1DLCLOSE(3P) POSIX Programmer's Manual DLCLOSE(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 dlclose - close a dlopen object
13
15 #include <dlfcn.h>
16 int dlclose(void *handle);
18
21 The dlclose() function shall inform the system that the object refer‐
22 enced by a handle returned from a previous dlopen() invocation is no
23 longer needed by the application.
24 The use of dlclose() reflects a statement of intent on the part of the
26 process, but does not create any requirement upon the implementation,
27 such as removal of the code or symbols referenced by handle. Once an
28 object has been closed using dlclose() an application should assume
29 that its symbols are no longer available to dlsym(). All objects loaded
30 automatically as a result of invoking dlopen() on the referenced object
31 shall also be closed if this is the last reference to it.
32 Although a dlclose() operation is not required to remove structures
34 from an address space, neither is an implementation prohibited from
35 doing so. The only restriction on such a removal is that no object
36 shall be removed to which references have been relocated, until or
37 unless all such references are removed. For instance, an object that
38 had been loaded with a dlopen() operation specifying the RTLD_GLOBAL
39 flag might provide a target for dynamic relocations performed in the
40 processing of other objects-in such environments, an application may
41 assume that no relocation, once made, shall be undone or remade unless
42 the object requiring the relocation has itself been removed.
43
45 If the referenced object was successfully closed, dlclose() shall
46 return 0. If the object could not be closed, or if handle does not
47 refer to an open object, dlclose() shall return a non-zero value. More
48 detailed diagnostic information shall be available through dlerror().
49
51 No errors are defined.
52 The following sections are informative.
54
56 The following example illustrates use of dlopen() and dlclose():
57 ...
60 /* Open a dynamic library and then close it ... */
61 #include <dlfcn.h>
64 void *mylib;
65 int eret;
66 mylib = dlopen("mylib.so", RTLD_LOCAL | RTLD_LAZY);
69 ...
70 eret = dlclose(mylib);
71 ...
72
74 A conforming application should employ a handle returned from a
75 dlopen() invocation only within a given scope bracketed by the dlopen()
76 and dlclose() operations. Implementations are free to use reference
77 counting or other techniques such that multiple calls to dlopen() ref‐
78 erencing the same object may return the same object for handle. Imple‐
79 mentations are also free to reuse a handle. For these reasons, the
80 value of a handle must be treated as an opaque object by the applica‐
81 tion, used only in calls to dlsym() and dlclose().
82
84 None.
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87 None.
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90 dlerror(), dlopen(), dlsym(), the Base Definitions volume of
91 IEEE Std 1003.1-2001, <dlfcn.h>
92
94 Portions of this text are reprinted and reproduced in electronic form
95 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
96 -- Portable Operating System Interface (POSIX), The Open Group Base
97 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
98 Electrical and Electronics Engineers, Inc and The Open Group. In the
99 event of any discrepancy between this version and the original IEEE and
100 The Open Group Standard, the original IEEE and The Open Group Standard
101 is the referee document. The original Standard can be obtained online
102 at http://www.opengroup.org/unix/online.html .
103IEEE/The Open Group 2003 DLCLOSE(3P)