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// Copyright 2015 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "cobalt/storage/store_upgrade/sql_vfs.h"
#include "base/logging.h"
#include "base/rand_util.h"
#include "base/strings/string_util.h"
#include "base/synchronization/lock.h"
#include "cobalt/storage/store_upgrade/virtual_file.h"
#include "cobalt/storage/store_upgrade/virtual_file_system.h"
#include "third_party/sqlite/sqlite3.h"
namespace cobalt {
namespace storage {
namespace store_upgrade {
namespace {
// A "subclass" of sqlite3_file with our required data structures added.
struct virtual_file {
sqlite3_file sql_internal_file;
VirtualFile* file;
base::Lock* lock;
int current_lock;
int shared;
};
int VfsClose(sqlite3_file* file) {
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
delete vfile->lock;
return SQLITE_OK;
}
int VfsRead(sqlite3_file* file, void* out, int bytes, sqlite_int64 offset) {
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
vfile->file->Read(out, bytes, static_cast<int>(offset));
return SQLITE_OK;
}
int VfsWrite(sqlite3_file* file, const void* data, int bytes,
sqlite3_int64 offset) {
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
vfile->file->Write(data, bytes, static_cast<int>(offset));
return SQLITE_OK;
}
int VfsSync(sqlite3_file* pFile, int flags) {
return SQLITE_OK;
}
int VfsFileControl(sqlite3_file* pFile, int op, void* pArg) {
return SQLITE_OK;
}
int VfsSectorSize(sqlite3_file* file) {
// The number of bytes that can be read without disturbing other bytes in the
// file.
return 1;
}
int VfsLock(sqlite3_file* file, const int mode) {
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
base::AutoLock lock(*vfile->lock);
// If there is already a lock of this type or more restrictive, do nothing
if (vfile->current_lock >= mode) {
return SQLITE_OK;
}
if (mode == SQLITE_LOCK_SHARED) {
DCHECK_EQ(vfile->current_lock, SQLITE_LOCK_NONE);
vfile->shared++;
vfile->current_lock = SQLITE_LOCK_SHARED;
}
if (mode == SQLITE_LOCK_RESERVED) {
DCHECK_EQ(vfile->current_lock, SQLITE_LOCK_SHARED);
vfile->current_lock = SQLITE_LOCK_RESERVED;
}
if (mode == SQLITE_LOCK_EXCLUSIVE) {
if (vfile->current_lock >= SQLITE_LOCK_PENDING) {
return SQLITE_BUSY;
}
vfile->current_lock = SQLITE_LOCK_PENDING;
if (vfile->shared > 1) {
// There are some outstanding shared locks (greater than one because the
// pending lock is an "upgraded" shared lock)
return SQLITE_BUSY;
}
// Acquire the exclusive lock
vfile->current_lock = SQLITE_LOCK_EXCLUSIVE;
}
return SQLITE_OK;
}
int VfsUnlock(sqlite3_file* file, int mode) {
DCHECK_LE(mode, SQLITE_LOCK_SHARED);
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
base::AutoLock lock(*vfile->lock);
COMPILE_ASSERT(SQLITE_LOCK_NONE < SQLITE_LOCK_SHARED,
sqlite_lock_constants_order_has_changed);
COMPILE_ASSERT(SQLITE_LOCK_SHARED < SQLITE_LOCK_RESERVED,
sqlite_lock_constants_order_has_changed);
COMPILE_ASSERT(SQLITE_LOCK_RESERVED < SQLITE_LOCK_PENDING,
sqlite_lock_constants_order_has_changed);
COMPILE_ASSERT(SQLITE_LOCK_PENDING < SQLITE_LOCK_EXCLUSIVE,
sqlite_lock_constants_order_has_changed);
if (mode == SQLITE_LOCK_NONE && vfile->current_lock >= SQLITE_LOCK_SHARED) {
vfile->shared--;
}
vfile->current_lock = mode;
return SQLITE_OK;
}
int VfsCheckReservedLock(sqlite3_file* file, int* result) {
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
base::AutoLock lock(*vfile->lock);
// The function expects a result is 1 if the lock is reserved, pending, or
// exclusive; 0 otherwise.
