94 lines
1.9 KiB
Go
94 lines
1.9 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// The goroutines package contains utilities for getting active goroutines.
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package goroutines
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import (
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"bytes"
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"fmt"
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"runtime"
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"strconv"
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)
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// ScrubbedGoroutineDump returns either the current goroutine's stack or all
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// goroutines' stacks, but with the actual values of arguments scrubbed out,
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// lest it contain some private key material.
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func ScrubbedGoroutineDump(all bool) []byte {
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var buf []byte
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// Grab stacks multiple times into increasingly larger buffer sizes
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// to minimize the risk that we blow past our iOS memory limit.
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for size := 1 << 10; size <= 1<<20; size += 1 << 10 {
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buf = make([]byte, size)
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buf = buf[:runtime.Stack(buf, all)]
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if len(buf) < size {
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// It fit.
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break
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}
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}
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return scrubHex(buf)
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}
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func scrubHex(buf []byte) []byte {
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saw := map[string][]byte{} // "0x123" => "v1%3" (unique value 1 and its value mod 8)
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foreachHexAddress(buf, func(in []byte) {
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if string(in) == "0x0" {
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return
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}
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if v, ok := saw[string(in)]; ok {
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for i := range in {
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in[i] = '_'
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}
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copy(in, v)
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return
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}
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inStr := string(in)
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u64, err := strconv.ParseUint(string(in[2:]), 16, 64)
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for i := range in {
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in[i] = '_'
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}
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if err != nil {
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in[0] = '?'
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return
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}
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v := []byte(fmt.Sprintf("v%d%%%d", len(saw)+1, u64%8))
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saw[inStr] = v
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copy(in, v)
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})
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return buf
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}
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var ohx = []byte("0x")
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// foreachHexAddress calls f with each subslice of b that matches
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// regexp `0x[0-9a-f]*`.
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func foreachHexAddress(b []byte, f func([]byte)) {
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for len(b) > 0 {
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i := bytes.Index(b, ohx)
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if i == -1 {
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return
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}
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b = b[i:]
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hx := hexPrefix(b)
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f(hx)
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b = b[len(hx):]
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}
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}
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func hexPrefix(b []byte) []byte {
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for i, c := range b {
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if i < 2 {
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continue
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}
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if !isHexByte(c) {
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return b[:i]
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}
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}
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return b
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}
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func isHexByte(b byte) bool {
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return '0' <= b && b <= '9' || 'a' <= b && b <= 'f' || 'A' <= b && b <= 'F'
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}
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