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#include "base/file_util.h"
6
7#include <windows.h>
8#include <psapi.h>
9#include <shellapi.h>
10#include <shlobj.h>
11#include <time.h>
12
13#include <algorithm>
14#include <limits>
15#include <string>
16
17#include "base/files/file_path.h"
18#include "base/logging.h"
19#include "base/metrics/histogram.h"
20#include "base/process/process_handle.h"
21#include "base/rand_util.h"
22#include "base/strings/string_number_conversions.h"
23#include "base/strings/string_util.h"
24#include "base/strings/utf_string_conversions.h"
25#include "base/threading/thread_restrictions.h"
26#include "base/time/time.h"
27#include "base/win/scoped_handle.h"
28#include "base/win/windows_version.h"
29
30namespace base {
31
32namespace {
33
34const DWORD kFileShareAll =
35    FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
36
37bool ShellCopy(const FilePath& from_path,
38               const FilePath& to_path,
39               bool recursive) {
40  // WinXP SHFileOperation doesn't like trailing separators.
41  FilePath stripped_from = from_path.StripTrailingSeparators();
42  FilePath stripped_to = to_path.StripTrailingSeparators();
43
44  ThreadRestrictions::AssertIOAllowed();
45
46  // NOTE: I suspect we could support longer paths, but that would involve
47  // analyzing all our usage of files.
48  if (stripped_from.value().length() >= MAX_PATH ||
49      stripped_to.value().length() >= MAX_PATH) {
50    return false;
51  }
52
53  // SHFILEOPSTRUCT wants the path to be terminated with two NULLs,
54  // so we have to use wcscpy because wcscpy_s writes non-NULLs
55  // into the rest of the buffer.
56  wchar_t double_terminated_path_from[MAX_PATH + 1] = {0};
57  wchar_t double_terminated_path_to[MAX_PATH + 1] = {0};
58#pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
59  wcscpy(double_terminated_path_from, stripped_from.value().c_str());
60#pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
61  wcscpy(double_terminated_path_to, stripped_to.value().c_str());
62
63  SHFILEOPSTRUCT file_operation = {0};
64  file_operation.wFunc = FO_COPY;
65  file_operation.pFrom = double_terminated_path_from;
66  file_operation.pTo = double_terminated_path_to;
67  file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION |
68                          FOF_NOCONFIRMMKDIR;
69  if (!recursive)
70    file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
71
72  return (SHFileOperation(&file_operation) == 0);
73}
74
75}  // namespace
76
77FilePath MakeAbsoluteFilePath(const FilePath& input) {
78  ThreadRestrictions::AssertIOAllowed();
79  wchar_t file_path[MAX_PATH];
80  if (!_wfullpath(file_path, input.value().c_str(), MAX_PATH))
81    return FilePath();
82  return FilePath(file_path);
83}
84
85bool DeleteFile(const FilePath& path, bool recursive) {
86  ThreadRestrictions::AssertIOAllowed();
87
88  if (path.value().length() >= MAX_PATH)
89    return false;
90
91  if (!recursive) {
92    // If not recursing, then first check to see if |path| is a directory.
93    // If it is, then remove it with RemoveDirectory.
94    PlatformFileInfo file_info;
95    if (GetFileInfo(path, &file_info) && file_info.is_directory)
96      return RemoveDirectory(path.value().c_str()) != 0;
97
98    // Otherwise, it's a file, wildcard or non-existant. Try DeleteFile first
99    // because it should be faster. If DeleteFile fails, then we fall through
100    // to SHFileOperation, which will do the right thing.
101    if (::DeleteFile(path.value().c_str()) != 0)
102      return true;
103  }
104
105  // SHFILEOPSTRUCT wants the path to be terminated with two NULLs,
106  // so we have to use wcscpy because wcscpy_s writes non-NULLs
107  // into the rest of the buffer.
