Use ashmem for CursorWindows.
Bug: 5332296

The memory dealer introduces additional delays for reclaiming
the memory owned by CursorWindows because the Binder object must
be finalized.  Using ashmem instead gives CursorWindow more
direct control over the lifetime of the shared memory region.

The provider now allocates the CursorWindows and returns them
to clients with a read-only protection bit set on the ashmem
region.

Improved the encapsulation of CursorWindow.  Callers shouldn't
need to care about details like how string fields are allocated.

Removed the compile-time configuration of string and numeric
storage modes to remove some dead weight.

Change-Id: I07c2bc2a9c573d7e435dcaecd269d25ea9807acd
diff --git a/libs/binder/CursorWindow.cpp b/libs/binder/CursorWindow.cpp
index b02374f..1b85a71 100644
--- a/libs/binder/CursorWindow.cpp
+++ b/libs/binder/CursorWindow.cpp
@@ -19,8 +19,9 @@
 
 #include <utils/Log.h>
 #include <binder/CursorWindow.h>
-#include <binder/MemoryHeapBase.h>
-#include <binder/MemoryBase.h>
+
+#include <cutils/ashmem.h>
+#include <sys/mman.h>
 
 #include <assert.h>
 #include <string.h>
@@ -28,350 +29,325 @@
 
 namespace android {
 
-CursorWindow::CursorWindow(size_t maxSize) :
-    mMaxSize(maxSize)
-{
+CursorWindow::CursorWindow(const String8& name, int ashmemFd,
+        void* data, size_t size, bool readOnly) :
+        mName(name), mAshmemFd(ashmemFd), mData(data), mSize(size), mReadOnly(readOnly) {
+    mHeader = static_cast<Header*>(mData);
 }
 
-bool CursorWindow::setMemory(const sp<IMemory>& memory)
-{
-    mMemory = memory;
-    mData = (uint8_t *) memory->pointer();
-    if (mData == NULL) {
-        return false;
-    }
-    mHeader = (window_header_t *) mData;
-
-    // Make the window read-only
-    ssize_t size = memory->size();
-    mSize = size;
-    mMaxSize = size;
-    mFreeOffset = size;
-LOG_WINDOW("Created CursorWindow from existing IMemory: mFreeOffset = %d, numRows = %d, numColumns = %d, mSize = %d, mMaxSize = %d, mData = %p", mFreeOffset, mHeader->numRows, mHeader->numColumns, mSize, mMaxSize, mData);
-    return true;
+CursorWindow::~CursorWindow() {
+    ::munmap(mData, mSize);
+    ::close(mAshmemFd);
 }
 
-bool CursorWindow::initBuffer(bool localOnly)
-{
-    //TODO Use a non-memory dealer mmap region for localOnly
+status_t CursorWindow::create(const String8& name, size_t size, bool localOnly,
+        CursorWindow** outCursorWindow) {
+    String8 ashmemName("CursorWindow: ");
+    ashmemName.append(name);
+    ashmemName.append(localOnly ? " (local)" : " (remote)");
 
