Chromium Code Reviews| Index: base/files/file_util_win.cc |
| diff --git a/base/files/file_util_win.cc b/base/files/file_util_win.cc |
| index d70454df3836a7067f71eecf5a0ae8673376f474..cbf2f255e7d7d6f01ba1ded985cda53cbdaf167c 100644 |
| --- a/base/files/file_util_win.cc |
| +++ b/base/files/file_util_win.cc |
| @@ -11,13 +11,16 @@ |
| #include <shlobj.h> |
| #include <stddef.h> |
| #include <stdint.h> |
| +#include <string.h> |
| #include <time.h> |
| +#include <winioctl.h> |
| #include <winsock2.h> |
| #include <algorithm> |
| #include <limits> |
| #include <string> |
| +#include "base/base32.h" |
| #include "base/files/file_enumerator.h" |
| #include "base/files/file_path.h" |
| #include "base/logging.h" |
| @@ -40,32 +43,378 @@ namespace { |
| const DWORD kFileShareAll = |
| FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE; |
| -// Deletes all files and directories in a path. |
| -// Returns false on the first failure it encounters. |
| -bool DeleteFileRecursive(const FilePath& path, |
| - const FilePath::StringType& pattern, |
| - bool recursive) { |
| - FileEnumerator traversal(path, false, |
| - FileEnumerator::FILES | FileEnumerator::DIRECTORIES, |
| - pattern); |
| - for (FilePath current = traversal.Next(); !current.empty(); |
| - current = traversal.Next()) { |
| - // Try to clear the read-only bit if we find it. |
| - FileEnumerator::FileInfo info = traversal.GetInfo(); |
| - if ((info.find_data().dwFileAttributes & FILE_ATTRIBUTE_READONLY) && |
| - (recursive || !info.IsDirectory())) { |
| - SetFileAttributes( |
| - current.value().c_str(), |
| - info.find_data().dwFileAttributes & ~FILE_ATTRIBUTE_READONLY); |
| - } |
| +// The workhorse of base::DeleteFile. This class implements a robust file and |
| +// directory deletion strategy to work with Windows' pecurlarity around file |
| +// deletion -- on Windows, one does not simply delete a file. The Win32 |
| +// DeleteFile function is deceptively named (though properly documented) as it |
| +// marks a file for deletion at some unspecified time in the future when all |
| +// handles are closed. This here workhorse accomplishes two goals: recursive |
| +// deletes can succeed in the face of other software operating therein (so long |
| +// as they open files with SHARE_DELETE) and it's much more likely that callers |
| +// can delete a file or directory and then immediately create another with the |
| +// same name. This class implementes DeleteFile as follows: |
| +// - Open the item to be deleted. |
| +// - Rob the item of its read-only status, if applicable. |
| +// - In the case of a directory that is not a mount point or a symlink, |
| +// recursively delete everything contained therein using the strategy |
| +// described here. |
| +// - Paint the item with delete-on-close to make sure it is deletable. |
| +// - Hide the item. |
| +// - Clear the delete-on-close bit so that it can... |
| +// - Move the item up one directory (with a random name). |
| +// - Paint the item with delete-on-close for good. |
| +// |
| +// Failure possibilities are: |
| +// - The item could not be opened. |
| +// - The item's attributes could not be read. |
| +// - The item was read-only and this attribute could not be cleared. |
| +// - The item could not be deleted for various legitimate reasons such as it |
| +// being open without SHARE_DELETE access, or the current user not having |
| +// permission to delete it. |
