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/* @(#)avoffset.c 1.24 04/05/09 Copyright 1987, 1995-2004 J. Schilling */
#ifndef lint
static char sccsid[] =
"@(#)avoffset.c 1.24 04/05/09 Copyright 1987, 1995-2004 J. Schilling";
#endif
/*
* This program is a tool to generate the file "avoffset.h".
* It is used by functions that trace the stack to get to the top of the stack.
*
* It generates two defines:
* AV_OFFSET - offset of argv relative to the main() frame pointer
* FP_INDIR - number of stack frames above main()
* before encountering a NULL pointer.
*
* Copyright (c) 1987, 1995-2004 J. Schilling
*/
/*
* This program is free software; 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, or (at your option)
* any later version.
*
* This program 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 program; see the file COPYING. If not, write to the Free Software
* Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <mconfig.h>
#include <stdio.h>
#include <standard.h>
#include <schily.h>
#include <stdxlib.h>
#include <signal.h>
#ifdef HAVE_SCANSTACK
# include <stkframe.h>
#endif
LOCAL RETSIGTYPE handler __PR((int signo));
EXPORT int main __PR((int ac, char **av));
LOCAL int stack_direction __PR((long *lp));
LOCAL RETSIGTYPE
handler(signo)
int signo;
{
fprintf(stderr, "Warning: Cannot scan stack on this environment.\n");
exit(0);
}
int
main(ac, av)
int ac;
char **av;
{
int stdir;
#ifdef HAVE_SCANSTACK
register struct frame *fp;
register int i = 0;
register int o = 0;
/*
* As the SCO OpenServer C-Compiler has a bug that may cause
* the first function call to getfp() been done before the
* new stack frame is created, we call getfp() twice.
*/
(void) getfp();
fp = (struct frame *)getfp();
#endif
#ifdef SIGBUS
signal(SIGBUS, handler);
#endif
signal(SIGSEGV, handler);
printf("/*\n");
printf(" * This file has been generated automatically\n");
printf(" * by %s\n", sccsid);
printf(" * do not edit by hand.\n");
printf(" *\n");
printf(" * This file includes definitions for AV_OFFSET and FP_INDIR.\n");
printf(" * FP_INDIR is the number of fp chain elements above 'main'.\n");
printf(" * AV_OFFSET is the offset of &av[0] relative to the frame pointer in 'main'.\n");
printf(" *\n");
printf(" * If getav0() does not work on a specific architecture\n");
printf(" * the program which generated this include file may dump core.\n");
printf(" * In this case, the generated include file does not include\n");
printf(" * definitions for AV_OFFSET and FP_INDIR but ends after this comment.\n");
printf(" * If AV_OFFSET or FP_INDIR are missing in this file, all programs\n");
printf(" * which use the definitions are automatically disabled.\n");
printf(" */\n");
stdir = stack_direction(0);
printf("#define STACK_DIRECTION %d\n", stdir);
fflush(stdout);
#ifdef HAVE_SCANSTACK
/*
* Note: Scanning the stack to look for argc/argv
* works only in the main thread.
*/
while (fp->fr_savfp) {
if (fp->fr_savpc == 0)
break;
fp = (struct frame *)fp->fr_savfp;
i++;
}
/*
* Do not add any printf()'s before this line to allow avoffset
* to abort without printing more than the comment above.
*/
fp = (struct frame *)getfp();
o = ((char *)av) - ((char *)fp);
if ((o % sizeof (char *)) != 0) {
fprintf(stderr, "AV_OFFSET value (%d) not a multiple of pointer size.\n", o);
fprintf(stderr, "Disabling scanning the stack.\n");
exit(0);
}
if (o < -1000 || o > 1000) {
fprintf(stderr, "AV_OFFSET value (%d) does not look reasonable.\n", o);
fprintf(stderr, "Disabling scanning the stack.\n");
exit(0);
}
printf("#define AV_OFFSET %d\n", o);
printf("#define FP_INDIR %d\n", i);
#endif
exit(0);
return (0); /* keep lint happy */
}
LOCAL int
stack_direction(lp)
long *lp;
{
auto long *dummy[4];
int i;
for (i = 0; i < 4; i++)
dummy[i] = lp;
if (lp == 0) {
return (stack_direction((long *)dummy));
} else {
if ((long *)dummy == lp)
return (0);
return (((long *)dummy > lp) ? 1 : -1);
}
}
#define IS_AVOFFSET
#include <getfp.c>
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