libs/androidfw/CursorWindow.cpp - android_frameworks_base - Gitiles

 /*
  * Copyright (C) 2006-2007 The Android Open Source Project
  *
  * 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.
  */

 #define LOG_TAG "CursorWindow"

 #include <androidfw/CursorWindow.h>

 #include <sys/mman.h>

 #include "android-base/logging.h"
 #include "cutils/ashmem.h"

 namespace android {

 /**
  * By default windows are lightweight inline allocations of this size;
  * they're only inflated to ashmem regions when more space is needed.
  */
 static constexpr const size_t kInlineSize = 16384;

 static constexpr const size_t kSlotShift = 4;
 static constexpr const size_t kSlotSizeBytes = 1 << kSlotShift;

 CursorWindow::CursorWindow() {
 }

 CursorWindow::~CursorWindow() {
     if (mAshmemFd != -1) {
         ::munmap(mData, mSize);
         ::close(mAshmemFd);
     } else {
         free(mData);
     }
 }

 status_t CursorWindow::create(const String8 &name, size_t inflatedSize, CursorWindow **outWindow) {
     *outWindow = nullptr;

     CursorWindow* window = new CursorWindow();
     if (!window) goto fail;

     window->mName = name;
     window->mSize = std::min(kInlineSize, inflatedSize);
     window->mInflatedSize = inflatedSize;
     window->mData = malloc(window->mSize);
     if (!window->mData) goto fail;
     window->mReadOnly = false;

     window->clear();
     window->updateSlotsData();

     *outWindow = window;
     return OK;

 fail:
     LOG(ERROR) << "Failed create";
 fail_silent:
     delete window;
     return UNKNOWN_ERROR;
 }

 status_t CursorWindow::maybeInflate() {
     int ashmemFd = 0;
     void* newData = nullptr;

     // Bail early when we can't expand any further
     if (mReadOnly || mSize == mInflatedSize) {
         return INVALID_OPERATION;
     }

     String8 ashmemName("CursorWindow: ");
     ashmemName.append(mName);

     ashmemFd = ashmem_create_region(ashmemName.string(), mInflatedSize);
     if (ashmemFd < 0) {
         PLOG(ERROR) << "Failed ashmem_create_region";
         goto fail_silent;
     }

     if (ashmem_set_prot_region(ashmemFd, PROT_READ | PROT_WRITE) < 0) {
         PLOG(ERROR) << "Failed ashmem_set_prot_region";
         goto fail_silent;
     }

     newData = ::mmap(nullptr, mInflatedSize, PROT_READ | PROT_WRITE, MAP_SHARED, ashmemFd, 0);
     if (newData == MAP_FAILED) {
         PLOG(ERROR) << "Failed mmap";
         goto fail_silent;
     }

     if (ashmem_set_prot_region(ashmemFd, PROT_READ) < 0) {
         PLOG(ERROR) << "Failed ashmem_set_prot_region";
         goto fail_silent;
     }

     {
         // Migrate existing contents into new ashmem region
         uint32_t slotsSize = mSize - mSlotsOffset;
         uint32_t newSlotsOffset = mInflatedSize - slotsSize;
         memcpy(static_cast<uint8_t*>(newData),
                 static_cast<uint8_t*>(mData), mAllocOffset);
         memcpy(static_cast<uint8_t*>(newData) + newSlotsOffset,
                 static_cast<uint8_t*>(mData) + mSlotsOffset, slotsSize);

         free(mData);
         mAshmemFd = ashmemFd;
         mData = newData;
         mSize = mInflatedSize;
         mSlotsOffset = newSlotsOffset;

         updateSlotsData();
     }

     LOG(DEBUG) << "Inflated: " << this->toString();
     return OK;

 fail:
     LOG(ERROR) << "Failed maybeInflate";
 fail_silent:
     ::munmap(newData, mInflatedSize);
     ::close(ashmemFd);
     return UNKNOWN_ERROR;
 }

 status_t CursorWindow::createFromParcel(Parcel* parcel, CursorWindow** outWindow) {
     *outWindow = nullptr;