| +// - The file was moved out to the parent directory, could not be deleted, and |
| +// could not be moved back to its original location. This will DCHECK in a |
| +// debug build, as it is highly undesirable and so far outside of expectation. |
| +// |
| +// There also exists a partial success case where the item could not be moved |
| +// prior to deletion but was deleted in situ. This is essentially the Win32 |
| +// DeleteFile behavior, also known as "better than nothing". |
| +class TreeDeleter { |
| + public: |
| + // Deletes a single item (a file, directory, mount point, symlink, etc). |
| + // Returns false if the item could not be deleted. |
| + static bool DeleteItem(const FilePath& path); |
| + |
| + // Recursively deletes |path| and its contents if |path| is a directory and |
| + // is not a mount point or a symlink. |
| + static bool DeleteRecursive(const FilePath& path); |
| + |
| + private: |
| + // Constructs an instance to delete |path| recursively or not. |
| + explicit TreeDeleter(const FilePath& path); |
| + |
| + // Main entrypoint to delete |path|. |recurse|, when true, indicates that an |
| + // instance created for recursion should recurse into directories. |
| + bool Delete(const FilePath& path, bool recurse); |
| + |
| + // Deletes as much of the contents of |path| as possible, returning |true| |
| + // only if everything within was deleted. |
| + bool DeleteContents(const FilePath& path); |
| + |
| + // Deletes |to_delete|, using |basic_info| to adjust its attributes in the |
| + // process. |
| + bool DoDelete(const FilePath& path, |
| + const win::ScopedHandle& to_delete, |
| + FILE_BASIC_INFO* basic_info); |
| + |
| + // Moves |to_delete| out into the parent directory of the operation. |
| + // |to_delete| is expected to already have its delete-on-close attribute set. |
| + // This function will clear it, move the file, and re-establish |
| + // delete-on-close. Returns false if the delete-on-close attribute is not set |
| + // on exit. |
| + bool MoveToParent(const FilePath& path, const win::ScopedHandle& to_delete); |
| + |
| + // Returns a buffer used to determine if a directory is a mount point or a |
| + // symlink. |
| + REPARSE_GUID_DATA_BUFFER* GetReparseDataBuffer(); |
| + |
| + // Returns |true| if |to_delete| (whose attributes are represented in |
| + // |basic_info|) is a mount point (a.k.a. a junction point) or a symlink. |
| + bool IsMountPointOrSymlink(const win::ScopedHandle& to_delete, |
| + const FILE_BASIC_INFO& basic_info); |
| + |
| + // Renames the item |to_delete| to |target|. |
| + bool MoveTo(const win::ScopedHandle& to_delete, const FilePath& target); |
| + |
| + // The parent directory into which items are to be moved immediately prior to |
| + // deletion. |
| + FilePath parent_directory_; |
| + |
| + // The size, in bytes, of the FILE_RENAME_INFO block. |
| + size_t rename_info_buffer_size_ = 0; |
| + |
| + // Holds a FILE_RENAME_INFO when the instance will be used to move files out |
| + // of their current directory prior to deletion. |
| + std::unique_ptr<uint8_t> rename_info_buffer_; |
| + |
| + // A buffer of size MAXIMUM_REPARSE_DATA_BUFFER_SIZE used to determine if a |
| + // directory with a reparse point is either a mount point or a symlink. Only |
| + // used for recursive deletes. |
| + std::unique_ptr<uint8_t> reparse_data_buffer_; |
| + |
| + DISALLOW_COPY_AND_ASSIGN(TreeDeleter); |
| +}; |
| + |
| +// static |
