log: send crash output to a sep fd

Author: ignoramous

intra/backend/protect.go

@@ -15,6 +15,7 @@ const ( // see protect/protect.go
 type Console interface {
 	Log(int32, *Gostr)
 	LogFD(readAfterDup int) bool
+	CrashFD(readUntilEOF int) bool
 }
 
 // Controller provides a way to bind and protect socket file descriptors.

intra/log/fconsole.go

@@ -3,7 +3,6 @@ package log
 import (
 	"io"
 	"os"
-	"strings"
 	"syscall"
 	"unsafe"
 )
@@ -51,32 +50,11 @@ func setNonblock(f *os.File) error {
 	return syscall.SetNonblock(int(f.Fd()), true)
 }
 
-func (f *fconsole) write(msg Logmsg) {
-	if len(msg) == 0 {
-		return
-	}
-	for msgline := range strings.SplitSeq(msg, "\n") {
-		if len(msgline) <= 0 {
-			continue
-		}
-		if len(msgline) <= charsPerLine {
-			f.doWrite(msgline)
-		}
-
-		for len(msgline) > 0 {
-			m := msgline
-			if len(m) > charsPerLine {
-				m = m[:charsPerLine]
-			}
-			if err := f.doWrite(m); err != nil {
-				return
-			}
-			msgline = msgline[len(m):]
-		}
+func (f *fconsole) write(m Logmsg) error {
+	if len(m) == 0 {
+		return nil
 	}
-}
 
-func (f *fconsole) doWrite(m string) error {
 	w := f.w
 	if w == nil {
 		return io.ErrClosedPipe

intra/tun2socks.go

@@ -254,6 +254,20 @@ func FatalAtRandom(y bool) {
 	log.I("tun: fatal at random? %t", y)
 }
 
+func pipeCrashOutput(bdg Bridge) (ok bool) {
+	r, w, err := os.Pipe()
+	if err != nil {
+		log.E("tun: err crash output pipe: %v", err)
+		return false
+	}
+	if setCrashFd(w) && bdg.CrashFD(int(r.Fd())) {
+		return true
+	}
+	core.Close(r)
+	core.Close(w)
+	return false
+}
+
 // setCrashFd sets dup(f) as output file to write go runtime crashes in to.
 func setCrashFd(f *os.File) (ok bool) {
 	// f is dup()ed by debug.SetCrashOutput before use

intra/tunnel.go

@@ -187,15 +187,13 @@ func NewTunnel2(fd, linkmtu, tunmtu int, ifaddrs, fakedns string, dtr DefaultDNS
 	const dualstack = settings.IP46
 
 	logfd := false
-	crashfd := false
 	if r, c, err := log.NewFilebased(); err == nil {
 		closeall := func() {
 			core.Close(c)
 			core.Close(r)
 		}
 		if logfd = bdg.LogFD(int(r.Fd())); logfd {
 			log.SetConsole(ctx, c)
-			crashfd = setCrashFd(c.File())
 			context.AfterFunc(ctx, closeall)
 		} else {
 			closeall()
@@ -205,6 +203,8 @@ func NewTunnel2(fd, linkmtu, tunmtu int, ifaddrs, fakedns string, dtr DefaultDNS
 		log.SetConsole(ctx, &clogAdapter{bdg})
 	}
 
+	crashfd := pipeCrashOutput(bdg)
+
 	natpt := x64.NewNatPt2(ctx)
 	proxies := ipn.NewProxifier(ctx, dualstack, linkmtu, bdg, bdg)
 	services := rnet.NewServices(ctx, proxies, bdg, bdg)