     CursorWindow* window = new CursorWindow();
     if (!window) goto fail;

     if (parcel->readString8(&window->mName)) goto fail;
     if (parcel->readUint32(&window->mNumRows)) goto fail;
     if (parcel->readUint32(&window->mNumColumns)) goto fail;
     if (parcel->readUint32(&window->mSize)) goto fail;

     if ((window->mNumRows * window->mNumColumns * kSlotSizeBytes) > window->mSize) {
         LOG(ERROR) << "Unexpected size " << window->mSize << " for " << window->mNumRows
                 << " rows and " << window->mNumColumns << " columns";
         goto fail_silent;
     }

     bool isAshmem;
     if (parcel->readBool(&isAshmem)) goto fail;
     if (isAshmem) {
         window->mAshmemFd = parcel->readFileDescriptor();
         if (window->mAshmemFd < 0) {
             LOG(ERROR) << "Failed readFileDescriptor";
             goto fail_silent;
         }

         window->mAshmemFd = ::fcntl(window->mAshmemFd, F_DUPFD_CLOEXEC, 0);
         if (window->mAshmemFd < 0) {
             PLOG(ERROR) << "Failed F_DUPFD_CLOEXEC";
             goto fail_silent;
         }

         window->mData = ::mmap(nullptr, window->mSize, PROT_READ, MAP_SHARED, window->mAshmemFd, 0);
         if (window->mData == MAP_FAILED) {
             PLOG(ERROR) << "Failed mmap";
             goto fail_silent;
         }
     } else {
         window->mAshmemFd = -1;

         if (window->mSize > kInlineSize) {
             LOG(ERROR) << "Unexpected size " << window->mSize << " for inline window";
             goto fail_silent;
         }

         window->mData = malloc(window->mSize);
         if (!window->mData) goto fail;

         if (parcel->read(window->mData, window->mSize)) goto fail;
     }

     // We just came from a remote source, so we're read-only
     // and we can't inflate ourselves
     window->mInflatedSize = window->mSize;
     window->mReadOnly = true;

     window->updateSlotsData();

     LOG(DEBUG) << "Created from parcel: " << window->toString();
     *outWindow = window;
     return OK;

 fail:
     LOG(ERROR) << "Failed createFromParcel";
 fail_silent:
     delete window;
     return UNKNOWN_ERROR;
 }

 status_t CursorWindow::writeToParcel(Parcel* parcel) {
     LOG(DEBUG) << "Writing to parcel: " << this->toString();

     if (parcel->writeString8(mName)) goto fail;
     if (parcel->writeUint32(mNumRows)) goto fail;
     if (parcel->writeUint32(mNumColumns)) goto fail;
     if (mAshmemFd != -1) {
         if (parcel->writeUint32(mSize)) goto fail;
         if (parcel->writeBool(true)) goto fail;
         if (parcel->writeDupFileDescriptor(mAshmemFd)) goto fail;
     } else {
         // Since we know we're going to be read-only on the remote side,
         // we can compact ourselves on the wire, with just enough padding
         // to ensure our slots stay aligned
         size_t slotsSize = mSize - mSlotsOffset;
         size_t compactedSize = mAllocOffset + slotsSize;
         compactedSize = (compactedSize + 3) & ~3;
         if (parcel->writeUint32(compactedSize)) goto fail;
         if (parcel->writeBool(false)) goto fail;
         void* dest = parcel->writeInplace(compactedSize);
         if (!dest) goto fail;
         memcpy(static_cast<uint8_t*>(dest),
                 static_cast<uint8_t*>(mData), mAllocOffset);
         memcpy(static_cast<uint8_t*>(dest) + compactedSize - slotsSize,
                 static_cast<uint8_t*>(mData) + mSlotsOffset, slotsSize);
     }
     return OK;

 fail:
     LOG(ERROR) << "Failed writeToParcel";
 fail_silent:
     return UNKNOWN_ERROR;
 }

