dlclose(3p) — Linux manual page


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

PROLOG         top

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

NAME         top

       dlclose — close a symbol table handle

SYNOPSIS         top

       #include <dlfcn.h>

       int dlclose(void *handle);

DESCRIPTION         top

       The dlclose() function shall inform the system that the symbol table
       handle specified by handle is no longer needed by the application.

       An application writer may use dlclose() to make a statement of intent
       on the part of the process, but this statement does not create any
       requirement upon the implementation. When the symbol table handle is
       closed, the implementation may unload the executable object files
       that were loaded by dlopen() when the symbol table handle was opened
       and those that were loaded by dlsym() when using the symbol table
       handle identified by handle.

       Once a symbol table handle has been closed, an application should
       assume that any symbols (function identifiers and data object
       identifiers) made visible using handle, are no longer available to
       the process.

       Although a dlclose() operation is not required to remove any
       functions or data objects from the address space, neither is an
       implementation prohibited from doing so. The only restriction on such
       a removal is that no function nor data object shall be removed to
       which references have been relocated, until or unless all such
       references are removed. For instance, an executable object file 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 relocatable objects—in such environments, an
       application may assume that no relocation, once made, shall be undone
       or remade unless the executable object file containing the relocated
       object has itself been removed.

RETURN VALUE         top

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

ERRORS         top

       No errors are defined.

       The following sections are informative.

EXAMPLES         top

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

           #include <dlfcn.h>
           int eret;
           void *mylib;
           /* Open a dynamic library and then close it ... */
           mylib = dlopen("mylib.so", RTLD_LOCAL | RTLD_LAZY);
           eret = dlclose(mylib);


       A conforming application should employ a symbol table handle returned
       from a dlopen() invocation only within a given scope bracketed by a
       dlopen() operation and the corresponding dlclose() operation.
       Implementations are free to use reference counting or other
       techniques such that multiple calls to dlopen() referencing the same
       executable object file may return a pointer to the same data object
       as the symbol table handle.

       Implementations are also free to re-use a handle. For these reasons,
       the value of a handle must be treated as an opaque data type by the
       application, used only in calls to dlsym() and dlclose().

RATIONALE         top




SEE ALSO         top

       dlerror(3p), dlopen(3p), dlsym(3p)

       The Base Definitions volume of POSIX.1‐2008, dlfcn.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                         DLCLOSE(3P)

Pages that refer to this page: dlfcn.h(0p)dlerror(3p)dlopen(3p)dlsym(3p)