-    sp<MemoryHeapBase> heap;
-    heap = new MemoryHeapBase(mMaxSize, 0, "CursorWindow");
-    if (heap != NULL) {
-        mMemory = new MemoryBase(heap, 0, mMaxSize);
-        if (mMemory != NULL) {
-            mData = (uint8_t *) mMemory->pointer();
-            if (mData) {
-                mHeader = (window_header_t *) mData;
-                mSize = mMaxSize;
-
-                // Put the window into a clean state
-                clear();
-            LOG_WINDOW("Created CursorWindow with new MemoryDealer: mFreeOffset = %d, mSize = %d, mMaxSize = %d, mData = %p", mFreeOffset, mSize, mMaxSize, mData);
-                return true;                
-            }
-        } 
-        LOGE("CursorWindow heap allocation failed");
-        return false;
+    status_t result;
+    int ashmemFd = ashmem_create_region(ashmemName.string(), size);
+    if (ashmemFd < 0) {
+        result = -errno;
     } else {
-        LOGE("failed to create the CursorWindow heap");
-        return false;
+        result = ashmem_set_prot_region(ashmemFd, PROT_READ | PROT_WRITE);
+        if (result >= 0) {
+            void* data = ::mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, ashmemFd, 0);
+            if (data == MAP_FAILED) {
+                result = -errno;
+            } else {
+                result = ashmem_set_prot_region(ashmemFd, PROT_READ);
+                if (result >= 0) {
+                    CursorWindow* window = new CursorWindow(name, ashmemFd,
+                            data, size, false /*readOnly*/);
+                    result = window->clear();
+                    if (!result) {
+                        LOG_WINDOW("Created new CursorWindow: freeOffset=%d, "
+                                "numRows=%d, numColumns=%d, mSize=%d, mData=%p",
+                                window->mHeader->freeOffset,
+                                window->mHeader->numRows,
+                                window->mHeader->numColumns,
+                                window->mSize, window->mData);
+                        *outCursorWindow = window;
+                        return OK;
+                    }
+                    delete window;
+                }
+            }
+            ::munmap(data, size);
+        }
+        ::close(ashmemFd);
     }
+    *outCursorWindow = NULL;
+    return result;
 }
 
-CursorWindow::~CursorWindow()
-{
-    // Everything that matters is a smart pointer
+status_t CursorWindow::createFromParcel(Parcel* parcel, CursorWindow** outCursorWindow) {
+    String8 name = parcel->readString8();
+
+    status_t result;
+    int ashmemFd = parcel->readFileDescriptor();
+    if (ashmemFd == int(BAD_TYPE)) {
+        result = BAD_TYPE;
+    } else {
+        ssize_t size = ashmem_get_size_region(ashmemFd);
+        if (size < 0) {
+            result = UNKNOWN_ERROR;
+        } else {
+            int dupAshmemFd = ::dup(ashmemFd);
+            if (dupAshmemFd < 0) {
+                result = -errno;
+            } else {
+                void* data = ::mmap(NULL, size, PROT_READ, MAP_SHARED, dupAshmemFd, 0);
+                if (data == MAP_FAILED) {
+                    result = -errno;
+                } else {
+                    CursorWindow* window = new CursorWindow(name, dupAshmemFd,
+                            data, size, true /*readOnly*/);
+                    LOG_WINDOW("Created CursorWindow from parcel: freeOffset=%d, "
+                            "numRows=%d, numColumns=%d, mSize=%d, mData=%p",
+                            window->mHeader->freeOffset,
+                            window->mHeader->numRows,
+                            window->mHeader->numColumns,
+                            window->mSize, window->mData);
+                    *outCursorWindow = window;
+                    return OK;
+                }
+                ::close(dupAshmemFd);
+            }
+        }
+    }
+    *outCursorWindow = NULL;
+    return result;
 }
 
-void CursorWindow::clear()
-{
+status_t CursorWindow::writeToParcel(Parcel* parcel) {
+    status_t status = parcel->writeString8(mName);
+    if (!status) {
+        status = parcel->writeDupFileDescriptor(mAshmemFd);
+    }
+    return status;
+}
+
+status_t CursorWindow::clear() {
+    if (mReadOnly) {
+        return INVALID_OPERATION;
+    }
+
+    mHeader->freeOffset = sizeof(Header) + sizeof(RowSlotChunk);
+    mHeader->firstChunkOffset = sizeof(Header);
     mHeader->numRows = 0;
     mHeader->numColumns = 0;
-    mFreeOffset = sizeof(window_header_t) + ROW_SLOT_CHUNK_SIZE;
-    // Mark the first chunk's next 'pointer' as null
-    *((uint32_t *)(mData + mFreeOffset - sizeof(uint32_t))) = 0;
+
+    RowSlotChunk* firstChunk = static_cast<RowSlotChunk*>(offsetToPtr(mHeader->firstChunkOffset));
+    firstChunk->nextChunkOffset = 0;
+    return OK;
 }
 
