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      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 // This file contains utility functions for dealing with the local
      6 // filesystem.
      7 
      8 #ifndef BASE_FILES_FILE_UTIL_H_
      9 #define BASE_FILES_FILE_UTIL_H_
     10 
     11 #include "build/build_config.h"
     12 
     13 #if defined(OS_WIN)
     14 #include <windows.h>
     15 #elif defined(OS_POSIX)
     16 #include <sys/stat.h>
     17 #include <unistd.h>
     18 #endif
     19 
     20 #include <stdio.h>
     21 
     22 #include <set>
     23 #include <string>
     24 #include <vector>
     25 
     26 #include "base/base_export.h"
     27 #include "base/basictypes.h"
     28 #include "base/files/file.h"
     29 #include "base/files/file_path.h"
     30 #include "base/memory/scoped_ptr.h"
     31 #include "base/strings/string16.h"
     32 
     33 #if defined(OS_POSIX)
     34 #include "base/file_descriptor_posix.h"
     35 #include "base/logging.h"
     36 #include "base/posix/eintr_wrapper.h"
     37 #endif
     38 
     39 namespace base {
     40 
     41 class Time;
     42 
     43 //-----------------------------------------------------------------------------
     44 // Functions that involve filesystem access or modification:
     45 
     46 // Returns an absolute version of a relative path. Returns an empty path on
     47 // error. On POSIX, this function fails if the path does not exist. This
     48 // function can result in I/O so it can be slow.
     49 BASE_EXPORT FilePath MakeAbsoluteFilePath(const FilePath& input);
     50 
     51 // Returns the total number of bytes used by all the files under |root_path|.
     52 // If the path does not exist the function returns 0.
     53 //
     54 // This function is implemented using the FileEnumerator class so it is not
     55 // particularly speedy in any platform.
     56 BASE_EXPORT int64 ComputeDirectorySize(const FilePath& root_path);
     57 
     58 // Deletes the given path, whether it's a file or a directory.
     59 // If it's a directory, it's perfectly happy to delete all of the
     60 // directory's contents.  Passing true to recursive deletes
     61 // subdirectories and their contents as well.
     62 // Returns true if successful, false otherwise. It is considered successful
     63 // to attempt to delete a file that does not exist.
     64 //
     65 // In posix environment and if |path| is a symbolic link, this deletes only
     66 // the symlink. (even if the symlink points to a non-existent file)
     67 //
     68 // WARNING: USING THIS WITH recursive==true IS EQUIVALENT
     69 //          TO "rm -rf", SO USE WITH CAUTION.
     70 BASE_EXPORT bool DeleteFile(const FilePath& path, bool recursive);
     71 
     72 #if defined(OS_WIN)
     73 // Schedules to delete the given path, whether it's a file or a directory, until
     74 // the operating system is restarted.
     75 // Note:
     76 // 1) The file/directory to be deleted should exist in a temp folder.
     77 // 2) The directory to be deleted must be empty.
     78 BASE_EXPORT bool DeleteFileAfterReboot(const FilePath& path);
     79 #endif
     80 
     81 // Moves the given path, whether it's a file or a directory.
     82 // If a simple rename is not possible, such as in the case where the paths are
     83 // on different volumes, this will attempt to copy and delete. Returns
     84 // true for success.
     85 // This function fails if either path contains traversal components ('..').
     86 BASE_EXPORT bool Move(const FilePath& from_path, const FilePath& to_path);
     87 
     88 // Renames file |from_path| to |to_path|. Both paths must be on the same
     89 // volume, or the function will fail. Destination file will be created
     90 // if it doesn't exist. Prefer this function over Move when dealing with
     91 // temporary files. On Windows it preserves attributes of the target file.
     92 // Returns true on success, leaving *error unchanged.
     93 // Returns false on failure and sets *error appropriately, if it is non-NULL.
     94 BASE_EXPORT bool ReplaceFile(const FilePath& from_path,
     95                              const FilePath& to_path,
     96                              File::Error* error);
     97 
     98 // Copies a single file. Use CopyDirectory to copy directories.
     99 // This function fails if either path contains traversal components ('..').
    100 //
    101 // This function keeps the metadata on Windows. The read only bit on Windows is
    102 // not kept.
    103 BASE_EXPORT bool CopyFile(const FilePath& from_path, const FilePath& to_path);
    104 
    105 // Copies the given path, and optionally all subdirectories and their contents
    106 // as well.
