1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // FilePath is a container for pathnames stored in a platform's native string 6 // type, providing containers for manipulation in according with the 7 // platform's conventions for pathnames. It supports the following path 8 // types: 9 // 10 // POSIX Windows 11 // --------------- ---------------------------------- 12 // Fundamental type char[] wchar_t[] 13 // Encoding unspecified* UTF-16 14 // Separator / \, tolerant of / 15 // Drive letters no case-insensitive A-Z followed by : 16 // Alternate root // (surprise!) \\, for UNC paths 17 // 18 // * The encoding need not be specified on POSIX systems, although some 19 // POSIX-compliant systems do specify an encoding. Mac OS X uses UTF-8. 20 // Chrome OS also uses UTF-8. 21 // Linux does not specify an encoding, but in practice, the locale's 22 // character set may be used. 23 // 24 // For more arcane bits of path trivia, see below. 25 // 26 // FilePath objects are intended to be used anywhere paths are. An 27 // application may pass FilePath objects around internally, masking the 28 // underlying differences between systems, only differing in implementation 29 // where interfacing directly with the system. For example, a single 30 // OpenFile(const FilePath &) function may be made available, allowing all 31 // callers to operate without regard to the underlying implementation. On 32 // POSIX-like platforms, OpenFile might wrap fopen, and on Windows, it might 33 // wrap _wfopen_s, perhaps both by calling file_path.value().c_str(). This 34 // allows each platform to pass pathnames around without requiring conversions 35 // between encodings, which has an impact on performance, but more imporantly, 36 // has an impact on correctness on platforms that do not have well-defined 37 // encodings for pathnames. 38 // 39 // Several methods are available to perform common operations on a FilePath 40 // object, such as determining the parent directory (DirName), isolating the 41 // final path component (BaseName), and appending a relative pathname string 42 // to an existing FilePath object (Append). These methods are highly 43 // recommended over attempting to split and concatenate strings directly. 44 // These methods are based purely on string manipulation and knowledge of 45 // platform-specific pathname conventions, and do not consult the filesystem 46 // at all, making them safe to use without fear of blocking on I/O operations. 47 // These methods do not function as mutators but instead return distinct 48 // instances of FilePath objects, and are therefore safe to use on const 49 // objects. The objects themselves are safe to share between threads. 50 // 51 // To aid in initialization of FilePath objects from string literals, a 52 // FILE_PATH_LITERAL macro is provided, which accounts for the difference 53 // between char[]-based pathnames on POSIX systems and wchar_t[]-based 54 // pathnames on Windows. 55 // 56 // As a precaution against premature truncation, paths can't contain NULs. 57 // 58 // Because a FilePath object should not be instantiated at the global scope, 59 // instead, use a FilePath::CharType[] and initialize it with 60 // FILE_PATH_LITERAL. At runtime, a FilePath object can be created from the 61 // character array. Example: 62 // 63 // | const FilePath::CharType kLogFileName[] = FILE_PATH_LITERAL("log.txt"); 64 // | 65 // | void Function() { 66 // | FilePath log_file_path(kLogFileName); 67 // | [...] 68 // | } 69 // 70 // WARNING: FilePaths should ALWAYS be displayed with LTR directionality, even 71 // when the UI language is RTL. This means you always need to pass filepaths 72 // through base::i18n::WrapPathWithLTRFormatting() before displaying it in the 73 // RTL UI. 74 // 75 // This is a very common source of bugs, please try to keep this in mind. 76 // 77 // ARCANE BITS OF PATH TRIVIA 78 // 79 // - A double leading slash is actually part of the POSIX standard. Systems 80 // are allowed to treat // as an alternate root, as Windows does for UNC 81 // (network share) paths. Most POSIX systems don't do anything special 82 // with two leading slashes, but FilePath handles this case properly 83 // in case it ever comes across such a system. FilePath needs this support 84 // for Windows UNC paths, anyway. 