108  wchar_t double_terminated_path[MAX_PATH + 1] = {0};
109#pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
110  wcscpy(double_terminated_path, path.value().c_str());
111
112  SHFILEOPSTRUCT file_operation = {0};
113  file_operation.wFunc = FO_DELETE;
114  file_operation.pFrom = double_terminated_path;
115  file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION;
116  if (!recursive)
117    file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
118  int err = SHFileOperation(&file_operation);
119
120  // Since we're passing flags to the operation telling it to be silent,
121  // it's possible for the operation to be aborted/cancelled without err
122  // being set (although MSDN doesn't give any scenarios for how this can
123  // happen).  See MSDN for SHFileOperation and SHFILEOPTSTRUCT.
124  if (file_operation.fAnyOperationsAborted)
125    return false;
126
127  // Some versions of Windows return ERROR_FILE_NOT_FOUND (0x2) when deleting
128  // an empty directory and some return 0x402 when they should be returning
129  // ERROR_FILE_NOT_FOUND. MSDN says Vista and up won't return 0x402.
130  return (err == 0 || err == ERROR_FILE_NOT_FOUND || err == 0x402);
131}
132
133bool DeleteFileAfterReboot(const FilePath& path) {
134  ThreadRestrictions::AssertIOAllowed();
135
136  if (path.value().length() >= MAX_PATH)
137    return false;
138
139  return MoveFileEx(path.value().c_str(), NULL,
140                    MOVEFILE_DELAY_UNTIL_REBOOT |
141                        MOVEFILE_REPLACE_EXISTING) != FALSE;
142}
143
144bool ReplaceFile(const FilePath& from_path,
145                 const FilePath& to_path,
146                 PlatformFileError* error) {
147  ThreadRestrictions::AssertIOAllowed();
148  // Try a simple move first.  It will only succeed when |to_path| doesn't
149  // already exist.
150  if (::MoveFile(from_path.value().c_str(), to_path.value().c_str()))
151    return true;
152  // Try the full-blown replace if the move fails, as ReplaceFile will only
153  // succeed when |to_path| does exist. When writing to a network share, we may
154  // not be able to change the ACLs. Ignore ACL errors then
155  // (REPLACEFILE_IGNORE_MERGE_ERRORS).
156  if (::ReplaceFile(to_path.value().c_str(), from_path.value().c_str(), NULL,
157                    REPLACEFILE_IGNORE_MERGE_ERRORS, NULL, NULL)) {
158    return true;
159  }
160  if (error)
161    *error = LastErrorToPlatformFileError(GetLastError());
162  return false;
163}
164
165bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
166                   bool recursive) {
167  ThreadRestrictions::AssertIOAllowed();
168
169  if (recursive)
170    return ShellCopy(from_path, to_path, true);
171
172  // The following code assumes that from path is a directory.
173  DCHECK(DirectoryExists(from_path));
174
175  // Instead of creating a new directory, we copy the old one to include the
176  // security information of the folder as part of the copy.
177  if (!PathExists(to_path)) {
178    // Except that Vista fails to do that, and instead do a recursive copy if
179    // the target directory doesn't exist.
180    if (base::win::GetVersion() >= base::win::VERSION_VISTA)
181      CreateDirectory(to_path);
182    else
183      ShellCopy(from_path, to_path, false);
184  }
185
186  FilePath directory = from_path.Append(L"*.*");
187  return ShellCopy(directory, to_path, false);
188}
189
190bool PathExists(const FilePath& path) {
191  ThreadRestrictions::AssertIOAllowed();
192  return (GetFileAttributes(path.value().c_str()) != INVALID_FILE_ATTRIBUTES);
193}
194
195bool PathIsWritable(const FilePath& path) {
196  ThreadRestrictions::AssertIOAllowed();
197  HANDLE dir =
198      CreateFile(path.value().c_str(), FILE_ADD_FILE, kFileShareAll,
199                 NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
200
201  if (dir == INVALID_HANDLE_VALUE)
202    return false;
203
204  CloseHandle(dir);
205  return true;
206}
207
208bool DirectoryExists(const FilePath& path) {
209  ThreadRestrictions::AssertIOAllowed();
210  DWORD fileattr = GetFileAttributes(path.value().c_str());
211  if (fileattr != INVALID_FILE_ATTRIBUTES)
212    return (fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0;
213  return false;
214}
215
216bool GetTempDir(FilePath* path) {
217  wchar_t temp_path[MAX_PATH + 1];
218  DWORD path_len = ::GetTempPath(MAX_PATH, temp_path);
219  if (path_len >= MAX_PATH || path_len <= 0)
220    return false;
221  // TODO(evanm): the old behavior of this function was to always strip the
222  // trailing slash.  We duplicate this here, but it shouldn't be necessary
223  // when everyone is using the appropriate FilePath APIs.
