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/* Run with a larger (mmap'd) stack.
Copyright (C) 2003 Free Software Foundation, Inc.
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; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Written by Jim Meyering. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdio.h>
#include <assert.h>
#include <unistd.h>
#include <stdarg.h>
#if HAVE_SYS_MMAN_H
# include <sys/mman.h>
#endif
#if HAVE_UCONTEXT_H
# include <ucontext.h>
#endif
#include "mmap-stack.h"
#ifndef MAP_ANONYMOUS
# ifdef MAP_ANON
# define MAP_ANONYMOUS MAP_ANON
# else
# define MAP_ANONYMOUS 0
# endif
#endif
/* Set up context, *CTX, so that it may be used via makecontext,
using a block of SIZE bytes of mmap'd memory for its stack.
Return nonzero upon error. */
static int
get_context (ucontext_t *ctx, size_t size)
{
void *stack;
int fd = -1; /* This must be -1 in order for Solaris' MAP_ANON to work. */
if (getcontext (ctx))
return 1;
/* use tmpfile if MAP_ANONYMOUS is not useful. */
#if MAP_ANONYMOUS == 0
{
FILE *fp = tmpfile ();
if (!fp)
return 1;
fd = fileno (fp);
}
#endif
stack = mmap (NULL, size,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, fd, 0);
if (stack == MAP_FAILED)
return 1;
ctx->uc_stack.ss_sp = stack;
ctx->uc_stack.ss_size = size;
ctx->uc_link = NULL;
return 0;
}
/* Yep, this is arbitrary. tough :-) */
#define ARGC_MAX 6
/* Set up a context without conventional stack limitations,
then call function FUNC with the specified number (ARGC) of arguments.
If get_context and setcontext succeed, this function does not return,
so FUNC must be sure to exit appropriately. Otherwise, this function
does return, and the caller should diagnose the failure. */
void
run_on_mmaped_stack (void (*func) (void), size_t argc, ...)
{
ucontext_t ctx;
size_t size = 256 * 1024 * 1024;
long argv[ARGC_MAX];
unsigned i;
va_list ap;
assert (argc <= ARGC_MAX);
va_start (ap, argc);
for (i = 0; i < argc; i++)
argv[i] = va_arg (ap, long);
va_end (ap);
if (get_context (&ctx, size) == 0)
{
makecontext (&ctx, func, argc,
argv[0], argv[1], argv[2],
argv[3], argv[4], argv[5]);
setcontext (&ctx);
}
/* get_context or setcontext failed;
Resort to using the conventional stack. */
}
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