khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame] | 1 | // Copyright 2015 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | // Package fileutil implements utility functions related to files and paths. |
| 16 | package fileutil |
| 17 | |
| 18 | import ( |
| 19 | "fmt" |
| 20 | "io" |
| 21 | "io/ioutil" |
| 22 | "os" |
| 23 | "path/filepath" |
| 24 | "sort" |
| 25 | |
| 26 | "github.com/coreos/pkg/capnslog" |
| 27 | ) |
| 28 | |
| 29 | const ( |
| 30 | // PrivateFileMode grants owner to read/write a file. |
| 31 | PrivateFileMode = 0600 |
| 32 | ) |
| 33 | |
| 34 | var ( |
| 35 | plog = capnslog.NewPackageLogger("github.com/coreos/etcd", "pkg/fileutil") |
| 36 | ) |
| 37 | |
| 38 | // IsDirWriteable checks if dir is writable by writing and removing a file |
| 39 | // to dir. It returns nil if dir is writable. |
| 40 | func IsDirWriteable(dir string) error { |
| 41 | f := filepath.Join(dir, ".touch") |
| 42 | if err := ioutil.WriteFile(f, []byte(""), PrivateFileMode); err != nil { |
| 43 | return err |
| 44 | } |
| 45 | return os.Remove(f) |
| 46 | } |
| 47 | |
| 48 | // ReadDir returns the filenames in the given directory in sorted order. |
| 49 | func ReadDir(dirpath string) ([]string, error) { |
| 50 | dir, err := os.Open(dirpath) |
| 51 | if err != nil { |
| 52 | return nil, err |
| 53 | } |
| 54 | defer dir.Close() |
| 55 | names, err := dir.Readdirnames(-1) |
| 56 | if err != nil { |
| 57 | return nil, err |
| 58 | } |
| 59 | sort.Strings(names) |
| 60 | return names, nil |
| 61 | } |
| 62 | |
| 63 | // TouchDirAll is similar to os.MkdirAll. It creates directories with 0700 permission if any directory |
| 64 | // does not exists. TouchDirAll also ensures the given directory is writable. |
| 65 | func TouchDirAll(dir string) error { |
| 66 | // If path is already a directory, MkdirAll does nothing and returns nil, so, |
| 67 | // first check if dir exist with an expected permission mode. |
| 68 | if Exist(dir) { |
| 69 | err := CheckDirPermission(dir, PrivateDirMode) |
| 70 | if err != nil { |
| 71 | plog.Warningf("check file permission: %v", err) |
| 72 | } |
| 73 | } else { |
| 74 | err := os.MkdirAll(dir, PrivateDirMode) |
| 75 | if err != nil { |
| 76 | // if mkdirAll("a/text") and "text" is not |
| 77 | // a directory, this will return syscall.ENOTDIR |
| 78 | return err |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | return IsDirWriteable(dir) |
| 83 | } |
| 84 | |
| 85 | // CreateDirAll is similar to TouchDirAll but returns error |
| 86 | // if the deepest directory was not empty. |
| 87 | func CreateDirAll(dir string) error { |
| 88 | err := TouchDirAll(dir) |
| 89 | if err == nil { |
| 90 | var ns []string |
| 91 | ns, err = ReadDir(dir) |
| 92 | if err != nil { |
| 93 | return err |
| 94 | } |
| 95 | if len(ns) != 0 { |
| 96 | err = fmt.Errorf("expected %q to be empty, got %q", dir, ns) |
| 97 | } |
| 98 | } |
| 99 | return err |
| 100 | } |
| 101 | |
| 102 | func Exist(name string) bool { |
| 103 | _, err := os.Stat(name) |
| 104 | return err == nil |
| 105 | } |
| 106 | |
| 107 | // ZeroToEnd zeros a file starting from SEEK_CUR to its SEEK_END. May temporarily |
| 108 | // shorten the length of the file. |
| 109 | func ZeroToEnd(f *os.File) error { |
| 110 | // TODO: support FALLOC_FL_ZERO_RANGE |
| 111 | off, err := f.Seek(0, io.SeekCurrent) |
| 112 | if err != nil { |
| 113 | return err |
| 114 | } |
| 115 | lenf, lerr := f.Seek(0, io.SeekEnd) |
| 116 | if lerr != nil { |
| 117 | return lerr |
| 118 | } |
| 119 | if err = f.Truncate(off); err != nil { |
| 120 | return err |
| 121 | } |
| 122 | // make sure blocks remain allocated |
| 123 | if err = Preallocate(f, lenf, true); err != nil { |
| 124 | return err |
| 125 | } |
| 126 | _, err = f.Seek(off, io.SeekStart) |
| 127 | return err |
| 128 | } |
| 129 | |
| 130 | // CheckDirPermission checks permission on an existing dir. |
| 131 | // Returns error if dir is empty or exist with a different permission than specified. |
| 132 | func CheckDirPermission(dir string, perm os.FileMode) error { |
| 133 | if !Exist(dir) { |
| 134 | return fmt.Errorf("directory %q empty, cannot check permission.", dir) |
| 135 | } |
| 136 | //check the existing permission on the directory |
| 137 | dirInfo, err := os.Stat(dir) |
| 138 | if err != nil { |
| 139 | return err |
| 140 | } |
| 141 | dirMode := dirInfo.Mode().Perm() |
| 142 | if dirMode != perm { |
| 143 | err = fmt.Errorf("directory %q exist, but the permission is %q. The recommended permission is %q to prevent possible unprivileged access to the data.", dir, dirInfo.Mode(), os.FileMode(PrivateDirMode)) |
| 144 | return err |
| 145 | } |
| 146 | return nil |
| 147 | } |