224  *path = FilePath(temp_path).StripTrailingSeparators();
225  return true;
226}
227
228bool GetShmemTempDir(bool executable, FilePath* path) {
229  return GetTempDir(path);
230}
231
232bool CreateTemporaryFile(FilePath* path) {
233  ThreadRestrictions::AssertIOAllowed();
234
235  FilePath temp_file;
236
237  if (!GetTempDir(path))
238    return false;
239
240  if (CreateTemporaryFileInDir(*path, &temp_file)) {
241    *path = temp_file;
242    return true;
243  }
244
245  return false;
246}
247
248FILE* CreateAndOpenTemporaryShmemFile(FilePath* path, bool executable) {
249  ThreadRestrictions::AssertIOAllowed();
250  return CreateAndOpenTemporaryFile(path);
251}
252
253// On POSIX we have semantics to create and open a temporary file
254// atomically.
255// TODO(jrg): is there equivalent call to use on Windows instead of
256// going 2-step?
257FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* path) {
258  ThreadRestrictions::AssertIOAllowed();
259  if (!CreateTemporaryFileInDir(dir, path)) {
260    return NULL;
261  }
262  // Open file in binary mode, to avoid problems with fwrite. On Windows
263  // it replaces \n's with \r\n's, which may surprise you.
264  // Reference: http://msdn.microsoft.com/en-us/library/h9t88zwz(VS.71).aspx
265  return OpenFile(*path, "wb+");
266}
267
268bool CreateTemporaryFileInDir(const FilePath& dir, FilePath* temp_file) {
269  ThreadRestrictions::AssertIOAllowed();
270
271  wchar_t temp_name[MAX_PATH + 1];
272
273  if (!GetTempFileName(dir.value().c_str(), L"", 0, temp_name)) {
274    DPLOG(WARNING) << "Failed to get temporary file name in "
275                   << UTF16ToUTF8(dir.value());
276    return false;
277  }
278
279  wchar_t long_temp_name[MAX_PATH + 1];
280  DWORD long_name_len = GetLongPathName(temp_name, long_temp_name, MAX_PATH);
281  if (long_name_len > MAX_PATH || long_name_len == 0) {
282    // GetLongPathName() failed, but we still have a temporary file.
283    *temp_file = FilePath(temp_name);
284    return true;
285  }
286
287  FilePath::StringType long_temp_name_str;
288  long_temp_name_str.assign(long_temp_name, long_name_len);
289  *temp_file = FilePath(long_temp_name_str);
290  return true;
291}
292
293bool CreateTemporaryDirInDir(const FilePath& base_dir,
294                             const FilePath::StringType& prefix,
295                             FilePath* new_dir) {
296  ThreadRestrictions::AssertIOAllowed();
297
298  FilePath path_to_create;
299
300  for (int count = 0; count < 50; ++count) {
301    // Try create a new temporary directory with random generated name. If
302    // the one exists, keep trying another path name until we reach some limit.
303    string16 new_dir_name;
304    new_dir_name.assign(prefix);
305    new_dir_name.append(IntToString16(GetCurrentProcId()));
306    new_dir_name.push_back('_');
307    new_dir_name.append(IntToString16(RandInt(0, kint16max)));
308
309    path_to_create = base_dir.Append(new_dir_name);
310    if (::CreateDirectory(path_to_create.value().c_str(), NULL)) {
311      *new_dir = path_to_create;
312      return true;
313    }
314  }
315
316  return false;
317}
318
319bool CreateNewTempDirectory(const FilePath::StringType& prefix,
320                            FilePath* new_temp_path) {
321  ThreadRestrictions::AssertIOAllowed();
322
323  FilePath system_temp_dir;
324  if (!GetTempDir(&system_temp_dir))
325    return false;
326
327  return CreateTemporaryDirInDir(system_temp_dir, prefix, new_temp_path);
328}
329
330bool CreateDirectoryAndGetError(const FilePath& full_path,
331                                PlatformFileError* error) {
332  ThreadRestrictions::AssertIOAllowed();
333
334  // If the path exists, we've succeeded if it's a directory, failed otherwise.
