Add InfoLogger support and move logs before mount completion to InfoLogger

connection.go

@@ -61,6 +61,7 @@ const maxReadahead = 1 << 20
 type Connection struct {
 	cfg         MountConfig
 	debugLogger *log.Logger
+	infoLogger  *log.Logger
 	errorLogger *log.Logger
 	wireLogger  io.Writer
 
@@ -109,12 +110,14 @@ func GetWirelog(ctx context.Context) *WireLogRecord {
 func newConnection(
 	cfg MountConfig,
 	debugLogger *log.Logger,
+	infoLogger *log.Logger,
 	errorLogger *log.Logger,
 	wireLogger io.Writer,
 	dev *os.File) (*Connection, error) {
 	c := &Connection{
 		cfg:         cfg,
 		debugLogger: debugLogger,
+		infoLogger:  infoLogger,
 		errorLogger: errorLogger,
 		wireLogger:  wireLogger,
 		dev:         dev,

log_util.go

@@ -0,0 +1,30 @@
+// Copyright 2026 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fuse
+
+import (
+	"log"
+)
+
+// firstLogger returns the first non-nil logger from the provided list.
+// If all are nil, it returns no-op logger
+func FirstLogger(loggers ...*log.Logger) *log.Logger {
+	for _, l := range loggers {
+		if l != nil {
+			return l
+		}
+	}
+	return nil
+}

mount.go

@@ -54,16 +54,17 @@ func Mount(
 	}
 
 	// Begin the mounting process, which will continue in the background.
-	if config.DebugLogger != nil {
-		config.DebugLogger.Println("Beginning the mounting kickoff process")
+	infoDebugFallbackLogger := FirstLogger(config.InfoLogger, config.DebugLogger)
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Beginning the mounting kickoff process")
 	}
 	ready := make(chan error, 1)
 	dev, err := mount(dir, config, ready)
 	if err != nil {
 		return nil, fmt.Errorf("mount: %v", err)
 	}
-	if config.DebugLogger != nil {
-		config.DebugLogger.Println("Completed the mounting kickoff process")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Completed the mounting kickoff process")
 	}
 
 	// Choose a parent context for ops.
@@ -72,21 +73,22 @@ func Mount(
 		cfgCopy.OpContext = context.Background()
 	}
 
-	if config.DebugLogger != nil {
-		config.DebugLogger.Println("Creating a connection object")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Creating a connection object")
 	}
 	// Create a Connection object wrapping the device.
 	connection, err := newConnection(
 		cfgCopy,
 		config.DebugLogger,
+		config.InfoLogger,
 		config.ErrorLogger,
 		config.WireLogger,
 		dev)
 	if err != nil {
 		return nil, fmt.Errorf("newConnection: %v", err)
 	}
-	if config.DebugLogger != nil {
-		config.DebugLogger.Println("Successfully created the connection")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Successfully created the connection")
 	}
 
 	// Serve the connection in the background. When done, set the join status.
@@ -96,8 +98,8 @@ func Mount(
 		close(mfs.joinStatusAvailable)
 	}()
 
-	if config.DebugLogger != nil {
-		config.DebugLogger.Println("Waiting for mounting process to complete")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Waiting for mounting process to complete")
 	}
 
 	// Wait for the mount process to complete.
@@ -128,18 +130,19 @@ func checkMountPoint(dir string) error {
 	return nil
 }
 
-func fusermount(binary string, argv []string, additionalEnv []string, wait bool, debugLogger *log.Logger) (*os.File, error) {
-	if debugLogger != nil {
-		debugLogger.Println("Creating a socket pair")
+func fusermount(binary string, argv []string, additionalEnv []string, wait bool, debugLogger *log.Logger, infoLogger *log.Logger) (*os.File, error) {
+	infoDebugFallbackLogger := FirstLogger(infoLogger, debugLogger)
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Creating a socket pair")
 	}
 	// Create a socket pair.
 	fds, err := syscall.Socketpair(syscall.AF_UNIX, syscall.SOCK_STREAM, 0)
 	if err != nil {
 		return nil, fmt.Errorf("Socketpair: %v", err)
 	}
 
-	if debugLogger != nil {
-		debugLogger.Println("Creating files to wrap the sockets")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Creating files to wrap the sockets")
 	}
 	// Wrap the sockets into os.File objects that we will pass off to fusermount.
 	writeFile := os.NewFile(uintptr(fds[0]), "fusermount-child-writes")
@@ -148,8 +151,8 @@ func fusermount(binary string, argv []string, additionalEnv []string, wait bool,
 	readFile := os.NewFile(uintptr(fds[1]), "fusermount-parent-reads")
 	defer readFile.Close()
 