    107 //
    108 // If there are files existing under to_path, always overwrite. Returns true
    109 // if successful, false otherwise. Wildcards on the names are not supported.
    110 //
    111 // This function calls into CopyFile() so the same behavior w.r.t. metadata
    112 // applies.
    113 //
    114 // If you only need to copy a file use CopyFile, it's faster.
    115 BASE_EXPORT bool CopyDirectory(const FilePath& from_path,
    116                                const FilePath& to_path,
    117                                bool recursive);
    118 
    119 // Returns true if the given path exists on the local filesystem,
    120 // false otherwise.
    121 BASE_EXPORT bool PathExists(const FilePath& path);
    122 
    123 // Returns true if the given path is writable by the user, false otherwise.
    124 BASE_EXPORT bool PathIsWritable(const FilePath& path);
    125 
    126 // Returns true if the given path exists and is a directory, false otherwise.
    127 BASE_EXPORT bool DirectoryExists(const FilePath& path);
    128 
    129 // Returns true if the contents of the two files given are equal, false
    130 // otherwise.  If either file can't be read, returns false.
    131 BASE_EXPORT bool ContentsEqual(const FilePath& filename1,
    132                                const FilePath& filename2);
    133 
    134 // Returns true if the contents of the two text files given are equal, false
    135 // otherwise.  This routine treats "\r\n" and "\n" as equivalent.
    136 BASE_EXPORT bool TextContentsEqual(const FilePath& filename1,
    137                                    const FilePath& filename2);
    138 
    139 // Reads the file at |path| into |contents| and returns true on success and
    140 // false on error.  For security reasons, a |path| containing path traversal
    141 // components ('..') is treated as a read error and |contents| is set to empty.
    142 // In case of I/O error, |contents| holds the data that could be read from the
    143 // file before the error occurred.
    144 // |contents| may be NULL, in which case this function is useful for its side
    145 // effect of priming the disk cache (could be used for unit tests).
    146 BASE_EXPORT bool ReadFileToString(const FilePath& path, std::string* contents);
    147 
    148 // Reads the file at |path| into |contents| and returns true on success and
    149 // false on error.  For security reasons, a |path| containing path traversal
    150 // components ('..') is treated as a read error and |contents| is set to empty.
    151 // In case of I/O error, |contents| holds the data that could be read from the
    152 // file before the error occurred.  When the file size exceeds |max_size|, the
    153 // function returns false with |contents| holding the file truncated to
    154 // |max_size|.
    155 // |contents| may be NULL, in which case this function is useful for its side
    156 // effect of priming the disk cache (could be used for unit tests).
    157 BASE_EXPORT bool ReadFileToString(const FilePath& path,
    158                                   std::string* contents,
    159                                   size_t max_size);
    160 
    161 #if defined(OS_POSIX)
    162 
    163 // Read exactly |bytes| bytes from file descriptor |fd|, storing the result
    164 // in |buffer|. This function is protected against EINTR and partial reads.
    165 // Returns true iff |bytes| bytes have been successfully read from |fd|.
    166 BASE_EXPORT bool ReadFromFD(int fd, char* buffer, size_t bytes);
    167 
    168 // Creates a symbolic link at |symlink| pointing to |target|.  Returns
    169 // false on failure.
    170 BASE_EXPORT bool CreateSymbolicLink(const FilePath& target,
    171                                     const FilePath& symlink);
    172 
    173 // Reads the given |symlink| and returns where it points to in |target|.
    174 // Returns false upon failure.
    175 BASE_EXPORT bool ReadSymbolicLink(const FilePath& symlink, FilePath* target);
    176 
    177 // Bits and masks of the file permission.