85 // References: 86 // The Open Group Base Specifications Issue 7, sections 3.267 ("Pathname") 87 // and 4.12 ("Pathname Resolution"), available at: 88 // http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_267 89 // http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_12 90 // 91 // - Windows treats c:\\ the same way it treats \\. This was intended to 92 // allow older applications that require drive letters to support UNC paths 93 // like \\server\share\path, by permitting c:\\server\share\path as an 94 // equivalent. Since the OS treats these paths specially, FilePath needs 95 // to do the same. Since Windows can use either / or \ as the separator, 96 // FilePath treats c://, c:\\, //, and \\ all equivalently. 97 // Reference: 98 // The Old New Thing, "Why is a drive letter permitted in front of UNC 99 // paths (sometimes)?", available at: 100 // http://blogs.msdn.com/oldnewthing/archive/2005/11/22/495740.aspx 101 102 #ifndef BASE_FILES_FILE_PATH_H_ 103 #define BASE_FILES_FILE_PATH_H_ 104 105 #include <stddef.h> 106 107 #include <iosfwd> 108 #include <string> 109 #include <vector> 110 111 #include "base/base_export.h" 112 #include "base/compiler_specific.h" 113 #include "base/containers/hash_tables.h" 114 #include "base/macros.h" 115 #include "base/strings/string16.h" 116 #include "base/strings/string_piece.h" 117 #include "build/build_config.h" 118 119 // Windows-style drive letter support and pathname separator characters can be 120 // enabled and disabled independently, to aid testing. These #defines are 121 // here so that the same setting can be used in both the implementation and 122 // in the unit test. 123 #if defined(OS_WIN) 124 #define FILE_PATH_USES_DRIVE_LETTERS 125 #define FILE_PATH_USES_WIN_SEPARATORS 126 #endif // OS_WIN 127 128 // To print path names portably use PRIsFP (based on PRIuS and friends from 129 // C99 and format_macros.h) like this: 130 // base::StringPrintf("Path is %" PRIsFP ".\n", path.value().c_str()); 131 #if defined(OS_POSIX) 132 #define PRIsFP "s" 133 #elif defined(OS_WIN) 134 #define PRIsFP "ls" 135 #endif // OS_WIN 136 137 namespace base { 138 139 class Pickle; 140 class PickleIterator; 141 class PickleSizer; 142 143 // An abstraction to isolate users from the differences between native 144 // pathnames on different platforms. 145 class BASE_EXPORT FilePath { 146 public: 147 #if defined(OS_POSIX) 148 // On most platforms, native pathnames are char arrays, and the encoding 149 // may or may not be specified. On Mac OS X, native pathnames are encoded 150 // in UTF-8. 151 typedef std::string StringType; 152 #elif defined(OS_WIN) 153 // On Windows, for Unicode-aware applications, native pathnames are wchar_t 154 // arrays encoded in UTF-16. 155 typedef std::wstring StringType; 156 #endif // OS_WIN 157 158 typedef BasicStringPiece<StringType> StringPieceType; 159 typedef StringType::value_type CharType; 160 161 // Null-terminated array of separators used to separate components in 162 // hierarchical paths. Each character in this array is a valid separator, 163 // but kSeparators[0] is treated as the canonical separator and will be used 164 // when composing pathnames. 165 static const CharType kSeparators[]; 166 167 // arraysize(kSeparators). 168 static const size_t kSeparatorsLength; 169 170 // A special path component meaning "this directory." 171 static const CharType kCurrentDirectory[]; 172 173 // A special path component meaning "the parent directory." 174 static const CharType kParentDirectory[]; 175 176 // The character used to identify a file extension. 177 static const CharType kExtensionSeparator; 178 179 FilePath(); 180 FilePath(const FilePath& that); 181 explicit FilePath(StringPieceType path); 182 ~FilePath(); 183 FilePath& operator=(const FilePath& that); 184 185 bool operator==(const FilePath& that) const; 186 187 bool operator!=(const FilePath& that) const; 188 189 // Required for some STL containers and operations 190 bool operator<(const FilePath& that) const { 191 return path_ < that.path_; 192 } 193 194 const StringType& value() const { return path_; } 195 196 bool empty() const { return path_.empty(); } 197 198 void clear() { path_.clear(); } 199 200 // Returns true if |character| is in kSeparators. 201 static bool IsSeparator(CharType character); 202 203 // Returns a vector of all of the components of the provided path. It is 204 // equivalent to calling DirName().value() on the path's root component, 205 // and BaseName().value() on each child component. 