runtime: send android stderr to /dev/log/main
I tried to submit this in Go 1.4 as cl/107540044 but tripped over the
changes for getting C off the G stack. This is a rewritten version that
avoids cgo and works directly with the underlying log device.
Change-Id: I14c227dbb4202690c2c67c5a613d6c6689a6662a
Reviewed-on: https://go-review.googlesource.com/1285
Reviewed-by: Keith Randall <khr@golang.org>
diff --git a/src/runtime/print1.go b/src/runtime/print1.go
index 3d812bd..7bec559 100644
--- a/src/runtime/print1.go
+++ b/src/runtime/print1.go
@@ -75,7 +75,7 @@
}
gp := getg()
if gp == nil || gp.writebuf == nil {
- write(2, unsafe.Pointer(&b[0]), int32(len(b)))
+ writeErr(b)
return
}
diff --git a/src/runtime/print1_write.go b/src/runtime/print1_write.go
new file mode 100644
index 0000000..5fd7d65
--- /dev/null
+++ b/src/runtime/print1_write.go
@@ -0,0 +1,9 @@
+// +build !android
+
+package runtime
+
+import "unsafe"
+
+func writeErr(b []byte) {
+ write(2, unsafe.Pointer(&b[0]), int32(len(b)))
+}
diff --git a/src/runtime/print1_write_android.go b/src/runtime/print1_write_android.go
new file mode 100644
index 0000000..d086e84
--- /dev/null
+++ b/src/runtime/print1_write_android.go
@@ -0,0 +1,44 @@
+package runtime
+
+import "unsafe"
+
+var (
+ writeHeader = []byte{6 /* ANDROID_LOG_ERROR */, 'G', 'o', 0}
+ writePath = []byte("/dev/log/main\x00")
+ writeFD uintptr
+ writeBuf [1024]byte
+ writePos int
+)
+
+func writeErr(b []byte) {
+ // Log format: "<priority 1 byte><tag n bytes>\x00<message m bytes>\x00"
+ // The entire log needs to be delivered in a single syscall (the NDK
+ // does this with writev). Each log is its own line, so we need to
+ // buffer writes until we see a newline.
+ if writeFD == 0 {
+ writeFD = uintptr(open(&writePath[0], 0x1 /* O_WRONLY */, 0))
+ if writeFD == 0 {
+ // It is hard to do anything here. Write to stderr just
+ // in case user has root on device and has run
+ // adb shell setprop log.redirect-stdio true
+ msg := []byte("runtime: cannot open /dev/log/main\x00")
+ write(2, unsafe.Pointer(&msg[0]), int32(len(msg)))
+ exit(2)
+ }
+ copy(writeBuf[:], writeHeader)
+ }
+ dst := writeBuf[len(writeHeader):]
+ for _, v := range b {
+ if v == 0 { // android logging won't print a zero byte
+ v = '0'
+ }
+ dst[writePos] = v
+ writePos++
+ if v == '\n' || writePos == len(dst)-1 {
+ dst[writePos] = 0
+ write(writeFD, unsafe.Pointer(&writeBuf[0]), int32(len(writeHeader)+writePos))
+ memclrBytes(dst)
+ writePos = 0
+ }
+ }
+}