    178 enum FilePermissionBits {
    179   FILE_PERMISSION_MASK              = S_IRWXU | S_IRWXG | S_IRWXO,
    180   FILE_PERMISSION_USER_MASK         = S_IRWXU,
    181   FILE_PERMISSION_GROUP_MASK        = S_IRWXG,
    182   FILE_PERMISSION_OTHERS_MASK       = S_IRWXO,
    183 
    184   FILE_PERMISSION_READ_BY_USER      = S_IRUSR,
    185   FILE_PERMISSION_WRITE_BY_USER     = S_IWUSR,
    186   FILE_PERMISSION_EXECUTE_BY_USER   = S_IXUSR,
    187   FILE_PERMISSION_READ_BY_GROUP     = S_IRGRP,
    188   FILE_PERMISSION_WRITE_BY_GROUP    = S_IWGRP,
    189   FILE_PERMISSION_EXECUTE_BY_GROUP  = S_IXGRP,
    190   FILE_PERMISSION_READ_BY_OTHERS    = S_IROTH,
    191   FILE_PERMISSION_WRITE_BY_OTHERS   = S_IWOTH,
    192   FILE_PERMISSION_EXECUTE_BY_OTHERS = S_IXOTH,
    193 };
    194 
    195 // Reads the permission of the given |path|, storing the file permission
    196 // bits in |mode|. If |path| is symbolic link, |mode| is the permission of
    197 // a file which the symlink points to.
    198 BASE_EXPORT bool GetPosixFilePermissions(const FilePath& path, int* mode);
    199 // Sets the permission of the given |path|. If |path| is symbolic link, sets
    200 // the permission of a file which the symlink points to.
    201 BASE_EXPORT bool SetPosixFilePermissions(const FilePath& path, int mode);
    202 
    203 #endif  // OS_POSIX
    204 
    205 // Returns true if the given directory is empty
    206 BASE_EXPORT bool IsDirectoryEmpty(const FilePath& dir_path);
    207 
    208 // Get the temporary directory provided by the system.
    209 //
    210 // WARNING: In general, you should use CreateTemporaryFile variants below
    211 // instead of this function. Those variants will ensure that the proper
    212 // permissions are set so that other users on the system can't edit them while
    213 // they're open (which can lead to security issues).
    214 BASE_EXPORT bool GetTempDir(FilePath* path);
    215 
    216 // Get the home directory. This is more complicated than just getenv("HOME")
    217 // as it knows to fall back on getpwent() etc.
    218 //
    219 // You should not generally call this directly. Instead use DIR_HOME with the
    220 // path service which will use this function but cache the value.
    221 // Path service may also override DIR_HOME.
    222 BASE_EXPORT FilePath GetHomeDir();
    223 
    224 // Creates a temporary file. The full path is placed in |path|, and the
    225 // function returns true if was successful in creating the file. The file will
    226 // be empty and all handles closed after this function returns.
    227 BASE_EXPORT bool CreateTemporaryFile(FilePath* path);
    228 
    229 // Same as CreateTemporaryFile but the file is created in |dir|.
    230 BASE_EXPORT bool CreateTemporaryFileInDir(const FilePath& dir,
    231                                           FilePath* temp_file);
    232 
    233 // Create and open a temporary file.  File is opened for read/write.
    234 // The full path is placed in |path|.
    235 // Returns a handle to the opened file or NULL if an error occurred.
    236 BASE_EXPORT FILE* CreateAndOpenTemporaryFile(FilePath* path);
    237 
    238 // Similar to CreateAndOpenTemporaryFile, but the file is created in |dir|.
    239 BASE_EXPORT FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir,
    240                                                   FilePath* path);
    241 
    242 // Create a new directory. If prefix is provided, the new directory name is in
    243 // the format of prefixyyyy.
    244 // NOTE: prefix is ignored in the POSIX implementation.
    245 // If success, return true and output the full path of the directory created.
    246 BASE_EXPORT bool CreateNewTempDirectory(const FilePath::StringType& prefix,
    247                                         FilePath* new_temp_path);
    248 
    249 // Create a directory within another directory.
    250 // Extra characters will be appended to |prefix| to ensure that the
    251 // new directory does not have the same name as an existing directory.
    252 BASE_EXPORT bool CreateTemporaryDirInDir(const FilePath& base_dir,
    253                                          const FilePath::StringType& prefix,
    254                                          FilePath* new_dir);
    255 
    256 // Creates a directory, as well as creating any parent directories, if they
    257 // don't exist. Returns 'true' on successful creation, or if the directory
    258 // already exists.  The directory is only readable by the current user.
    259 // Returns true on success, leaving *error unchanged.
    260 // Returns false on failure and sets *error appropriately, if it is non-NULL.
    261 BASE_EXPORT bool CreateDirectoryAndGetError(const FilePath& full_path,
    262                                             File::Error* error);
    263 
    264 // Backward-compatible convenience method for the above.
    265 BASE_EXPORT bool CreateDirectory(const FilePath& full_path);
    266 
    267 // Returns the file size. Returns true on success.
