agola/internal/objectstorage/posixflat.go

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// Copyright 2019 Sorint.lab
//
// 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 objectstorage
import (
"io"
"os"
"path"
"path/filepath"
"strconv"
"strings"
"unicode/utf8"
errors "golang.org/x/xerrors"
)
const (
splitLength = 8
)
func shouldEscape(c rune) bool {
return c == '/' || c == '%'
}
// escape does percent encoding to '/' and adds a slash every 8 (of the original
// string) chars
func escape(s string) string {
sepCount, hexCount := 0, 0
nc := 0
for _, c := range s {
nc++
if shouldEscape(c) {
hexCount++
}
if nc%splitLength == 0 {
sepCount++
}
}
if sepCount == 0 && hexCount == 0 {
return s
}
hasFileMarker := nc%splitLength == 0
l := len(s) + sepCount + 2*hexCount
// if the string length is a multiple of 8 then we have to add a file marker
// ".f" to not ovverride a possible directory in our fs representation
if hasFileMarker {
l++
}
t := make([]byte, l)
j := 0
nc = 0
for _, c := range s {
nc++
switch {
case shouldEscape(c):
t[j] = '%'
t[j+1] = "0123456789ABCDEF"[c>>4]
t[j+2] = "0123456789ABCDEF"[c&15]
j += 3
default:
s := string(c)
for i := 0; i < len(s); i++ {
t[j] = s[i]
j++
}
}
if nc%splitLength == 0 {
t[j] = '/'
j++
}
}
// add file marker
if hasFileMarker {
t[j-1] = '.'
t[j] = 'f'
}
return string(t)
}
func ishex(c byte) bool {
switch {
case '0' <= c && c <= '9':
return true
case 'a' <= c && c <= 'f':
return true
case 'A' <= c && c <= 'F':
return true
}
return false
}
func unhex(c byte) byte {
switch {
case '0' <= c && c <= '9':
return c - '0'
case 'a' <= c && c <= 'f':
return c - 'a' + 10
case 'A' <= c && c <= 'F':
return c - 'A' + 10
}
return 0
}
type EscapeError string
func (e EscapeError) Error() string {
return "invalid URL escape " + strconv.Quote(string(e))
}
func unescape(s string) (string, bool, error) {
// number of percent encoded
n := 0
// number of slashes
ns := 0
// number of char in the unescaped string
nc := 0
for i := 0; i < len(s); {
r, width := utf8.DecodeRuneInString(s[i:])
if r == utf8.RuneError {
return "", false, errors.Errorf("bad UTF-8 string")
}
switch r {
case '%':
n++
if i+2 >= len(s) || !ishex(s[i+1]) || !ishex(s[i+2]) {
s = s[i:]
if len(s) > 3 {
s = s[:3]
}
return "", false, EscapeError(s)
}
i += 3
nc++
case '/':
ns++
if nc%splitLength != 0 {
return "", false, EscapeError(s)
}
i++
default:
i += width
nc++
}
}
// check and remove trailing file marker
hasFileMarker := false
if nc > splitLength && nc%splitLength == 2 && s[len(s)-2:] == ".f" {
hasFileMarker = true
s = s[:len(s)-2]
}
if n == 0 && ns == 0 {
return s, hasFileMarker, nil
}
// destination string is
// the length of the escaped one (with the ending file marker already removed) - number of percent * 2 - number os slashes
t := make([]byte, len(s)-n*2-ns)
j := 0
for i := 0; i < len(s); {
r, width := utf8.DecodeRuneInString(s[i:])
if r == utf8.RuneError {
return "", false, errors.Errorf("bad UTF-8 string")
}
switch r {
case '%':
t[j] = unhex(s[i+1])<<4 | unhex(s[i+2])
j++
i += 3
case '/':
// skip "/"
i++
default:
for k := 0; k < width; k++ {
t[j] = s[i]
j++
i++
}
}
}
return string(t), hasFileMarker, nil
}
type PosixFlatStorage struct {
dataDir string
tmpDir string
}
func NewPosixFlat(baseDir string) (*PosixFlatStorage, error) {
if err := os.MkdirAll(baseDir, 0770); err != nil {
return nil, err
}
dataDir := filepath.Join(baseDir, dataDirName)
tmpDir := filepath.Join(baseDir, tmpDirName)
if err := os.MkdirAll(dataDir, 0770); err != nil {
return nil, errors.Errorf("failed to create data dir: %w", err)
}
if err := os.MkdirAll(tmpDir, 0770); err != nil {
return nil, errors.Errorf("failed to create tmp dir: %w", err)
}
return &PosixFlatStorage{
dataDir: dataDir,
tmpDir: tmpDir,
}, nil
}
func (s *PosixFlatStorage) fsPath(p string) (string, error) {
if p == "" {
return "", errors.Errorf("empty key name")
}
return filepath.Join(s.dataDir, escape(p)), nil
}
func (s *PosixFlatStorage) Stat(p string) (*ObjectInfo, error) {
fspath, err := s.fsPath(p)
if err != nil {
return nil, err
}
fi, err := os.Stat(fspath)
if err != nil {