| +bool TreeDeleter::DeleteItem(const FilePath& path) { |
| + return TreeDeleter(path).Delete(path, false /* !recurse */); |
| +} |
| + |
| +// static |
| +bool TreeDeleter::DeleteRecursive(const FilePath& path) { |
| + return TreeDeleter(path).Delete(path, true /* recurse */); |
| +} |
| + |
| +TreeDeleter::TreeDeleter(const FilePath& path) { |
| + const FilePath directory = path.DirName(); |
| + const FilePath parent_directory = directory.DirName(); |
| + |
| + // Prepare to move files up to the parent directory while deleting them if the |
| + // path to be deleted is not at the root of a volume. |
| + if (parent_directory != directory) |
| + parent_directory_ = parent_directory; |
| +} |
| + |
| +bool TreeDeleter::Delete(const FilePath& path, bool recurse) { |
| + // Open the item to be deleted with permission to hide and delete it with full |
| + // sharing. Note that backup semantics are required to open a directory. |
| + // Operate on a link or a mount point (implemented via reparse points) itself |
| + // rather than on its target. |
| + win::ScopedHandle to_delete(::CreateFile( |
| + path.value().c_str(), |
| + DELETE | FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES, |
| + FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, nullptr, |
| + OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT, |
| + nullptr)); |
| + if (!to_delete.IsValid()) { |
| + DWORD error = ::GetLastError(); |
| + if (error == ERROR_FILE_NOT_FOUND || error == ERROR_PATH_NOT_FOUND) |
| + return true; |
| + // Try a straight-up delete as a fallback. |
| + if (::DeleteFile(path.value().c_str())) |
| + return true; |
| + ::SetLastError(error); |
| + PLOG(ERROR) << "Failed to open " << path.value() << " for deletion"; |
| + return false; |
| + } |
| - if (info.IsDirectory()) { |
| - if (recursive && (!DeleteFileRecursive(current, pattern, true) || |
| - !RemoveDirectory(current.value().c_str()))) |
| - return false; |
| - } else if (!::DeleteFile(current.value().c_str())) { |
| + // Remove the item's read-only bit if it is set. This is required for |
| + // deletion. |
| + bool read_only_set = false; |
| + FILE_BASIC_INFO basic_info = {}; |
| + if (!::GetFileInformationByHandleEx(to_delete.Get(), FileBasicInfo, |
| + &basic_info, sizeof(basic_info))) { |
| + PLOG(ERROR) << "Failed to read attributes of " << path.value(); |
| + return false; |
| + } |
| + if ((basic_info.FileAttributes & FILE_ATTRIBUTE_READONLY) != 0) { |
| + basic_info.FileAttributes &= ~FILE_ATTRIBUTE_READONLY; |
| + if (!::SetFileInformationByHandle(to_delete.Get(), FileBasicInfo, |
| + &basic_info, sizeof(basic_info))) { |
| + PLOG(ERROR) << "Failed to strip read-only attribute of " << path.value(); |
| return false; |
| } |
| + read_only_set = true; |
| + } |
| + |
| + // Recurse into this item if desired, this item is a directory, and this item |
| + // is neither a mount point nor a symlink. |
| + if (recurse && (basic_info.FileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0 && |
| + !IsMountPointOrSymlink(to_delete, basic_info) && !DeleteContents(path)) { |
|
grt (UTC plus 2)
2016/12/04 08:52:06
i wonder if this is overkill. a directory with a r
jschuh
2016/12/04 14:10:46
For IsMountPointOrSymlink()? Doesn't seem like ove
grt (UTC plus 2)
2016/12/04 21:31:48
I'm not too familiar with the other uses for repar
jschuh
2016/12/06 22:16:34
Ah, I see. I think it would probably be safe enoug
grt (UTC plus 2)
2016/12/07 08:34:39
Done.