    268 BASE_EXPORT bool GetFileSize(const FilePath& file_path, int64* file_size);
    269 
    270 // Sets |real_path| to |path| with symbolic links and junctions expanded.
    271 // On windows, make sure the path starts with a lettered drive.
    272 // |path| must reference a file.  Function will fail if |path| points to
    273 // a directory or to a nonexistent path.  On windows, this function will
    274 // fail if |path| is a junction or symlink that points to an empty file,
    275 // or if |real_path| would be longer than MAX_PATH characters.
    276 BASE_EXPORT bool NormalizeFilePath(const FilePath& path, FilePath* real_path);
    277 
    278 #if defined(OS_WIN)
    279 
    280 // Given a path in NT native form ("\Device\HarddiskVolumeXX\..."),
    281 // return in |drive_letter_path| the equivalent path that starts with
    282 // a drive letter ("C:\...").  Return false if no such path exists.
    283 BASE_EXPORT bool DevicePathToDriveLetterPath(const FilePath& device_path,
    284                                              FilePath* drive_letter_path);
    285 
    286 // Given an existing file in |path|, set |real_path| to the path
    287 // in native NT format, of the form "\Device\HarddiskVolumeXX\..".
    288 // Returns false if the path can not be found. Empty files cannot
    289 // be resolved with this function.
    290 BASE_EXPORT bool NormalizeToNativeFilePath(const FilePath& path,
    291                                            FilePath* nt_path);
    292 #endif
    293 
    294 // This function will return if the given file is a symlink or not.
    295 BASE_EXPORT bool IsLink(const FilePath& file_path);
    296 
    297 // Returns information about the given file path.
    298 BASE_EXPORT bool GetFileInfo(const FilePath& file_path, File::Info* info);
    299 
    300 // Sets the time of the last access and the time of the last modification.
    301 BASE_EXPORT bool TouchFile(const FilePath& path,
    302                            const Time& last_accessed,
    303                            const Time& last_modified);
    304 
    305 // Wrapper for fopen-like calls. Returns non-NULL FILE* on success.
    306 BASE_EXPORT FILE* OpenFile(const FilePath& filename, const char* mode);
    307 
    308 // Closes file opened by OpenFile. Returns true on success.
    309 BASE_EXPORT bool CloseFile(FILE* file);
    310 
    311 // Associates a standard FILE stream with an existing File. Note that this
    312 // functions take ownership of the existing File.
    313 BASE_EXPORT FILE* FileToFILE(File file, const char* mode);
    314 
    315 // Truncates an open file to end at the location of the current file pointer.
    316 // This is a cross-platform analog to Windows' SetEndOfFile() function.
    317 BASE_EXPORT bool TruncateFile(FILE* file);
    318 
    319 // Reads at most the given number of bytes from the file into the buffer.
    320 // Returns the number of read bytes, or -1 on error.
    321 BASE_EXPORT int ReadFile(const FilePath& filename, char* data, int max_size);
    322 
    323 // Writes the given buffer into the file, overwriting any data that was
    324 // previously there.  Returns the number of bytes written, or -1 on error.
    325 BASE_EXPORT int WriteFile(const FilePath& filename, const char* data,
    326                           int size);
    327 
    328 #if defined(OS_POSIX)
    329 // Append the data to |fd|. Does not close |fd| when done.
    330 BASE_EXPORT int WriteFileDescriptor(const int fd, const char* data, int size);
    331 #endif
    332 
    333 // Append the given buffer into the file. Returns the number of bytes written,
    334 // or -1 on error.
    335 BASE_EXPORT int AppendToFile(const FilePath& filename,
    336                              const char* data, int size);
    337 
    338 // Gets the current working directory for the process.
    339 BASE_EXPORT bool GetCurrentDirectory(FilePath* path);
    340 
    341 // Sets the current working directory for the process.
    342 BASE_EXPORT bool SetCurrentDirectory(const FilePath& path);
    343 
    344 // Attempts to find a number that can be appended to the |path| to make it
    345 // unique. If |path| does not exist, 0 is returned.  If it fails to find such
    346 // a number, -1 is returned. If |suffix| is not empty, also checks the
    347 // existence of it with the given suffix.
    348 BASE_EXPORT int GetUniquePathNumber(const FilePath& path,
    349                                     const FilePath::StringType& suffix);
    350 
    351 #if defined(OS_POSIX)
    352 // Test that |path| can only be changed by a given user and members of
    353 // a given set of groups.