if os.IsNotExist(err) {
return nil, NewErrNotExist(errors.Errorf("object %q doesn't exist", p))
}
return nil, err
}
return &ObjectInfo{Path: p, LastModified: fi.ModTime(), Size: fi.Size()}, nil
}
func (s *PosixFlatStorage) ReadObject(p string) (ReadSeekCloser, error) {
fspath, err := s.fsPath(p)
if err != nil {
return nil, err
}
f, err := os.Open(fspath)
if err != nil && os.IsNotExist(err) {
return nil, NewErrNotExist(errors.Errorf("object %q doesn't exist", p))
}
return f, err
}
func (s *PosixFlatStorage) WriteObject(p string, data io.Reader, size int64, persist bool) error {
fspath, err := s.fsPath(p)
if err != nil {
return err
}
if err := os.MkdirAll(path.Dir(fspath), 0770); err != nil {
return err
}
r := data
if size >= 0 {
r = io.LimitReader(data, size)
}
return writeFileAtomicFunc(fspath, s.dataDir, s.tmpDir, 0660, persist, func(f io.Writer) error {
_, err := io.Copy(f, r)
return err
})
}
func (s *PosixFlatStorage) DeleteObject(p string) error {
fspath, err := s.fsPath(p)
if err != nil {
return err
}
if err := os.Remove(fspath); err != nil {
if os.IsNotExist(err) {
return NewErrNotExist(errors.Errorf("object %q doesn't exist", p))
}
return err
}
// try to remove parent empty dirs
// TODO(sgotti) if this fails we ignore errors and the dirs will be left as
// empty, clean them asynchronously
pdir := filepath.Dir(fspath)
for {
if pdir == s.dataDir || !strings.HasPrefix(pdir, s.dataDir) {
break
}
f, err := os.Open(pdir)
if err != nil {
return nil
}
_, err = f.Readdirnames(1)
if errors.Is(err, io.EOF) {
f.Close()
if err := os.Remove(pdir); err != nil {
return nil
}
} else {
f.Close()
break
}
pdir = filepath.Dir(pdir)
}
return nil
}
func (s *PosixFlatStorage) List(prefix, startWith, delimiter string, doneCh <-chan struct{}) <-chan ObjectInfo {
objectCh := make(chan ObjectInfo, 1)
if len(delimiter) > 1 {
objectCh <- ObjectInfo{Err: errors.Errorf("wrong delimiter %q", delimiter)}
return objectCh
}
if startWith != "" && !strings.Contains(startWith, prefix) {
objectCh <- ObjectInfo{Err: errors.Errorf("wrong startwith value %q for prefix %q", startWith, prefix)}
return objectCh
}
recursive := delimiter == ""
// remove leading slash from prefix
prefix = strings.TrimPrefix(prefix, "/")
fprefix := filepath.Join(s.dataDir, escape(prefix))
root := filepath.Dir(fprefix)
if len(root) < len(s.dataDir) {
root = s.dataDir
}
// remove leading slash
startWith = strings.TrimPrefix(startWith, "/")
go func(objectCh chan<- ObjectInfo) {
var prevp string
defer close(objectCh)
err := filepath.Walk(root, func(ep string, info os.FileInfo, err error) error {
if err != nil && !os.IsNotExist(err) {
return err
}
if os.IsNotExist(err) {
return nil
}
p := ep
// get the path with / separator
p = filepath.ToSlash(p)
p, err = filepath.Rel(s.dataDir, p)
if err != nil {
return err
}
p, _, err = unescape(p)
if err != nil {
return err
}
if !recursive && len(p) > len(prefix) {
rel := strings.TrimPrefix(p, prefix)
skip := strings.Contains(rel, delimiter)
if info.IsDir() && skip {
return filepath.SkipDir
}
if skip {
return nil
}
}
// don't list dirs if there's not a file with the same name (with filemarker)
// it's not an issue if the file in the meantime has been removed, it won't
// just be listed
hasFile := true
_, err = os.Stat(ep + ".f")
if err != nil && !os.IsNotExist(err) {
return err
}
if os.IsNotExist(err) {
hasFile = false
}
if info.IsDir() && !hasFile {
return nil
}
if strings.HasPrefix(p, prefix) && p > startWith {
// skip keys smaller than the previously returned one. This happens when we
// receive a file with a file marker that we already returned previously
// when we received a dir with the same name
// it'not an issue if the dir has been removed since we already returned the file
if p > prevp {
select {
// Send object content.
case objectCh <- ObjectInfo{Path: p, LastModified: info.ModTime(), Size: info.Size()}:
// If receives done from the caller, return here.
case <-doneCh:
return io.EOF
}
}
prevp = p
}
return nil
})
if err != nil && !errors.Is(err, io.EOF) {
objectCh <- ObjectInfo{
Err: err,
}
return
}
}(objectCh)
return objectCh
}