DLCLOSE(3P)                                         POSIX Programmer's Manual                                        DLCLOSE(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       dlclose - close a dlopen object

SYNOPSIS
       #include <dlfcn.h>

       int dlclose(void *handle);


DESCRIPTION
       The  dlclose()  function shall 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  automati-
       cally as a result of invoking dlopen() on the referenced object shall also be closed if this is the last reference to it.

       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 shall 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  pro-
       cessing  of  other objects-in such environments, an application may assume that no relocation, once made, shall be undone
       or remade unless the object requiring the relocation has itself been removed.

RETURN VALUE
       If the referenced object was successfully closed, dlclose() shall return 0. If the object could not be closed, or if han-
       dle does not refer to an open object, dlclose() shall return a non-zero value. More detailed diagnostic information shall
       be available through dlerror().

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       The following example illustrates use of dlopen() and dlclose():


              ...
              /* Open a dynamic library and then close it ... */


              #include <dlfcn.h>
              void *mylib;
              int eret;


              mylib = dlopen("mylib.so", RTLD_LOCAL | RTLD_LAZY);
              ...
              eret = dlclose(mylib);
              ...

APPLICATION USAGE
       A conforming application should 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 reuse a handle. For these reasons, the value of a handle must be treated as an opaque object by the applica-
       tion, used only in calls to dlsym() and dlclose().

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       dlerror(), dlopen(), dlsym(), the Base Definitions volume of IEEE Std 1003.1-2001, <dlfcn.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                   DLCLOSE(3P)