    354 // Specifically, test that all parts of |path| under (and including) |base|:
    355 // * Exist.
    356 // * Are owned by a specific user.
    357 // * Are not writable by all users.
    358 // * Are owned by a member of a given set of groups, or are not writable by
    359 //   their group.
    360 // * Are not symbolic links.
    361 // This is useful for checking that a config file is administrator-controlled.
    362 // |base| must contain |path|.
    363 BASE_EXPORT bool VerifyPathControlledByUser(const base::FilePath& base,
    364                                             const base::FilePath& path,
    365                                             uid_t owner_uid,
    366                                             const std::set<gid_t>& group_gids);
    367 #endif  // defined(OS_POSIX)
    368 
    369 #if defined(OS_MACOSX) && !defined(OS_IOS)
    370 // Is |path| writable only by a user with administrator privileges?
    371 // This function uses Mac OS conventions.  The super user is assumed to have
    372 // uid 0, and the administrator group is assumed to be named "admin".
    373 // Testing that |path|, and every parent directory including the root of
    374 // the filesystem, are owned by the superuser, controlled by the group
    375 // "admin", are not writable by all users, and contain no symbolic links.
    376 // Will return false if |path| does not exist.
    377 BASE_EXPORT bool VerifyPathControlledByAdmin(const base::FilePath& path);
    378 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
    379 
    380 // Returns the maximum length of path component on the volume containing
    381 // the directory |path|, in the number of FilePath::CharType, or -1 on failure.
    382 BASE_EXPORT int GetMaximumPathComponentLength(const base::FilePath& path);
    383 
    384 #if defined(OS_LINUX)
    385 // Broad categories of file systems as returned by statfs() on Linux.
    386 enum FileSystemType {
    387   FILE_SYSTEM_UNKNOWN,  // statfs failed.
    388   FILE_SYSTEM_0,        // statfs.f_type == 0 means unknown, may indicate AFS.
    389   FILE_SYSTEM_ORDINARY,       // on-disk filesystem like ext2
    390   FILE_SYSTEM_NFS,
    391   FILE_SYSTEM_SMB,
    392   FILE_SYSTEM_CODA,
    393   FILE_SYSTEM_MEMORY,         // in-memory file system
    394   FILE_SYSTEM_CGROUP,         // cgroup control.
    395   FILE_SYSTEM_OTHER,          // any other value.
    396   FILE_SYSTEM_TYPE_COUNT
    397 };
    398 
    399 // Attempts determine the FileSystemType for |path|.
    400 // Returns false if |path| doesn't exist.
    401 BASE_EXPORT bool GetFileSystemType(const FilePath& path, FileSystemType* type);
    402 #endif
    403 
    404 #if defined(OS_POSIX)
    405 // Get a temporary directory for shared memory files. The directory may depend
    406 // on whether the destination is intended for executable files, which in turn
    407 // depends on how /dev/shmem was mounted. As a result, you must supply whether
    408 // you intend to create executable shmem segments so this function can find
    409 // an appropriate location.
    410 BASE_EXPORT bool GetShmemTempDir(bool executable, FilePath* path);
    411 #endif
    412 
    413 // Internal --------------------------------------------------------------------
    414 
    415 namespace internal {
    416 
    417 // Same as Move but allows paths with traversal components.
    418 // Use only with extreme care.
    419 BASE_EXPORT bool MoveUnsafe(const FilePath& from_path,
    420                             const FilePath& to_path);
    421 
    422 // Same as CopyFile but allows paths with traversal components.
    423 // Use only with extreme care.
    424 BASE_EXPORT bool CopyFileUnsafe(const FilePath& from_path,
    425                                 const FilePath& to_path);
    426 
    427 #if defined(OS_WIN)
    428 // Copy from_path to to_path recursively and then delete from_path recursively.
    429 // Returns true if all operations succeed.
    430 // This function simulates Move(), but unlike Move() it works across volumes.
    431 // This function is not transactional.
    432 BASE_EXPORT bool CopyAndDeleteDirectory(const FilePath& from_path,
    433                                         const FilePath& to_path);
    434 #endif  // defined(OS_WIN)
    435 
    436 }  // namespace internal
    437 }  // namespace base
    438 
    439 #endif  // BASE_FILES_FILE_UTIL_H_
    440