1DLCLOSE(P) POSIX Programmer's Manual DLCLOSE(P)
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6 dlclose - close a dlopen object
7
9 #include <dlfcn.h>
10 int dlclose(void *handle);
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15 The dlclose() function shall inform the system that the object refer‐
16 enced by a handle returned from a previous dlopen() invocation is no
17 longer needed by the application.
18 The use of dlclose() reflects a statement of intent on the part of the
20 process, but does not create any requirement upon the implementation,
21 such as removal of the code or symbols referenced by handle. Once an
22 object has been closed using dlclose() an application should assume
23 that its symbols are no longer available to dlsym(). All objects loaded
24 automatically as a result of invoking dlopen() on the referenced object
25 shall also be closed if this is the last reference to it.
26 Although a dlclose() operation is not required to remove structures
28 from an address space, neither is an implementation prohibited from
29 doing so. The only restriction on such a removal is that no object
30 shall be removed to which references have been relocated, until or
31 unless all such references are removed. For instance, an object that
32 had been loaded with a dlopen() operation specifying the RTLD_GLOBAL
33 flag might provide a target for dynamic relocations performed in the
34 processing of other objects-in such environments, an application may
35 assume that no relocation, once made, shall be undone or remade unless
36 the object requiring the relocation has itself been removed.
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39 If the referenced object was successfully closed, dlclose() shall
40 return 0. If the object could not be closed, or if handle does not
41 refer to an open object, dlclose() shall return a non-zero value. More
42 detailed diagnostic information shall be available through dlerror().
43
45 No errors are defined.
46 The following sections are informative.
48
50 The following example illustrates use of dlopen() and dlclose():
51 ...
54 /* Open a dynamic library and then close it ... */
55 #include <dlfcn.h>
58 void *mylib;
59 int eret;
60 mylib = dlopen("mylib.so", RTLD_LOCAL | RTLD_LAZY);
63 ...
64 eret = dlclose(mylib);
65 ...
66
68 A conforming application should employ a handle returned from a
69 dlopen() invocation only within a given scope bracketed by the dlopen()
70 and dlclose() operations. Implementations are free to use reference
71 counting or other techniques such that multiple calls to dlopen() ref‐
72 erencing the same object may return the same object for handle. Imple‐
73 mentations are also free to reuse a handle. For these reasons, the
74 value of a handle must be treated as an opaque object by the applica‐
75 tion, used only in calls to dlsym() and dlclose().
76
78 None.
79
81 None.
82
84 dlerror() , dlopen() , dlsym() , the Base Definitions volume of
85 IEEE Std 1003.1-2001, <dlfcn.h>
86
88 Portions of this text are reprinted and reproduced in electronic form
89 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
90 -- Portable Operating System Interface (POSIX), The Open Group Base
91 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
92 Electrical and Electronics Engineers, Inc and The Open Group. In the
93 event of any discrepancy between this version and the original IEEE and
94 The Open Group Standard, the original IEEE and The Open Group Standard
95 is the referee document. The original Standard can be obtained online
96 at http://www.opengroup.org/unix/online.html .
97IEEE/The Open Group 2003 DLCLOSE(P)