Golang : zlib compress file example
This tutorial will show you how to read an uncompress file content into a buffer, use zlib on the buffer and write out the buffer content into a new file.
Here we go :
package main
import (
"bufio"
"bytes"
"compress/zlib"
"flag"
"fmt"
"io/ioutil"
"os"
)
func main() {
flag.Parse() // get the arguments from command line
filename := flag.Arg(0)
if filename == "" {
fmt.Println("Usage : go-zlib sourcefile")
os.Exit(1)
}
rawfile, err := os.Open(filename)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
defer rawfile.Close()
// calculate the buffer size for rawfile
info, _ := rawfile.Stat()
var size int64 = info.Size()
rawbytes := make([]byte, size)
// read rawfile content into buffer
buffer := bufio.NewReader(rawfile)
_, err = buffer.Read(rawbytes)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
var buf bytes.Buffer
writer := zlib.NewWriter(&buf)
writer.Write(rawbytes)
writer.Close()
err = ioutil.WriteFile(filename+".zlib", buf.Bytes(), info.Mode())
// use 0666 to replace info.Mode() if you prefer
if err != nil {
fmt.Println(err)
os.Exit(1)
}
fmt.Printf("%s compressed to %s\n", filename, filename+".zlib")
}
References :
http://golang.org/pkg/compress/zlib/
https://www.socketloop.com/tutorials/golang-read-binary-file-into-memory
By Adam Ng
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