seems to work now! needs more features

Makefile

@@ -13,7 +13,7 @@ GOFLAGS = -ldflags "$(GOLDFLAGS)"
 default: rundebug
 
 rundebug: build
-	./xsum -d
+	./xsum -v
 
 run: build
 	./xsum

README.md

@@ -1,9 +1,15 @@
 # xsum
 
-this stores a file mtime and cryptographically secure content checksum
+This stores a file mtime, a size, and a cryptographically secure content checksum
 in an xattr, so that you can verify that your files aren't corrupted
 on filesystems that are dumb and don't include data checksums (e.g. apfs)
 
+# background
+
+You can dd a few random bytes into the middle of an hfs+ or apfs filesystem,
+and, if they land in file data, an fsck/Disk First Aid on the filesystem
+will pass with flying colors.  There is no file content checksum.
+
 # author
 
-sneak <sneak@sneak.berlin>
+Jeffrey Paul [sneak@sneak.berlin](mailto:sneak@sneak.berlin) 

main.go

@@ -4,12 +4,12 @@ package main
 
 import "crypto/sha256"
 import "fmt"
-import "github.com/sirupsen/logrus"
+import "github.com/jessevdk/go-flags"
-import "github.com/multiformats/go-multihash"
 import "github.com/mr-tron/base58"
+import "github.com/multiformats/go-multihash"
 import "github.com/pkg/xattr"
+import "github.com/sirupsen/logrus"
 
-//import "errors"
 import "os"
 import "io"
 import "flag"
@@ -40,9 +40,21 @@ func xsum() int {
 	log = logrus.New()
 	log.SetLevel(logrus.ErrorLevel)
 	log.SetReportCaller(false)
-	debugPtr := flag.Bool("d", false, "debug mode")
+
-	flag.Parse()
+	var opts struct {
-	if *debugPtr == true {
+		// Slice of bool will append 'true' each time the option
+		// is encountered (can be set multiple times, like -vvv)
+		Verbose bool `short:"v" long:"verbose" description:"Show verbose debug information"`
+	}
+
+	args, err := flags.Parse(&opts)
+
+	if err != nil {
+		usage()
+		return -1
+	}
+
+	if opts.Verbose == true {
 		log.SetReportCaller(true)
 		log.SetLevel(logrus.DebugLevel)
 	}
@@ -55,15 +67,20 @@ func xsum() int {
 		Builduser,
 	)
 
-	paths := flag.Args()
+	if len(args) < 2 {
-	if len(paths) > 1 {
+		usage()
-		paths = paths[1:]
+		return -1
 	}
-	switch flag.Arg(0) {
+
+	mode := args[0]
+
+	paths := args[1:]
+
+	switch mode {
 	case "cron":
 		x := xsfCheckAndUpdate(paths)
 		if x != nil {
-			log.Error(x)
+			log.Debug(x)
 			return -1
 		} else {
 			return 0
@@ -71,7 +88,7 @@ func xsum() int {
 	case "check-and-update":
 		x := xsfCheckAndUpdate(paths)
 		if x != nil {
-			log.Error(x)
+			log.Debug(x)
 			return -1
 		} else {
 			return 0
@@ -79,7 +96,7 @@ func xsum() int {
 	case "check":
 		x := xsfCheck(paths)
 		if x != nil {
-			log.Error(x)
+			log.Debug(x)
 			return -1
 		} else {
 			return 0
@@ -87,7 +104,7 @@ func xsum() int {
 	case "update":
 		x := xsfUpdate(paths)
 		if x != nil {
-			log.Error(x)
+			log.Debug(x)
 			return -1
 		} else {
 			return 0
@@ -99,7 +116,7 @@ func xsum() int {
 }
 
 func usage() {
-	fmt.Fprintf(os.Stderr, "usage: %s [-d] <update|check|check-and-update|cron> <path> [path2] [...]\n", os.Args[0])
+	fmt.Fprintf(os.Stderr, "usage: %s [-v] <update|check|check-and-update|cron> <path> [path2] [...]\n", os.Args[0])
 	flag.PrintDefaults()
 }
 
