491 lines
10 KiB
Go
491 lines
10 KiB
Go
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// Copyright 2019 Sorint.lab
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package objectstorage
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import (
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"io"
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"io/ioutil"
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"os"
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"path"
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"path/filepath"
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"strconv"
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"strings"
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"unicode/utf8"
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"github.com/pkg/errors"
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)
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const (
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dataDirName = "data"
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tmpDirName = "tmp"
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splitLength = 8
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)
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func shouldEscape(c rune) bool {
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return c == '/' || c == '%'
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}
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// escape does percent encoding to '/' and adds a slash every 8 (of the original
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// string) chars
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func escape(s string) string {
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sepCount, hexCount := 0, 0
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nc := 0
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for _, c := range s {
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nc++
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if shouldEscape(c) {
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hexCount++
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}
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if nc%splitLength == 0 {
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sepCount++
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}
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}
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if sepCount == 0 && hexCount == 0 {
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return s
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}
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hasFileMarker := nc%splitLength == 0
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l := len(s) + sepCount + 2*hexCount
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// if the string length is a multiple of 8 then we have to add a file marker
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// ".f" to not ovverride a possible directory in our fs representation
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if hasFileMarker {
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l++
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}
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t := make([]byte, l)
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j := 0
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nc = 0
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for _, c := range s {
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nc++
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switch {
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case shouldEscape(c):
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t[j] = '%'
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t[j+1] = "0123456789ABCDEF"[c>>4]
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t[j+2] = "0123456789ABCDEF"[c&15]
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j += 3
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default:
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s := string(c)
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for i := 0; i < len(s); i++ {
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t[j] = s[i]
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j++
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}
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}
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if nc%splitLength == 0 {
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t[j] = '/'
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j++
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}
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}
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// add file marker
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if hasFileMarker {
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t[j-1] = '.'
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t[j] = 'f'
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}
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return string(t)
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}
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func ishex(c byte) bool {
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switch {
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case '0' <= c && c <= '9':
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return true
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case 'a' <= c && c <= 'f':
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return true
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case 'A' <= c && c <= 'F':
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return true
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}
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return false
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}
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func unhex(c byte) byte {
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switch {
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case '0' <= c && c <= '9':
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return c - '0'
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case 'a' <= c && c <= 'f':
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return c - 'a' + 10
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case 'A' <= c && c <= 'F':
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return c - 'A' + 10
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}
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return 0
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}
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type EscapeError string
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func (e EscapeError) Error() string {
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return "invalid URL escape " + strconv.Quote(string(e))
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}
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func unescape(s string) (string, bool, error) {
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// number of percent encoded
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n := 0
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// number of slashes
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ns := 0
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// number of char in the unescaped string
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nc := 0
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for i := 0; i < len(s); {
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r, width := utf8.DecodeRuneInString(s[i:])
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if r == utf8.RuneError {
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return "", false, errors.Errorf("bad UTF-8 string")
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}
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switch r {
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case '%':
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n++
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if i+2 >= len(s) || !ishex(s[i+1]) || !ishex(s[i+2]) {
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s = s[i:]
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if len(s) > 3 {
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s = s[:3]
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}
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return "", false, EscapeError(s)
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}
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i += 3
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nc++
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case '/':
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ns++
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if nc%splitLength != 0 {
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return "", false, EscapeError(s)
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}
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i++
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default:
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i += width
