dotcloud/docker

//go:build ignore

// Simple tool to create an archive stream from an old and new directory
//
// By default it will stream the comparison of two temporary directories with junk files
package main

import (
    "flag"
    "fmt"
    "io"
    "os"
    "path"

    "github.com/containerd/log"
    "github.com/docker/docker/pkg/archive"
)

var (
    flDebug  = flag.Bool("D", false, "debugging output")
    flNewDir = flag.String("newdir", "", "")
    flOldDir = flag.String("olddir", "", "")
    log      = log.G(ctx).New()
)

func main() {
    flag.Usage = func() {
        fmt.Println("Produce a tar from comparing two directory paths. By default a demo tar is created of around 200 files (including hardlinks)")
        fmt.Printf("%s [OPTIONS]\n", os.Args[0])
        flag.PrintDefaults()
    }
    flag.Parse()
    log.Out = os.Stderr
    if (len(os.Getenv("DEBUG")) > 0) || *flDebug {
        log.G(ctx).SetLevel(logrus.DebugLevel)
    }
    var newDir, oldDir string

    if len(*flNewDir) == 0 {
        var err error
        newDir, err = os.MkdirTemp("", "docker-test-newDir")
        if err != nil {
            log.Fatal(err)
        }
        defer os.RemoveAll(newDir)
        if _, err := prepareUntarSourceDirectory(100, newDir, true); err != nil {
            log.Fatal(err)
        }
    } else {
        newDir = *flNewDir
    }

    if len(*flOldDir) == 0 {
        oldDir, err := os.MkdirTemp("", "docker-test-oldDir")
        if err != nil {
            log.Fatal(err)
        }
        defer os.RemoveAll(oldDir)
    } else {
        oldDir = *flOldDir
    }

    changes, err := archive.ChangesDirs(newDir, oldDir)
    if err != nil {
        log.Fatal(err)
    }

    a, err := archive.ExportChanges(newDir, changes)
    if err != nil {
        log.Fatal(err)
    }
    defer a.Close()

    i, err := io.Copy(os.Stdout, a)
    if err != nil && err != io.EOF {
        log.Fatal(err)
    }
    fmt.Fprintf(os.Stderr, "wrote archive of %d bytes", i)
}

func prepareUntarSourceDirectory(numberOfFiles int, targetPath string, makeLinks bool) (int, error) {
    fileData := []byte("fooo")
    for n := 0; n < numberOfFiles; n++ {
        fileName := fmt.Sprintf("file-%d", n)
        if err := os.WriteFile(path.Join(targetPath, fileName), fileData, 0o700); err != nil {
            return 0, err
        }
        if makeLinks {
            if err := os.Link(path.Join(targetPath, fileName), path.Join(targetPath, fileName+"-link")); err != nil {
                return 0, err
            }
        }
    }
    totalSize := numberOfFiles * len(fileData)
    return totalSize, nil
}