| // Copyright 2023 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CHROME_BROWSER_ASH_FUSEBOX_FUSEBOX_COPY_TO_FD_H_ |
| #define CHROME_BROWSER_ASH_FUSEBOX_FUSEBOX_COPY_TO_FD_H_ |
| |
| #include "base/files/scoped_file.h" |
| #include "base/functional/callback_forward.h" |
| #include "base/types/expected.h" |
| #include "storage/browser/file_system/file_system_context.h" |
| |
| namespace fusebox { |
| |
| // CopyToFileDescriptor copies the contents of |src_fs_url| to the |
| // |dst_scoped_fd|. Ownership of that base::ScopedFD is passed to the callee |
| // and returned (via the callback) when done. |
| // |
| // It should only be called from the content::BrowserThread::IO thread. |
| // |
| // It is a bit like storage::FileSystemOperation::Copy (or CopyInForeignFile) |
| // but the destination is an already-open file descriptor (possibly a nameless |
| // O_TMPFILE file), not a storage::FileSystemURL (which can only refer to |
| // namable things). |
| // |
| // It is a bit like storage::FileSystemOperation::CreateSnapshotFile but it |
| // always copies the bytes. CreateSnapshotFile can sometimes be effectively a |
| // no-op, if the source file is already on the local disk. This works when the |
| // snapshot is only read from (not written to) but can introduce aliasing or |
| // ownership questions when the destination file will be further modified. |
| // |
| // CreateSnapshotFile (a cross-platform API) also does not write to an |
| // automatically deleted-on-close O_TMPFILE file (a Linux-specific concept) |
| // which means that the CreateSnapshotFile caller needs to explicitly manage |
| // and garbage-collect snapshot files after use. |
| void CopyToFileDescriptor( |
| scoped_refptr<storage::FileSystemContext> fs_context, |
| const storage::FileSystemURL& src_fs_url, |
| base::ScopedFD dst_scoped_fd, |
| // The E=int in the base::expected<T, E> is a POSIX error code. |
| base::OnceCallback<void(base::expected<base::ScopedFD, int>)> callback); |
| |
| } // namespace fusebox |
| |
| #endif // CHROME_BROWSER_ASH_FUSEBOX_FUSEBOX_COPY_TO_FD_H_ |