 status_t CursorWindow::clear() {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }
     mAllocOffset = 0;
     mSlotsOffset = mSize;
     mNumRows = 0;
     mNumColumns = 0;
     return OK;
 }

 void CursorWindow::updateSlotsData() {
     mSlotsStart = static_cast<uint8_t*>(mData) + mSize - kSlotSizeBytes;
     mSlotsEnd = static_cast<uint8_t*>(mData) + mSlotsOffset;
 }

 void* CursorWindow::offsetToPtr(uint32_t offset, uint32_t bufferSize = 0) {
     if (offset > mSize) {
         LOG(ERROR) << "Offset " << offset
                 << " out of bounds, max value " << mSize;
         return nullptr;
     }
     if (offset + bufferSize > mSize) {
         LOG(ERROR) << "End offset " << (offset + bufferSize)
                 << " out of bounds, max value " << mSize;
         return nullptr;
     }
     return static_cast<uint8_t*>(mData) + offset;
 }

 uint32_t CursorWindow::offsetFromPtr(void* ptr) {
     return static_cast<uint8_t*>(ptr) - static_cast<uint8_t*>(mData);
 }

 status_t CursorWindow::setNumColumns(uint32_t numColumns) {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }
     uint32_t cur = mNumColumns;
     if ((cur > 0 || mNumRows > 0) && cur != numColumns) {
         LOG(ERROR) << "Trying to go from " << cur << " columns to " << numColumns;
         return INVALID_OPERATION;
     }
     mNumColumns = numColumns;
     return OK;
 }

 status_t CursorWindow::allocRow() {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }
     size_t size = mNumColumns * kSlotSizeBytes;
     int32_t newOffset = mSlotsOffset - size;
     if (newOffset < (int32_t) mAllocOffset) {
         maybeInflate();
         newOffset = mSlotsOffset - size;
         if (newOffset < (int32_t) mAllocOffset) {
             return NO_MEMORY;
         }
     }
     memset(offsetToPtr(newOffset), 0, size);
     mSlotsOffset = newOffset;
     updateSlotsData();
     mNumRows++;
     return OK;
 }

 status_t CursorWindow::freeLastRow() {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }
     size_t size = mNumColumns * kSlotSizeBytes;
     size_t newOffset = mSlotsOffset + size;
     if (newOffset > mSize) {
         return NO_MEMORY;
     }
     mSlotsOffset = newOffset;
     updateSlotsData();
     mNumRows--;
     return OK;
 }

 status_t CursorWindow::alloc(size_t size, uint32_t* outOffset) {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }
     size_t alignedSize = (size + 3) & ~3;
     size_t newOffset = mAllocOffset + alignedSize;
     if (newOffset > mSlotsOffset) {
         maybeInflate();
         newOffset = mAllocOffset + alignedSize;
         if (newOffset > mSlotsOffset) {
             return NO_MEMORY;
         }
     }
     *outOffset = mAllocOffset;
     mAllocOffset = newOffset;
     return OK;
 }

 CursorWindow::FieldSlot* CursorWindow::getFieldSlot(uint32_t row, uint32_t column) {
     // This is carefully tuned to use as few cycles as
     // possible, since this is an extremely hot code path;
     // see CursorWindow_bench.cpp for more details
     void *result = static_cast<uint8_t*>(mSlotsStart)
             - (((row * mNumColumns) + column) << kSlotShift);
     if (result < mSlotsEnd || result > mSlotsStart || column >= mNumColumns) {
         LOG(ERROR) << "Failed to read row " << row << ", column " << column
                 << " from a window with " << mNumRows << " rows, " << mNumColumns << " columns";
         return nullptr;
     } else {
         return static_cast<FieldSlot*>(result);
     }
 }

 status_t CursorWindow::putBlob(uint32_t row, uint32_t column, const void* value, size_t size) {
     return putBlobOrString(row, column, value, size, FIELD_TYPE_BLOB);
 }

 status_t CursorWindow::putString(uint32_t row, uint32_t column, const char* value,
         size_t sizeIncludingNull) {
     return putBlobOrString(row, column, value, sizeIncludingNull, FIELD_TYPE_STRING);
 }

 status_t CursorWindow::putBlobOrString(uint32_t row, uint32_t column,
         const void* value, size_t size, int32_t type) {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }

     FieldSlot* fieldSlot = getFieldSlot(row, column);
     if (!fieldSlot) {
         return BAD_VALUE;
     }

     uint32_t offset;
     if (alloc(size, &offset)) {
         return NO_MEMORY;
     }

     memcpy(offsetToPtr(offset), value, size);

     fieldSlot = getFieldSlot(row, column);
     fieldSlot->type = type;
     fieldSlot->data.buffer.offset = offset;
     fieldSlot->data.buffer.size = size;
     return OK;
 }

 status_t CursorWindow::putLong(uint32_t row, uint32_t column, int64_t value) {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }

     FieldSlot* fieldSlot = getFieldSlot(row, column);
     if (!fieldSlot) {
         return BAD_VALUE;
     }

     fieldSlot->type = FIELD_TYPE_INTEGER;
     fieldSlot->data.l = value;
     return OK;
 }

 status_t CursorWindow::putDouble(uint32_t row, uint32_t column, double value) {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }

     FieldSlot* fieldSlot = getFieldSlot(row, column);
     if (!fieldSlot) {
         return BAD_VALUE;
     }

     fieldSlot->type = FIELD_TYPE_FLOAT;
     fieldSlot->data.d = value;
     return OK;
 }

 status_t CursorWindow::putNull(uint32_t row, uint32_t column) {
     if (mReadOnly) {
         return INVALID_OPERATION;
     }

     FieldSlot* fieldSlot = getFieldSlot(row, column);
     if (!fieldSlot) {
         return BAD_VALUE;
     }

     fieldSlot->type = FIELD_TYPE_NULL;
     fieldSlot->data.buffer.offset = 0;
     fieldSlot->data.buffer.size = 0;
     return OK;
 }

 }; // namespace android
	/*
	* Copyright (C) 2006-2007 The Android Open Source Project
	*
	* 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.
	*/

	#define LOG_TAG "CursorWindow"

	#include <androidfw/CursorWindow.h>

	#include <sys/mman.h>

	#include "android-base/logging.h"
	#include "cutils/ashmem.h"

	namespace android {

	/**
	* By default windows are lightweight inline allocations of this size;
	* they're only inflated to ashmem regions when more space is needed.
	*/
	static constexpr const size_t kInlineSize = 16384;

	static constexpr const size_t kSlotShift = 4;
	static constexpr const size_t kSlotSizeBytes = 1 << kSlotShift;

	CursorWindow::CursorWindow() {
	}

	CursorWindow::~CursorWindow() {
	if (mAshmemFd != -1) {
	::munmap(mData, mSize);
	::close(mAshmemFd);
	} else {
	free(mData);
	}
	}

	status_t CursorWindow::create(const String8 &name, size_t inflatedSize, CursorWindow **outWindow) {
	*outWindow = nullptr;

	CursorWindow* window = new CursorWindow();
	if (!window) goto fail;

	window->mName = name;
	window->mSize = std::min(kInlineSize, inflatedSize);
	window->mInflatedSize = inflatedSize;
	window->mData = malloc(window->mSize);
	if (!window->mData) goto fail;
	window->mReadOnly = false;

	window->clear();
	window->updateSlotsData();

	*outWindow = window;
	return OK;

	fail:
	LOG(ERROR) << "Failed create";
	fail_silent:
	delete window;
	return UNKNOWN_ERROR;
	}

	status_t CursorWindow::maybeInflate() {
	int ashmemFd = 0;
	void* newData = nullptr;

	// Bail early when we can't expand any further
	if (mReadOnly \|\| mSize == mInflatedSize) {
	return INVALID_OPERATION;
	}

