mirror of
https://github.com/jart/cosmopolitan.git
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85 lines
3.2 KiB
C
85 lines
3.2 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include <cosmo.h>
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#include <limits.h>
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#include <pthread.h>
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#include <signal.h>
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#include <unistd.h>
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/**
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* stack overflow recovery technique #5
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* use the cosmo posix threads extensions
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*/
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sig_atomic_t smashed_stack;
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void CrashHandler(int sig) {
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smashed_stack = true;
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pthread_exit(0);
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}
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int StackOverflow(int d) {
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char A[8];
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for (int i = 0; i < sizeof(A); i++)
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A[i] = d + i;
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if (__veil("r", d))
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return StackOverflow(d + 1) + A[d % sizeof(A)];
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return 0;
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}
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void *MyPosixThread(void *arg) {
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exit(StackOverflow(0));
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return 0;
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}
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int main() {
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// choose the most dangerously small size possible
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size_t sigstacksize = sysconf(_SC_MINSIGSTKSZ) + 2048;
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// setup signal handler
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struct sigaction sa;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = SA_ONSTACK;
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sa.sa_handler = CrashHandler;
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if (sigaction(SIGBUS, &sa, 0))
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return 1;
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if (sigaction(SIGSEGV, &sa, 0))
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return 2;
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// create thread with signal stack
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pthread_t id;
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pthread_attr_t attr;
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if (pthread_attr_init(&attr))
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return 3;
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if (pthread_attr_setguardsize(&attr, getpagesize()))
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return 4;
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if (pthread_attr_setsigaltstacksize_np(&attr, sigstacksize))
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return 5;
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if (pthread_create(&id, &attr, MyPosixThread, 0))
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return 6;
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if (pthread_attr_destroy(&attr))
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return 7;
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if (pthread_join(id, 0))
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return 8;
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if (!smashed_stack)
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return 9;
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CheckForMemoryLeaks();
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}
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