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- // Copyright (c) 2017 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "sql/vfs_wrapper.h"
- #include <algorithm>
- #include <string>
- #include <vector>
- #include "base/check_op.h"
- #include "base/debug/leak_annotations.h"
- #include "base/files/file_path.h"
- #include "base/memory/ptr_util.h"
- #include "base/metrics/histogram_macros.h"
- #include "base/notreached.h"
- #include "base/strings/string_piece.h"
- #include "build/build_config.h"
- #if BUILDFLAG(IS_APPLE)
- #include "base/mac/backup_util.h"
- #endif
- #if BUILDFLAG(IS_FUCHSIA)
- #include "sql/vfs_wrapper_fuchsia.h"
- #endif
- namespace sql {
- namespace {
- // https://www.sqlite.org/vfs.html - documents the overall VFS system.
- //
- // https://www.sqlite.org/c3ref/vfs.html - VFS methods. This code tucks the
- // wrapped VFS pointer into the wrapper's pAppData pointer.
- //
- // https://www.sqlite.org/c3ref/file.html - instance of an open file. This code
- // allocates a VfsFile for this, which contains a pointer to the wrapped file.
- // Idiomatic SQLite would take the wrapped VFS szOsFile and increase it to store
- // additional data as a prefix.
- sqlite3_vfs* GetWrappedVfs(sqlite3_vfs* wrapped_vfs) {
- return static_cast<sqlite3_vfs*>(wrapped_vfs->pAppData);
- }
- VfsFile* AsVfsFile(sqlite3_file* wrapper_file) {
- return reinterpret_cast<VfsFile*>(wrapper_file);
- }
- sqlite3_file* GetWrappedFile(sqlite3_file* wrapper_file) {
- return AsVfsFile(wrapper_file)->wrapped_file;
- }
- int Close(sqlite3_file* sqlite_file) {
- #if BUILDFLAG(IS_FUCHSIA)
- // Other platforms automatically unlock when the file descriptor is closed,
- // but the fuchsia virtual implementation doesn't have that so it needs an
- // explicit unlock on close.
- Unlock(sqlite_file, SQLITE_LOCK_NONE);
- #endif
- VfsFile* file = AsVfsFile(sqlite_file);
- int r = file->wrapped_file->pMethods->xClose(file->wrapped_file);
- sqlite3_free(file->wrapped_file);
- // Memory will be freed with sqlite3_free(), so the destructor needs to be
- // called explicitly.
- file->~VfsFile();
- memset(file, '\0', sizeof(*file));
- return r;
- }
- int Read(sqlite3_file* sqlite_file, void* buf, int amt, sqlite3_int64 ofs)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xRead(wrapped_file, buf, amt, ofs);
- }
- int Write(sqlite3_file* sqlite_file, const void* buf, int amt,
- sqlite3_int64 ofs)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xWrite(wrapped_file, buf, amt, ofs);
- }
- int Truncate(sqlite3_file* sqlite_file, sqlite3_int64 size)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xTruncate(wrapped_file, size);
- }
- int Sync(sqlite3_file* sqlite_file, int flags)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xSync(wrapped_file, flags);
- }
- int FileSize(sqlite3_file* sqlite_file, sqlite3_int64* size)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xFileSize(wrapped_file, size);
- }
- #if !BUILDFLAG(IS_FUCHSIA)
- int Lock(sqlite3_file* sqlite_file, int file_lock)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xLock(wrapped_file, file_lock);
- }
- int Unlock(sqlite3_file* sqlite_file, int file_lock)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xUnlock(wrapped_file, file_lock);
- }
- int CheckReservedLock(sqlite3_file* sqlite_file, int* result)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xCheckReservedLock(wrapped_file, result);
- }
- #endif // !BUILDFLAG(IS_FUCHSIA)
- // Else these functions are imported via vfs_wrapper_fuchsia.h.
- int FileControl(sqlite3_file* sqlite_file, int op, void* arg)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xFileControl(wrapped_file, op, arg);
- }
- int SectorSize(sqlite3_file* sqlite_file)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xSectorSize(wrapped_file);
- }
- int DeviceCharacteristics(sqlite3_file* sqlite_file)
- {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xDeviceCharacteristics(wrapped_file);
- }
- int ShmMap(sqlite3_file *sqlite_file, int region, int size,
- int extend, void volatile **pp) {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xShmMap(
- wrapped_file, region, size, extend, pp);
- }
- int ShmLock(sqlite3_file *sqlite_file, int ofst, int n, int flags) {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xShmLock(wrapped_file, ofst, n, flags);
- }
- void ShmBarrier(sqlite3_file *sqlite_file) {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- wrapped_file->pMethods->xShmBarrier(wrapped_file);
- }
- int ShmUnmap(sqlite3_file *sqlite_file, int del) {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xShmUnmap(wrapped_file, del);
- }
- int Fetch(sqlite3_file *sqlite_file, sqlite3_int64 off, int amt, void **pp) {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xFetch(wrapped_file, off, amt, pp);
- }
- int Unfetch(sqlite3_file *sqlite_file, sqlite3_int64 off, void *p) {
- sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
- return wrapped_file->pMethods->xUnfetch(wrapped_file, off, p);
- }
- int Open(sqlite3_vfs* vfs, const char* file_name, sqlite3_file* wrapper_file,
- int desired_flags, int* used_flags) {
- sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
- sqlite3_file* wrapped_file = static_cast<sqlite3_file*>(
- sqlite3_malloc(wrapped_vfs->szOsFile));
- if (!wrapped_file)
- return SQLITE_NOMEM;
- // NOTE(shess): SQLite's unixOpen() makes assumptions about the structure of
- // |file_name|. Do not pass a local copy, here, only the passed-in value.
