81 lines
1.7 KiB
Go
81 lines
1.7 KiB
Go
// Copyright © 2018 Inanc Gumus
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// Learn Go Programming Course
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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//
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// For more tutorials : https://learngoprogramming.com
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// In-person training : https://www.linkedin.com/in/inancgumus/
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// Follow me on twitter: https://twitter.com/inancgumus
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package main
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import (
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"fmt"
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"io/ioutil"
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"os"
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)
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func main() {
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args := os.Args[1:]
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if len(args) == 0 {
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fmt.Println("Provide a directory")
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return
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}
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files, err := ioutil.ReadDir(args[0])
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if err != nil {
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fmt.Println(err)
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return
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}
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// 1st: You can also take the average of the total file length
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// across platforms. It's about 255.
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//
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// https://en.wikipedia.org/wiki/Comparison_of_file_systems#Limits
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//
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// BTRFS 255 bytes
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// exFAT 255 UTF-16 characters
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// ext2 255 bytes
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// ext3 255 bytes
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// ext3cow 255 bytes
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// ext4 255 bytes
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// FAT32 255 bytes
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// NTFS 255 characters
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// XFS 255 bytes
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//
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// total := len(files) * 256
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// 1st B: To be exact, find the total size of all the empty files
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var total int
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for _, file := range files {
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if file.Size() == 0 {
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// +1 for the newline character
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// when printing the filename afterward
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total += len(file.Name()) + 1
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}
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}
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fmt.Printf("Total required space: %d bytes.\n", total)
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// 2nd: allocate a large enough byte slice in one go
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names := make([]byte, 0, total)
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for _, file := range files {
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if file.Size() == 0 {
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name := file.Name()
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names = append(names, name...)
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names = append(names, '\n')
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}
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}
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err = ioutil.WriteFile("out.txt", names, 0644)
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if err != nil {
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fmt.Println(err)
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return
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}
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fmt.Printf("%s", names)
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}
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// See: https://www.tutorialspoint.com/unix/unix-file-permission.htm
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// See: http://permissions-calculator.org/
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