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nc++
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}
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}
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// check and remove trailing file marker
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hasFileMarker := false
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if nc > splitLength && nc%splitLength == 2 && s[len(s)-2:] == ".f" {
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hasFileMarker = true
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s = s[:len(s)-2]
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nc -= 2
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}
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if n == 0 && ns == 0 {
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return s, hasFileMarker, nil
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}
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// destination string is
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// the length of the escaped one (with the ending file marker already removed) - number of percent * 2 - number os slashes
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t := make([]byte, len(s)-n*2-ns)
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j := 0
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for i := 0; i < len(s); {
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r, width := utf8.DecodeRuneInString(s[i:])
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if r == utf8.RuneError {
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return "", false, errors.Errorf("bad UTF-8 string")
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}
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switch r {
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case '%':
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t[j] = unhex(s[i+1])<<4 | unhex(s[i+2])
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j++
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i += 3
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case '/':
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// skip "/"
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i++
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default:
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for k := 0; k < width; k++ {
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t[j] = s[i]
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j++
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i++
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}
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}
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}
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return string(t), hasFileMarker, nil
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}
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type PosixStorage struct {
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dataDir string
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tmpDir string
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}
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func NewPosixStorage(baseDir string) (*PosixStorage, error) {
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if err := os.MkdirAll(baseDir, 0770); err != nil {
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return nil, err
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}
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dataDir := filepath.Join(baseDir, dataDirName)
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tmpDir := filepath.Join(baseDir, tmpDirName)
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if err := os.MkdirAll(dataDir, 0770); err != nil {
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return nil, errors.Wrapf(err, "failed to create data dir")
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}
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if err := os.MkdirAll(tmpDir, 0770); err != nil {
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return nil, errors.Wrapf(err, "failed to create tmp dir")
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}
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return &PosixStorage{
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dataDir: dataDir,
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tmpDir: tmpDir,
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}, nil
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}
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func (s *PosixStorage) fsPath(p string) (string, error) {
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if p == "" {
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return "", errors.Errorf("empty key name")
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}
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return filepath.Join(s.dataDir, escape(p)), nil
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}
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func (s *PosixStorage) Stat(p string) (*ObjectInfo, error) {
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fspath, err := s.fsPath(p)
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if err != nil {
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return nil, err
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}
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if _, err := os.Stat(fspath); err != nil {
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if os.IsNotExist(err) {
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return nil, ErrNotExist
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}
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return nil, err
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}
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return &ObjectInfo{Path: p}, nil
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}
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func (s *PosixStorage) ReadObject(p string) (io.ReadCloser, error) {
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fspath, err := s.fsPath(p)
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if err != nil {
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return nil, err
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}
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f, err := os.Open(fspath)
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if err != nil && os.IsNotExist(err) {
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return nil, ErrNotExist
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}
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return f, err
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}
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func (s *PosixStorage) WriteObject(p string, data io.Reader) error {
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fspath, err := s.fsPath(p)
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if err != nil {
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return err
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}
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if err := os.MkdirAll(path.Dir(fspath), 0770); err != nil {
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return err
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}
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return s.WriteFileAtomicFunc(fspath, 0660, func(f io.Writer) error {
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_, err := io.Copy(f, data)
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return err
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})
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}
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func (s *PosixStorage) DeleteObject(p string) error {
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fspath, err := s.fsPath(p)
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if err != nil {
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return err
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}
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if err := os.Remove(fspath); err != nil {
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if os.IsNotExist(err) {
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return ErrNotExist
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}
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return err
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}
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// try to remove parent empty dirs
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// TODO(sgotti) if this fails we ignore errors and the dirs will be left as
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// empty, clean them asynchronously
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pdir := filepath.Dir(fspath)
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for {
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if pdir == s.dataDir || !strings.HasPrefix(pdir, s.dataDir) {
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break
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}
