/*
Copyright 2015 The Kubernetes Authors All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
	"flag"
	"fmt"
	"io/ioutil"
	"os"
	"syscall"
	"time"
)

var (
	fsTypePath                = ""
	fileModePath              = ""
	filePermPath              = ""
	newFilePath0644           = ""
	newFilePath0666           = ""
	newFilePath0777           = ""
	readFileContentPath       = ""
	readFileContentInLoopPath = ""
	retryDuration             = 180
)

func init() {
	flag.StringVar(&fsTypePath, "fs_type", "", "Path to print the fs type for")
	flag.StringVar(&fileModePath, "file_mode", "", "Path to print the mode bits of")
	flag.StringVar(&filePermPath, "file_perm", "", "Path to print the perms of")
	flag.StringVar(&newFilePath0644, "new_file_0644", "", "Path to write to and read from with perm 0644")
	flag.StringVar(&newFilePath0666, "new_file_0666", "", "Path to write to and read from with perm 0666")
	flag.StringVar(&newFilePath0777, "new_file_0777", "", "Path to write to and read from with perm 0777")
	flag.StringVar(&readFileContentPath, "file_content", "", "Path to read the file content from")
	flag.StringVar(&readFileContentInLoopPath, "file_content_in_loop", "", "Path to read the file content in loop from")
	flag.IntVar(&retryDuration, "retry_time", 180, "Retry time during the loop")
}

// This program performs some tests on the filesystem as dictated by the
// flags passed by the user.
func main() {
	flag.Parse()

	var (
		err  error
		errs = []error{}
	)

	// Clear the umask so we can set any mode bits we want.
	syscall.Umask(0000)

	// NOTE: the ordering of execution of the various command line
	// flags is intentional and allows a single command to:
	//
	// 1.  Check the fstype of a path
	// 2.  Write a new file within that path
	// 3.  Check that the file's content can be read
	//
	// Changing the ordering of the following code will break tests.

	err = fsType(fsTypePath)
	if err != nil {
		errs = append(errs, err)
	}

	err = readWriteNewFile(newFilePath0644, 0644)
	if err != nil {
		errs = append(errs, err)
	}

	err = readWriteNewFile(newFilePath0666, 0666)
	if err != nil {
		errs = append(errs, err)
	}

	err = readWriteNewFile(newFilePath0777, 0777)
	if err != nil {
		errs = append(errs, err)
	}

	err = fileMode(fileModePath)
	if err != nil {
		errs = append(errs, err)
	}

	err = filePerm(filePermPath)
	if err != nil {
		errs = append(errs, err)
	}

	err = readFileContent(readFileContentPath)
	if err != nil {
		errs = append(errs, err)
	}

	err = readFileContentInLoop(readFileContentInLoopPath, retryDuration)
	if err != nil {
		errs = append(errs, err)
	}

	if len(errs) != 0 {
		os.Exit(1)
	}

	os.Exit(0)
}

// Defined by Linux (sys/statfs.h) - the type number for tmpfs mounts.
const linuxTmpfsMagic = 0x01021994

func fsType(path string) error {
	if path == "" {
		return nil
	}

	buf := syscall.Statfs_t{}
	if err := syscall.Statfs(path, &buf); err != nil {
		fmt.Printf("error from statfs(%q): %v\n", path, err)
		return err
	}

	if buf.Type == linuxTmpfsMagic {
		fmt.Printf("mount type of %q: tmpfs\n", path)
	} else {
		fmt.Printf("mount type of %q: %v\n", path, buf.Type)
	}

	return nil
}

func fileMode(path string) error {
	if path == "" {
		return nil
	}

	fileinfo, err := os.Lstat(path)
	if err != nil {
		fmt.Printf("error from Lstat(%q): %v\n", path, err)
		return err
	}

	fmt.Printf("mode of file %q: %v\n", path, fileinfo.Mode())
	return nil
}

func filePerm(path string) error {
	if path == "" {
		return nil
	}

	fileinfo, err := os.Lstat(path)
	if err != nil {
		fmt.Printf("error from Lstat(%q): %v\n", path, err)
		return err
	}

	fmt.Printf("perms of file %q: %v\n", path, fileinfo.Mode().Perm())
	return nil
}

func readFileContent(path string) error {
	if path == "" {
		return nil
	}

	contentBytes, err := ioutil.ReadFile(path)
	if err != nil {
		fmt.Printf("error reading file content for %q: %v\n", path, err)
		return err
	}

	fmt.Printf("content of file %q: %v\n", path, string(contentBytes))

	return nil
}

func readWriteNewFile(path string, perm os.FileMode) error {
	if path == "" {
		return nil
	}

	content := "mount-tester new file\n"
	err := ioutil.WriteFile(path, []byte(content), perm)
	if err != nil {
		fmt.Printf("error writing new file %q: %v\n", path, err)
		return err
	}

	return readFileContent(path)
}

func readFileContentInLoop(path string, retryDuration int) error {
	if path == "" {
		return nil
	}
	var content []byte
	content = testFileContent(path, retryDuration)

	fmt.Printf("content of file %q: %v\n", path, string(content))

	return nil
}

func testFileContent(filePath string, retryDuration int) []byte {
	var (
		contentBytes []byte
		err          error
	)

	retryTime := time.Second * time.Duration(retryDuration)
	for start := time.Now(); time.Since(start) < retryTime; time.Sleep(2 * time.Second) {
		contentBytes, err = ioutil.ReadFile(filePath)
		if err == nil {
			//Expected content "mount-tester new file\n", length 22
			if len(contentBytes) == 22 {
				break
			} else {
				fmt.Printf("Unexpected length of file: found %d, expected %d.Retry", len(contentBytes), 22)
			}
		} else {
			fmt.Printf("Error read file %s: %v, retry", filePath, err)
		}

	}

	return contentBytes
}
