package main

import (
    "archive/zip"
    "fmt"
    "io/ioutil"
)

type myCloser interface {
    Close() error
}

// closeFile is a helper function which streamlines closing
// with error checking on different file types.
func closeFile(f myCloser) {
    err := f.Close()
    check(err)
}

// readAll is a wrapper function for ioutil.ReadAll. It accepts a zip.File as
// its parameter, opens it, reads its content and returns it as a byte slice.
func readAll(file *zip.File) []byte {
    fc, err := file.Open()
    check(err)
    defer closeFile(fc)

    content, err := ioutil.ReadAll(fc)
    check(err)

    return content
}

// check is a helper function which streamlines error checking
func check(e error) {
    if e != nil {
        panic(e)
    }
}

func main() {
    zipFile := "superman.zip"
    // superman.def
    def := zipFile[:len(zipFile)-4] + ".def"

    zf, zerr := zip.OpenReader(zipFile)
    check(zerr)
    defer closeFile(zf)

    for _, file := range zf.File {
        //fmt.Printf("%s\n", file.Name)

        // print out superman.def contents
        if file.Name == def {
            fmt.Printf("%s\n\n", readAll(file)) // file content
        }
    }
}