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| 1 | +// Copyright 2009 The Go Authors. All rights reserved. |
| 2 | +// Use of this source code is governed by a BSD-style |
| 3 | +// license that can be found in the LICENSE file. |
| 4 | + |
| 5 | +// Package tar implements access to tar archives. |
| 6 | +// It aims to cover most of the variations, including those produced |
| 7 | +// by GNU and BSD tars. |
| 8 | +// |
| 9 | +// References: |
| 10 | +// http://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5 |
| 11 | +// http://www.gnu.org/software/tar/manual/html_node/Standard.html |
| 12 | +// http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html |
| 13 | +package tar |
| 14 | + |
| 15 | +import ( |
| 16 | + "errors" |
| 17 | + "fmt" |
| 18 | + "os" |
| 19 | + "path" |
| 20 | + "time" |
| 21 | +) |
| 22 | + |
| 23 | +// BUG: Use of the Uid and Gid fields in Header could overflow on 32-bit |
| 24 | +// architectures. If a large value is encountered when decoding, the result |
| 25 | +// stored in Header will be the truncated version. |
| 26 | + |
| 27 | +// Header type flags. |
| 28 | +const ( |
| 29 | + TypeReg = '0' // regular file |
| 30 | + TypeRegA = '\x00' // regular file |
| 31 | + TypeLink = '1' // hard link |
| 32 | + TypeSymlink = '2' // symbolic link |
| 33 | + TypeChar = '3' // character device node |
| 34 | + TypeBlock = '4' // block device node |
| 35 | + TypeDir = '5' // directory |
| 36 | + TypeFifo = '6' // fifo node |
| 37 | + TypeCont = '7' // reserved |
| 38 | + TypeXHeader = 'x' // extended header |
| 39 | + TypeXGlobalHeader = 'g' // global extended header |
| 40 | + TypeGNULongName = 'L' // Next file has a long name |
| 41 | + TypeGNULongLink = 'K' // Next file symlinks to a file w/ a long name |
| 42 | + TypeGNUSparse = 'S' // sparse file |
| 43 | +) |
| 44 | + |
| 45 | +// A Header represents a single header in a tar archive. |
| 46 | +// Some fields may not be populated. |
| 47 | +type Header struct { |
| 48 | + Name string // name of header file entry |
| 49 | + Mode int64 // permission and mode bits |
| 50 | + Uid int // user id of owner |
| 51 | + Gid int // group id of owner |
| 52 | + Size int64 // length in bytes |
| 53 | + ModTime time.Time // modified time |
| 54 | + Typeflag byte // type of header entry |
| 55 | + Linkname string // target name of link |
| 56 | + Uname string // user name of owner |
| 57 | + Gname string // group name of owner |
| 58 | + Devmajor int64 // major number of character or block device |
| 59 | + Devminor int64 // minor number of character or block device |
| 60 | + AccessTime time.Time // access time |
| 61 | + ChangeTime time.Time // status change time |
| 62 | + Xattrs map[string]string |
| 63 | +} |
| 64 | + |
| 65 | +// FileInfo returns an os.FileInfo for the Header. |
| 66 | +func (h *Header) FileInfo() os.FileInfo { |
| 67 | + return headerFileInfo{h} |
| 68 | +} |
| 69 | + |
| 70 | +// headerFileInfo implements os.FileInfo. |
| 71 | +type headerFileInfo struct { |
| 72 | + h *Header |
| 73 | +} |
| 74 | + |
| 75 | +func (fi headerFileInfo) Size() int64 { return fi.h.Size } |
| 76 | +func (fi headerFileInfo) IsDir() bool { return fi.Mode().IsDir() } |
| 77 | +func (fi headerFileInfo) ModTime() time.Time { return fi.h.ModTime } |
| 78 | +func (fi headerFileInfo) Sys() interface{} { return fi.h } |
| 79 | + |
| 80 | +// Name returns the base name of the file. |
| 81 | +func (fi headerFileInfo) Name() string { |
| 82 | + if fi.IsDir() { |
