fuse: add Options.Logger

This allows for specializing the debug output.

Change-Id: Id6a24fd6207253af3f32ca0f7ed51db3db31ced4

fuse/api.go

@@ -122,6 +122,8 @@
 // [2] https://sylabs.io/guides/3.7/user-guide/bind_paths_and_mounts.html#fuse-mounts
 package fuse
 
+import "log"
+
 // Types for users to implement.
 
 // The result of Read is an array of bytes, but for performance
@@ -219,6 +221,9 @@ type MountOptions struct {
 	// If set, print debugging information.
 	Debug bool
 
+	// If set, sink for debug statements.
+	Logger *log.Logger
+
 	// If set, ask kernel to forward file locks to FUSE. If using,
 	// you must implement the GetLk/SetLk/SetLkw methods.
 	EnableLocks bool

fuse/mount_linux.go

@@ -7,7 +7,6 @@ package fuse
 import (
 	"bytes"
 	"fmt"
-	"log"
 	"os"
 	"os/exec"
 	"path"
@@ -69,7 +68,7 @@ func mountDirect(mountPoint string, opts *MountOptions, ready chan<- error) (fd
 	}
 
 	if opts.Debug {
-		log.Printf("mountDirect: calling syscall.Mount(%q, %q, %q, %#x, %q)",
+		opts.Logger.Printf("mountDirect: calling syscall.Mount(%q, %q, %q, %#x, %q)",
 			source, mountPoint, "fuse."+opts.Name, flags, strings.Join(r, ","))
 	}
 	err = syscall.Mount(source, mountPoint, "fuse."+opts.Name, flags, strings.Join(r, ","))
@@ -108,7 +107,7 @@ func callFusermount(mountPoint string, opts *MountOptions) (fd int, err error) {
 		cmd = append(cmd, "-o", strings.Join(s, ","))
 	}
 	if opts.Debug {
-		log.Printf("callFusermount: executing %q", cmd)
+		opts.Logger.Printf("callFusermount: executing %q", cmd)
 	}
 	proc, err := os.StartProcess(bin,
 		cmd,
@@ -145,7 +144,7 @@ func mount(mountPoint string, opts *MountOptions, ready chan<- error) (fd int, e
 		if err == nil {
 			return fd, nil
 		} else if opts.Debug {
-			log.Printf("mount: failed to do direct mount: %s", err)
+			opts.Logger.Printf("mount: failed to do direct mount: %s", err)
 		}
 		if opts.DirectMountStrict {
 			return -1, err
@@ -157,7 +156,7 @@ func mount(mountPoint string, opts *MountOptions, ready chan<- error) (fd int, e
 	fd = parseFuseFd(mountPoint)
 	if fd >= 0 {
 		if opts.Debug {
-			log.Printf("mount: magic mountpoint %q, using fd %d", mountPoint, fd)
+			opts.Logger.Printf("mount: magic mountpoint %q, using fd %d", mountPoint, fd)
 		}
 	} else {
 		// Usual case: mount via the `fusermount` suid helper
@@ -194,7 +193,7 @@ func unmount(mountPoint string, opts *MountOptions) (err error) {
 	cmd := exec.Command(bin, "-u", mountPoint)
 	cmd.Stderr = &errBuf
 	if opts.Debug {
-		log.Printf("unmount: executing %q", cmd.Args)
+		opts.Logger.Printf("unmount: executing %q", cmd.Args)
 	}
 	err = cmd.Run()
 	if errBuf.Len() > 0 {

fuse/opcode.go

@@ -229,7 +229,7 @@ func doNotifyReply(server *Server, req *request) {
 	server.retrieveMu.Unlock()
 
 	badf := func(format string, argv ...interface{}) {
-		log.Printf("notify reply: "+format, argv...)
+		server.opts.Logger.Printf("notify reply: "+format, argv...)
 	}
 
 	if reading == nil {
@@ -328,7 +328,7 @@ func doBatchForget(server *Server, req *request) {
 	wantBytes := uintptr(in.Count) * unsafe.Sizeof(_ForgetOne{})
 	if uintptr(len(req.arg)) < wantBytes {
 		// We have no return value to complain, so log an error.
-		log.Printf("Too few bytes for batch forget. Got %d bytes, want %d (%d entries)",
+		server.opts.Logger.Printf("Too few bytes for batch forget. Got %d bytes, want %d (%d entries)",
 			len(req.arg), wantBytes, in.Count)
 	}
 
@@ -341,7 +341,7 @@ func doBatchForget(server *Server, req *request) {
 	forgets := *(*[]_ForgetOne)(unsafe.Pointer(h))
 	for i, f := range forgets {
 		if server.opts.Debug {
-			log.Printf("doBatchForget: rx %d %d/%d: FORGET n%d {Nlookup=%d}",
+			server.opts.Logger.Printf("doBatchForget: rx %d %d/%d: FORGET n%d {Nlookup=%d}",
 				req.inHeader.Unique, i+1, len(forgets), f.NodeId, f.Nlookup)
 		}
 		if f.NodeId == pollHackInode {

fuse/server.go

@@ -165,7 +165,9 @@ func NewServer(fs RawFileSystem, mountPoint string, opts *MountOptions) (*Server
 		}
 	}
 	o := *opts
-
+	if o.Logger == nil {
+		o.Logger = log.Default()
+	}
 	if o.MaxWrite < 0 {
 		o.MaxWrite = 0
 	}
@@ -483,11 +485,11 @@ exit:
 		case ENODEV:
 			// unmount
 			if ms.opts.Debug {
-				log.Printf("received ENODEV (unmount request), thread exiting")
+				ms.opts.Logger.Printf("received ENODEV (unmount request), thread exiting")
 			}
 			break exit
 		default: // some other error?
-			log.Printf("Failed to read from fuse conn: %v", errNo)
+			ms.opts.Logger.Printf("Failed to read from fuse conn: %v", errNo)
 			break exit
 		}
 