335  const wchar_t* full_path_str = full_path.value().c_str();
336  DWORD fileattr = ::GetFileAttributes(full_path_str);
337  if (fileattr != INVALID_FILE_ATTRIBUTES) {
338    if ((fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
339      DVLOG(1) << "CreateDirectory(" << full_path_str << "), "
340               << "directory already exists.";
341      return true;
342    }
343    DLOG(WARNING) << "CreateDirectory(" << full_path_str << "), "
344                  << "conflicts with existing file.";
345    if (error) {
346      *error = PLATFORM_FILE_ERROR_NOT_A_DIRECTORY;
347    }
348    return false;
349  }
350
351  // Invariant:  Path does not exist as file or directory.
352
353  // Attempt to create the parent recursively.  This will immediately return
354  // true if it already exists, otherwise will create all required parent
355  // directories starting with the highest-level missing parent.
356  FilePath parent_path(full_path.DirName());
357  if (parent_path.value() == full_path.value()) {
358    if (error) {
359      *error = PLATFORM_FILE_ERROR_NOT_FOUND;
360    }
361    return false;
362  }
363  if (!CreateDirectoryAndGetError(parent_path, error)) {
364    DLOG(WARNING) << "Failed to create one of the parent directories.";
365    if (error) {
366      DCHECK(*error != PLATFORM_FILE_OK);
367    }
368    return false;
369  }
370
371  if (!::CreateDirectory(full_path_str, NULL)) {
372    DWORD error_code = ::GetLastError();
373    if (error_code == ERROR_ALREADY_EXISTS && DirectoryExists(full_path)) {
374      // This error code ERROR_ALREADY_EXISTS doesn't indicate whether we
375      // were racing with someone creating the same directory, or a file
376      // with the same path.  If DirectoryExists() returns true, we lost the
377      // race to create the same directory.
378      return true;
379    } else {
380      if (error)
381        *error = LastErrorToPlatformFileError(error_code);
382      DLOG(WARNING) << "Failed to create directory " << full_path_str
383                    << ", last error is " << error_code << ".";
384      return false;
385    }
386  } else {
387    return true;
388  }
389}
390
391bool NormalizeFilePath(const FilePath& path, FilePath* real_path) {
392  ThreadRestrictions::AssertIOAllowed();
393  FilePath mapped_file;
394  if (!NormalizeToNativeFilePath(path, &mapped_file))
395    return false;
396  // NormalizeToNativeFilePath() will return a path that starts with
397  // "\Device\Harddisk...".  Helper DevicePathToDriveLetterPath()
398  // will find a drive letter which maps to the path's device, so
399  // that we return a path starting with a drive letter.
400  return DevicePathToDriveLetterPath(mapped_file, real_path);
401}
402
403bool DevicePathToDriveLetterPath(const FilePath& nt_device_path,
404                                 FilePath* out_drive_letter_path) {
405  ThreadRestrictions::AssertIOAllowed();
406
407  // Get the mapping of drive letters to device paths.
408  const int kDriveMappingSize = 1024;
409  wchar_t drive_mapping[kDriveMappingSize] = {'\0'};
410  if (!::GetLogicalDriveStrings(kDriveMappingSize - 1, drive_mapping)) {
411    DLOG(ERROR) << "Failed to get drive mapping.";
412    return false;
413  }
414
415  // The drive mapping is a sequence of null terminated strings.
416  // The last string is empty.
