zipstream

Package zipstream is a stream on the fly extractor/reader for zip archive like Java's java.util.zip.ZipInputStream, there is no need to provide io.ReaderAt and total archive size parameters, that is, just need only one io.Reader parameter.

Implementation

Most code of this package is copied directly from golang standard library archive/zip, .ZIP archive format specification reference is here

Usage

go get github.com/zhyee/zipstream

Examples

package main

import (
	"io"
	"log"
	"net/http"

	"github.com/zhyee/zipstream"
)

func main() {

	resp, err := http.Get("https://github.com/golang/go/archive/refs/tags/go1.16.10.zip")
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()

	zr := zipstream.NewReader(resp.Body)

	for {
		e, err := zr.GetNextEntry()
		if err == io.EOF {
			break
		}
		if err != nil {
			log.Fatalf("unable to get next entry: %s", err)
		}

		log.Println("entry name: ", e.Name)
		log.Println("entry comment: ", e.Comment)
		log.Println("entry reader version: ", e.ReaderVersion)
		log.Println("entry modify time: ", e.Modified)
		log.Println("entry compressed size: ", e.CompressedSize64)
		log.Println("entry uncompressed size: ", e.UncompressedSize64)
		log.Println("entry is a dir: ", e.IsDir())

		if !e.IsDir() {
			rc, err := e.Open()
			if err != nil {
				log.Fatalf("unable to open zip file: %s", err)
			}
			content, err := io.ReadAll(rc)
			if err != nil {
				log.Fatalf("read zip file content fail: %s", err)
			}

			log.Println("file length:", len(content))

			if uint64(len(content)) != e.UncompressedSize64 {
				log.Fatalf("read zip file length not equal with UncompressedSize64")
			}
			if err := rc.Close(); err != nil {
				log.Fatalf("close zip entry reader fail: %s", err)
			}
		}
	}
}

Limitation

• Every file in zip archive can read only once for a new Reader, Repeated read is unsupported.
• Some central directory header field is not resolved, such as version made by, internal file attributes, external file attributes, relative offset of local header, some central directory header field may differ from local file header, such as extra field.
• Unable to read multi files concurrently.