|
| + return false; |
| + } |
| + |
| + if (DoDelete(path, to_delete, &basic_info)) |
| + return true; |
| + |
| + // Restore the item's read-only state on failure. |
| + if (read_only_set) { |
|
Scott Hess - ex-Googler
2016/12/06 08:15:56
Maybe split this function into a helper, so that y
grt (UTC plus 2)
2016/12/07 08:34:39
Nice catch! Indeed, the block above belongs in DoD
|
| + basic_info.FileAttributes |= FILE_ATTRIBUTE_READONLY; |
| + if (!::SetFileInformationByHandle(to_delete.Get(), FileBasicInfo, |
| + &basic_info, sizeof(basic_info))) { |
| + PLOG(ERROR) << "Failed to restore read-only attribute of " |
| + << path.value(); |
| + } |
| + } |
| + return false; |
| +} |
| + |
| +bool TreeDeleter::DeleteContents(const FilePath& path) { |
| + // Recurse through all subdirectories to clear them out. Ignore errors during |
| + // this pass -- they will be reported if the directories themselves cannot be |
| + // deleted below. |
| + { |
| + FileEnumerator enumer(path, false, FileEnumerator::DIRECTORIES); |
| + for (FilePath item = enumer.Next(); !item.empty(); item = enumer.Next()) |
| + Delete(item, true /* recurse */); |
| + } |
| + |
| + // Now that the contents of all subdirectories have been cleared, repeatedly |
| + // pass over the contents of this directory until there is nothing left that |
| + // can be deleted. Bail out after five fruitless iterations. This is a |
| + // mitigation for the failure mode where the item could not be moved out to |
| + // the parent directory before deletion. |
| + bool items_failed; |
| + int retries = 0; |
| + do { |
| + items_failed = false; |
| + FileEnumerator enumer( |
| + path, false, (FileEnumerator::DIRECTORIES | FileEnumerator::FILES)); |
| + for (FilePath item = enumer.Next(); !item.empty(); item = enumer.Next()) { |
| + if (Delete(item, false /* !recurse */)) |
| + retries = 0; // Reset the retry count on any success. |
| + else |
| + items_failed = true; |
| + } |
| + } while (items_failed && ++retries < 5); |
|
grt (UTC plus 2)
2016/12/07 08:34:39
wdyt of a short sleep here to give the system time
|
| + |
| + // Report success if the last pass encountered no errors. |
| + return !items_failed; |
| +} |
| + |
| +bool TreeDeleter::DoDelete(const FilePath& path, |
| + const win::ScopedHandle& to_delete, |
| + FILE_BASIC_INFO* basic_info) { |
| + // Check to see if it's possible to delete this item. A non-empty directory, |
| + // for example, cannot be deleted. |
| + FILE_DISPOSITION_INFO disposition = {TRUE}; // DeleteFile |
| + if (!::SetFileInformationByHandle(to_delete.Get(), FileDispositionInfo, |
| + &disposition, sizeof(disposition))) { |
| + PLOG(ERROR) << "Unable to delete " << path.value(); |
| + return false; |
| + } |
| + |
| + // The item will now be deleted when all handles are closed. Hide it so that |
| + // it appears to vanish right away and so that any other procs (e.g., |
| + // explorer.exe) observing the parent directory have a greater liklihood of |
| + // not reacting when a new file suddenly appears and disappears. |
| + bool hidden_set = false; |
| + if ((basic_info->FileAttributes & FILE_ATTRIBUTE_HIDDEN) == 0) { |
| + basic_info->FileAttributes |= FILE_ATTRIBUTE_HIDDEN; |
| + if (!::SetFileInformationByHandle(to_delete.Get(), FileBasicInfo, |
| + basic_info, sizeof(*basic_info))) { |
| + PLOG(WARNING) << "Failed to hide " << path.value(); |
| + } |
| + hidden_set = true; |
| + } |
| + |
| + if (MoveToParent(path, to_delete)) |
| + return true; |
| + |
| + // The item couldn't be deleted. Restore its visibility. |
| + if (hidden_set) { |
| + basic_info->FileAttributes &= ~FILE_ATTRIBUTE_HIDDEN; |
| + if (!::SetFileInformationByHandle(to_delete.Get(), FileBasicInfo, |
| + basic_info, sizeof(*basic_info))) { |
| + PLOG(WARNING) << "Failed to unhide " << path.value(); |
| + } |
| + } |
| + return false; |
| +} |
| + |
| +bool TreeDeleter::MoveToParent(const FilePath& path, |
|
jschuh
2016/12/04 14:10:46
Is there a better place to move to than the parent
grt (UTC plus 2)
2016/12/04 21:35:46
I had similar misgivings about doing this, and I'm
Scott Hess - ex-Googler
2016/12/06 08:15:56
In most cases in our code, there probably is going
jschuh
2016/12/06 22:16:34
I just worry about accumulating a bunch of files i
grt (UTC plus 2)
2016/12/07 08:34:39
The next two things on my plate are:
- Survey curr
grt (UTC plus 2)
2016/12/07 15:03:10
I've added this. PTAL.