-	if debugLogger != nil {
-		debugLogger.Println("Starting fusermount/os mount")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Starting fusermount/os mount")
 	}
 	// Start fusermount/mount_macfuse/mount_osxfuse.
 	cmd := exec.Command(binary, argv...)
@@ -168,8 +171,8 @@ func fusermount(binary string, argv []string, additionalEnv []string, wait bool,
 		return nil, fmt.Errorf("running %v: %v", binary, err)
 	}
 
-	if debugLogger != nil {
-		debugLogger.Println("Wrapping socket pair in a connection")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Wrapping socket pair in a connection")
 	}
 	// Wrap the socket file in a connection.
 	c, err := net.FileConn(readFile)
@@ -178,17 +181,17 @@ func fusermount(binary string, argv []string, additionalEnv []string, wait bool,
 	}
 	defer c.Close()
 
-	if debugLogger != nil {
-		debugLogger.Println("Checking that we have a unix domain socket")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Checking that we have a unix domain socket")
 	}
 	// We expect to have a Unix domain socket.
 	uc, ok := c.(*net.UnixConn)
 	if !ok {
 		return nil, fmt.Errorf("Expected UnixConn, got %T", c)
 	}
 
-	if debugLogger != nil {
-		debugLogger.Println("Read a message from socket")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Read a message from socket")
 	}
 	// Read a message.
 	buf := make([]byte, 32) // expect 1 byte
@@ -211,8 +214,8 @@ func fusermount(binary string, argv []string, additionalEnv []string, wait bool,
 
 	scm := scms[0]
 
-	if debugLogger != nil {
-		debugLogger.Println("Successfully read the socket message.")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Successfully read the socket message.")
 	}
 
 	// Pull out the FD returned by fusermount
@@ -225,8 +228,8 @@ func fusermount(binary string, argv []string, additionalEnv []string, wait bool,
 		return nil, fmt.Errorf("wanted 1 fd; got %#v", gotFds)
 	}
 
-	if debugLogger != nil {
-		debugLogger.Println("Converting FD into os.File")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Converting FD into os.File")
 	}
 	// Turn the FD into an os.File.
 	return os.NewFile(uintptr(gotFds[0]), "/dev/fuse"), nil

mount_config.go

@@ -48,6 +48,10 @@ type MountConfig struct {
 	// performed.
 	DebugLogger *log.Logger
 
+	// A logger to use for logging info information. If nil, no info logging is
+	// performed.
+	InfoLogger *log.Logger
+
 	// A logger to use for logging fuse wire requests. If nil, no wire logging is
 	// performed.
 	WireLogger io.Writer

mount_darwin.go

@@ -209,7 +209,7 @@ func callMountCommFD(
 	env = append(env, "_FUSE_COMMVERS=2")
 	argv = append(argv, dir)
 
-	return fusermount(bin, argv, env, false, cfg.DebugLogger)
+	return fusermount(bin, argv, env, false, cfg.DebugLogger, cfg.InfoLogger)
 }
 
 // Begin the process of mounting at the given directory, returning a connection
@@ -298,9 +298,11 @@ func startFuseTServer(binary string, argv []string,
 	additionalEnv []string,
 	wait bool,
 	debugLogger *log.Logger,
+	infoLogger *log.Logger,
 	ready chan<- error) (*os.File, error) {
-	if debugLogger != nil {
-		debugLogger.Println("Creating a socket pair")
+	infoDebugFallbackLogger := FirstLogger(infoLogger, debugLogger)
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Creating a socket pair")
 	}
 
 	var err error
@@ -319,12 +321,12 @@ func startFuseTServer(binary string, argv []string,
 	syscall.CloseOnExec(int(local.Fd()))
 	syscall.CloseOnExec(int(local_mon.Fd()))
 
-	if debugLogger != nil {
-		debugLogger.Println("Creating files to wrap the sockets")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Creating files to wrap the sockets")
 	}
 
-	if debugLogger != nil {
-		debugLogger.Println("Starting fusermount/os mount")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Starting fusermount/os mount")
 	}
 	// Start fusermount/mount_macfuse/mount_osxfuse.
 	cmd := exec.Command(binary, argv...)
@@ -346,16 +348,16 @@ func startFuseTServer(binary string, argv []string,
 		return nil, fmt.Errorf("running %v: %v", binary, err)
 	}
 
-	if debugLogger != nil {
-		debugLogger.Println("Wrapping socket pair in a connection")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Wrapping socket pair in a connection")
 	}
 