| 83 | + return path.Base(path.Clean(fi.h.Name)) |
| 84 | + } |
| 85 | + return path.Base(fi.h.Name) |
| 86 | +} |
| 87 | + |
| 88 | +// Mode returns the permission and mode bits for the headerFileInfo. |
| 89 | +func (fi headerFileInfo) Mode() (mode os.FileMode) { |
| 90 | + // Set file permission bits. |
| 91 | + mode = os.FileMode(fi.h.Mode).Perm() |
| 92 | + |
| 93 | + // Set setuid, setgid and sticky bits. |
| 94 | + if fi.h.Mode&c_ISUID != 0 { |
| 95 | + // setuid |
| 96 | + mode |= os.ModeSetuid |
| 97 | + } |
| 98 | + if fi.h.Mode&c_ISGID != 0 { |
| 99 | + // setgid |
| 100 | + mode |= os.ModeSetgid |
| 101 | + } |
| 102 | + if fi.h.Mode&c_ISVTX != 0 { |
| 103 | + // sticky |
| 104 | + mode |= os.ModeSticky |
| 105 | + } |
| 106 | + |
| 107 | + // Set file mode bits. |
| 108 | + // clear perm, setuid, setgid and sticky bits. |
| 109 | + m := os.FileMode(fi.h.Mode) &^ 07777 |
| 110 | + if m == c_ISDIR { |
| 111 | + // directory |
| 112 | + mode |= os.ModeDir |
| 113 | + } |
| 114 | + if m == c_ISFIFO { |
| 115 | + // named pipe (FIFO) |
| 116 | + mode |= os.ModeNamedPipe |
| 117 | + } |
| 118 | + if m == c_ISLNK { |
| 119 | + // symbolic link |
| 120 | + mode |= os.ModeSymlink |
| 121 | + } |
| 122 | + if m == c_ISBLK { |
| 123 | + // device file |
| 124 | + mode |= os.ModeDevice |
| 125 | + } |
| 126 | + if m == c_ISCHR { |
| 127 | + // Unix character device |
| 128 | + mode |= os.ModeDevice |
| 129 | + mode |= os.ModeCharDevice |
| 130 | + } |
| 131 | + if m == c_ISSOCK { |
| 132 | + // Unix domain socket |
| 133 | + mode |= os.ModeSocket |
| 134 | + } |
| 135 | + |
| 136 | + switch fi.h.Typeflag { |
| 137 | + case TypeSymlink: |
| 138 | + // symbolic link |
| 139 | + mode |= os.ModeSymlink |
| 140 | + case TypeChar: |
| 141 | + // character device node |
| 142 | + mode |= os.ModeDevice |
| 143 | + mode |= os.ModeCharDevice |
| 144 | + case TypeBlock: |
| 145 | + // block device node |
| 146 | + mode |= os.ModeDevice |
| 147 | + case TypeDir: |
| 148 | + // directory |
| 149 | + mode |= os.ModeDir |
| 150 | + case TypeFifo: |
| 151 | + // fifo node |
| 152 | + mode |= os.ModeNamedPipe |
| 153 | + } |
| 154 | + |
| 155 | + return mode |
| 156 | +} |
| 157 | + |
| 158 | +// sysStat, if non-nil, populates h from system-dependent fields of fi. |
| 159 | +var sysStat func(fi os.FileInfo, h *Header) error |
| 160 | + |
| 161 | +// Mode constants from the tar spec. |
| 162 | +const ( |
| 163 | + c_ISUID = 04000 // Set uid |
| 164 | + c_ISGID = 02000 // Set gid |
| 165 | + c_ISVTX = 01000 // Save text (sticky bit) |
| 166 | + c_ISDIR = 040000 // Directory |
| 167 | + c_ISFIFO = 010000 // FIFO |
| 168 | + c_ISREG = 0100000 // Regular file |
| 169 | + c_ISLNK = 0120000 // Symbolic link |
| 170 | + c_ISBLK = 060000 // Block special file |
| 171 | + c_ISCHR = 020000 // Character special file |
| 172 | + c_ISSOCK = 0140000 // Socket |
| 173 | +) |
| 174 | + |
| 175 | +// Keywords for the PAX Extended Header |
| 176 | +const ( |
| 177 | + paxAtime = "atime" |
| 178 | + paxCharset = "charset" |
| 179 | + paxComment = "comment" |
| 180 | + paxCtime = "ctime" // please note that ctime is not a valid pax header. |
| 181 | + paxGid = "gid" |
| 182 | + paxGname = "gname" |
| 183 | + paxLinkpath = "linkpath" |
| 184 | + paxMtime = "mtime" |
| 185 | + paxPath = "path" |
| 186 | + paxSize = "size" |
| 187 | + paxUid = "uid" |
| 188 | + paxUname = "uname" |
| 189 | + paxXattr = "SCHILY.xattr." |
| 190 | + paxNone = "" |
| 191 | +) |
| 192 | + |
