240 lines
6.0 KiB
C
240 lines
6.0 KiB
C
/* $NetBSD: c-stack.c,v 1.1.1.1 2003/01/26 00:43:15 wiz Exp $ */
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/* Stack overflow handling.
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Copyright (C) 2002 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* Written by Paul Eggert. */
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/* This module assumes that each stack frame is smaller than a page.
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If you use alloca, dynamic arrays, or large local variables, your
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program may extend the stack by more than a page at a time. If so,
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the code below may incorrectly report a program error, or worse
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yet, may not detect the overflow at all. To avoid this problem,
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don't use large local arrays. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "gettext.h"
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#define _(msgid) gettext (msgid)
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#include <errno.h>
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#ifndef ENOTSUP
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# define ENOTSUP EINVAL
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#endif
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#if HAVE_INTTYPES_H
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# include <inttypes.h>
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#else
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# if HAVE_STDINT_H
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# include <stdint.h>
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# endif
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#endif
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#include <signal.h>
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#include <stdlib.h>
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#include <string.h>
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#ifndef STDERR_FILENO
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# define STDERR_FILENO 2
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#endif
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#include "c-stack.h"
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#include "exitfail.h"
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extern char *program_name;
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#if HAVE_XSI_STACK_OVERFLOW_HEURISTIC
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# include <ucontext.h>
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/* Storage for the alternate signal stack. */
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static union
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{
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char buffer[SIGSTKSZ];
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/* These other members are for proper alignment. There's no
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standard way to guarantee stack alignment, but this seems enough
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in practice. */
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long double ld;
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uintmax_t u;
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void *p;
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} alternate_signal_stack;
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/* Direction of the C runtime stack. This function is
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async-signal-safe. */
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# if STACK_DIRECTION
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# define find_stack_direction(ptr) STACK_DIRECTION
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# else
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static int
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find_stack_direction (char const *addr)
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{
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char dummy;
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return ! addr ? find_stack_direction (&dummy) : addr < &dummy ? 1 : -1;
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}
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# endif
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/* The SIGSEGV handler. */
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static void (* volatile segv_action) (int, siginfo_t *, void *);
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/* Handle a segmentation violation and exit. This function is
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async-signal-safe. */
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static void
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segv_handler (int signo, siginfo_t *info, void *context)
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{
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/* Clear SIGNO if it seems to have been a stack overflow. */
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if (0 < info->si_code)
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{
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/* If the faulting address is within the stack, or within one
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page of the stack end, assume that it is a stack
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overflow. */
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ucontext_t const *user_context = context;
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char const *stack_min = user_context->uc_stack.ss_sp;
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size_t stack_size = user_context->uc_stack.ss_size;
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char const *faulting_address = info->si_addr;
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size_t s = faulting_address - stack_min;
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size_t page_size = sysconf (_SC_PAGESIZE);
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if (find_stack_direction (0) < 0)
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s += page_size;
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if (s < stack_size + page_size)
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signo = 0;
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}
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segv_action (signo, info, context);
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}
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#endif /* HAVE_XSI_STACK_OVERFLOW_HEURISTIC */
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/* Translated messages for program errors and stack overflow. Do not
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translate them in the signal handler, since gettext is not
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async-signal-safe. */
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static char const * volatile program_error_message;
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static char const * volatile stack_overflow_message;
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/* Output an error message, then exit with status EXIT_FAILURE if it
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appears to have been a stack overflow, or with a core dump
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otherwise. This function is async-signal-safe. */
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void
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c_stack_die (int signo, siginfo_t *info, void *context)
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{
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char const *message =
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signo ? program_error_message : stack_overflow_message;
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write (STDERR_FILENO, program_name, strlen (program_name));
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write (STDERR_FILENO, ": ", 2);
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write (STDERR_FILENO, message, strlen (message));
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write (STDERR_FILENO, "\n", 1);
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if (! signo)
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_exit (exit_failure);
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#if HAVE_SIGINFO_T
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if (context && info && 0 <= info->si_code)
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{
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/* Re-raise the exception at the same address. */
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char *addr = info->si_addr;
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*addr = 0;
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}
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#endif
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kill (getpid (), signo);
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}
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/* Set up ACTION so that it is invoked on C stack overflow. Return -1
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(setting errno) if this cannot be done.
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ACTION must invoke only async-signal-safe functions. ACTION
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together with its callees must not require more than SIGSTKSZ bytes
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of stack space. */
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int
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c_stack_action (void (*action) (int, siginfo_t *, void *))
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{
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#if ! HAVE_XSI_STACK_OVERFLOW_HEURISTIC
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errno = ENOTSUP;
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return -1;
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#else
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struct sigaction act;
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stack_t st;
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int r;
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st.ss_flags = 0;
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st.ss_sp = alternate_signal_stack.buffer;
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st.ss_size = sizeof alternate_signal_stack.buffer;
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r = sigaltstack (&st, 0);
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if (r != 0)
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return r;
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program_error_message = _("program error");
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stack_overflow_message = _("stack overflow");
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segv_action = action;
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sigemptyset (&act.sa_mask);
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/* POSIX 1003.1-2001 says SA_RESETHAND implies SA_NODEFER, but this
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is not true on Solaris 8 at least. It doesn't hurt to use
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SA_NODEFER here, so leave it in. */
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act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND | SA_SIGINFO;
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act.sa_sigaction = segv_handler;
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return sigaction (SIGSEGV, &act, 0);
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#endif
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}
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#if DEBUG
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#include <stdio.h>
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int volatile exit_failure;
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static long
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recurse (char *p)
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{
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char array[500];
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array[0] = 1;
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return *p + recurse (array);
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}
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char *program_name;
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int
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main (int argc, char **argv)
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{
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program_name = argv[0];
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c_stack_action (c_stack_die);
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return recurse ("\1");
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}
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#endif /* DEBUG */
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/*
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Local Variables:
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compile-command: "gcc -D_GNU_SOURCE -DDEBUG \
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-DHAVE_INTTYPES_H -DHAVE_SIGINFO_T \
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-DHAVE_XSI_STACK_OVERFLOW_HEURISTIC -DHAVE_UNISTD_H \
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-Wall -W -g c-stack.c -o c-stack"
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End:
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*/
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