marek_z_piekarek

CCrraawwlleerrggoohello

                    // passgen <thinkofher, github.com/thinkofher>
//
// Go is truth.
//
// Building and usage:
//
// $ go build -o passgen .
// $ ./passgen 32
// OHa0)j3:MijW%u)j1g{{siz/'NTx=QMv
// $ ./passgen 16
// %(k9pD+]52dPU/-
//
package main

import (
	"fmt"
	"math/rand"
	"os"
	"strconv"
	"time"
)

// You have to start with something
// clever, right? No? Whatever.
const MIN = int('!')
const MAX = int('}')

func main() {
	// First argument is always program that you run.
	// So if user provides less than two arguments, that means
	// he/she's providing zero arguments, that we can call useful.
	if len(os.Args) < 2 {
		fmt.Fprintf(os.Stderr, "You have to provide password length!")
		// That's old unix tradition.
		// Things gone wrong? Return 1 and forget.
		os.Exit(1)
	}

	// Convert first (not counting program name) argument to integer.
	passLen, err := strconv.Atoi(os.Args[1])
	if err != nil {
		// Error occurs! That means user had tried to trick us
		// and write something stupid like 'foobar' instead of
		// giving us sweet like poney-honey password length as integer
		// number.
		fmt.Fprintf(os.Stderr, "%s is not a numerical value!", os.Args[1])
		os.Exit(1)
	}

	if passLen < 0 {
		// You thought that I missed that detail?
		// I must admit, you're really smart, but not
		// smarter than my password generator!
		fmt.Fprintf(os.Stderr, "Password length can not be negative number.")
		os.Exit(1)
	}

	// Do you remember that? I bet you do.
	// Namespaces are good. Don't fight them!
	// They will never harm you if you'll treat them
	// with due respect.
	rand.Seed(time.Now().UnixNano())

	// That's something new.
	result := make([]byte, passLen)

	// And finally.
	for i := range result {
		result[i] = byte(rand.Intn(MAX-MIN) + MIN)
	}
	// We're home.
	fmt.Fprintf(os.Stdin, "%s", string(result))

	// Of course don't use that stupid password.
	// Computers doesn't give a damn about how
	// funny are bytes in your password, as long
	// as you have many of them.
}