.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
.\" drawing on material by Justin Pryzby <pryzbyj@justinpryzby.com>
.\"
.\" Permission is hereby granted, free of charge, to any person obtaining
.\" a copy of this software and associated documentation files (the
.\" "Software"), to deal in the Software without restriction, including
.\" without limitation the rights to use, copy, modify, merge, publish,
.\" distribute, sublicense, and/or sell copies of the Software, and to
.\" permit persons to whom the Software is furnished to do so, subject to
.\" the following conditions:
.\"
.\" The above copyright notice and this permission notice shall be
.\" included in all copies or substantial portions of the Software.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
.\" IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
.\" CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
.\" TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
.\" SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
.\"
.\" References:
.\"   glibc manual and source
.\"
.\" Japanese Version Copyright (c) 2007  Akihiro MOTOKI
.\"         all rights reserved.
.\" Translated 2007-10-16, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v2.66
.\"
.TH BACKTRACE 3 2008-06-14 GNU "Linux Programmer's Manual"
.SH ̾
backtrace, backtrace_symbols, backtrace_symbols_fd \- 
ץꥱ󼫿ȤǤΥǥХåΥݡ
.SH 
.B #include <execinfo.h>

.B int backtrace(void
.BI ** buffer ,
.B int
.IB size );

.B char **backtrace_symbols(void *const
.BI * buffer ,
.B int
.IB size );

.B void backtrace_symbols_fd(void *const
.BI * buffer ,
.B int
.IB size ,
.B int
.IB fd );
.SH 
.BR backtrace ()
ϡƤӽФץΥХåȥ졼
.I buffer
ؤ֤Хåȥ졼ϡץ
ưδؿƤӽФ¤ӤǤ롣
.I buffer
ؤθġǤ \fIvoid *\fP ǡ
б륹åե졼फΥ꥿󥢥ɥ쥹Ǥ롣
.I size

.I buffer
˳ǼǤ륢ɥ쥹κĿꤹ롣
Хåȥ졼
.I size
礭硢
.I size
ĤľδؿƤӽФб륢ɥ쥹֤롣
ʥХåȥ졼뤿ˤϡμ¤
.I buffer

.I size
ʬ礭ʤ褦ˤ뤳ȡ

.BR backtrace ()
ˤä
.I buffer
˥ɥ쥹ν礬줿顢
.BR backtrace_symbols ()
ˤäơɥ쥹򡢤Υɥ쥹򥷥ܥɽʸ
Ǥ롣
.I size

.I buffer
˳Ǽ줿ɥ쥹οꤹ롣
ġΥɥ쥹Υܥɽϡؿ̾ (Ǥ)
ؿؤΥեå (16ɽ)ºݤΥ꥿󥢥ɥ쥹 (16ɽ)
鹽롣
.BR backtrace_symbols ()
μ¹Է̤ȤƤϡ
ʸݥ󥿤Υɥ쥹֤롣

.BR backtrace_symbols ()
ˤä
.BR malloc (3)
졢ƤӽФ¦ free ʤФʤʤ
(ݥ󥿤󤬻ؤġʸ free ɬפϤʤ
free ٤Ǥʤ)

.BR backtrace_symbols_fd ()
ϡ
.BR backtrace_symbols ()
Ʊ
.I buffer

.I size
Ȥ뤬ƤӽФ¦ʸ֤ˡ
ʸեǥץ
.I fd
 1 Ԥ 1 ȥηǽ񤭹ࡣ
.BR backtrace_symbols_fd ()

.BR malloc (3)
ƤӽФʤ
Τᡢ³ؿԤǽǤѤǤ롣
.SH ֤
.BR backtrace ()

.I buffer
˳Ǽɥ쥹θĿ֤θĿ
.I size
礭ʤ뤳ȤϤʤ
֤ͤ
.I size
꾮硢Хåȥ졼ΤǼƤ롣֤ͤ
.I size
硢Хåȥ졼ڤͤƤ뤫⤷ʤ
ڤͤ줿硢ǤŤåե졼Υɥ쥹
֤ʤȤˤʤ롣

.BR backtrace_symbols ()
ϡȡθƤӽФ
.BR malloc (3)
줿ؤΥݥ󥿤֤
顼ξ硢 NULL ֤
.SH С
.BR backtrace (),
.BR backtrace_symbols (),
.BR backtrace_symbols_fd ()
ϥС 2.1 ʹߤ glibc 󶡤Ƥ롣
.SH 
δؿ GNU ˤĥǤ롣
.SH 
δؿϡؿΥ꥿󥢥ɥ쥹åǤɤΤ褦˳Ǽ뤫
˴ؤƤ벾֤Ƥ롣
ʲա
.IP * 3
.RB ( gcc (1)
 0 ʳκŬ٥ǰۤΤ˹Ԥ)
ե졼ݥ󥿤ξάԤȡǽ롣
.IP *
饤ؿϥåե졼ʤ
.IP *
ƤӽФκŬ (tail-call optimization) Ԥȡ
륹åե졼ब̤Υåե졼֤ǽ롣
.PP
ܥ̤̾ʥ󥫡ץѤʤѤǤʤ礬롣
GNU 󥫤Ѥ륷ƥǤϡ
.I \-rdynamic
󥫡ץȤɬפ롣
"static" ʴؿΥܥ̾ϸ줺
Хåȥ졼ǤѤǤʤդ뤳ȡ
.SH 
ʲΥץϡ
.BR backtrace ()

.BR backtrace_symbols ()
λ򼨤ΤǤ롣
ʲ˼Υåϡ
Υץưݤμ¹Ǥ롣
.nf
.in +4n

.RB "$" " cc \-rdynamic prog.c \-o prog"
.RB "$" " ./prog 3"
backtrace() returned 8 addresses
\&./prog(myfunc3+0x5c) [0x80487f0]
\&./prog [0x8048871]
\&./prog(myfunc+0x21) [0x8048894]
\&./prog(myfunc+0x1a) [0x804888d]
\&./prog(myfunc+0x1a) [0x804888d]
\&./prog(main+0x65) [0x80488fb]
\&/lib/libc.so.6(__libc_start_main+0xdc) [0xb7e38f9c]
\&./prog [0x8048711]
.in
.fi
.SS ץΥ
\&
.nf
#include <execinfo.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

void
myfunc3(void)
{
    int j, nptrs;
#define SIZE 100
    void *buffer[100];
    char **strings;

    nptrs = backtrace(buffer, SIZE);
    printf("backtrace() returned %d addresses\\n", nptrs);

    /* backtrace_symbols_fd(buffer, nptrs, STDOUT_FILENO) 
       ƤӽФƤ⡢ʲƱͤνϤ롣 */

    strings = backtrace_symbols(buffer, nptrs);
    if (strings == NULL) {
        perror("backtrace_symbols");
        exit(EXIT_FAILURE);
    }

    for (j = 0; j < nptrs; j++)
        printf("%s\\n", strings[j]);

    free(strings);
}

static void   /* "static" ϥܥʤȤ̣ */
myfunc2(void)
{
    myfunc3();
}

void
myfunc(int ncalls)
{
    if (ncalls > 1)
        myfunc(ncalls \- 1);
    else
        myfunc2();
}

int
main(int argc, char *argv[])
{
    if (argc != 2) {
        fprintf(stderr, "%s num\-calls\\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    myfunc(atoi(argv[1]));
    exit(EXIT_SUCCESS);
}
.fi
.SH Ϣ
.BR gcc (1),
.BR ld (1),
.BR dlopen (3),
.BR malloc (3)