	String8 ashmemName("CursorWindow: ");
	ashmemName.append(mName);

	ashmemFd = ashmem_create_region(ashmemName.string(), mInflatedSize);
	if (ashmemFd < 0) {
	PLOG(ERROR) << "Failed ashmem_create_region";
	goto fail_silent;
	}

	if (ashmem_set_prot_region(ashmemFd, PROT_READ \| PROT_WRITE) < 0) {
	PLOG(ERROR) << "Failed ashmem_set_prot_region";
	goto fail_silent;
	}

	newData = ::mmap(nullptr, mInflatedSize, PROT_READ \| PROT_WRITE, MAP_SHARED, ashmemFd, 0);
	if (newData == MAP_FAILED) {
	PLOG(ERROR) << "Failed mmap";
	goto fail_silent;
	}

	if (ashmem_set_prot_region(ashmemFd, PROT_READ) < 0) {
	PLOG(ERROR) << "Failed ashmem_set_prot_region";
	goto fail_silent;
	}

	{
	// Migrate existing contents into new ashmem region
	uint32_t slotsSize = mSize - mSlotsOffset;
	uint32_t newSlotsOffset = mInflatedSize - slotsSize;
	memcpy(static_cast<uint8_t*>(newData),
	static_cast<uint8_t*>(mData), mAllocOffset);
	memcpy(static_cast<uint8_t*>(newData) + newSlotsOffset,
	static_cast<uint8_t*>(mData) + mSlotsOffset, slotsSize);

	free(mData);
	mAshmemFd = ashmemFd;
	mData = newData;
	mSize = mInflatedSize;
	mSlotsOffset = newSlotsOffset;

	updateSlotsData();
	}

	LOG(DEBUG) << "Inflated: " << this->toString();
	return OK;

	fail:
	LOG(ERROR) << "Failed maybeInflate";
	fail_silent:
	::munmap(newData, mInflatedSize);
	::close(ashmemFd);
	return UNKNOWN_ERROR;
	}

	status_t CursorWindow::createFromParcel(Parcel* parcel, CursorWindow** outWindow) {
	*outWindow = nullptr;

	CursorWindow* window = new CursorWindow();
	if (!window) goto fail;

	if (parcel->readString8(&window->mName)) goto fail;
	if (parcel->readUint32(&window->mNumRows)) goto fail;
	if (parcel->readUint32(&window->mNumColumns)) goto fail;
	if (parcel->readUint32(&window->mSize)) goto fail;

	if ((window->mNumRows * window->mNumColumns * kSlotSizeBytes) > window->mSize) {
	LOG(ERROR) << "Unexpected size " << window->mSize << " for " << window->mNumRows
	<< " rows and " << window->mNumColumns << " columns";
	goto fail_silent;
	}

	bool isAshmem;
	if (parcel->readBool(&isAshmem)) goto fail;
	if (isAshmem) {
	window->mAshmemFd = parcel->readFileDescriptor();
	if (window->mAshmemFd < 0) {
	LOG(ERROR) << "Failed readFileDescriptor";
	goto fail_silent;
	}

	window->mAshmemFd = ::fcntl(window->mAshmemFd, F_DUPFD_CLOEXEC, 0);
	if (window->mAshmemFd < 0) {
	PLOG(ERROR) << "Failed F_DUPFD_CLOEXEC";
	goto fail_silent;
	}

	window->mData = ::mmap(nullptr, window->mSize, PROT_READ, MAP_SHARED, window->mAshmemFd, 0);
	if (window->mData == MAP_FAILED) {
	PLOG(ERROR) << "Failed mmap";
	goto fail_silent;
	}
	} else {
	window->mAshmemFd = -1;

	if (window->mSize > kInlineSize) {
	LOG(ERROR) << "Unexpected size " << window->mSize << " for inline window";
	goto fail_silent;
	}

	window->mData = malloc(window->mSize);
	if (!window->mData) goto fail;

	if (parcel->read(window->mData, window->mSize)) goto fail;
	}

	// We just came from a remote source, so we're read-only
	// and we can't inflate ourselves
	window->mInflatedSize = window->mSize;
	window->mReadOnly = true;

	window->updateSlotsData();

