golang errror, archive/zip not a valid zip file , Why?

[小菜]

package main

import (

"fmt"

"io"

//"net/http"

"os"

"archive/zip"

"log"

)

func main() {

// Open a zip archive for reading.

r, err := zip.OpenReader("xxx.zip")

if err != nil {

log.Fatal(err)

}

defer r.Close()

// Iterate through the files in the archive,

// printing some of their contents.

for _, f := range r.File {

fmt.Printf("Contents of %s:\n", f.Name)

rc, err := f.Open()

if err != nil {

log.Fatal(err)

}

_, err = io.CopyN(os.Stdout, rc, 68)

if err != nil {

log.Fatal(err)

}

rc.Close()

fmt.Println()

}

}

go run t.go

2014/06/12 16:47:41 zip: not a valid zip file

the zip file  can open by WinRAR, why  can't open by golang?

[Dave Cheney]

This is not a zip file

% file xxx.zip
xxx.zip: ERROR: line 5: regexec error 17, (illegal byte sequence)

[egon]

It's not a plain zip file it's this: https://developer.chrome.com/extensions/crx

+ egon