|
| + const win::ScopedHandle& to_delete) { |
| + // Do the shuffle to move the item out to the parent directory so that a new |
| + // item with the same name can be created immediately in this directory, or |
| + // so that the containing directory can be deleted immediately. |
| + |
| + // There is nothing to do when deleting at the root of a volume. |
| + if (parent_directory_.empty()) |
| + return true; |
| + |
| + // Revoke deletion so that the item can be moved. |
| + FILE_DISPOSITION_INFO disposition = {FALSE}; // DeleteFile |
| + if (!::SetFileInformationByHandle(to_delete.Get(), FileDispositionInfo, |
| + &disposition, sizeof(disposition))) { |
| + PLOG(WARNING) << "Unable to revoke deletion of " << path.value() |
| + << "; skipping move to parent"; |
| + return true; |
| + } |
| + |
| + // Move the file out to the parent directory. Failure to move is not a fatal |
| + // failure, though it will lead to a race when deleting the containing |
| + // directory. This is mitigated by retries in directory deletion. |
| + bool file_moved = false; |
| + int attempts = 0; |
| + do { |
| + char random[5]; |
| + base::RandBytes(&random[0], sizeof(random)); |
| + file_moved = MoveTo( |
| + to_delete, |
| + parent_directory_.AppendASCII( |
| + base::Base32Encode(base::StringPiece(&random[0], sizeof(random))) |
| + .append(".tmp"))); |
|
Scott Hess - ex-Googler
2016/12/06 08:15:56
IMHO adding .tmp is just putting lipstick on the p
jschuh
2016/12/06 22:16:34
I disagree. I think this is a good indicator if so
grt (UTC plus 2)
2016/12/07 08:34:38
This was my thinking exactly.
|
| + } while (!file_moved && ++attempts < 5); |
| + |
| + // Mark the file to be deleted on close once again. |
| + disposition.DeleteFile = TRUE; |
| + if (!::SetFileInformationByHandle(to_delete.Get(), FileDispositionInfo, |
| + &disposition, sizeof(disposition))) { |
| + // This is highly unexpected since the file was to be deleted moments ago. |
| + PLOG(ERROR) << "Failed to mark file to be deleted on close"; |
| + |
| + if (file_moved) { |
| + // Try to move the file back to where it was. If this fails, we're in the |
| + // town of cats and leaving the file in the wrong place. Regardless, make |
| + // a final attempt to mark the file for deletion. |
| + bool file_moved_back = MoveTo(to_delete, path); |
| + LONG error = ::GetLastError(); |
| + if (::SetFileInformationByHandle(to_delete.Get(), FileDispositionInfo, |
| + &disposition, sizeof(disposition))) { |
| + // Whew! The file will eventually be deleted in situ. |
| + return true; |
| + } |
| + if (!file_moved_back) { |
| + ::SetLastError(error); |
| + PLOG(DFATAL) << "Failed to move item back to original location"; |
| + } |
| + } |
| + return false; |
| + } |
| + |
| + return true; |
| +} |
| + |
| +REPARSE_GUID_DATA_BUFFER* TreeDeleter::GetReparseDataBuffer() { |
| + if (!reparse_data_buffer_) |
| + reparse_data_buffer_.reset(new uint8_t[MAXIMUM_REPARSE_DATA_BUFFER_SIZE]); |
| + return reinterpret_cast<REPARSE_GUID_DATA_BUFFER*>( |
| + reparse_data_buffer_.get()); |
| +} |
| + |
| +bool TreeDeleter::IsMountPointOrSymlink(const win::ScopedHandle& to_delete, |
| + const FILE_BASIC_INFO& basic_info) { |
| + if ((basic_info.FileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) == 0) |
| + return false; |
| + |
