reimplement in go

safe_mv/safe_mv

@@ -91,7 +91,7 @@ sub cmdline {
 	if ($#ARGV < 1) { &help; }
 
 	$targetdir=pop(@ARGV);
-	if ( ! -d $targetdir ) { &help; }
+	if ( ! -d $targetdir ) { print "Destination not a directory\n"; &help; }
 	if ( $DEBUG ) { print "$targetdir\n"; }
 
 	@sources = @ARGV;

safe_mv/smv2.go

@@ -0,0 +1,182 @@
+// 2>/dev/null||/usr/bin/env go run "$0" "$@"; exit $?
+
+package main
+
+import (
+	"bytes"
+	"flag"
+	"io"
+	"log"
+	"os"
+	"regexp"
+)
+
+var removePtr = flag.Bool("r", false, "Don't move, but remove doubles")
+var noActionPtr = flag.Bool("n", false, "Don't actually move or remove files")
+var sources = []string{}
+var targetDir = ""
+var rePath = regexp.MustCompile("^.*/")
+
+func cmdline() {
+	flag.Parse()
+
+	// log.Println("remove only: ", *removePtr)
+	// log.Println("no action: ", *noActionPtr)
+	// log.Println("tail:", flag.Args())
+
+	sources = flag.Args()
+	targetDir, sources = sources[len(sources)-1], sources[:len(sources)-1]
+
+	// log.Println("sources: ", sources)
+
+}
+
+func checkTargetDir() {
+	// log.Println("target dir: ", targetDir)
+	// Check if targetDir is a dir and writable
+	if stat, err := os.Stat(targetDir); err == nil && stat.IsDir() {
+		// path is a directory
+		// log.Println("is dir")
+	} else {
+		log.Println("Target not a directory: ", targetDir)
+		os.Exit(10)
+	}
+}
+
+func processSources() {
+	// log.Println("Processing sources:")
+	source := ""
+	target := ""
+	for _, source = range sources {
+		target = targetDir + "/" + rePath.ReplaceAllLiteralString(source, "")
+		if sourceStat, err := os.Stat(source); err == nil && sourceStat.Mode().IsRegular() {
+			// log.Println("source: ", source)
+			// log.Println("target: ", target)
+			targetStat, err := os.Stat(target)
+			if err == nil {
+				if os.SameFile(sourceStat, targetStat) {
+					log.Println("Skipped mv", source, "->", target, "same actual file")
+					continue
+				}
+				if targetStat.Mode().IsRegular() {
+					// target exists and is a file
+					if sameFileContent(source, target) {
+						// delete source
+						log.Println("Files are the same. Deleting", source)
+						if !*noActionPtr {
+							err := os.Remove(source)
+							if err != nil {
+								log.Fatal(err)
+							}
+						}
+					} else {
+						// Not the same, skip file
+						log.Println("Skipped mv", source, "->", target, "files differ")
+					}
+				} else {
+					// target exists and is not a regular file. Bail out?
+					log.Println("Skipped mv", source, "->", target, "target exists, but not a file")
+					continue
+				}
+			} else {
+				// target does not exist: Move file if noActionPtr not set
+				log.Println("mv", source, "->", target)
+				if !*noActionPtr && !*removePtr {
+					move(source, target)
+				}
+			}
+		} else {
+			log.Println("Skipped mv", source, "->", target, "source not a regular file")
+		}
+	}
+}
+
+func sameFileContent(source string, target string) bool {
+	// 2 ways to go about this. Calculate a hash for both files
+	// or do a blockwise compare of both files.
+	// As we're not reusing things the blockwise compare is likely
+	// slightly faster
+	// Modern SSDs work with 8Kb blocks, so that's a good size as a start.
+	// Could also do 8Mb blocks, because, meh.
+	bufSize := 8096
+	// log.Println("reading file...")
+
+	sourceFH, err := os.Open(source)
+	if err != nil {
+		log.Println("Can't open source file for reading: ", source)
+	}
+	sourceBuf := make([]byte, bufSize)
+
+	targetFH, err := os.Open(target)
+	if err != nil {
+		log.Println("Can't open target file for reading: ", target)
+	}
+	targetBuf := make([]byte, bufSize)
+
+	eofSource, eofTarget := false, false
+	sourceBytesRead, targetBytesRead := 0, 0
+
+	for !eofSource && !eofTarget {
+		if sourceBytesRead, err = sourceFH.Read(sourceBuf); err != nil {
+			switch err {
+			case io.EOF:
+				eofSource = true
+			case nil:
+			default:
+				log.Println(err)
+			}
+		}
+		if targetBytesRead, err = targetFH.Read(targetBuf); err != nil {
+			switch err {
+			case io.EOF:
+				eofTarget = true
+			case nil:
+			default:
+				log.Println(err)
+			}
+		}
+		if bytes.Compare(sourceBuf[:sourceBytesRead], targetBuf[:targetBytesRead]) != 0 {
+			// fmt.Println("Files not same")
+			return false
+		}
+	}
+
+	// fmt.Println("files same")
+	return true
+}
+
+func move(source string, target string) {
+	err := os.Rename(source, target)
+	if err != nil {
+		// Renaming only works within same partition.
+		// If different partitions, copy & delete source
+		newerr := copy(source, target)
+		if newerr != nil {
+			log.Fatal("Copy failed ", source, " -> ", target, ":", newerr)
+		}
+		err := os.Remove(source)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+}
+
+func copy(source string, target string) error {
+	sourceFH, err := os.Open(source)
+	if err != nil {
+		log.Println("Can't open source file for reading: ", source)
+	}
+
+	targetFH, err := os.Create(target)
+	if err != nil {
+		log.Println("Can't open target file for reading: ", target)
+	}
+	_, copyerr := io.Copy(targetFH, sourceFH)
+	return copyerr
+}
+
+func main() {
+	cmdline()
+	checkTargetDir()
+	processSources()
+}