417  wchar_t* drive_map_ptr = drive_mapping;
418  wchar_t device_path_as_string[MAX_PATH];
419  wchar_t drive[] = L" :";
420
421  // For each string in the drive mapping, get the junction that links
422  // to it.  If that junction is a prefix of |device_path|, then we
423  // know that |drive| is the real path prefix.
424  while (*drive_map_ptr) {
425    drive[0] = drive_map_ptr[0];  // Copy the drive letter.
426
427    if (QueryDosDevice(drive, device_path_as_string, MAX_PATH)) {
428      FilePath device_path(device_path_as_string);
429      if (device_path == nt_device_path ||
430          device_path.IsParent(nt_device_path)) {
431        *out_drive_letter_path = FilePath(drive +
432            nt_device_path.value().substr(wcslen(device_path_as_string)));
433        return true;
434      }
435    }
436    // Move to the next drive letter string, which starts one
437    // increment after the '\0' that terminates the current string.
438    while (*drive_map_ptr++);
439  }
440
441  // No drive matched.  The path does not start with a device junction
442  // that is mounted as a drive letter.  This means there is no drive
443  // letter path to the volume that holds |device_path|, so fail.
444  return false;
445}
446
447bool NormalizeToNativeFilePath(const FilePath& path, FilePath* nt_path) {
448  ThreadRestrictions::AssertIOAllowed();
449  // In Vista, GetFinalPathNameByHandle() would give us the real path
450  // from a file handle.  If we ever deprecate XP, consider changing the
451  // code below to a call to GetFinalPathNameByHandle().  The method this
452  // function uses is explained in the following msdn article:
453  // http://msdn.microsoft.com/en-us/library/aa366789(VS.85).aspx
454  base::win::ScopedHandle file_handle(
455      ::CreateFile(path.value().c_str(),
456                   GENERIC_READ,
457                   kFileShareAll,
458                   NULL,
459                   OPEN_EXISTING,
460                   FILE_ATTRIBUTE_NORMAL,
461                   NULL));
462  if (!file_handle)
463    return false;
464
465  // Create a file mapping object.  Can't easily use MemoryMappedFile, because
466  // we only map the first byte, and need direct access to the handle. You can
467  // not map an empty file, this call fails in that case.
468  base::win::ScopedHandle file_map_handle(
469      ::CreateFileMapping(file_handle.Get(),
470                          NULL,
471                          PAGE_READONLY,
472                          0,
473                          1,  // Just one byte.  No need to look at the data.
474                          NULL));
475  if (!file_map_handle)
476    return false;
477
478  // Use a view of the file to get the path to the file.
479  void* file_view = MapViewOfFile(file_map_handle.Get(),
480                                  FILE_MAP_READ, 0, 0, 1);
481  if (!file_view)
482    return false;
483
484  // The expansion of |path| into a full path may make it longer.
485  // GetMappedFileName() will fail if the result is longer than MAX_PATH.
486  // Pad a bit to be safe.  If kMaxPathLength is ever changed to be less
487  // than MAX_PATH, it would be nessisary to test that GetMappedFileName()
488  // not return kMaxPathLength.  This would mean that only part of the
489  // path fit in |mapped_file_path|.
490  const int kMaxPathLength = MAX_PATH + 10;
491  wchar_t mapped_file_path[kMaxPathLength];
492  bool success = false;
493  HANDLE cp = GetCurrentProcess();
494  if (::GetMappedFileNameW(cp, file_view, mapped_file_path, kMaxPathLength)) {
495    *nt_path = FilePath(mapped_file_path);
496    success = true;
497  }
498  ::UnmapViewOfFile(file_view);
499  return success;
500}
501
502// TODO(rkc): Work out if we want to handle NTFS junctions here or not, handle
503// them if we do decide to.
