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111 lines
3.8 KiB
Plaintext
111 lines
3.8 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "DLCLOSE" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" dlclose
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.SH NAME
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dlclose \- close a dlopen object
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.SH SYNOPSIS
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.LP
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\fB#include <dlfcn.h>
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.br
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.sp
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int dlclose(void *\fP\fIhandle\fP\fB); \fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIdlclose\fP() function shall inform the system that the object
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referenced by a \fIhandle\fP returned from a previous \fIdlopen\fP()
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invocation is no longer needed by the application.
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.LP
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The use of \fIdlclose\fP() reflects a statement of intent on the part
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of the process, but does not create any requirement upon
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the implementation, such as removal of the code or symbols referenced
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by \fIhandle\fP. Once an object has been closed using
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\fIdlclose\fP() an application should assume that its symbols are
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no longer available to \fIdlsym\fP(). All objects loaded automatically
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as a result of invoking \fIdlopen\fP() on the referenced object shall
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also be closed if this is the last reference to
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it.
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.LP
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Although a \fIdlclose\fP() operation is not required to remove structures
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from an address space, neither is an implementation
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prohibited from doing so. The only restriction on such a removal is
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that no object shall be removed to which references have been
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relocated, until or unless all such references are removed. For instance,
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an object that had been loaded with a \fIdlopen\fP() operation specifying
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the RTLD_GLOBAL flag might provide a target for dynamic
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relocations performed in the processing of other objects-in such environments,
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an application may assume that no relocation, once
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made, shall be undone or remade unless the object requiring the relocation
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has itself been removed.
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.SH RETURN VALUE
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.LP
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If the referenced object was successfully closed, \fIdlclose\fP()
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shall return 0. If the object could not be closed, or if
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\fIhandle\fP does not refer to an open object, \fIdlclose\fP() shall
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return a non-zero value. More detailed diagnostic
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information shall be available through \fIdlerror\fP().
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.SH ERRORS
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.LP
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No errors are defined.
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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The following example illustrates use of \fIdlopen\fP() and \fIdlclose\fP():
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.sp
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.RS
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.nf
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\fB\&...
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/* Open a dynamic library and then close it ... */
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.sp
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#include <dlfcn.h>
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void *mylib;
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int eret;
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.sp
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mylib = dlopen("mylib.so", RTLD_LOCAL | RTLD_LAZY);
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\&...
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eret = dlclose(mylib);
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\&...
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\fP
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.fi
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.RE
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.SH APPLICATION USAGE
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.LP
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A conforming application should employ a \fIhandle\fP returned from
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a \fIdlopen\fP()
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invocation only within a given scope bracketed by the \fIdlopen\fP()
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and \fIdlclose\fP()
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operations. Implementations are free to use reference counting or
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other techniques such that multiple calls to \fIdlopen\fP() referencing
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the same object may return the same object for \fIhandle\fP.
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Implementations are also free to reuse a \fIhandle\fP. For these reasons,
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the value of a \fIhandle\fP must be treated as an
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opaque object by the application, used only in calls to \fIdlsym\fP()
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and
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\fIdlclose\fP().
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIdlerror\fP() , \fIdlopen\fP() , \fIdlsym\fP() , the Base Definitions
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volume of IEEE\ Std\ 1003.1-2001, \fI<dlfcn.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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