mirror of
https://github.com/jart/cosmopolitan.git
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88 lines
3.5 KiB
C
88 lines
3.5 KiB
C
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 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 "libc/intrin/bits.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/log/backtrace.internal.h"
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#include "libc/log/log.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/symbols.internal.h"
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#include "libc/sysv/errfuns.h"
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static bool __watch_busy;
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static void *__watch_addr;
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static size_t __watch_size;
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static char __watch_last[4096];
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void __watch_hook(void);
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static noinstrument inline void Copy(char *p, char *q, size_t n) {
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size_t i;
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for (i = 0; i < n; ++i) {
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p[i] = q[i];
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}
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}
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static noinstrument inline int Cmp(char *p, char *q, size_t n) {
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int c;
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if (n == 8) return READ64LE(p) != READ64LE(q);
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if (n == 4) return READ32LE(p) != READ32LE(q);
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for (; n; ++p, ++q, --n) {
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if (*p != *q) {
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return 1;
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}
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}
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return 0;
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}
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noinstrument void __watcher(void) {
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if (__watch_busy) return;
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__watch_busy = true;
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if (Cmp(__watch_last, __watch_addr, __watch_size)) {
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kprintf("watchpoint %p changed:\n"
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"%#.*hhs\n"
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"%#.*hhs\n",
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__watch_addr, //
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__watch_size, __watch_last, //
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__watch_size, __watch_addr);
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Copy(__watch_last, __watch_addr, __watch_size);
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ShowBacktrace(2, __builtin_frame_address(0));
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}
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__watch_busy = false;
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}
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/**
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* Watches memory address for changes.
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*
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* It's useful for situations when ASAN and GDB both aren't working.
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*/
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int __watch(void *addr, size_t size) {
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static bool once;
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if (__watch_busy) ebusy();
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if (size > sizeof(__watch_last)) return einval();
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if (!once) {
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if (!GetSymbolTable()) return -1;
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if (__hook(__watch_hook, GetSymbolTable()) == -1) return -1;
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once = true;
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}
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__watch_addr = addr;
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__watch_size = size;
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Copy(__watch_last, __watch_addr, __watch_size);
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return 0;
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}
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