mirror of
https://github.com/autc04/Retro68.git
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161 lines
4.6 KiB
Go
161 lines
4.6 KiB
Go
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "unsafe"
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var (
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writeHeader = []byte{6 /* ANDROID_LOG_ERROR */, 'G', 'o', 0}
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writePath = []byte("/dev/log/main\x00")
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writeLogd = []byte("/dev/socket/logdw\x00")
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// guarded by printlock/printunlock.
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writeFD uintptr
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writeBuf [1024]byte
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writePos int
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)
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// Prior to Android-L, logging was done through writes to /dev/log files implemented
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// in kernel ring buffers. In Android-L, those /dev/log files are no longer
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// accessible and logging is done through a centralized user-mode logger, logd.
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//
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// https://android.googlesource.com/platform/system/core/+/master/liblog/logd_write.c
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type loggerType int32
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const (
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unknown loggerType = iota
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legacy
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logd
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// TODO(hakim): logging for emulator?
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)
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var logger loggerType
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func writeErr(b []byte) {
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if logger == unknown {
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// Use logd if /dev/socket/logdw is available.
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if v := uintptr(access(&writeLogd[0], 0x02 /* W_OK */)); v == 0 {
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logger = logd
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initLogd()
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} else {
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logger = legacy
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initLegacy()
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}
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}
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// Write to stderr for command-line programs.
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write(2, unsafe.Pointer(&b[0]), int32(len(b)))
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// Log format: "<header>\x00<message m bytes>\x00"
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//
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// <header>
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// In legacy mode: "<priority 1 byte><tag n bytes>".
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// In logd mode: "<android_log_header_t 11 bytes><priority 1 byte><tag n bytes>"
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//
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// The entire log needs to be delivered in a single syscall (the NDK
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// does this with writev). Each log is its own line, so we need to
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// buffer writes until we see a newline.
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var hlen int
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switch logger {
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case logd:
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hlen = writeLogdHeader()
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case legacy:
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hlen = len(writeHeader)
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}
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dst := writeBuf[hlen:]
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for _, v := range b {
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if v == 0 { // android logging won't print a zero byte
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v = '0'
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}
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dst[writePos] = v
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writePos++
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if v == '\n' || writePos == len(dst)-1 {
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dst[writePos] = 0
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write(writeFD, unsafe.Pointer(&writeBuf[0]), int32(hlen+writePos))
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memclrBytes(dst)
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writePos = 0
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}
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}
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}
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func initLegacy() {
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// In legacy mode, logs are written to /dev/log/main
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writeFD = uintptr(open(&writePath[0], 0x1 /* O_WRONLY */, 0))
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if writeFD == 0 {
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// It is hard to do anything here. Write to stderr just
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// in case user has root on device and has run
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// adb shell setprop log.redirect-stdio true
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msg := []byte("runtime: cannot open /dev/log/main\x00")
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write(2, unsafe.Pointer(&msg[0]), int32(len(msg)))
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exit(2)
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}
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// Prepopulate the invariant header part.
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copy(writeBuf[:len(writeHeader)], writeHeader)
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}
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// used in initLogdWrite but defined here to avoid heap allocation.
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var logdAddr sockaddr_un
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func initLogd() {
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// In logd mode, logs are sent to the logd via a unix domain socket.
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logdAddr.family = _AF_UNIX
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copy(logdAddr.path[:], writeLogd)
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// We are not using non-blocking I/O because writes taking this path
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// are most likely triggered by panic, we cannot think of the advantage of
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// non-blocking I/O for panic but see disadvantage (dropping panic message),
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// and blocking I/O simplifies the code a lot.
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fd := socket(_AF_UNIX, _SOCK_DGRAM|_O_CLOEXEC, 0)
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if fd < 0 {
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msg := []byte("runtime: cannot create a socket for logging\x00")
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write(2, unsafe.Pointer(&msg[0]), int32(len(msg)))
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exit(2)
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}
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errno := connect(fd, unsafe.Pointer(&logdAddr), int32(unsafe.Sizeof(logdAddr)))
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if errno < 0 {
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msg := []byte("runtime: cannot connect to /dev/socket/logdw\x00")
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write(2, unsafe.Pointer(&msg[0]), int32(len(msg)))
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// TODO(hakim): or should we just close fd and hope for better luck next time?
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exit(2)
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}
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writeFD = uintptr(fd)
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// Prepopulate invariant part of the header.
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// The first 11 bytes will be populated later in writeLogdHeader.
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copy(writeBuf[11:11+len(writeHeader)], writeHeader)
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}
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// writeLogdHeader populates the header and returns the length of the payload.
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func writeLogdHeader() int {
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hdr := writeBuf[:11]
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// The first 11 bytes of the header corresponds to android_log_header_t
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// as defined in system/core/include/private/android_logger.h
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// hdr[0] log type id (unsigned char), defined in <log/log.h>
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// hdr[1:2] tid (uint16_t)
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// hdr[3:11] log_time defined in <log/log_read.h>
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// hdr[3:7] sec unsigned uint32, little endian.
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// hdr[7:11] nsec unsigned uint32, little endian.
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hdr[0] = 0 // LOG_ID_MAIN
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sec, nsec := time_now()
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packUint32(hdr[3:7], uint32(sec))
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packUint32(hdr[7:11], uint32(nsec))
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// TODO(hakim): hdr[1:2] = gettid?
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return 11 + len(writeHeader)
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}
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func packUint32(b []byte, v uint32) {
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// little-endian.
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b[0] = byte(v)
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b[1] = byte(v >> 8)
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b[2] = byte(v >> 16)
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b[3] = byte(v >> 24)
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}
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