-	if debugLogger != nil {
-		debugLogger.Println("Checking that we have a unix domain socket")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Checking that we have a unix domain socket")
 	}
 
-	if debugLogger != nil {
-		debugLogger.Println("Read a message from socket")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Read a message from socket")
 	}
 
 	go func() {
@@ -373,8 +375,8 @@ func startFuseTServer(binary string, argv []string,
 		close(ready)
 	}()
 
-	if debugLogger != nil {
-		debugLogger.Println("Successfully read the socket message.")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Successfully read the socket message.")
 	}
 
 	return local, nil
@@ -406,7 +408,7 @@ func mountFuset(
 	env = append(env, "_FUSE_COMMVERS=2")
 	argv = append(argv, dir)
 
-	return startFuseTServer(fuseTBin, argv, env, false, cfg.DebugLogger, ready)
+	return startFuseTServer(fuseTBin, argv, env, false, cfg.DebugLogger, cfg.InfoLogger, ready)
 }
 
 func mount(

mount_linux.go

@@ -55,8 +55,9 @@ var mountflagopts = map[string]func(uintptr) uintptr{
 var errFallback = errors.New("sentinel: fallback to fusermount(1)")
 
 func directmount(dir string, cfg *MountConfig) (*os.File, error) {
-	if cfg.DebugLogger != nil {
-		cfg.DebugLogger.Println("Preparing for direct mounting")
+	infoDebugFallbackLogger := FirstLogger(cfg.InfoLogger, cfg.DebugLogger)
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Preparing for direct mounting")
 	}
 	// We use syscall.Open + os.NewFile instead of os.OpenFile so that the file
 	// is opened in blocking mode. When opened in non-blocking mode, the Go
@@ -67,8 +68,8 @@ func directmount(dir string, cfg *MountConfig) (*os.File, error) {
 	}
 	dev := os.NewFile(uintptr(fd), "/dev/fuse")
 
-	if cfg.DebugLogger != nil {
-		cfg.DebugLogger.Println("Successfully opened the /dev/fuse in blocking mode")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Successfully opened the /dev/fuse in blocking mode")
 	}
 	// As per libfuse/fusermount.c:847: https://bit.ly/2SgtWYM#L847
 	data := fmt.Sprintf("fd=%d,rootmode=40000,user_id=%d,group_id=%d",
@@ -93,8 +94,8 @@ func directmount(dir string, cfg *MountConfig) (*os.File, error) {
 	delete(opts, "subtype")
 	data += "," + mapToOptionsString(opts)
 
-	if cfg.DebugLogger != nil {
-		cfg.DebugLogger.Println("Starting the unix mounting")
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Starting the unix mounting")
 	}
 	if err := unix.Mount(
 		fsname,    // source
@@ -123,8 +124,10 @@ func mount(dir string, cfg *MountConfig, ready chan<- error) (*os.File, error) {
 	// On linux, mounting is never delayed.
 	ready <- nil
 
-	if cfg.DebugLogger != nil {
-		cfg.DebugLogger.Println("Parsing fuse file descriptor")
+	infoDebugFallbackLogger := FirstLogger(cfg.InfoLogger, cfg.DebugLogger)
+
+	if infoDebugFallbackLogger != nil {
+		infoDebugFallbackLogger.Println("Parsing fuse file descriptor")
 	}
 	// If the mountpoint is /dev/fd/N, assume that the file descriptor N is an
 	// already open FUSE channel. Parse it, cast it to an fd, and don't do any
@@ -138,8 +141,8 @@ func mount(dir string, cfg *MountConfig, ready chan<- error) (*os.File, error) {
 	// have the CAP_SYS_ADMIN capability.
 	dev, err := directmount(dir, cfg)
 	if err == errFallback {
-		if cfg.DebugLogger != nil {
-			cfg.DebugLogger.Println("Directmount failed. Trying fallback.")
+		if infoDebugFallbackLogger != nil {
+			infoDebugFallbackLogger.Println("Directmount failed. Trying fallback.")
 		}
 		fusermountPath, err := findFusermount()
 		if err != nil {
@@ -150,7 +153,7 @@ func mount(dir string, cfg *MountConfig, ready chan<- error) (*os.File, error) {
 			"--",
 			dir,
 		}
-		dev, err := fusermount(fusermountPath, argv, []string{}, true, cfg.DebugLogger)
+		dev, err := fusermount(fusermountPath, argv, []string{}, true, cfg.DebugLogger, cfg.InfoLogger)
 		if err == nil {
 			return dev, nil
 		}