206 // 207 // To make sure this is lossless so we can differentiate absolute and 208 // relative paths, the root slash will be included even though no other 209 // slashes will be. The precise behavior is: 210 // 211 // Posix: "/foo/bar" -> [ "/", "foo", "bar" ] 212 // Windows: "C:\foo\bar" -> [ "C:", "\\", "foo", "bar" ] 213 void GetComponents(std::vector<FilePath::StringType>* components) const; 214 215 // Returns true if this FilePath is a strict parent of the |child|. Absolute 216 // and relative paths are accepted i.e. is /foo parent to /foo/bar and 217 // is foo parent to foo/bar. Does not convert paths to absolute, follow 218 // symlinks or directory navigation (e.g. ".."). A path is *NOT* its own 219 // parent. 220 bool IsParent(const FilePath& child) const; 221 222 // If IsParent(child) holds, appends to path (if non-NULL) the 223 // relative path to child and returns true. For example, if parent 224 // holds "/Users/johndoe/Library/Application Support", child holds 225 // "/Users/johndoe/Library/Application Support/Google/Chrome/Default", and 226 // *path holds "/Users/johndoe/Library/Caches", then after 227 // parent.AppendRelativePath(child, path) is called *path will hold 228 // "/Users/johndoe/Library/Caches/Google/Chrome/Default". Otherwise, 229 // returns false. 230 bool AppendRelativePath(const FilePath& child, FilePath* path) const; 231 232 // Returns a FilePath corresponding to the directory containing the path 233 // named by this object, stripping away the file component. If this object 234 // only contains one component, returns a FilePath identifying 235 // kCurrentDirectory. If this object already refers to the root directory, 236 // returns a FilePath identifying the root directory. 237 FilePath DirName() const WARN_UNUSED_RESULT; 238 239 // Returns a FilePath corresponding to the last path component of this 240 // object, either a file or a directory. If this object already refers to 241 // the root directory, returns a FilePath identifying the root directory; 242 // this is the only situation in which BaseName will return an absolute path. 243 FilePath BaseName() const WARN_UNUSED_RESULT; 244 245 // Returns ".jpg" for path "C:\pics\jojo.jpg", or an empty string if 246 // the file has no extension. If non-empty, Extension() will always start 247 // with precisely one ".". The following code should always work regardless 248 // of the value of path. For common double-extensions like .tar.gz and 249 // .user.js, this method returns the combined extension. For a single 250 // component, use FinalExtension(). 251 // new_path = path.RemoveExtension().value().append(path.Extension()); 252 // ASSERT(new_path == path.value()); 253 // NOTE: this is different from the original file_util implementation which 254 // returned the extension without a leading "." ("jpg" instead of ".jpg") 255 StringType Extension() const WARN_UNUSED_RESULT; 256 257 // Returns the path's file extension, as in Extension(), but will 258 // never return a double extension. 259 // 260 // TODO(davidben): Check all our extension-sensitive code to see if 261 // we can rename this to Extension() and the other to something like 262 // LongExtension(), defaulting to short extensions and leaving the 263 // long "extensions" to logic like base::GetUniquePathNumber(). 264 StringType FinalExtension() const WARN_UNUSED_RESULT; 265 266 // Returns "C:\pics\jojo" for path "C:\pics\jojo.jpg" 267 // NOTE: this is slightly different from the similar file_util implementation 268 // which returned simply 'jojo'. 269 FilePath RemoveExtension() const WARN_UNUSED_RESULT; 270 271 // Removes the path's file extension, as in RemoveExtension(), but 272 // ignores double extensions. 273 FilePath RemoveFinalExtension() const WARN_UNUSED_RESULT; 274 275 // Inserts |suffix| after the file name portion of |path| but before the 276 // extension. Returns "" if BaseName() == "." or "..". 277 // Examples: 278 // path == "C:\pics\jojo.jpg" suffix == " (1)", returns "C:\pics\jojo (1).jpg" 279 // path == "jojo.jpg" suffix == " (1)", returns "jojo (1).jpg" 280 // path == "C:\pics\jojo" suffix == " (1)", returns "C:\pics\jojo (1)" 281 // path == "C:\pics.old\jojo" suffix == " (1)", returns "C:\pics.old\jojo (1)" 282 FilePath InsertBeforeExtension( 283 StringPieceType suffix) const WARN_UNUSED_RESULT; 284 FilePath InsertBeforeExtensionASCII( 285 StringPiece suffix) const WARN_UNUSED_RESULT; 286 287 // Adds |extension| to |file_name|. Returns the current FilePath if 288 // |extension| is empty. Returns "" if BaseName() == "." or "..". 