Add two parts of Mark's/Gary's dlopen() changes that I missed before.

This commit is contained in:
jkh 1995-02-08 17:56:27 +00:00
parent e44dd23d15
commit 66c6af057e
2 changed files with 244 additions and 0 deletions

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lib/csu/i386/dlfcn.h Normal file
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/*
* Copyright (c) 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)err.h 8.1 (Berkeley) 6/2/93
*/
#ifndef _DLFCN_H_
#define _DLFCN_H_
#include <sys/cdefs.h>
__BEGIN_DECLS
void *dlopen __P((const char *, int));
void *dlsym __P((void *, const char *));
char *dlerror __P((void));
int dlclose __P((void *));
__END_DECLS
#endif /* !_DLFCN_H_ */

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lib/csu/i386/dlopen.3 Normal file
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.\" This source code is a product of Sun Microsystems, Inc. and is provided
.\" for unrestricted use provided that this legend is included on all tape
.\" media and as a part of the software program in whole or part. Users
.\" may copy or modify this source code without charge, but are not authorized
.\" to license or distribute it to anyone else except as part of a product or
.\" program developed by the user.
.\"
.\" THIS PROGRAM CONTAINS SOURCE CODE COPYRIGHTED BY SUN MICROSYSTEMS, INC.
.\" SUN MICROSYSTEMS, INC., MAKES NO REPRESENTATIONS ABOUT THE SUITABLITY
.\" OF SUCH SOURCE CODE FOR ANY PURPOSE. IT IS PROVIDED "AS IS" WITHOUT
.\" EXPRESS OR IMPLIED WARRANTY OF ANY KIND. SUN MICROSYSTEMS, INC. DISCLAIMS
.\" ALL WARRANTIES WITH REGARD TO SUCH SOURCE CODE, INCLUDING ALL IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN
.\" NO EVENT SHALL SUN MICROSYSTEMS, INC. BE LIABLE FOR ANY SPECIAL, INDIRECT,
.\" INCIDENTAL, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
.\" FROM USE OF SUCH SOURCE CODE, REGARDLESS OF THE THEORY OF LIABILITY.
.\"
.\" This source code is provided with no support and without any obligation on
.\" the part of Sun Microsystems, Inc. to assist in its use, correction,
.\" modification or enhancement.
.\"
.\" SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
.\" INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS
.\" SOURCE CODE OR ANY PART THEREOF.
.\"
.\" Sun Microsystems, Inc.
.\" 2550 Garcia Avenue
.\" Mountain View, California 94043
.\"
.\" Copyright (c) 1991 Sun Microsystems, Inc.
.\"
.\" @(#) dlopen.3 1.6 90/01/31 SMI
.TH DLOPEN 3 "24 September 1989"
.SH NAME
dlopen, dlsym, dlerror, dlclose \- simple programmatic interface to the dynamic linker
.SH SYNOPSIS
.nf
.ft B
#include <dlfcn.h>
.LP
.ft B
.nf
void *dlopen(path, mode)
const char *path; int mode;
.fi
.ft R
.LP
.ft B
.nfvoid *dlopen(path, mode)
.fi
.ft R
.LP
.ft B
.nf
void *dlsym(handle, symbol)
void *handle; const char *symbol;
.fi
.ft R
.LP
.ft B
.nf
char *dlerror(\|)
.fi
.ft R
.LP
.ft B
.nf
int dlclose(handle);
void *handle;
.fi
.ft R
.ft R
.fi
.SH DESCRIPTION
.IX "dlopen()" "" "\fLdlopen()\fP \(em dynamically load a shared object"
.IX "programmatic interface to dynamic linker" dlopen() "" \fLdlopen()\fP
.IX "dlsym()" "" "\fLdlsym()\fP \(em dynamically lookup a symbol"
.IX "programmatic interface to dynamic linker" dlsym "" \fLdlsym()\fP
.IX "dlerror()" "" "\fLdlerror()\fP \(em dynamic linking error string"
.IX "programmatic interface to dynamic linker" dlerror() "" \fLdlerror()\fP
.IX "dlclose()" "" "\fLdlclose()\fP \(em unload a shared object"
.IX "programmatic interface to dynamic linker" dlclose() "" \fLdlclose()\fP
.LP
These functions provide a simple programmatic interface to the services of the
dynamic link-editor.
Operations are provided to add a new shared object to an
program's address space, obtain the address bindings of symbols defined by such
objects, and to remove such objects when their use is no longer required.
.LP
.B dlopen(\|)
provides access to the shared object in
.IR path ,
returning a descriptor that can be used for later
references to the object in calls to
.B dlsym(\|)
and
.BR dlclose(\|) .
If
.I path
was not in the address space prior to the call to
.BR dlopen(\|) ,
then it will be placed in the address space, and if it defines a function
with the name
.I _init
that function will be called by
.BR dlopen(\|) .
If, however,
.I path
has already been placed in the address space in a previous call to
.BR dlopen(\|) ,
then it will not be added a
second time, although a count of
.B dlopen(\|)
operations on
.I path
will be maintained.
.I mode
is an integer containing flags describing options to be applied to the opening
and loading process \(em it is reserved for future expansion and must always have
the value 1.
A null pointer supplied for
.I path
is interpreted as a reference to the \*(lqmain\*(rq
executable of the process.
If
.B dlopen(\|)
fails, it will return a null pointer.
.LP
.B dlsym(\|)
returns the address binding of the symbol described in the null-terminated
character string
.I symbol
as it occurs in the shared object identified by
.IR handle .
The symbols exported by objects added to the address space by
.B dlopen(\|)
can be accessed
.I only
through calls to
.BR dlsym(\|) ,
such symbols do not supersede any definition of those symbols already present
in the address space when the object is loaded, nor are they available to
satisfy \*(lqnormal\*(rq dynamic linking references.
.B dlsym(\|)
returns a null pointer if the symbol can not be found.
A null pointer supplied as the value of
.I handle
is interpreted as a reference to the executable from which the call to
.B dlsym(\|)
is being made \(em thus a shared object can reference its own symbols.
.LP
.B dlerror
returns a null-terminated character string describing the last error that
occurred during a
.BR dlopen(\|) ,
.BR dlsym(\|) ,
or
.BR dlclose(\|) .
If no such error has occurred, then
.B dlerror(\|)
will return a null pointer.
At each call to
.BR dlerror(\|) ,
the \*(lqlast error\*(rq indication will be reset, thus in the case of two calls
to
.BR dlerror(\|) ,
and where the second call follows the first immediately, the second call
will always return a null pointer.
.LP
.B dlclose(\|)
deletes a reference to the shared object referenced by
.IR handle .
If the reference count drops to 0, then if the object referenced by
.I handle
defines a function
.IR _fini ,
that function will be called, the object
removed from the address space, and
.I handle
destroyed.
If
.B dlclose(\|)
is successful, it will return a value of 0.
A failing call to
.B dlclose(\|)
will return a non-zero value.
.LP
The object-intrinsic functions
.I _init
and
.I _fini
are called with no arguments and treated as though their types were
.BR void .
.SH SEE ALSO
.BR ld (1),
.BR link (5)
.SH NOTES