| 193 | +// FileInfoHeader creates a partially-populated Header from fi. |
| 194 | +// If fi describes a symlink, FileInfoHeader records link as the link target. |
| 195 | +// If fi describes a directory, a slash is appended to the name. |
| 196 | +// Because os.FileInfo's Name method returns only the base name of |
| 197 | +// the file it describes, it may be necessary to modify the Name field |
| 198 | +// of the returned header to provide the full path name of the file. |
| 199 | +func FileInfoHeader(fi os.FileInfo, link string) (*Header, error) { |
| 200 | + if fi == nil { |
| 201 | + return nil, errors.New("tar: FileInfo is nil") |
| 202 | + } |
| 203 | + fm := fi.Mode() |
| 204 | + h := &Header{ |
| 205 | + Name: fi.Name(), |
| 206 | + ModTime: fi.ModTime(), |
| 207 | + Mode: int64(fm.Perm()), // or'd with c_IS* constants later |
| 208 | + } |
| 209 | + switch { |
| 210 | + case fm.IsRegular(): |
| 211 | + h.Mode |= c_ISREG |
| 212 | + h.Typeflag = TypeReg |
| 213 | + h.Size = fi.Size() |
| 214 | + case fi.IsDir(): |
| 215 | + h.Typeflag = TypeDir |
| 216 | + h.Mode |= c_ISDIR |
| 217 | + h.Name += "/" |
| 218 | + case fm&os.ModeSymlink != 0: |
| 219 | + h.Typeflag = TypeSymlink |
| 220 | + h.Mode |= c_ISLNK |
| 221 | + h.Linkname = link |
| 222 | + case fm&os.ModeDevice != 0: |
| 223 | + if fm&os.ModeCharDevice != 0 { |
| 224 | + h.Mode |= c_ISCHR |
| 225 | + h.Typeflag = TypeChar |
| 226 | + } else { |
| 227 | + h.Mode |= c_ISBLK |
| 228 | + h.Typeflag = TypeBlock |
| 229 | + } |
| 230 | + case fm&os.ModeNamedPipe != 0: |
| 231 | + h.Typeflag = TypeFifo |
| 232 | + h.Mode |= c_ISFIFO |
| 233 | + case fm&os.ModeSocket != 0: |
| 234 | + h.Mode |= c_ISSOCK |
| 235 | + default: |
| 236 | + return nil, fmt.Errorf("archive/tar: unknown file mode %v", fm) |
| 237 | + } |
| 238 | + if fm&os.ModeSetuid != 0 { |
| 239 | + h.Mode |= c_ISUID |
| 240 | + } |
| 241 | + if fm&os.ModeSetgid != 0 { |
| 242 | + h.Mode |= c_ISGID |
| 243 | + } |
| 244 | + if fm&os.ModeSticky != 0 { |
| 245 | + h.Mode |= c_ISVTX |
| 246 | + } |
| 247 | + // If possible, populate additional fields from OS-specific |
| 248 | + // FileInfo fields. |
| 249 | + if sys, ok := fi.Sys().(*Header); ok { |
| 250 | + // This FileInfo came from a Header (not the OS). Use the |
| 251 | + // original Header to populate all remaining fields. |
| 252 | + h.Uid = sys.Uid |
| 253 | + h.Gid = sys.Gid |
| 254 | + h.Uname = sys.Uname |
| 255 | + h.Gname = sys.Gname |
| 256 | + h.AccessTime = sys.AccessTime |
| 257 | + h.ChangeTime = sys.ChangeTime |
| 258 | + if sys.Xattrs != nil { |
| 259 | + h.Xattrs = make(map[string]string) |
| 260 | + for k, v := range sys.Xattrs { |
| 261 | + h.Xattrs[k] = v |
| 262 | + } |
| 263 | + } |
| 264 | + if sys.Typeflag == TypeLink { |
| 265 | + // hard link |
| 266 | + h.Typeflag = TypeLink |
| 267 | + h.Size = 0 |
| 268 | + h.Linkname = sys.Linkname |
| 269 | + } |
| 270 | + } |
| 271 | + if sysStat != nil { |
| 272 | + return h, sysStat(fi, h) |
| 273 | + } |
| 274 | + return h, nil |
| 275 | +} |
| 276 | + |
| 277 | +// isHeaderOnlyType checks if the given type flag is of the type that has no |
| 278 | +// data section even if a size is specified. |
| 279 | +func isHeaderOnlyType(flag byte) bool { |
| 280 | + switch flag { |
| 281 | + case TypeLink, TypeSymlink, TypeChar, TypeBlock, TypeDir, TypeFifo: |
| 282 | + return true |
| 283 | + default: |
| 284 | + return false |
| 285 | + } |
| 286 | +} |
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