Break the fs package up into smaller parts.

The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.

The new code layout is documented in CONTRIBUTING.

fs/log/log.go

@@ -0,0 +1,89 @@
+// Package log provides logging for rclone
+package log
+
+import (
+	"log"
+	"os"
+	"reflect"
+	"runtime"
+	"strings"
+
+	"github.com/ncw/rclone/fs"
+	"github.com/ncw/rclone/fs/config/flags"
+)
+
+// Flags
+var (
+	logFile        = flags.StringP("log-file", "", "", "Log everything to this file")
+	useSyslog      = flags.BoolP("syslog", "", false, "Use Syslog for logging")
+	syslogFacility = flags.StringP("syslog-facility", "", "DAEMON", "Facility for syslog, eg KERN,USER,...")
+)
+
+// fnName returns the name of the calling +2 function
+func fnName() string {
+	pc, _, _, ok := runtime.Caller(2)
+	name := "*Unknown*"
+	if ok {
+		name = runtime.FuncForPC(pc).Name()
+		dot := strings.LastIndex(name, ".")
+		if dot >= 0 {
+			name = name[dot+1:]
+		}
+	}
+	return name
+}
+
+// Trace debugs the entry and exit of the calling function
+//
+// It is designed to be used in a defer statement so it returns a
+// function that logs the exit parameters.
+//
+// Any pointers in the exit function will be dereferenced
+func Trace(o interface{}, format string, a ...interface{}) func(string, ...interface{}) {
+	if fs.Config.LogLevel < fs.LogLevelDebug {
+		return func(format string, a ...interface{}) {}
+	}
+	name := fnName()
+	fs.LogPrintf(fs.LogLevelDebug, o, name+": "+format, a...)
+	return func(format string, a ...interface{}) {
+		for i := range a {
+			// read the values of the pointed to items
+			typ := reflect.TypeOf(a[i])
+			if typ.Kind() == reflect.Ptr {
+				value := reflect.ValueOf(a[i])
+				if value.IsNil() {
+					a[i] = nil
+				} else {
+					pointedToValue := reflect.Indirect(value)
+					a[i] = pointedToValue.Interface()
+				}
+			}
+		}
+		fs.LogPrintf(fs.LogLevelDebug, o, ">"+name+": "+format, a...)
+	}
+}
+
+// InitLogging start the logging as per the command line flags
+func InitLogging() {
+	// Log file output
+	if *logFile != "" {
+		f, err := os.OpenFile(*logFile, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0640)
+		if err != nil {
+			log.Fatalf("Failed to open log file: %v", err)
+		}
+		_, err = f.Seek(0, os.SEEK_END)
+		if err != nil {
+			fs.Errorf(nil, "Failed to seek log file to end: %v", err)
+		}
+		log.SetOutput(f)
+		redirectStderr(f)
+	}
+
+	// Syslog output
+	if *useSyslog {
+		if *logFile != "" {
+			log.Fatalf("Can't use --syslog and --log-file together")
+		}
+		startSysLog()
+	}
+}

fs/log/redirect_stderr.go

@@ -0,0 +1,16 @@
+// Log the panic to the log file - for oses which can't do this
+
+// +build !windows,!darwin,!dragonfly,!freebsd,!linux,!nacl,!netbsd,!openbsd
+
+package log
+
+import (
+	"os"
+
+	"github.com/ncw/rclone/fs"
+)
+
+// redirectStderr to the file passed in
+func redirectStderr(f *os.File) {
+	fs.Errorf(nil, "Can't redirect stderr to file")
+}

fs/log/redirect_stderr_unix.go

@@ -0,0 +1,20 @@
+// Log the panic under unix to the log file
+
+// +build !windows,!solaris,!plan9
+
+package log
+
+import (
+	"log"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// redirectStderr to the file passed in
+func redirectStderr(f *os.File) {
+	err := unix.Dup2(int(f.Fd()), int(os.Stderr.Fd()))
+	if err != nil {
+		log.Fatalf("Failed to redirect stderr to file: %v", err)
+	}
+}