	LOG(DEBUG) << "Created from parcel: " << window->toString();
	*outWindow = window;
	return OK;

	fail:
	LOG(ERROR) << "Failed createFromParcel";
	fail_silent:
	delete window;
	return UNKNOWN_ERROR;
	}

	status_t CursorWindow::writeToParcel(Parcel* parcel) {
	LOG(DEBUG) << "Writing to parcel: " << this->toString();

	if (parcel->writeString8(mName)) goto fail;
	if (parcel->writeUint32(mNumRows)) goto fail;
	if (parcel->writeUint32(mNumColumns)) goto fail;
	if (mAshmemFd != -1) {
	if (parcel->writeUint32(mSize)) goto fail;
	if (parcel->writeBool(true)) goto fail;
	if (parcel->writeDupFileDescriptor(mAshmemFd)) goto fail;
	} else {
	// Since we know we're going to be read-only on the remote side,
	// we can compact ourselves on the wire, with just enough padding
	// to ensure our slots stay aligned
	size_t slotsSize = mSize - mSlotsOffset;
	size_t compactedSize = mAllocOffset + slotsSize;
	compactedSize = (compactedSize + 3) & ~3;
	if (parcel->writeUint32(compactedSize)) goto fail;
	if (parcel->writeBool(false)) goto fail;
	void* dest = parcel->writeInplace(compactedSize);
	if (!dest) goto fail;
	memcpy(static_cast<uint8_t*>(dest),
	static_cast<uint8_t*>(mData), mAllocOffset);
	memcpy(static_cast<uint8_t*>(dest) + compactedSize - slotsSize,
	static_cast<uint8_t*>(mData) + mSlotsOffset, slotsSize);
	}
	return OK;

	fail:
	LOG(ERROR) << "Failed writeToParcel";
	fail_silent:
	return UNKNOWN_ERROR;
	}

	status_t CursorWindow::clear() {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}
	mAllocOffset = 0;
	mSlotsOffset = mSize;
	mNumRows = 0;
	mNumColumns = 0;
	return OK;
	}

	void CursorWindow::updateSlotsData() {
	mSlotsStart = static_cast<uint8_t*>(mData) + mSize - kSlotSizeBytes;
	mSlotsEnd = static_cast<uint8_t*>(mData) + mSlotsOffset;
	}

	void* CursorWindow::offsetToPtr(uint32_t offset, uint32_t bufferSize = 0) {
	if (offset > mSize) {
	LOG(ERROR) << "Offset " << offset
	<< " out of bounds, max value " << mSize;
	return nullptr;
	}
	if (offset + bufferSize > mSize) {
	LOG(ERROR) << "End offset " << (offset + bufferSize)
	<< " out of bounds, max value " << mSize;
	return nullptr;
	}
	return static_cast<uint8_t*>(mData) + offset;
	}

	uint32_t CursorWindow::offsetFromPtr(void* ptr) {
	return static_cast<uint8_t>(ptr) - static_cast<uint8_t>(mData);
	}

	status_t CursorWindow::setNumColumns(uint32_t numColumns) {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}
	uint32_t cur = mNumColumns;
	if ((cur > 0 \|\| mNumRows > 0) && cur != numColumns) {
	LOG(ERROR) << "Trying to go from " << cur << " columns to " << numColumns;
	return INVALID_OPERATION;
	}
	mNumColumns = numColumns;
	return OK;
	}

	status_t CursorWindow::allocRow() {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}
	size_t size = mNumColumns * kSlotSizeBytes;
	int32_t newOffset = mSlotsOffset - size;
	if (newOffset < (int32_t) mAllocOffset) {
	maybeInflate();
	newOffset = mSlotsOffset - size;
	if (newOffset < (int32_t) mAllocOffset) {
	return NO_MEMORY;
	}
	}
	memset(offsetToPtr(newOffset), 0, size);
	mSlotsOffset = newOffset;
	updateSlotsData();
	mNumRows++;
	return OK;
	}