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f, err := os.Open(pdir)
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if err != nil {
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return nil
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}
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_, err = f.Readdirnames(1)
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if err == io.EOF {
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f.Close()
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if err := os.Remove(pdir); err != nil {
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return nil
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}
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} else {
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f.Close()
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break
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}
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pdir = filepath.Dir(pdir)
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}
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return nil
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}
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func (s *PosixStorage) List(prefix, startWith, delimiter string, doneCh <-chan struct{}) <-chan ObjectInfo {
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objectCh := make(chan ObjectInfo, 1)
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if len(delimiter) > 1 {
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objectCh <- ObjectInfo{Err: errors.Errorf("wrong delimiter %q", delimiter)}
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return objectCh
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}
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if startWith != "" && !strings.Contains(startWith, prefix) {
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objectCh <- ObjectInfo{Err: errors.Errorf("wrong startwith value %q for prefix %q", startWith, prefix)}
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return objectCh
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}
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recursive := delimiter == ""
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// remove leading slash from prefix
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if strings.HasPrefix(prefix, "/") {
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prefix = strings.TrimPrefix(prefix, "/")
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}
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fprefix := filepath.Join(s.dataDir, escape(prefix))
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root := filepath.Dir(fprefix)
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if len(root) < len(s.dataDir) {
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root = s.dataDir
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}
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// remove leading slash
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if strings.HasPrefix(startWith, "/") {
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startWith = strings.TrimPrefix(startWith, "/")
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}
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go func(objectCh chan<- ObjectInfo) {
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var prevp string
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defer close(objectCh)
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err := filepath.Walk(root, func(ep string, info os.FileInfo, err error) error {
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if err != nil && !os.IsNotExist(err) {
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return err
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}
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if os.IsNotExist(err) {
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return nil
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}
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p := ep
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// get the path with / separator
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p = filepath.ToSlash(p)
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p, err = filepath.Rel(s.dataDir, p)
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if err != nil {
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return err
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}
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p, _, err = unescape(p)
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if err != nil {
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return err
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}
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if !recursive && len(p) > len(prefix) {
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rel := strings.TrimPrefix(p, prefix)
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skip := strings.Contains(rel, delimiter)
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if info.IsDir() && skip {
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return filepath.SkipDir
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}
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if skip {
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return nil
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}
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}
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// don't list dirs if there's not a file with the same name (with filemarker)
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// it's not an issue if the file in the meantime has been removed, it won't
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// just be listed
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hasFile := true
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_, err = os.Stat(ep + ".f")
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if err != nil && !os.IsNotExist(err) {
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return err
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}
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if os.IsNotExist(err) {
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hasFile = false
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}
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if info.IsDir() && !hasFile {
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return nil
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}
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if strings.HasPrefix(p, prefix) && p > startWith {
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// skip keys smaller than the previously returned one. This happens when we
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// receive a file with a file marker that we already returned previously
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// when we received a dir with the same name
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|
|
// 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}:
|
||
|
|
// If receives done from the caller, return here.
|
||
|
|
case <-doneCh:
|
||
|
|
return io.EOF
|
||
|
|
}
|
||
|
|
}
|
||
|
|
prevp = p
|
||
|
|
}
|
||
|
|
|
||
|
|
return nil
|
||
|
|
})
|
||
|
|
if err != nil && err != io.EOF {
|
||
|
|
objectCh <- ObjectInfo{
|
||
|
|
Err: err,
|
||
|
|
}
|
||
|
|
return
|
||
|
|
}
|
||
|
|
}(objectCh)
|
||
|
|
|
||
|
|
return objectCh
|
||
|
|
}
|
||
|
|
|
||
|
|
// WriteFileAtomicFunc atomically writes a file, it achieves this by creating a
|
||
|
|
// temporary file and then moving it. writeFunc is the func that will write
|
||
|
|
// data to the file.
|
||
|
|
// TODO(sgotti) remove left over tmp files if process crashes before calling
|
||
|
|
// os.Remove
|
||
|
|
func (s *PosixStorage) WriteFileAtomicFunc(p string, perm os.FileMode, writeFunc func(f io.Writer) error) error {
|
||
|
|
f, err := ioutil.TempFile(s.tmpDir, "tmpfile")
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
err = writeFunc(f)
|
||
|
|
if err == nil {
|
||
|
|
err = f.Sync()
|
||
|
|
}
|
||
|
|
if closeErr := f.Close(); err == nil {
|
||
|
|
err = closeErr
|
||
|
|
}
|
||
|
|
if permErr := os.Chmod(f.Name(), perm); err == nil {
|
||
|
|
err = permErr
|
||
|
|
}
|
||
|
|
if err == nil {
|
||
|
|
err = os.Rename(f.Name(), p)
|
||
|
|
}
|
||
|
|
if err != nil {
|
||
|
|
os.Remove(f.Name())
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
|
||
|
|
// sync parent dirs
|
||
|
|
pdir := filepath.Dir(p)
|
||
|
|
for {
|
||
|
|
if !strings.HasPrefix(pdir, s.dataDir) {
|
||
|
|
break
|
||
|
|
}
|
||
|
|
f, err := os.Open(pdir)
|
||
|
|
if err != nil {
|
||
|
|
f.Close()
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
if err := f.Sync(); err != nil {
|
||
|
|
f.Close()
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
f.Close()
|
||
|
|
|
||
|
|
pdir = filepath.Dir(pdir)
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func (s *PosixStorage) WriteFileAtomic(filename string, perm os.FileMode, data []byte) error {
|
||
|
|
return s.WriteFileAtomicFunc(filename, perm,
|
||
|
|
func(f io.Writer) error {
|
||
|
|
_, err := f.Write(data)
|
||
|
|
return err
|
||
|
|
})
|
||
|
|
}
|