504bool IsLink(const FilePath& file_path) {
505  return false;
506}
507
508bool GetFileInfo(const FilePath& file_path, PlatformFileInfo* results) {
509  ThreadRestrictions::AssertIOAllowed();
510
511  WIN32_FILE_ATTRIBUTE_DATA attr;
512  if (!GetFileAttributesEx(file_path.value().c_str(),
513                           GetFileExInfoStandard, &attr)) {
514    return false;
515  }
516
517  ULARGE_INTEGER size;
518  size.HighPart = attr.nFileSizeHigh;
519  size.LowPart = attr.nFileSizeLow;
520  results->size = size.QuadPart;
521
522  results->is_directory =
523      (attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
524  results->last_modified = Time::FromFileTime(attr.ftLastWriteTime);
525  results->last_accessed = Time::FromFileTime(attr.ftLastAccessTime);
526  results->creation_time = Time::FromFileTime(attr.ftCreationTime);
527
528  return true;
529}
530
531FILE* OpenFile(const FilePath& filename, const char* mode) {
532  ThreadRestrictions::AssertIOAllowed();
533  std::wstring w_mode = ASCIIToWide(std::string(mode));
534  return _wfsopen(filename.value().c_str(), w_mode.c_str(), _SH_DENYNO);
535}
536
537int ReadFile(const FilePath& filename, char* data, int size) {
538  ThreadRestrictions::AssertIOAllowed();
539  base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
540                                          GENERIC_READ,
541                                          FILE_SHARE_READ | FILE_SHARE_WRITE,
542                                          NULL,
543                                          OPEN_EXISTING,
544                                          FILE_FLAG_SEQUENTIAL_SCAN,
545                                          NULL));
546  if (!file)
547    return -1;
548
549  DWORD read;
550  if (::ReadFile(file, data, size, &read, NULL) &&
551      static_cast<int>(read) == size)
552    return read;
553  return -1;
554}
555
556}  // namespace base
557
558// -----------------------------------------------------------------------------
559
560namespace file_util {
561
562using base::DirectoryExists;
563using base::FilePath;
564using base::kFileShareAll;
565
566FILE* OpenFile(const std::string& filename, const char* mode) {
567  base::ThreadRestrictions::AssertIOAllowed();
568  return _fsopen(filename.c_str(), mode, _SH_DENYNO);
569}
570
571int WriteFile(const FilePath& filename, const char* data, int size) {
572  base::ThreadRestrictions::AssertIOAllowed();
573  base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
574                                          GENERIC_WRITE,
575                                          0,
576                                          NULL,
577                                          CREATE_ALWAYS,
578                                          0,
579                                          NULL));
580  if (!file) {
581    DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
582                               << filename.value();
583    return -1;
584  }
585
586  DWORD written;
587  BOOL result = ::WriteFile(file, data, size, &written, NULL);
588  if (result && static_cast<int>(written) == size)
589    return written;
590
591  if (!result) {
592    // WriteFile failed.
593    DLOG_GETLASTERROR(WARNING) << "writing file " << filename.value()
594                               << " failed";
595  } else {
596    // Didn't write all the bytes.
597    DLOG(WARNING) << "wrote" << written << " bytes to "
598                  << filename.value() << " expected " << size;
599  }
600  return -1;
601}
602
603int AppendToFile(const FilePath& filename, const char* data, int size) {
604  base::ThreadRestrictions::AssertIOAllowed();
605  base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
606                                          FILE_APPEND_DATA,
607                                          0,
608                                          NULL,
609                                          OPEN_EXISTING,
610                                          0,
611                                          NULL));
612  if (!file) {
613    DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
614                               << filename.value();
615    return -1;
616  }
617
618  DWORD written;
619  BOOL result = ::WriteFile(file, data, size, &written, NULL);
620  if (result && static_cast<int>(written) == size)
621    return written;
622
623  if (!result) {
624    // WriteFile failed.
625    DLOG_GETLASTERROR(WARNING) << "writing file " << filename.value()
626                               << " failed";
627  } else {
628    // Didn't write all the bytes.
629    DLOG(WARNING) << "wrote" << written << " bytes to "
630                  << filename.value() << " expected " << size;
631  }
632  return -1;
633}
634
635// Gets the current working directory for the process.