*result = vfile->current_lock >= SQLITE_LOCK_RESERVED ? 1 : 0;
return SQLITE_OK;
}
int VfsFileSize(sqlite3_file* file, sqlite3_int64* out_size) {
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
*out_size = vfile->file->Size();
return SQLITE_OK;
}
int VfsTruncate(sqlite3_file* file, sqlite3_int64 size) {
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
vfile->file->Truncate(static_cast<int>(size));
return SQLITE_OK;
}
int VfsDeviceCharacteristics(sqlite3_file* file) {
return 0;
}
const sqlite3_io_methods s_cobalt_vfs_io = {
1, // Structure version number
VfsClose, // xClose
VfsRead, // xRead
VfsWrite, // xWrite
VfsTruncate, // xTruncate
VfsSync, // xSync
VfsFileSize, // xFileSize
VfsLock, // xLock
VfsUnlock, // xUnlock
VfsCheckReservedLock, // xCheckReservedLock
VfsFileControl, // xFileControl
VfsSectorSize, // xSectorSize
VfsDeviceCharacteristics // xDeviceCharacteristics
};
int VfsOpen(sqlite3_vfs* sql_vfs, const char* path, sqlite3_file* file,
int flags, int* out_flags) {
DCHECK(path) << "NULL filename not supported.";
virtual_file* vfile = reinterpret_cast<virtual_file*>(file);
vfile->lock = new base::Lock;
file->pMethods = &s_cobalt_vfs_io;
VirtualFileSystem* vfs =
reinterpret_cast<VirtualFileSystem*>(sql_vfs->pAppData);
vfile->file = vfs->Open(path);
return SQLITE_OK;
}
int VfsDelete(sqlite3_vfs* sql_vfs, const char* path, int sync_dir) {
VirtualFileSystem* vfs =
reinterpret_cast<VirtualFileSystem*>(sql_vfs->pAppData);
vfs->Delete(path);
return SQLITE_OK;
}
int VfsFullPathname(sqlite3_vfs* sql_vfs, const char* path, int out_size,
char* out_path) {
size_t path_size = static_cast<size_t>(out_size);
if (base::strlcpy(out_path, path, path_size) < path_size) {
return SQLITE_OK;
}
return SQLITE_ERROR;
}
int VfsAccess(sqlite3_vfs* sql_vfs, const char* name, int flags, int* result) {
// We should always have a valid, readable/writable file.
*result |= SQLITE_ACCESS_EXISTS | SQLITE_ACCESS_READWRITE;
return SQLITE_OK;
}
int VfsRandomness(sqlite3_vfs* sql_vfs, int bytes, char* out) {
base::RandBytes(out, static_cast<size_t>(bytes));
return SQLITE_OK;
}
} // namespace
SqlVfs::SqlVfs(const std::string& name, VirtualFileSystem* vfs)
: sql_vfs_(new sqlite3_vfs()) {
memset(sql_vfs_.get(), 0, sizeof(sqlite3_vfs));
sql_vfs_->iVersion = 1;
sql_vfs_->szOsFile = sizeof(virtual_file);
sql_vfs_->mxPathname = VirtualFile::kMaxVfsPathname;
sql_vfs_->pNext = NULL;
sql_vfs_->zName = name.c_str();
sql_vfs_->pAppData = vfs;
sql_vfs_->xOpen = VfsOpen;
sql_vfs_->xDelete = VfsDelete;
sql_vfs_->xAccess = VfsAccess;
sql_vfs_->xFullPathname = VfsFullPathname;
sql_vfs_->xRandomness = VfsRandomness;
// Ensure we are not registering multiple of these with the same name.
// Behavior is undefined in that case.
DCHECK(sqlite3_vfs_find(name.c_str()) == NULL);
int ret = sqlite3_vfs_register(sql_vfs_.get(), 1 /* make_default */);
DCHECK_EQ(ret, SQLITE_OK);
}
SqlVfs::~SqlVfs() {
int ret = sqlite3_vfs_unregister(sql_vfs_.get());
DCHECK_EQ(ret, SQLITE_OK);
}
} // namespace store_upgrade
} // namespace storage
} // namespace cobalt