fs/log/redirect_stderr_windows.go

@@ -0,0 +1,39 @@
+// Log the panic under windows to the log file
+//
+// Code from minix, via
+//
+// https://play.golang.org/p/kLtct7lSUg
+
+// +build windows
+
+package log
+
+import (
+	"log"
+	"os"
+	"syscall"
+)
+
+var (
+	kernel32         = syscall.MustLoadDLL("kernel32.dll")
+	procSetStdHandle = kernel32.MustFindProc("SetStdHandle")
+)
+
+func setStdHandle(stdhandle int32, handle syscall.Handle) error {
+	r0, _, e1 := syscall.Syscall(procSetStdHandle.Addr(), 2, uintptr(stdhandle), uintptr(handle), 0)
+	if r0 == 0 {
+		if e1 != 0 {
+			return error(e1)
+		}
+		return syscall.EINVAL
+	}
+	return nil
+}
+
+// redirectStderr to the file passed in
+func redirectStderr(f *os.File) {
+	err := setStdHandle(syscall.STD_ERROR_HANDLE, syscall.Handle(f.Fd()))
+	if err != nil {
+		log.Fatalf("Failed to redirect stderr to file: %v", err)
+	}
+}

fs/log/syslog.go

@@ -0,0 +1,16 @@
+// Syslog interface for non-Unix variants only
+
+// +build windows nacl plan9
+
+package log
+
+import (
+	"log"
+	"runtime"
+)
+
+// Starts syslog if configured, returns true if it was started
+func startSysLog() bool {
+	log.Fatalf("--syslog not supported on %s platform", runtime.GOOS)
+	return false
+}

fs/log/syslog_unix.go

@@ -0,0 +1,67 @@
+// Syslog interface for Unix variants only
+
+// +build !windows,!nacl,!plan9
+
+package log
+
+import (
+	"log"
+	"log/syslog"
+	"os"
+	"path"
+
+	"github.com/ncw/rclone/fs"
+)
+
+var (
+	syslogFacilityMap = map[string]syslog.Priority{
+		"KERN":     syslog.LOG_KERN,
+		"USER":     syslog.LOG_USER,
+		"MAIL":     syslog.LOG_MAIL,
+		"DAEMON":   syslog.LOG_DAEMON,
+		"AUTH":     syslog.LOG_AUTH,
+		"SYSLOG":   syslog.LOG_SYSLOG,
+		"LPR":      syslog.LOG_LPR,
+		"NEWS":     syslog.LOG_NEWS,
+		"UUCP":     syslog.LOG_UUCP,
+		"CRON":     syslog.LOG_CRON,
+		"AUTHPRIV": syslog.LOG_AUTHPRIV,
+		"FTP":      syslog.LOG_FTP,
+	}
+)
+
+// Starts syslog
+func startSysLog() bool {
+	facility, ok := syslogFacilityMap[*syslogFacility]
+	if !ok {
+		log.Fatalf("Unknown syslog facility %q - man syslog for list", *syslogFacility)
+	}
+	Me := path.Base(os.Args[0])
+	w, err := syslog.New(syslog.LOG_NOTICE|facility, Me)
+	if err != nil {
+		log.Fatalf("Failed to start syslog: %v", err)
+	}
+	log.SetFlags(0)
+	log.SetOutput(w)
+	fs.LogPrint = func(level fs.LogLevel, text string) {
+		switch level {
+		case fs.LogLevelEmergency:
+			_ = w.Emerg(text)
+		case fs.LogLevelAlert:
+			_ = w.Alert(text)
+		case fs.LogLevelCritical:
+			_ = w.Crit(text)
+		case fs.LogLevelError:
+			_ = w.Err(text)
+		case fs.LogLevelWarning:
+			_ = w.Warning(text)
+		case fs.LogLevelNotice:
+			_ = w.Notice(text)
+		case fs.LogLevelInfo:
+			_ = w.Info(text)
+		case fs.LogLevelDebug:
+			_ = w.Debug(text)
+		}
+	}
+	return true
+}