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
13 dlclose — close a symbol table handle
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16 #include <dlfcn.h>
17 int dlclose(void *handle);
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21 The dlclose() function shall inform the system that the symbol table
22 handle specified by handle is no longer needed by the application.
23 An application writer may use dlclose() to make a statement of intent
25 on the part of the process, but this statement does not create any
26 requirement upon the implementation. When the symbol table handle is
27 closed, the implementation may unload the executable object files that
28 were loaded by dlopen() when the symbol table handle was opened and
29 those that were loaded by dlsym() when using the symbol table handle
30 identified by handle.
31 Once a symbol table handle has been closed, an application should
33 assume that any symbols (function identifiers and data object identi‐
34 fiers) made visible using handle, are no longer available to the
35 process.
36 Although a dlclose() operation is not required to remove any functions
38 or data objects from the address space, neither is an implementation
39 prohibited from doing so. The only restriction on such a removal is
40 that no function nor data object shall be removed to which references
41 have been relocated, until or unless all such references are removed.
42 For instance, an executable object file that had been loaded with a
43 dlopen() operation specifying the RTLD_GLOBAL flag might provide a tar‐
44 get for dynamic relocations performed in the processing of other relo‐
45 catable objects—in such environments, an application may assume that no
46 relocation, once made, shall be undone or remade unless the executable
47 object file containing the relocated object has itself been removed.
48
50 If the referenced symbol table handle was successfully closed,
51 dlclose() shall return 0. If handle does not refer to an open symbol
52 table handle or if the symbol table handle could not be closed,
53 dlclose() shall return a non-zero value. More detailed diagnostic
54 information shall be available through dlerror().
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57 No errors are defined.
58 The following sections are informative.
60
62 The following example illustrates use of dlopen() and dlclose():
63 #include <dlfcn.h>
65 int eret;
66 void *mylib;
67 ...
68 /* Open a dynamic library and then close it ... */
69 mylib = dlopen("mylib.so", RTLD_LOCAL | RTLD_LAZY);
70 ...
71 eret = dlclose(mylib);
72 ...
73
75 A conforming application should employ a symbol table handle returned
76 from a dlopen() invocation only within a given scope bracketed by a
77 dlopen() operation and the corresponding dlclose() operation. Implemen‐
78 tations are free to use reference counting or other techniques such
79 that multiple calls to dlopen() referencing the same executable object
80 file may return a pointer to the same data object as the symbol table
81 handle.
82 Implementations are also free to re-use a handle. For these reasons,
84 the value of a handle must be treated as an opaque data type by the
85 application, used only in calls to dlsym() and dlclose().
86
88 None.
89
91 None.
92
94 dlerror(), dlopen(), dlsym()
95 The Base Definitions volume of POSIX.1‐2008, <dlfcn.h>
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99 Portions of this text are reprinted and reproduced in electronic form
100 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
101 -- Portable Operating System Interface (POSIX), The Open Group Base
102 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
103 cal and Electronics Engineers, Inc and The Open Group. (This is
104 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
105 event of any discrepancy between this version and the original IEEE and
106 The Open Group Standard, the original IEEE and The Open Group Standard
107 is the referee document. The original Standard can be obtained online
108 at http://www.unix.org/online.html .
109 Any typographical or formatting errors that appear in this page are
111 most likely to have been introduced during the conversion of the source
112 files to man page format. To report such errors, see https://www.ker‐
113 nel.org/doc/man-pages/reporting_bugs.html .
114IEEE/The Open Group 2013 DLCLOSE(3P)