| + REPARSE_GUID_DATA_BUFFER* buffer = GetReparseDataBuffer(); |
| + DWORD bytes_used = 0; |
| + if (!::DeviceIoControl(to_delete.Get(), FSCTL_GET_REPARSE_POINT, nullptr, 0, |
| + buffer, MAXIMUM_REPARSE_DATA_BUFFER_SIZE, &bytes_used, |
| + nullptr) || |
| + bytes_used < sizeof(DWORD)) { |
| + PLOG(ERROR) << "Failed getting reparse data"; |
| + return true; // Err on the safe side. |
| + } |
| + |
| + return buffer->ReparseTag == IO_REPARSE_TAG_MOUNT_POINT || |
| + buffer->ReparseTag == IO_REPARSE_TAG_SYMLINK; |
| +} |
| + |
| +bool TreeDeleter::MoveTo(const win::ScopedHandle& to_delete, |
| + const FilePath& target) { |
| + // Compute the proper size of the FILE_RENAME_INFO including the target path. |
| + size_t path_bytes = (target.value().length() + 1) * sizeof(wchar_t); |
| + size_t struct_size = offsetof(FILE_RENAME_INFO, FileName) + path_bytes; |
| + |
| + // Allocate a new buffer if needed. |
| + if (rename_info_buffer_size_ < struct_size) { |
| + rename_info_buffer_.reset(); |
| + rename_info_buffer_.reset(new uint8_t[struct_size]); |
| + rename_info_buffer_size_ = struct_size; |
| + } |
| + |
| + // Formulate a FILE_RENAME_INFO struct in the buffer. |
| + FILE_RENAME_INFO* file_rename_info = |
| + reinterpret_cast<FILE_RENAME_INFO*>(rename_info_buffer_.get()); |
| + file_rename_info->ReplaceIfExists = FALSE; |
| + file_rename_info->RootDirectory = nullptr; |
| + file_rename_info->FileNameLength = target.value().length(); |
| + ::memcpy(&file_rename_info->FileName[0], target.value().c_str(), path_bytes); |
| + |
| + if (!::SetFileInformationByHandle(to_delete.Get(), FileRenameInfo, |
| + file_rename_info, struct_size)) { |
| + PLOG(ERROR) << "Failed to move item to " << target.value(); |
| + return false; |
| } |
| return true; |
| } |
| @@ -83,36 +432,18 @@ FilePath MakeAbsoluteFilePath(const FilePath& input) { |
| bool DeleteFile(const FilePath& path, bool recursive) { |
| ThreadRestrictions::AssertIOAllowed(); |
| + // Wildcards are not supported. |
| + DCHECK_EQ(path.BaseName().value().find_first_of(L"*?"), |
| + FilePath::StringType::npos); |
| + |
| if (path.empty()) |
| return true; |
| if (path.value().length() >= MAX_PATH) |
| return false; |
| - // Handle any path with wildcards. |
| - if (path.BaseName().value().find_first_of(L"*?") != |
| - FilePath::StringType::npos) { |
| - return DeleteFileRecursive(path.DirName(), path.BaseName().value(), |
| - recursive); |
| - } |
| - DWORD attr = GetFileAttributes(path.value().c_str()); |
| - // We're done if we can't find the path. |
| - if (attr == INVALID_FILE_ATTRIBUTES) |
| - return true; |
| - // We may need to clear the read-only bit. |
| - if ((attr & FILE_ATTRIBUTE_READONLY) && |
| - !SetFileAttributes(path.value().c_str(), |
| - attr & ~FILE_ATTRIBUTE_READONLY)) { |
| - return false; |
| - } |
| - // Directories are handled differently if they're recursive. |
| - if (!(attr & FILE_ATTRIBUTE_DIRECTORY)) |
| - return !!::DeleteFile(path.value().c_str()); |
| - // Handle a simple, single file delete. |
| - if (!recursive || DeleteFileRecursive(path, L"*", true)) |
| - return !!RemoveDirectory(path.value().c_str()); |
| - |
| - return false; |
| + return recursive ? TreeDeleter::DeleteRecursive(path) |
| + : TreeDeleter::DeleteItem(path); |
| } |
| bool DeleteFileAfterReboot(const FilePath& path) { |