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// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_SQLITE_VFS_SQLITE_DATABASE_VFS_FILE_SET_H_
#define COMPONENTS_SQLITE_VFS_SQLITE_DATABASE_VFS_FILE_SET_H_
#include <memory>
#include <optional>
#include "base/component_export.h"
#include "base/files/file.h"
#include "base/files/file_path.h"
#include "base/memory/unsafe_shared_memory_region.h"
#include "components/sqlite_vfs/lock_state.h"
#include "components/sqlite_vfs/sandboxed_file.h"
namespace sqlite_vfs {
enum class Client;
struct PendingFileSet;
// Contains `SanboxedFile` representations of the files necessary to the use of
// an `sql::Database`.
//
// This class owns the `SandboxedFile` files and must outlive any use of them.
class COMPONENT_EXPORT(SQLITE_VFS) SqliteVfsFileSet {
public:
// Returns a `SqliteVfsFileSet` holding the state from a `PendingFileSet`.
// Returns no value in case of error (e.g., the shared lock could not be
// mapped into the process's address space).
static std::optional<SqliteVfsFileSet> Bind(Client client,
PendingFileSet pending_file_set);
SqliteVfsFileSet(SqliteVfsFileSet& other) = delete;
SqliteVfsFileSet& operator=(const SqliteVfsFileSet& other) = delete;
SqliteVfsFileSet(SqliteVfsFileSet&& other);
SqliteVfsFileSet& operator=(SqliteVfsFileSet&& other);
~SqliteVfsFileSet();
// The virtual paths to the files exposed to the database.
base::FilePath GetDbVirtualFilePath() const;
base::FilePath GetJournalVirtualFilePath() const;
base::FilePath GetWalJournalVirtualFilePath() const;
// Returns the histogram variant for the file at `virtual_file_path`.
// - "DbFile" if `virtual_file_path` names a main database file.
// - "JournalFile" if `virtual_file_path` names a main journal file.
// - "WalJournalFile" if `virtual_file_path` names a write-ahead log file.
// Crashes the process on unexpected values.
static std::string_view GetVirtualFileHistogramVariant(
const base::FilePath& virtual_file_path);
SandboxedFile* GetSandboxedDbFile() const { return db_file_.get(); }
SandboxedFile* GetSandboxedJournalFile() const { return journal_file_.get(); }
SandboxedFile* GetSandboxedWalJournalFile() const {
CHECK(wal_journal_mode());
return wal_journal_file_.get();
}
bool read_only() const { return read_only_; }
// The underlying handles.
const base::File& GetDbFile() const;
const base::File& GetJournalFile() const;
const base::File& GetWalJournalFile() const;
const base::UnsafeSharedMemoryRegion& GetSharedLock() const {
return shared_lock_;
}
bool is_single_connection() const { return !shared_lock_.IsValid(); }
bool wal_journal_mode() const { return !!wal_journal_file_; }
// Permanently marks this file set's database as no longer suitable for use by
// any connection. Returns true if any connection to the database holds either
// a shared reader lock; or the reserved, pending, or exclusive lock. All
// subsequent attempts to lock the database by any connection will fail with
// SQLITE_IOERR_LOCK. Clients accessing a database by such a file set should
// handle this error by closing their connection. When `Abandon()` returns
// `kNotHeld`, it is safe to re-establish new connections to the same files.
// Conversely, the backing files should be deleted if a file set is abandoned
// while any other connection holds a lock since it is not possible to know
// when all outstanding connections have been closed.
LockState Abandon();
private:
SqliteVfsFileSet(std::unique_ptr<SandboxedFile> db_file,
std::unique_ptr<SandboxedFile> journal_file,
std::unique_ptr<SandboxedFile> wal_journal_file,
base::UnsafeSharedMemoryRegion shared_lock);
// The shared lock is absent if the file set supports only a single
// connection.
base::UnsafeSharedMemoryRegion shared_lock_;
std::unique_ptr<SandboxedFile> db_file_;
std::unique_ptr<SandboxedFile> journal_file_;
// The write-ahead journal file is only present if
std::unique_ptr<SandboxedFile> wal_journal_file_;
// SQLite databases use standard naming for their files. Since the vfs might
// register files for many databases at once it needs some way to
// differentiate them. This is guaranteed to be unique because it is based on
// a monotonically increasing integer.
base::FilePath virtual_fs_path_;
bool read_only_;
};
} // namespace sqlite_vfs
#endif // COMPONENTS_SQLITE_VFS_SQLITE_DATABASE_VFS_FILE_SET_H_
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