636bool GetCurrentDirectory(FilePath* dir) {
637  base::ThreadRestrictions::AssertIOAllowed();
638
639  wchar_t system_buffer[MAX_PATH];
640  system_buffer[0] = 0;
641  DWORD len = ::GetCurrentDirectory(MAX_PATH, system_buffer);
642  if (len == 0 || len > MAX_PATH)
643    return false;
644  // TODO(evanm): the old behavior of this function was to always strip the
645  // trailing slash.  We duplicate this here, but it shouldn't be necessary
646  // when everyone is using the appropriate FilePath APIs.
647  std::wstring dir_str(system_buffer);
648  *dir = FilePath(dir_str).StripTrailingSeparators();
649  return true;
650}
651
652// Sets the current working directory for the process.
653bool SetCurrentDirectory(const FilePath& directory) {
654  base::ThreadRestrictions::AssertIOAllowed();
655  BOOL ret = ::SetCurrentDirectory(directory.value().c_str());
656  return ret != 0;
657}
658
659int GetMaximumPathComponentLength(const FilePath& path) {
660  base::ThreadRestrictions::AssertIOAllowed();
661
662  wchar_t volume_path[MAX_PATH];
663  if (!GetVolumePathNameW(path.NormalizePathSeparators().value().c_str(),
664                          volume_path,
665                          arraysize(volume_path))) {
666    return -1;
667  }
668
669  DWORD max_length = 0;
670  if (!GetVolumeInformationW(volume_path, NULL, 0, NULL, &max_length, NULL,
671                             NULL, 0)) {
672    return -1;
673  }
674
675  // Length of |path| with path separator appended.
676  size_t prefix = path.StripTrailingSeparators().value().size() + 1;
677  // The whole path string must be shorter than MAX_PATH. That is, it must be
678  // prefix + component_length < MAX_PATH (or equivalently, <= MAX_PATH - 1).
679  int whole_path_limit = std::max(0, MAX_PATH - 1 - static_cast<int>(prefix));
680  return std::min(whole_path_limit, static_cast<int>(max_length));
681}
682
683}  // namespace file_util
684
685namespace base {
686namespace internal {
687
688bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path) {
689  ThreadRestrictions::AssertIOAllowed();
690
691  // NOTE: I suspect we could support longer paths, but that would involve
692  // analyzing all our usage of files.
693  if (from_path.value().length() >= MAX_PATH ||
694      to_path.value().length() >= MAX_PATH) {
695    return false;
696  }
697  if (MoveFileEx(from_path.value().c_str(), to_path.value().c_str(),
698                 MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING) != 0)
699    return true;
700
701  // Keep the last error value from MoveFileEx around in case the below
702  // fails.
703  bool ret = false;
704  DWORD last_error = ::GetLastError();
705
706  if (DirectoryExists(from_path)) {
707    // MoveFileEx fails if moving directory across volumes. We will simulate
708    // the move by using Copy and Delete. Ideally we could check whether
709    // from_path and to_path are indeed in different volumes.
710    ret = internal::CopyAndDeleteDirectory(from_path, to_path);
711  }
712
713  if (!ret) {
714    // Leave a clue about what went wrong so that it can be (at least) picked
715    // up by a PLOG entry.
716    ::SetLastError(last_error);
717  }
718
719  return ret;
720}
721
722bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
723  ThreadRestrictions::AssertIOAllowed();
724
725  // NOTE: I suspect we could support longer paths, but that would involve
726  // analyzing all our usage of files.
727  if (from_path.value().length() >= MAX_PATH ||
728      to_path.value().length() >= MAX_PATH) {
729    return false;
730  }
731  return (::CopyFile(from_path.value().c_str(), to_path.value().c_str(),
732                     false) != 0);
733}
734
735bool CopyAndDeleteDirectory(const FilePath& from_path,
736                            const FilePath& to_path) {
737  ThreadRestrictions::AssertIOAllowed();
738  if (CopyDirectory(from_path, to_path, true)) {
739    if (DeleteFile(from_path, true))
740      return true;
741
742    // Like Move, this function is not transactional, so we just
743    // leave the copied bits behind if deleting from_path fails.
744    // If to_path exists previously then we have already overwritten
745    // it by now, we don't get better off by deleting the new bits.
746  }
747  return false;
748}
749
750}  // namespace internal
751}  // namespace base
752