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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/downgrade/downgrade_utils.h"
#include "base/files/file_enumerator.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "build/build_config.h"
#include "chrome/browser/downgrade/user_data_downgrade.h"
#if BUILDFLAG(IS_WIN)
#include <windows.h>
#elif BUILDFLAG(IS_POSIX)
#include "base/files/file.h"
#endif
namespace downgrade {
base::FilePath GetTempDirNameForDelete(const base::FilePath& dir,
const base::FilePath& name) {
if (dir.empty())
return base::FilePath();
return base::GetUniquePath(
dir.Append(name).AddExtension(kDowngradeDeleteSuffix));
}
bool MoveWithoutFallback(const base::FilePath& source,
const base::FilePath& target) {
#if BUILDFLAG(IS_WIN)
// TODO(grt): check whether or not this is sufficiently atomic when |source|
// is on a network share.
auto result = ::MoveFileEx(source.value().c_str(), target.value().c_str(), 0);
PLOG_IF(ERROR, !result) << source << " -> " << target;
return result;
#elif BUILDFLAG(IS_POSIX)
// Windows compatibility: if |target| exists, |source| and |target|
// must be the same type, either both files, or both directories.
base::stat_wrapper_t target_info;
if (base::File::Stat(target, &target_info) == 0) {
base::stat_wrapper_t source_info;
if (base::File::Stat(source, &source_info) != 0) {
return false;
}
if (S_ISDIR(target_info.st_mode) != S_ISDIR(source_info.st_mode))
return false;
}
auto result = rename(source.value().c_str(), target.value().c_str());
PLOG_IF(ERROR, result) << source << " -> " << target;
return !result;
#endif
}
bool MoveContents(const base::FilePath& source,
const base::FilePath& target,
ExclusionPredicate exclusion_predicate) {
// Implementation note: moving is better than deleting in this case since it
// avoids certain failure modes. For example: on Windows, a file that is open
// with FILE_SHARE_DELETE can be moved or marked for deletion. If it is moved
// aside, the containing directory may then be eligible for deletion. If, on
// the other hand, it is marked for deletion, it cannot be moved nor can its
// containing directory be moved or deleted.
bool all_succeeded = base::CreateDirectory(target);
if (!all_succeeded) {
PLOG(ERROR) << target;
return all_succeeded;
}
base::FileEnumerator enumerator(
source, false,
base::FileEnumerator::FILES | base::FileEnumerator::DIRECTORIES);
for (base::FilePath path = enumerator.Next(); !path.empty();
path = enumerator.Next()) {
const base::FileEnumerator::FileInfo info = enumerator.GetInfo();
const base::FilePath name = info.GetName();
if (exclusion_predicate && exclusion_predicate.Run(name))
continue;
const base::FilePath this_target = target.Append(name);
// A directory can be moved unless any file within it is open. A simple file
// can be moved unless it is opened without FILE_SHARE_DELETE. (As with most
// things in life, there are exceptions to this rule, but they are
// uncommon. For example, a file opened without FILE_SHARE_DELETE can be
// moved as long as it was opened only with some combination of
// READ_CONTROL, WRITE_DAC, WRITE_OWNER, and SYNCHRONIZE access rights.
// Since this short list excludes such useful rights as FILE_EXECUTE,
// FILE_READ_DATA, and most anything else one would want a file for, it's
// likely an uncommon scenario. See OpenFileTest in base/files for more.)
if (MoveWithoutFallback(path, this_target))
continue;
if (!info.IsDirectory()) {
all_succeeded = false;
continue;
}
MoveContents(path, this_target, ExclusionPredicate());
// If everything within the directory was moved, it may be possible to
// delete it now.
if (!base::DeleteFile(path))
all_succeeded = false;
}
return all_succeeded;
}
} // namespace downgrade
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