289 FilePath AddExtension(StringPieceType extension) const WARN_UNUSED_RESULT; 290 291 // Replaces the extension of |file_name| with |extension|. If |file_name| 292 // does not have an extension, then |extension| is added. If |extension| is 293 // empty, then the extension is removed from |file_name|. 294 // Returns "" if BaseName() == "." or "..". 295 FilePath ReplaceExtension(StringPieceType extension) const WARN_UNUSED_RESULT; 296 297 // Returns true if the file path matches the specified extension. The test is 298 // case insensitive. Don't forget the leading period if appropriate. 299 bool MatchesExtension(StringPieceType extension) const; 300 301 // Returns a FilePath by appending a separator and the supplied path 302 // component to this object's path. Append takes care to avoid adding 303 // excessive separators if this object's path already ends with a separator. 304 // If this object's path is kCurrentDirectory, a new FilePath corresponding 305 // only to |component| is returned. |component| must be a relative path; 306 // it is an error to pass an absolute path. 307 FilePath Append(StringPieceType component) const WARN_UNUSED_RESULT; 308 FilePath Append(const FilePath& component) const WARN_UNUSED_RESULT; 309 310 // Although Windows StringType is std::wstring, since the encoding it uses for 311 // paths is well defined, it can handle ASCII path components as well. 312 // Mac uses UTF8, and since ASCII is a subset of that, it works there as well. 313 // On Linux, although it can use any 8-bit encoding for paths, we assume that 314 // ASCII is a valid subset, regardless of the encoding, since many operating 315 // system paths will always be ASCII. 316 FilePath AppendASCII(StringPiece component) const WARN_UNUSED_RESULT; 317 318 // Returns true if this FilePath contains an absolute path. On Windows, an 319 // absolute path begins with either a drive letter specification followed by 320 // a separator character, or with two separator characters. On POSIX 321 // platforms, an absolute path begins with a separator character. 322 bool IsAbsolute() const; 323 324 // Returns true if the patch ends with a path separator character. 325 bool EndsWithSeparator() const WARN_UNUSED_RESULT; 326 327 // Returns a copy of this FilePath that ends with a trailing separator. If 328 // the input path is empty, an empty FilePath will be returned. 329 FilePath AsEndingWithSeparator() const WARN_UNUSED_RESULT; 330 331 // Returns a copy of this FilePath that does not end with a trailing 332 // separator. 333 FilePath StripTrailingSeparators() const WARN_UNUSED_RESULT; 334 335 // Returns true if this FilePath contains an attempt to reference a parent 336 // directory (e.g. has a path component that is ".."). 337 bool ReferencesParent() const; 338 339 // Return a Unicode human-readable version of this path. 340 // Warning: you can *not*, in general, go from a display name back to a real 341 // path. Only use this when displaying paths to users, not just when you 342 // want to stuff a string16 into some other API. 343 string16 LossyDisplayName() const; 344 345 // Return the path as ASCII, or the empty string if the path is not ASCII. 346 // This should only be used for cases where the FilePath is representing a 347 // known-ASCII filename. 348 std::string MaybeAsASCII() const; 349 350 // Return the path as UTF-8. 351 // 352 // This function is *unsafe* as there is no way to tell what encoding is 353 // used in file names on POSIX systems other than Mac and Chrome OS, 354 // although UTF-8 is practically used everywhere these days. To mitigate 355 // the encoding issue, this function internally calls 356 // SysNativeMBToWide() on POSIX systems other than Mac and Chrome OS, 357 // per assumption that the current locale's encoding is used in file 358 // names, but this isn't a perfect solution. 359 // 360 // Once it becomes safe to to stop caring about non-UTF-8 file names, 361 // the SysNativeMBToWide() hack will be removed from the code, along 362 // with "Unsafe" in the function name. 363 std::string AsUTF8Unsafe() const; 364 365 // Similar to AsUTF8Unsafe, but returns UTF-16 instead. 366 string16 AsUTF16Unsafe() const; 367 368 // Returns a FilePath object from a path name in UTF-8. This function 369 // should only be used for cases where you are sure that the input 370 // string is UTF-8. 371 // 372 // Like AsUTF8Unsafe(), this function is unsafe. This function 373 // internally calls SysWideToNativeMB() on POSIX systems other than Mac 374 // and Chrome OS, to mitigate the encoding issue. See the comment at 375 // AsUTF8Unsafe() for details. 