Golang : Decompress zlib file example

Continuation from previous tutorial on how to zlib compress a file. In this part, we will learn how to decompress a file that was compressed with zlib compression algorithm.

Here are the codes :

 package main

 import (
 "compress/zlib"
 "flag"
 "fmt"
 "io"
 "os"
 "strings"
 )

 func main() {

 flag.Parse() // get the arguments from command line

 filename := flag.Arg(0)

 if filename == "" {
 fmt.Println("Usage : unzlib sourcefile.zlib")
 os.Exit(1)
 }

 zlibfile, err := os.Open(filename)

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 reader, err := zlib.NewReader(zlibfile)
 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }
 defer reader.Close()

 newfilename := strings.TrimSuffix(filename, ".zlib")

 writer, err := os.Create(newfilename)

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 defer writer.Close()

 if _, err = io.Copy(writer, reader); err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 fmt.Println("Decompressed to ", newfilename)

 }

Sample output :

./unzlib uncompressed.txt.zlib

Decompressed to uncompressed.txt

./unzlib

Usage : unzlib sourcefile.zlib

References :

http://golang.org/pkg/compress/zlib/

https://www.socketloop.com/tutorials/golang-zlib-compress-file-example