dlclose(3) [osf1 man page]
dlclose(3) Library Functions Manual dlclose(3) NAME
dlclose - Close a dlopen() object SYNOPSIS
#include <dlfcn.h> int dlclose(void *handle) PARAMETERS
A pointer to a global symbol object that is returned from a call to dlopen(). DESCRIPTION
The dlclose function is used to 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 requirements on the dynamic library loader, 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 refer- enced object are also closed. The dlclose function deallocates the address space for the library corresponding to handle. The results are undefined if any user function continues to call a symbol resolved in the address space of a library that has since been deallocated by dlclose. The dlclose operation will not remove an object 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, will be undone or remade unless the object requiring the relocation has itself been removed. RETURN VALUE
If the referenced object was successfully closed, dlclose() returns 0. If the object could not be closed or if handle does not refer to an open object, dlclose() returns a non-zero value. More detailed diagnostic information will be available through dlerror(). ERRORS
No errors are defined. NOTES
The dlopen and dlclose routines might dynamically change the resolution of certain symbols referenced by a program or its shared library dependencies. The dlopen routine might resolve symbols that were previously unresolved, and dlclose might cause resolved symbols to become unresolved or to be reresolved to a different symbol definition. A portable application will employ a handle returned from a dlopen() invocation only within a given scope bracketed by the dlopen() and dlclose() operations. The dynamic library loader is 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. The dynamic library loader is also free to re-use 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(). RELATED INFORMATION
dlerror(3), dlopen(3), dlsym(3). delim off dlclose(3)
Check Out this Related Man Page
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 (consult the correspond- ing 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 implementa- tion, 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 refer- enced 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 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 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() referenc- ing 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 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, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications 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 Standard, 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)