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) { |