	status_t CursorWindow::freeLastRow() {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}
	size_t size = mNumColumns * kSlotSizeBytes;
	size_t newOffset = mSlotsOffset + size;
	if (newOffset > mSize) {
	return NO_MEMORY;
	}
	mSlotsOffset = newOffset;
	updateSlotsData();
	mNumRows--;
	return OK;
	}

	status_t CursorWindow::alloc(size_t size, uint32_t* outOffset) {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}
	size_t alignedSize = (size + 3) & ~3;
	size_t newOffset = mAllocOffset + alignedSize;
	if (newOffset > mSlotsOffset) {
	maybeInflate();
	newOffset = mAllocOffset + alignedSize;
	if (newOffset > mSlotsOffset) {
	return NO_MEMORY;
	}
	}
	*outOffset = mAllocOffset;
	mAllocOffset = newOffset;
	return OK;
	}

	CursorWindow::FieldSlot* CursorWindow::getFieldSlot(uint32_t row, uint32_t column) {
	// This is carefully tuned to use as few cycles as
	// possible, since this is an extremely hot code path;
	// see CursorWindow_bench.cpp for more details
	void result = static_cast<uint8_t>(mSlotsStart)
	- (((row * mNumColumns) + column) << kSlotShift);
	if (result < mSlotsEnd \|\| result > mSlotsStart \|\| column >= mNumColumns) {
	LOG(ERROR) << "Failed to read row " << row << ", column " << column
	<< " from a window with " << mNumRows << " rows, " << mNumColumns << " columns";
	return nullptr;
	} else {
	return static_cast<FieldSlot*>(result);
	}
	}

	status_t CursorWindow::putBlob(uint32_t row, uint32_t column, const void* value, size_t size) {
	return putBlobOrString(row, column, value, size, FIELD_TYPE_BLOB);
	}

	status_t CursorWindow::putString(uint32_t row, uint32_t column, const char* value,
	size_t sizeIncludingNull) {
	return putBlobOrString(row, column, value, sizeIncludingNull, FIELD_TYPE_STRING);
	}

	status_t CursorWindow::putBlobOrString(uint32_t row, uint32_t column,
	const void* value, size_t size, int32_t type) {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}

	FieldSlot* fieldSlot = getFieldSlot(row, column);
	if (!fieldSlot) {
	return BAD_VALUE;
	}

	uint32_t offset;
	if (alloc(size, &offset)) {
	return NO_MEMORY;
	}

	memcpy(offsetToPtr(offset), value, size);

	fieldSlot = getFieldSlot(row, column);
	fieldSlot->type = type;
	fieldSlot->data.buffer.offset = offset;
	fieldSlot->data.buffer.size = size;
	return OK;
	}

	status_t CursorWindow::putLong(uint32_t row, uint32_t column, int64_t value) {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}

	FieldSlot* fieldSlot = getFieldSlot(row, column);
	if (!fieldSlot) {
	return BAD_VALUE;
	}

	fieldSlot->type = FIELD_TYPE_INTEGER;
	fieldSlot->data.l = value;
	return OK;
	}

	status_t CursorWindow::putDouble(uint32_t row, uint32_t column, double value) {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}

	FieldSlot* fieldSlot = getFieldSlot(row, column);
	if (!fieldSlot) {
	return BAD_VALUE;
	}

	fieldSlot->type = FIELD_TYPE_FLOAT;
	fieldSlot->data.d = value;
	return OK;
	}

	status_t CursorWindow::putNull(uint32_t row, uint32_t column) {
	if (mReadOnly) {
	return INVALID_OPERATION;
	}

	FieldSlot* fieldSlot = getFieldSlot(row, column);
	if (!fieldSlot) {
	return BAD_VALUE;
	}

	fieldSlot->type = FIELD_TYPE_NULL;
	fieldSlot->data.buffer.offset = 0;
	fieldSlot->data.buffer.size = 0;
	return OK;
	}

	}; // namespace android