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runzip.go
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runzip.go
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package main
import (
"fmt"
"io"
"os"
"path/filepath"
"strings"
"github.com/nwaples/rardecode"
)
var (
name = "runzip"
version string
date string
commit string
)
// workaround for `tinygo` ldflag replacement handling not allowing default values
// See <https://github.com/tinygo-org/tinygo/issues/2976>
func init() {
if len(version) == 0 {
version = "0.0.0-dev"
}
if len(date) == 0 {
date = "0001-01-01T00:00:00Z"
}
if len(commit) == 0 {
commit = "0000000"
}
}
func printVersion() {
fmt.Printf("%s v%s %s (%s)\n", name, version, commit[:7], date)
fmt.Printf("Copyright (C) 2024 AJ ONeal\n")
fmt.Printf("Licensed under the BSD 2-clause license\n")
}
func printUsage() {
fmt.Printf("%s v%s %s (%s)\n", name, version, commit[:7], date)
fmt.Printf("\n")
fmt.Printf("USAGE\n\trunzip <archive.rar> [./dst/]\n\n")
fmt.Printf("EXAMPLES\n\trunzip ./archive.rar\n\trunzip ./archive.rar ./unpacked/\n\n")
}
func main() {
nArgs := len(os.Args)
if nArgs >= 2 {
opt := os.Args[1]
subcmd := strings.TrimPrefix(opt, "-")
if opt == "-V" || subcmd == "version" {
printVersion()
os.Exit(0)
return
}
if subcmd == "help" {
printUsage()
os.Exit(0)
return
}
}
if nArgs < 2 || nArgs > 3 {
printUsage()
os.Exit(1)
return
}
// note: we only need to know that Getwd works once
// (otherwise something is wrong in the universe)
cwd, err := os.Getwd()
if err != nil {
fmt.Fprintf(os.Stderr, "sanity fail: %v\n", err)
os.Exit(1)
return
}
useInnerName := false
rarFile := os.Args[1]
finalDir := "."
if nArgs > 2 {
finalDir = os.Args[2]
}
finalDir, _ = filepath.Abs(finalDir)
// encapsulate
if _, err := os.Stat(finalDir); nil == err {
useInnerName = true
name := filepath.Base(rarFile)
ext := filepath.Ext(name)
name = strings.TrimSuffix(name, ext)
finalDir = filepath.Join(finalDir, name)
}
tmpDir, _ := filepath.Abs(finalDir + ".tmp")
tmpRel, _ := filepath.Rel(cwd, tmpDir)
if err := os.MkdirAll(tmpDir, os.ModePerm); err != nil {
fmt.Fprintf(os.Stderr, "error: could not create destination: %v\n", err)
os.Exit(1)
return
}
fmt.Fprintf(os.Stderr, "extracting to temporary path '%s/'...\n", tmpRel)
topLevelFiles, err := runzip(rarFile, tmpDir)
if err != nil {
fmt.Fprintf(os.Stderr, "error: could not unarchive: %v\n", err)
os.Exit(1)
return
}
finalDir, err = finalizeDestination(tmpDir, finalDir, topLevelFiles, useInnerName)
if err != nil {
fmt.Fprintf(os.Stderr, "error: could not rename directory: %v\n", err)
os.Exit(1)
return
}
finalRel, _ := filepath.Rel(cwd, finalDir)
fmt.Fprintf(os.Stderr, "extracted to '%s/'\n", finalRel)
}
func runzip(rarFile, absRoot string) ([]string, error) {
var err error
topLevelFiles := []string{}
f, err := os.Open(rarFile)
if err != nil {
return nil, err
}
defer f.Close()
r, err := rardecode.NewReader(f, "")
if err != nil {
return nil, err
}
for {
header, err := r.Next()
if err == io.EOF {
break
}
if err != nil {
return nil, err
}
// TODO: might this store symlinks that we should delay?
// header.Attributes
cleanPath, err := sanitizePath(absRoot, header.Name)
if err != nil {
return nil, err
}
cleanRel, _ := filepath.Rel(absRoot, cleanPath)
parts := strings.Split(cleanRel, string(filepath.Separator))
if len(parts) == 1 {
topLevelFiles = append(topLevelFiles, parts[0])
}
if header.IsDir {
err = os.MkdirAll(cleanPath, os.ModePerm)
if err != nil {
return nil, err
}
continue
}
if err := os.MkdirAll(filepath.Dir(cleanPath), os.ModePerm); err != nil {
return nil, err
}
outFile, err := os.Create(cleanPath)
if err != nil {
return nil, err
}
_, err = io.Copy(outFile, r)
if err != nil {
outFile.Close()
return nil, err
}
outFile.Close()
}
return topLevelFiles, nil
}
// sanitizePath prevents overwriting ../../../etc/passwd and the like
func sanitizePath(absRoot, filePath string) (string, error) {
dstPath := filepath.Join(absRoot, filePath)
absPath, _ := filepath.Abs(dstPath)
// guard against strings.HasPrefix(filepath.Abs("/etc/yo/../yolo"), "/etc/yo")
checkPath := absPath
if checkPath != "/" {
checkPath += "/"
}
if absRoot != "/" {
absRoot += "/"
}
if !strings.HasPrefix(checkPath, absRoot) {
return "", fmt.Errorf("potential path traversal detected: %s", absPath)
}
return absPath, nil
}
// finalizeDestination moves and/or unnests the extracted director to its final destination
func finalizeDestination(tmpDir, finalDir string, topLevelFiles []string, useInnerName bool) (string, error) {
if len(topLevelFiles) != 1 {
return finalDir, os.Rename(tmpDir, finalDir)
}
topLevelName := topLevelFiles[0]
topLevelPath := filepath.Join(tmpDir, topLevelName)
topLevelEntryInfo, err := os.Stat(topLevelPath)
if err != nil {
return finalDir, err
}
preserveFileName := false
if !topLevelEntryInfo.IsDir() {
preserveFileName = true
}
if useInnerName {
finalDir = filepath.Dir(finalDir)
finalDir = filepath.Join(finalDir, topLevelName)
} else if preserveFileName {
finalDir = filepath.Join(finalDir, topLevelName)
}
if err := os.Rename(topLevelPath, finalDir); err != nil {
return finalDir, err
}
// if the user has begun browsing this folder, it may .DS_Store,
// desktop.ini, thumbs.db, etc - or even files they've added.
_ = os.Remove(tmpDir)
return finalDir, nil
}