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DLCLOSE(3P) POSIX Programmer's Manual DLCLOSE(3P)
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.
dlclose — close a symbol table handle
#include <dlfcn.h>
int dlclose(void *handle);
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.
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().
No errors are defined.
The following sections are informative.
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().
None.
None.
dlerror(3p), dlopen(3p), dlsym(3p)
The Base Definitions volume of POSIX.1‐2008, dlfcn.h(0p)
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)