Let’s talk about how Golang decompresses files

Golang is a powerful programming language that provides many practical libraries and class libraries to facilitate developers to develop efficient applications. Among them, when processing compressed files, Golang provides many useful libraries to help us compress and decompress files easily.

In this article, we will introduce how Golang decompresses files.

1. Standard library - archive/tar and archive/zip

The archive/tar and archive/zip packages in the Golang standard library provide compression and decompression of tar and zip files. function.

Let’s take a look at an example of how to use the archive/zip package to decompress a zip file:

package main

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

func main() {
    zipReader, err := zip.OpenReader("example.zip")
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    defer zipReader.Close()

    for _, file := range zipReader.File {
        fmt.Println("Extracting ", file.Name)
        dest, err := os.Create(file.Name)
        if err != nil {
            fmt.Println(err)
            os.Exit(1)
        }
        defer dest.Close()

        src, err := file.Open()
        if err != nil {
            fmt.Println(err)
            os.Exit(1)
        }
        defer src.Close()

        _, err = io.Copy(dest, src)
        if err != nil {
            fmt.Println(err)
            os.Exit(1)
        }
    }
}

When we run this code, it will extract all the contents of the example.zip file and store them separately Copy them to the corresponding files in the current directory.

Similarly, using the archive/tar package, we can unzip the tar file as follows:

package main

import (
    "fmt"
    "io"
    "os"
    "archive/tar"
)

func main() {
    tarFile, err := os.Open("example.tar")
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    defer tarFile.Close()

    tarReader := tar.NewReader(tarFile)

    for true {
        header, err := tarReader.Next()
        if err == io.EOF {
            break
        }
        if err != nil {
            fmt.Println(err)
            os.Exit(1)
        }

        fmt.Println("Extracting ", header.Name)

        switch header.Typeflag {
        case tar.TypeDir:
            err = os.Mkdir(header.Name, 0755)

            if err != nil {
                fmt.Println(err)
                os.Exit(1)
            }
        case tar.TypeReg:
            dest, err := os.Create(header.Name)

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

            defer dest.Close()

            _, err = io.Copy(dest, tarReader)

            if err != nil {
                fmt.Println(err)
                os.Exit(1)
            }
        default:
            fmt.Printf("Unable to extract %s\n", header.Name)
        }
    }
}

This code will extract all the contents from the example.tar file and separate them Copy to the appropriate directory or file.

2. Third-party library - gzip

In addition to the archive/tar and archive/zip packages in the standard library, there are some other packages that can be used to decompress files. . One of the more well-known third-party libraries is the gzip package.

Our example code to decompress a gzip file using the gzip package is as follows:

package main

import (
    "fmt"
    "io"
    "os"
    "compress/gzip"
)

func main() {
    inFile, err := os.Open("example.gz")
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    defer inFile.Close()

    gzReader, err := gzip.NewReader(inFile)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    defer gzReader.Close()

    dest, err := os.Create("example")
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    defer dest.Close()

    _, err = io.Copy(dest, gzReader)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
}

This code will extract and decompress all the contents from the example.gz file and write it to a file named example in the current directory.

In this article, we learned how to decompress files using the archive/tar and archive/zip packages from the standard library and the gzip package from third-party libraries. Understanding how to use these libraries will help you manage and work with compressed files more easily.

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