- int rc = wrapped_vfs->xOpen(wrapped_vfs,
- file_name, wrapped_file,
- desired_flags, used_flags);
- if (rc != SQLITE_OK) {
- sqlite3_free(wrapped_file);
- return rc;
- }
- // NOTE(shess): Any early exit from here needs to call xClose() on
- // |wrapped_file|.
- #if BUILDFLAG(IS_APPLE)
- // When opening journal files, propagate backup exclusion from db.
- static int kJournalFlags =
- SQLITE_OPEN_MAIN_JOURNAL | SQLITE_OPEN_TEMP_JOURNAL |
- SQLITE_OPEN_SUBJOURNAL | SQLITE_OPEN_MASTER_JOURNAL;
- if (file_name && (desired_flags & kJournalFlags)) {
- // https://www.sqlite.org/c3ref/vfs.html indicates that the journal path
- // will have a suffix separated by "-" from the main database file name.
- base::StringPiece file_name_string_piece(file_name);
- size_t dash_index = file_name_string_piece.rfind('-');
- if (dash_index != base::StringPiece::npos) {
- base::StringPiece db_name(file_name, dash_index);
- if (base::mac::GetBackupExclusion(base::FilePath(db_name))) {
- base::mac::SetBackupExclusion(base::FilePath(file_name_string_piece));
- }
- }
- }
- #endif
- // |iVersion| determines what methods SQLite may call on the instance.
- // Having the methods which can't be proxied return an error may cause SQLite
- // to operate differently than if it didn't call those methods at all. To be
- // on the safe side, the wrapper sqlite3_io_methods version perfectly matches
- // the version of the wrapped files.
- //
- // At a first glance, it might be tempting to simplify the code by
- // restricting wrapping support to VFS version 3. However, this might fail on
- // Mac.
- //
- // On Mac, SQLite built with SQLITE_ENABLE_LOCKING_STYLE ends up using a VFS
- // that dynamically dispatches between a few variants of sqlite3_io_methods,
- // based on whether the opened database is on a local or on a remote (AFS,
- // NFS) filesystem. Some variants return a VFS version 1 structure.
- VfsFile* file = AsVfsFile(wrapper_file);
- // Call constructor explicitly since the memory is already allocated.
- new (file) VfsFile();
- file->wrapped_file = wrapped_file;
- #if BUILDFLAG(IS_FUCHSIA)
- file->file_name = file_name;
- #endif
- if (wrapped_file->pMethods->iVersion == 1) {
- static const sqlite3_io_methods io_methods = {
- 1,
- Close,
- Read,
- Write,
- Truncate,
- Sync,
- FileSize,
- Lock,
- Unlock,
- CheckReservedLock,
- FileControl,
- SectorSize,
- DeviceCharacteristics,
- };
- file->methods = &io_methods;
- } else if (wrapped_file->pMethods->iVersion == 2) {
- static const sqlite3_io_methods io_methods = {
- 2,
- Close,
- Read,
- Write,
- Truncate,
- Sync,
- FileSize,
- Lock,
- Unlock,
- CheckReservedLock,
- FileControl,
- SectorSize,
- DeviceCharacteristics,
- // Methods above are valid for version 1.
- ShmMap,
- ShmLock,
- ShmBarrier,
- ShmUnmap,
- };
- file->methods = &io_methods;
- } else {
- static const sqlite3_io_methods io_methods = {
- 3,
- Close,
- Read,
- Write,
- Truncate,
- Sync,
- FileSize,
- Lock,
- Unlock,
- CheckReservedLock,
- FileControl,
- SectorSize,
- DeviceCharacteristics,
- // Methods above are valid for version 1.
- ShmMap,
- ShmLock,
- ShmBarrier,
- ShmUnmap,
- // Methods above are valid for version 2.
