Add dirdiff command

cmd/dirdiff/main.go

@@ -0,0 +1,139 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"syscall"
+)
+
+const backlog = 100
+
+type entry struct {
+	path string
+	fi   os.FileInfo
+}
+
+func walk(dir string) <-chan *entry {
+	ch := make(chan *entry, 100)
+
+	go func() {
+		err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "error: %v\n", err)
+				return nil
+			}
+
+			name, err := filepath.Rel(dir, path)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "error: %v\n", err)
+				return nil
+			}
+
+			ch <- &entry{
+				path: name,
+				fi:   info,
+			}
+
+			return nil
+		})
+
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Walk() error: %v\n", err)
+		}
+
+		close(ch)
+	}()
+
+	// first element is root
+	_ = <-ch
+
+	return ch
+}
+
+func (e *entry) equals(other *entry) bool {
+	if e.path != other.path {
+		return false
+	}
+
+	if e.fi.Mode() != other.fi.Mode() {
+		return false
+	}
+
+	if e.fi.ModTime() != other.fi.ModTime() {
+		return false
+	}
+
+	stat, _ := e.fi.Sys().(*syscall.Stat_t)
+	stat2, _ := other.fi.Sys().(*syscall.Stat_t)
+
+	if stat.Uid != stat2.Uid || stat2.Gid != stat2.Gid {
+		return false
+	}
+
+	return true
+}
+
+func main() {
+	if len(os.Args) != 3 {
+		fmt.Fprintf(os.Stderr, "USAGE: %s DIR1 DIR2\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	ch1 := walk(os.Args[1])
+	ch2 := walk(os.Args[2])
+
+	changes := false
+
+	var a, b *entry
+	for {
+		var ok bool
+
+		if ch1 != nil && a == nil {
+			a, ok = <-ch1
+			if !ok {
+				ch1 = nil
+			}
+		}
+
+		if ch2 != nil && b == nil {
+			b, ok = <-ch2
+			if !ok {
+				ch2 = nil
+			}
+		}
+
+		if ch1 == nil && ch2 == nil {
+			break
+		}
+
+		if ch1 == nil {
+			fmt.Printf("+%v\n", b.path)
+			changes = true
+		} else if ch2 == nil {
+			fmt.Printf("-%v\n", a.path)
+			changes = true
+		} else if !a.equals(b) {
+			if a.path < b.path {
+				fmt.Printf("-%v\n", a.path)
+				changes = true
+				a = nil
+				continue
+			} else if a.path > b.path {
+				fmt.Printf("+%v\n", b.path)
+				changes = true
+				b = nil
+				continue
+			} else {
+				fmt.Printf("%%%v\n", a.path)
+				changes = true
+			}
+		}
+
+		a, b = nil, nil
+	}
+
+	if changes {
+		os.Exit(1)
+	}
+}