ld.so.1(1), atexit(3C), dladdr(3C), dldump(3C), dlerror(3C),
dlopen(3C), dlsym(3C), attributes(5), standards(5)
Linker and Libraries Guide
A successful invocation of dlclose() does not guarantee that the
objects associated with the handle are removed from the address space
of the current process. Objects can be referenced by multiple handles,
or by other objects. An object is not removed from the address space of
the current process until all references to that object are removed.
Once an object has been closed by dlclose(), referencing symbols con‐
tained in that object can cause undefined behavior.
As part of unloading an object, finalization code within the object is
called before the dlclose() returns. This finalization is user code,
and as such, can produce errors that can not be caught by dlclose().
For example, an object loaded using RTLD_LAZY that attempts to call a
function that can not be located, results in process termination. Erro‐
neous programming practices within the finalization code can also
result in process termination. The runtime linkers debugging facility
can offer help identifying these types of error. See the LD_DEBUG envi‐
ronment variable of ld.so.1(1).
Mar 1, 2004 DLCLOSE(3C)