376 static FilePath FromUTF8Unsafe(StringPiece utf8); 377 378 // Similar to FromUTF8Unsafe, but accepts UTF-16 instead. 379 static FilePath FromUTF16Unsafe(StringPiece16 utf16); 380 381 void GetSizeForPickle(PickleSizer* sizer) const; 382 void WriteToPickle(Pickle* pickle) const; 383 bool ReadFromPickle(PickleIterator* iter); 384 385 // Normalize all path separators to backslash on Windows 386 // (if FILE_PATH_USES_WIN_SEPARATORS is true), or do nothing on POSIX systems. 387 FilePath NormalizePathSeparators() const; 388 389 // Normalize all path separattors to given type on Windows 390 // (if FILE_PATH_USES_WIN_SEPARATORS is true), or do nothing on POSIX systems. 391 FilePath NormalizePathSeparatorsTo(CharType separator) const; 392 393 // Compare two strings in the same way the file system does. 394 // Note that these always ignore case, even on file systems that are case- 395 // sensitive. If case-sensitive comparison is ever needed, add corresponding 396 // methods here. 397 // The methods are written as a static method so that they can also be used 398 // on parts of a file path, e.g., just the extension. 399 // CompareIgnoreCase() returns -1, 0 or 1 for less-than, equal-to and 400 // greater-than respectively. 401 static int CompareIgnoreCase(StringPieceType string1, 402 StringPieceType string2); 403 static bool CompareEqualIgnoreCase(StringPieceType string1, 404 StringPieceType string2) { 405 return CompareIgnoreCase(string1, string2) == 0; 406 } 407 static bool CompareLessIgnoreCase(StringPieceType string1, 408 StringPieceType string2) { 409 return CompareIgnoreCase(string1, string2) < 0; 410 } 411 412 #if defined(OS_MACOSX) 413 // Returns the string in the special canonical decomposed form as defined for 414 // HFS, which is close to, but not quite, decomposition form D. See 415 // http://developer.apple.com/mac/library/technotes/tn/tn1150.html#UnicodeSubtleties 416 // for further comments. 417 // Returns the epmty string if the conversion failed. 418 static StringType GetHFSDecomposedForm(StringPieceType string); 419 420 // Special UTF-8 version of FastUnicodeCompare. Cf: 421 // http://developer.apple.com/mac/library/technotes/tn/tn1150.html#StringComparisonAlgorithm 422 // IMPORTANT: The input strings must be in the special HFS decomposed form! 423 // (cf. above GetHFSDecomposedForm method) 424 static int HFSFastUnicodeCompare(StringPieceType string1, 425 StringPieceType string2); 426 #endif 427 428 #if defined(OS_ANDROID) 429 // On android, file selection dialog can return a file with content uri 430 // scheme(starting with content://). Content uri needs to be opened with 431 // ContentResolver to guarantee that the app has appropriate permissions 432 // to access it. 433 // Returns true if the path is a content uri, or false otherwise. 434 bool IsContentUri() const; 435 #endif 436 437 private: 438 // Remove trailing separators from this object. If the path is absolute, it 439 // will never be stripped any more than to refer to the absolute root 440 // directory, so "////" will become "/", not "". A leading pair of 441 // separators is never stripped, to support alternate roots. This is used to 442 // support UNC paths on Windows. 443 void StripTrailingSeparatorsInternal(); 444 445 StringType path_; 446 }; 447 448 // This is required by googletest to print a readable output on test failures. 449 // This is declared here for use in gtest-based unit tests but is defined in 450 // the test_support_base target. Depend on that to use this in your unit test. 451 // This should not be used in production code - call ToString() instead. 452 void PrintTo(const FilePath& path, std::ostream* out); 453 454 } // namespace base 455 456 // Macros for string literal initialization of FilePath::CharType[], and for 457 // using a FilePath::CharType[] in a printf-style format string. 458 #if defined(OS_POSIX) 459 #define FILE_PATH_LITERAL(x) x 460 #define PRFilePath "s" 461 #elif defined(OS_WIN) 462 #define FILE_PATH_LITERAL(x) L ## x 463 #define PRFilePath "ls" 464 #endif // OS_WIN 465 466 // Provide a hash function so that hash_sets and maps can contain FilePath 467 // objects. 468 namespace BASE_HASH_NAMESPACE { 469 470 template<> 471 struct hash<base::FilePath> { 472 size_t operator()(const base::FilePath& f) const { 473 return hash<base::FilePath::StringType>()(f.value()); 474 } 475 }; 476 477 } // namespace BASE_HASH_NAMESPACE 478 479 #endif // BASE_FILES_FILE_PATH_H_ 480