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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 defined(OS_MACOSX) && !defined(OS_IOS)
#include "base/mac/mac_util.h"
#endif
#if defined(OS_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)
{
VfsFile* file = AsVfsFile(sqlite_file);
#if defined(OS_FUCHSIA)
FuchsiaVfsUnlock(sqlite_file, SQLITE_LOCK_NONE);
#endif
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 !defined(OS_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 // !defined(OS_FUCHSIA)
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 defined(OS_MACOSX) && !defined(OS_IOS)
// When opening journal files, propagate time-machine 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::GetFileBackupExclusion(base::FilePath(db_name))) {
base::mac::SetFileBackupExclusion(
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 defined(OS_FUCHSIA)
file->file_name = file_name;
file->lock_level = SQLITE_LOCK_NONE;
#endif
if (wrapped_file->pMethods->iVersion == 1) {
static const sqlite3_io_methods io_methods = {
1,
Close,
Read,
Write,
Truncate,
Sync,
FileSize,
#if !defined(OS_FUCHSIA)
Lock,
Unlock,
CheckReservedLock,
#else
FuchsiaVfsLock,
FuchsiaVfsUnlock,
FuchsiaVfsCheckReservedLock,
#endif
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,
#if !defined(OS_FUCHSIA)
Lock,
Unlock,
CheckReservedLock,
#else
FuchsiaVfsLock,
FuchsiaVfsUnlock,
FuchsiaVfsCheckReservedLock,
#endif
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,
#if !defined(OS_FUCHSIA)
Lock,
Unlock,
CheckReservedLock,
#else
FuchsiaVfsLock,
FuchsiaVfsUnlock,
FuchsiaVfsCheckReservedLock,
#endif
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() {
const 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.
const char* base_vfs_name = nullptr;
#if defined(OS_FUCHSIA)
base_vfs_name = "unix-none";
#endif
sqlite3_vfs* wrapped_vfs = sqlite3_vfs_find(base_vfs_name);
// 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