feat: implement mutate command

cmd/gomtree/cmd/mutate.go

@@ -0,0 +1,144 @@
+package cmd
+
+import (
+	"fmt"
+	"io"
+	"math"
+	"os"
+	"slices"
+	"strings"
+
+	cli "github.com/urfave/cli/v2"
+	"github.com/vbatts/go-mtree"
+)
+
+func NewMutateCommand() *cli.Command {
+
+	return &cli.Command{
+		Name:  "mutate",
+		Usage: "mutate an mtree",
+		Description: `Mutate an mtree to have different shapes.
+TODO: more info examples`,
+		Action:    mutateAction,
+		ArgsUsage: "<path to mtree> [path to output]",
+		Flags: []cli.Flag{
+			&cli.StringSliceFlag{
+				Name: "strip-prefix",
+			},
+			&cli.BoolFlag{
+				Name:  "keep-comments",
+				Value: false,
+			},
+			&cli.BoolFlag{
+				Name:  "keep-blank",
+				Value: false,
+			},
+			&cli.StringFlag{
+				Name:      "output",
+				TakesFile: true,
+			},
+		},
+	}
+}
+
+func mutateAction(c *cli.Context) error {
+	mtreePath := c.Args().Get(0)
+	outputPath := c.Args().Get(1)
+	stripPrexies := c.StringSlice("strip-prefix")
+	keepComments := c.Bool("keep-comments")
+	keepBlank := c.Bool("keep-blank")
+
+	if mtreePath == "" {
+		return fmt.Errorf("mtree path is required.")
+	} else if outputPath == "" {
+		outputPath = mtreePath
+	}
+
+	file, err := os.Open(mtreePath)
+	if err != nil {
+		return fmt.Errorf("opening %s: %w", mtreePath, err)
+	}
+
+	spec, err := mtree.ParseSpec(file)
+	if err != nil {
+		return fmt.Errorf("parsing mtree %s: %w", mtreePath, err)
+	}
+
+	dropDotDot := 0
+	droppedParents := []*mtree.Entry{}
+
+	entries := []mtree.Entry{}
+
+skip:
+	for _, entry := range spec.Entries {
+
+		if !keepComments && entry.Type == mtree.CommentType {
+			continue
+		}
+		if !keepBlank && entry.Type == mtree.BlankType {
+			continue
+		}
+
+		if entry.Parent != nil && slices.Contains(droppedParents, &entry) {
+			entry.Parent = nil
+			entry.Type = mtree.FullType
+			entry.Raw = ""
+		}
+
+		if entry.Type == mtree.FullType || entry.Type == mtree.RelativeType {
+			fp, err := entry.Path()
+			// fmt.Println("fp", fp, entry.Name)
+			if err != nil {
+				return err
+			}
+			pathSegments := strings.Split(fp, "/")
+
+			for _, prefix := range stripPrexies {
+
+				prefixSegments := strings.Split(prefix, "/")
+				minLen := int(math.Min(float64(len(pathSegments)), float64(len(prefixSegments))))
+				matches := make([]string, minLen)
+				for i := 0; i < minLen; i++ {
+					if pathSegments[i] == prefixSegments[i] {
+						matches[i] = prefixSegments[i]
+					}
+				}
+
+				strip := strings.Join(matches, "/")
+				if entry.Type == mtree.FullType {
+					entry.Name = strings.TrimPrefix(entry.Name, strip)
+					entry.Name = strings.TrimPrefix(entry.Name, "/")
+					if entry.Name == "" {
+						continue skip
+					}
+				} else {
+					if entry.IsDir() {
+						dropDotDot++
+						droppedParents = append(droppedParents, &entry)
+					}
+					if fp == strip {
+						continue skip
+					}
+				}
+			}
+		} else if dropDotDot > 0 && entry.Type == mtree.DotDotType {
+			dropDotDot--
+			continue skip
+		}
+		entries = append(entries, entry)
+	}
+
+	spec.Entries = entries
+
+	var writer io.Writer = os.Stdout
+	if outputPath != "-" {
+		writer, err = os.Create(outputPath)
+		if err != nil {
+			return fmt.Errorf("creating output %s: %w", outputPath, err)
+		}
+	}
+
+	spec.WriteTo(writer)
+
+	return nil
+}

cmd/gomtree/main.go

@@ -42,6 +42,7 @@ to support xattrs and interacting with tar archives.`
 	}
 	app.Commands = []*cli.Command{
 		cmd.NewValidateCommand(),
+		cmd.NewMutateCommand(),
 	}
 
 	// Unfortunately urfave/cli is not at good at using DefaultCommand

go.mod

@@ -1,6 +1,6 @@
 module github.com/vbatts/go-mtree
 
-go 1.17
+go 1.18
 
 require (
 	github.com/davecgh/go-spew v1.1.1

testdata/flat.relative.mtree

@@ -0,0 +1,20 @@
+# ./lib
+lib type=dir mode=0644
+    foo mode=0644 size=12288 time=1457644483.833957552 type=file
+
+# ./lib/dir
+lib type=dir mode=0644
+
+dir type=dir mode=0644
+
+# ./lib
+..
+
+# .
+..
+
+# ./lib/dir/sub
+lib/dir/sub type=dir
+lib/dir/sub/file.txt type=file
+
+lib/dir/PKG.info type=file mode=0644