@@ -109,7 +126,10 @@ func xsfCheck(paths []string) error {
 		x := newXsf(path)
 		err := x.Check()
 		if err != nil {
+			fmt.Printf("%s\tERROR (expected=%s actual=%s)\n", x.path, x.xmultihash, x.multihash)
 			return err
+		} else {
+			fmt.Printf("%s\tOK (hash=%s)\n", x.path, x.multihash)
 		}
 	}
 	return nil
@@ -125,8 +145,9 @@ func xsfUpdate(paths []string) error {
 		x := newXsf(path)
 		err := x.Update()
 		if err != nil {
-			showError(err)
+			failure := fmt.Errorf("%s\tERROR (error=%s)\n", x.path, err)
-			return err
+			log.Error(failure)
+			return failure
 		}
 	}
 	return nil
@@ -134,9 +155,12 @@ func xsfUpdate(paths []string) error {
 
 func xsfCheckAndUpdate(paths []string) error {
 	log.Debugf("check-and-update")
-	r := xsfCheck(paths)
+	err := xsfCheck(paths)
-	if r != nil {
+	if err != nil {
-		return r
+		//xsfCheck() does the printing of errors itself, we just need to
+		//bubble it up and not update
+		log.Error(err)
+		return err
 	}
 	return xsfUpdate(paths)
 }
@@ -252,12 +276,10 @@ func (x *xsf) readSizeXattr() error {
 	if err != nil {
 		return err
 	}
-
 	a, b := strconv.ParseInt(string(v), 10, 64)
 	if b != nil {
 		return b
 	}
-
 	x.xsize = uint64(a)
 	return nil
 }
@@ -358,8 +380,8 @@ func (x *xsf) Check() error {
 	actualHash := x.multihash
 
 	if predictedHash != actualHash {
-		log.Errorf("file corruption detected: expected=%s actual=%s", predictedHash, actualHash)
+		failure := fmt.Errorf("file corruption detected: expected=%s actual=%s", predictedHash, actualHash)
-		return err
+		return failure
 	} else {
 		log.Infof("file OK hash=%s", actualHash)
 		return nil
@@ -386,22 +408,37 @@ func (x *xsf) missingXattrs() bool {
 }
 
 func (x *xsf) needsUpdate() bool {
+	log.Debugf("checking if file needs update")
 	// this expects stat() to have been called on the xsf
 	// by Update already, so we have x.mtime et al populated from the
 	// filesystem
 
 	// if the file doesn't have all 3 xattrs, it needs an update.
-	if x.missingXattrs() == false {
+	if x.missingXattrs() == true {
+		log.Debugf("file is missing xattrs")
 		return true
 	}
 
 	// if the size doesn't match, it needs an update
+	e := x.readSizeXattr()
+	if e != nil {
+		log.Debugf("unable to read file size attribute")
+		return true
+	}
+
 	if x.size != x.xsize {
 		log.Debugf("file needs update, size is %s, xattr size is %s", x.size, x.xsize)
 		return true
 	}
 
 	// if the mtime is not the same, it needs an update
+
+	e2 := x.readMtimeXattr()
+	if e2 != nil {
+		log.Debugf("unable to read file mtime attribute")
+		return true
+	}
+
 	if x.mtime != x.xmtime {
 		log.Debugf("file needs update, mtime is %s, xattr mtime is %s", x.mtime, x.xmtime)
 		return true
@@ -419,13 +456,17 @@ func (x *xsf) Update() error {
 		return err
 	}
 
-	//FIXME check if size/mtime are defined first
-	//and skip update if match (and key 'multihash' exists)
-
 	if err = x.stat(); err != nil {
 		return err
 	}
 
+	// reminder: needsUpdate() must be called after stat() so that the
+	// struct is populated
+	if x.needsUpdate() == false {
+		log.Debugf("skipping update on already hashed file %s", x.path)
+		return nil
+	}
+
 	if err = x.hash(); err != nil {
 		return err
 	}