listmonk/internal/media/providers/filesystem/filesystem.go

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package filesystem
import (
"crypto/rand"
"fmt"
"io"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"github.com/knadh/listmonk/internal/media"
)
const tmpFilePrefix = "listmonk"
// Opts represents filesystem params
type Opts struct {
UploadPath string `koanf:"upload_path"`
UploadURI string `koanf:"upload_uri"`
RootURL string `koanf:"root_url"`
}
// Client implements `media.Store`
type Client struct {
opts Opts
}
// This matches filenames, sans extensions, of the format
// filename_(number). The number is incremented in case
// new file uploads conflict with existing filenames
// on the filesystem.
var fnameRegexp = regexp.MustCompile(`(.+?)_([0-9]+)$`)
// NewDiskStore initialises store for Filesystem provider.
func NewDiskStore(opts Opts) (media.Store, error) {
return &Client{
opts: opts,
}, nil
}
// Put accepts the filename, the content type and file object itself and stores the file in disk.
func (c *Client) Put(filename string, cType string, src io.ReadSeeker) (string, error) {
var out *os.File
// There's no explicit name. Use the one posted in the HTTP request.
if filename == "" {
filename = strings.TrimSpace(filename)
if filename == "" {
filename, _ = generateRandomString(10)
}
}
// Get the directory path
dir := getDir(c.opts.UploadPath)
filename = assertUniqueFilename(dir, filename)
o, err := os.OpenFile(filepath.Join(dir, filename), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0664)
if err != nil {
return "", err
}
out = o
defer out.Close()
if _, err := io.Copy(out, src); err != nil {
return "", err
}
return filename, nil
}
// Get accepts a filename and retrieves the full path from disk.
func (c *Client) Get(name string) string {
return fmt.Sprintf("%s%s/%s", c.opts.RootURL, c.opts.UploadURI, name)
}
// Delete accepts a filename and removes it from disk.
func (c *Client) Delete(file string) error {
dir := getDir(c.opts.UploadPath)
err := os.Remove(filepath.Join(dir, file))
if err != nil {
return err
}
return nil
}
// assertUniqueFilename takes a file path and check if it exists on the disk. If it doesn't,
// it returns the same name and if it does, it adds a small random hash to the filename
// and returns that.
func assertUniqueFilename(dir, fileName string) string {
var (
ext = filepath.Ext(fileName)
base = fileName[0 : len(fileName)-len(ext)]
num = 0
)
for {
// There's no name conflict.
if _, err := os.Stat(filepath.Join(dir, fileName)); os.IsNotExist(err) {
return fileName
}
// Does the name match the _(num) syntax?
r := fnameRegexp.FindAllStringSubmatch(fileName, -1)
if len(r) == 1 && len(r[0]) == 3 {
num, _ = strconv.Atoi(r[0][2])
}
num++
fileName = fmt.Sprintf("%s_%d%s", base, num, ext)
}
}
// generateRandomString generates a cryptographically random, alphanumeric string of length n.
func generateRandomString(n int) (string, error) {
const dictionary = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
var bytes = make([]byte, n)
if _, err := rand.Read(bytes); err != nil {
return "", err
}
for k, v := range bytes {
bytes[k] = dictionary[v%byte(len(dictionary))]
}
return string(bytes), nil
}
// getDir returns the current working directory path if no directory is specified,
// else returns the directory path specified itself.
func getDir(dir string) string {
if dir == "" {
dir, _ = os.Getwd()
}
return dir
}