- Fetch,
- Unfetch,
- };
- file->methods = &io_methods;
- }
- return SQLITE_OK;
- }
- int Delete(sqlite3_vfs* vfs, const char* file_name, int sync_dir) {
- sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
- return wrapped_vfs->xDelete(wrapped_vfs, file_name, sync_dir);
- }
- int Access(sqlite3_vfs* vfs, const char* file_name, int flag, int* res) {
- sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
- return wrapped_vfs->xAccess(wrapped_vfs, file_name, flag, res);
- }
- int FullPathname(sqlite3_vfs* vfs, const char* relative_path,
- int buf_size, char* absolute_path) {
- sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
- return wrapped_vfs->xFullPathname(
- wrapped_vfs, relative_path, buf_size, absolute_path);
- }
- int Randomness(sqlite3_vfs* vfs, int buf_size, char* buffer) {
- sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
- return wrapped_vfs->xRandomness(wrapped_vfs, buf_size, buffer);
- }
- int Sleep(sqlite3_vfs* vfs, int microseconds) {
- sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
- return wrapped_vfs->xSleep(wrapped_vfs, microseconds);
- }
- int GetLastError(sqlite3_vfs* vfs, int e, char* s) {
- sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
- return wrapped_vfs->xGetLastError(wrapped_vfs, e, s);
- }
- int CurrentTimeInt64(sqlite3_vfs* vfs, sqlite3_int64* now) {
- sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
- return wrapped_vfs->xCurrentTimeInt64(wrapped_vfs, now);
- }
- } // namespace
- sqlite3_vfs* VFSWrapper() {
- static constexpr char kVFSName[] = "VFSWrapper";
- // Return existing version if already registered.
- {
- sqlite3_vfs* vfs = sqlite3_vfs_find(kVFSName);
- if (vfs)
- return vfs;
- }
- // Get the default VFS on all platforms except Fuchsia.
- static constexpr const char* kBaseVfsName =
- #if BUILDFLAG(IS_FUCHSIA)
- "unix-none";
- #else
- nullptr;
- #endif
- sqlite3_vfs* wrapped_vfs = sqlite3_vfs_find(kBaseVfsName);
- // Give up if there is no VFS implementation for the current platform.
- if (!wrapped_vfs) {
- NOTREACHED();
- return nullptr;
- }
- std::unique_ptr<sqlite3_vfs, std::function<void(sqlite3_vfs*)>> wrapper_vfs(
- static_cast<sqlite3_vfs*>(sqlite3_malloc(sizeof(sqlite3_vfs))),
- [](sqlite3_vfs* v) {
- sqlite3_free(v);
- });
- memset(wrapper_vfs.get(), '\0', sizeof(sqlite3_vfs));
- // VFS implementations should always work with a SQLite that only knows about
- // earlier versions.
- constexpr int kSqliteVfsApiVersion = 3;
- wrapper_vfs->iVersion = kSqliteVfsApiVersion;
- // All the SQLite VFS implementations used by Chrome should support the
- // version proxied here.
- DCHECK_GE(wrapped_vfs->iVersion, kSqliteVfsApiVersion);
- // Caller of xOpen() allocates this much space.
- wrapper_vfs->szOsFile = sizeof(VfsFile);
- wrapper_vfs->mxPathname = wrapped_vfs->mxPathname;
- wrapper_vfs->pNext = nullptr; // Field used by SQLite.
- wrapper_vfs->zName = kVFSName;
- // Keep a reference to the wrapped vfs for use in methods.
- wrapper_vfs->pAppData = wrapped_vfs;
- // VFS methods.
- wrapper_vfs->xOpen = &Open;
- wrapper_vfs->xDelete = &Delete;
- wrapper_vfs->xAccess = &Access;
- wrapper_vfs->xFullPathname = &FullPathname;
- // SQLite's dynamic extension loading is disabled in Chrome. Not proxying
- // these methods lets us ship less logic and provides a tiny bit of extra
- // security, as we know for sure that SQLite will not dynamically load code.
- wrapper_vfs->xDlOpen = nullptr;
- wrapper_vfs->xDlError = nullptr;
- wrapper_vfs->xDlSym = nullptr;
- wrapper_vfs->xDlClose = nullptr;
- wrapper_vfs->xRandomness = &Randomness;
- wrapper_vfs->xSleep = &Sleep;
- // |xCurrentTime| is null when SQLite is built with SQLITE_OMIT_DEPRECATED, so
- // it does not need to be proxied.
- wrapper_vfs->xCurrentTime = nullptr;
- wrapper_vfs->xGetLastError = &GetLastError;
- // The methods above are in version 1 of SQLite's VFS API.
- DCHECK(wrapped_vfs->xCurrentTimeInt64 != nullptr);
- wrapper_vfs->xCurrentTimeInt64 = &CurrentTimeInt64;
- // The methods above are in version 2 of SQLite's VFS API.
- // The VFS system call interception API is intended for very low-level SQLite
- // testing and tweaks. Proxying these methods is not necessary because Chrome
- // does not do very low-level SQLite testing, and the VFS wrapper supports all
- // the needed tweaks.
- wrapper_vfs->xSetSystemCall = nullptr;
- wrapper_vfs->xGetSystemCall = nullptr;
- wrapper_vfs->xNextSystemCall = nullptr;
- // The methods above are in version 3 of sqlite_vfs.
- if (SQLITE_OK == sqlite3_vfs_register(wrapper_vfs.get(), 0)) {
- ANNOTATE_LEAKING_OBJECT_PTR(wrapper_vfs.get());
- wrapper_vfs.release();
- }
- return sqlite3_vfs_find(kVFSName);
- }
- } // namespace sql
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