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[linuxjm/jm.git] / manual / LDP_man-pages / release / man3 / dlopen.3

.\" -*- nroff -*-
.\" Copyright 1995 Yggdrasil Computing, Incorporated.
.\" written by Adam J. Richter (adam@yggdrasil.com),
.\" with typesetting help from Daniel Quinlan (quinlan@yggdrasil.com).
.\" and Copyright 2003 Michael Kerrisk (mtk.manpages@gmail.com).
.\"
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
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.\"
.\" The GNU General Public License's references to "object code"
.\" and "executables" are to be interpreted as the output of any
.\" document formatting or typesetting system, including
.\" intermediate and printed output.
.\"
.\" This manual is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public
.\" License along with this manual; if not, write to the Free
.\" Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
.\" USA.
.\"
.\" Modified by David A. Wheeler <dwheeler@dwheeler.com> 2000-11-28.
.\" Applied patch by Terran Melconian, aeb, 2001-12-14.
.\" Modified by Hacksaw <hacksaw@hacksaw.org> 2003-03-13.
.\" Modified by Matt Domsch, 2003-04-09: _init and _fini obsolete
.\" Modified by Michael Kerrisk <mtk.manpages@gmail.com> 2003-05-16.
.\" Modified by Walter Harms: dladdr, dlvsym
.\" Modified by Petr Baudis <pasky@suse.cz>, 2008-12-04: dladdr caveat
.\"
.\" Japanese Version Copyright (c) 1998 NAKANO Takeo all rights reserved.
.\" Translated Sat May 23 1998 by NAKANO Takeo <nakano@apm.seikei.ac.jp>
.\" Updated & Modified 1999-09-14, NAKANO Takeo
.\" Modified 2000-03-19, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated 2001-02-16, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2001-12-21, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2002-10-21, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2003-09-01, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2005-03-15, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2006-01-20, Akihiro MOTOKI
.\" Updated 2009-03-02, Akihiro MOTOKI, LDP v3.19
.\"
.\"WORD:        linker                  ¥ê¥ó¥«
.\"WORD:        dynamic linking         ưŪ¥ê¥ó¥¯
.\"WORD:        dynamic library         ưŪ¥é¥¤¥Ö¥é¥ê
.\"
.TH DLOPEN 3 2008-12-06 "Linux" "Linux Programmer's Manual"
.SH ̾Á°
dlclose, dlerror, dlopen, dlsym \- ưŪ¥ê¥ó¥¯¤ò¹Ô¤¦¥í¡¼¥À¤Ø¤Î
¥×¥í¥°¥é¥ß¥ó¥°¥¤¥ó¥¿¡¼¥Õ¥§¡¼¥¹
.SH ½ñ¼°
.B #include <dlfcn.h>
.sp
.BI "void *dlopen(const char *" filename ", int " flag );
.sp
.B "char *dlerror(void);"
.sp
.BI "void *dlsym(void *" handle ", const char *" symbol );
.sp
.BI "int dlclose(void *" handle );
.sp
\fI\-ldl\fP ¤Ç¥ê¥ó¥¯¤¹¤ë¡£
.SH ÀâÌÀ
.BR dlopen (),
.BR dlsym (),
.BR dlclose (),
.BR dlerror ()
¤Î 4¤Ä¤Î´Ø¿ô¤Ï¡¢Æ°Åª¥ê¥ó¥¯ (dynamic linking) ¤ò¹Ô¤¦¥í¡¼¥À¤Ø¤Î
¥¤¥ó¥¿¥Õ¥§¡¼¥¹¤ò¼ÂÁõ¤·¤¿¤â¤Î¤Ç¤¢¤ë¡£
.SS "dlerror()"
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.BR dlerror ()
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.BR dlerror ()
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.BR dlopen (),
.BR dlsym (),
.BR dlclose ()
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.SS "dlopen()"
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.BR dlopen ()
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.I filename
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(¾ÜºÙ¤Ï
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} Dl_info;
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#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>

int
main(int argc, char **argv)
{
    void *handle;
    double (*cosine)(double);
    char *error;

    handle = dlopen("libm.so", RTLD_LAZY);
    if (!handle) {
        fprintf(stderr, "%s\en", dlerror());
        exit(EXIT_FAILURE);
    }

    dlerror();    /* Clear any existing error */

    /* Writing: cosine = (double (*)(double)) dlsym(handle, "cos");
       would seem more natural, but the C99 standard leaves
       casting from "void *" to a function pointer undefined.
       The assignment used below is the POSIX.1\-2003 (Technical
       Corrigendum 1) workaround; see the Rationale for the
       POSIX specification of dlsym(). */

    *(void **) (&cosine) = dlsym(handle, "cos");
.\" But in fact "gcc -O2 -Wall" will complain about the preceding cast.

    if ((error = dlerror()) != NULL)  {
        fprintf(stderr, "%s\en", error);
        exit(EXIT_FAILURE);
    }

    printf("%f\en", (*cosine)(2.0));
    dlclose(handle);
    exit(EXIT_SUCCESS);
}
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.in
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.in
.SH ´ØÏ¢¹àÌÜ
.BR ld (1),
.BR ldd (1),
.BR dl_iterate_phdr (3),
.BR feature_test_macros (7),
.BR rtld-audit (7),
.BR ld.so (8),
.BR ldconfig (8),
ld.so info pages, gcc info pages, ld info pages