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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 dif-
       fer (consult 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 automatically 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 imple-
       mentation  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 processing 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 handle does not refer to an open object, dlclose() shall return a non-zero value. More detailed diagnos-
       tic 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 han-
       dle.  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 application, 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, Stan-
       dard  for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
       tions Issue 6, Copyright (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 Stan-
       dard, the original IEEE and The Open Group Standard is the referee  document.  The  original  Standard  can  be
       obtained online at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                          DLCLOSE(3P)