@@ -511,14 +513,14 @@ func (ms *Server) handleRequest(req *request) Status {
 	}
 
 	if req.status.Ok() && ms.opts.Debug {
-		log.Println(req.InputDebug())
+		ms.opts.Logger.Println(req.InputDebug())
 	}
 
 	if req.inHeader.NodeId == pollHackInode ||
 		req.inHeader.NodeId == FUSE_ROOT_ID && len(req.filenames) > 0 && req.filenames[0] == pollHackName {
 		doPollHackLookup(ms, req)
 	} else if req.status.Ok() && req.handler.Func == nil {
-		log.Printf("Unimplemented opcode %v", operationName(req.inHeader.Opcode))
+		ms.opts.Logger.Printf("Unimplemented opcode %v", operationName(req.inHeader.Opcode))
 		req.status = ENOSYS
 	} else if req.status.Ok() {
 		req.handler.Func(ms, req)
@@ -531,7 +533,7 @@ func (ms *Server) handleRequest(req *request) Status {
 		// kernel. This is a normal if the referred request already has
 		// completed.
 		if ms.opts.Debug || !(req.inHeader.Opcode == _OP_INTERRUPT && errNo == ENOENT) {
-			log.Printf("writer: Write/Writev failed, err: %v. opcode: %v",
+			ms.opts.Logger.Printf("writer: Write/Writev failed, err: %v. opcode: %v",
 				errNo, operationName(req.inHeader.Opcode))
 		}
 
@@ -577,7 +579,7 @@ func (ms *Server) write(req *request) Status {
 
 	header := req.serializeHeader(req.flatDataSize())
 	if ms.opts.Debug {
-		log.Println(req.OutputDebug())
+		ms.opts.Logger.Println(req.OutputDebug())
 	}
 
 	if header == nil {
@@ -614,7 +616,7 @@ func (ms *Server) InodeNotify(node uint64, off int64, length int64) Status {
 	ms.writeMu.Unlock()
 
 	if ms.opts.Debug {
-		log.Println("Response: INODE_NOTIFY", result)
+		ms.opts.Logger.Println("Response: INODE_NOTIFY", result)
 	}
 	return result
 }
@@ -673,7 +675,7 @@ func (ms *Server) inodeNotifyStoreCache32(node uint64, offset int64, data []byte
 	ms.writeMu.Unlock()
 
 	if ms.opts.Debug {
-		log.Printf("Response: INODE_NOTIFY_STORE_CACHE: %v", result)
+		ms.opts.Logger.Printf("Response: INODE_NOTIFY_STORE_CACHE: %v", result)
 	}
 	return result
 }
@@ -765,7 +767,7 @@ func (ms *Server) inodeRetrieveCache1(node uint64, offset int64, dest []byte) (n
 	ms.writeMu.Unlock()
 
 	if ms.opts.Debug {
-		log.Printf("Response: NOTIFY_RETRIEVE_CACHE: %v", result)
+		ms.opts.Logger.Printf("Response: NOTIFY_RETRIEVE_CACHE: %v", result)
 	}
 	if result != OK {
 		ms.retrieveMu.Lock()
@@ -779,7 +781,7 @@ func (ms *Server) inodeRetrieveCache1(node uint64, offset int64, dest []byte) (n
 			// unexpected NotifyReply with our notifyUnique, then
 			// retrieveNext wraps, makes full cycle, and another
 			// retrieve request is made with the same notifyUnique.
-			log.Printf("W: INODE_RETRIEVE_CACHE: request with notifyUnique=%d mutated", q.NotifyUnique)
+			ms.opts.Logger.Printf("W: INODE_RETRIEVE_CACHE: request with notifyUnique=%d mutated", q.NotifyUnique)
 		}
 		ms.retrieveMu.Unlock()
 		return 0, result
@@ -840,7 +842,7 @@ func (ms *Server) DeleteNotify(parent uint64, child uint64, name string) Status
 	ms.writeMu.Unlock()
 
 	if ms.opts.Debug {
-		log.Printf("Response: DELETE_NOTIFY: %v", result)
+		ms.opts.Logger.Printf("Response: DELETE_NOTIFY: %v", result)
 	}
 	return result
 }
@@ -876,7 +878,7 @@ func (ms *Server) EntryNotify(parent uint64, name string) Status {
 	ms.writeMu.Unlock()
 
 	if ms.opts.Debug {
-		log.Printf("Response: ENTRY_NOTIFY: %v", result)
+		ms.opts.Logger.Printf("Response: ENTRY_NOTIFY: %v", result)
 	}
 	return result
 }

fuse/server_linux.go

@@ -5,7 +5,6 @@
 package fuse
 
 import (
-	"log"
 	"syscall"
 )
 
@@ -25,7 +24,7 @@ func (ms *Server) systemWrite(req *request, header []byte) Status {
 				req.readResult.Done()
 				return OK
 			}
-			log.Println("trySplice:", err)
+			ms.opts.Logger.Println("trySplice:", err)
 		}
 
 		sz := req.flatDataSize()