-int32_t CursorWindow::freeSpace()
-{
-    int32_t freeSpace = mSize - mFreeOffset;
-    if (freeSpace < 0) {
-        freeSpace = 0;
+status_t CursorWindow::setNumColumns(uint32_t numColumns) {
+    if (mReadOnly) {
+        return INVALID_OPERATION;
     }
-    return freeSpace;
+
+    uint32_t cur = mHeader->numColumns;
+    if ((cur > 0 || mHeader->numRows > 0) && cur != numColumns) {
+        LOGE("Trying to go from %d columns to %d", cur, numColumns);
+        return INVALID_OPERATION;
+    }
+    mHeader->numColumns = numColumns;
+    return OK;
 }
 
-field_slot_t * CursorWindow::allocRow()
-{
+status_t CursorWindow::allocRow() {
+    if (mReadOnly) {
+        return INVALID_OPERATION;
+    }
+
     // Fill in the row slot
-    row_slot_t * rowSlot = allocRowSlot();
+    RowSlot* rowSlot = allocRowSlot();
     if (rowSlot == NULL) {
-        return NULL;
+        return NO_MEMORY;
     }
 
     // Allocate the slots for the field directory
-    size_t fieldDirSize = mHeader->numColumns * sizeof(field_slot_t);
-    uint32_t fieldDirOffset = alloc(fieldDirSize);
+    size_t fieldDirSize = mHeader->numColumns * sizeof(FieldSlot);
+    uint32_t fieldDirOffset = alloc(fieldDirSize, true /*aligned*/);
     if (!fieldDirOffset) {
         mHeader->numRows--;
-        LOG_WINDOW("The row failed, so back out the new row accounting from allocRowSlot %d", mHeader->numRows);
-        return NULL;
+        LOG_WINDOW("The row failed, so back out the new row accounting "
+                "from allocRowSlot %d", mHeader->numRows);
+        return NO_MEMORY;
     }
-    field_slot_t * fieldDir = (field_slot_t *)offsetToPtr(fieldDirOffset);
-    memset(fieldDir, 0x0, fieldDirSize);
+    FieldSlot* fieldDir = static_cast<FieldSlot*>(offsetToPtr(fieldDirOffset));
+    memset(fieldDir, 0, fieldDirSize);
 
-LOG_WINDOW("Allocated row %u, rowSlot is at offset %u, fieldDir is %d bytes at offset %u\n", (mHeader->numRows - 1), ((uint8_t *)rowSlot) - mData, fieldDirSize, fieldDirOffset);
+    LOG_WINDOW("Allocated row %u, rowSlot is at offset %u, fieldDir is %d bytes at offset %u\n",
+            mHeader->numRows - 1, offsetFromPtr(rowSlot), fieldDirSize, fieldDirOffset);
     rowSlot->offset = fieldDirOffset;
-
-    return fieldDir;
+    return OK;
 }
 
-uint32_t CursorWindow::alloc(size_t requestedSize, bool aligned)
-{
-    int32_t size;
+status_t CursorWindow::freeLastRow() {
+    if (mReadOnly) {
+        return INVALID_OPERATION;
+    }
+
+    if (mHeader->numRows > 0) {
+        mHeader->numRows--;
+    }
+    return OK;
+}
+
+uint32_t CursorWindow::alloc(size_t size, bool aligned) {
     uint32_t padding;
     if (aligned) {
         // 4 byte alignment
-        padding = 4 - (mFreeOffset & 0x3);
+        padding = (~mHeader->freeOffset + 1) & 3;
     } else {
         padding = 0;
     }
 
-    size = requestedSize + padding;
-
-    if (size > freeSpace()) {
-        LOGV("need to grow: mSize = %d, size = %d, freeSpace() = %d, numRows = %d", mSize, size,
-                freeSpace(), mHeader->numRows);
-        // Only grow the window if the first row doesn't fit
-        if (mHeader->numRows > 1) {
-            LOGV("not growing since there are already %d row(s), max size %d", mHeader->numRows,
-                    mMaxSize);
-            return 0;
-        }
-
-        // Find a new size that will fit the allocation
-        int allocated = mSize - freeSpace();
-        int newSize = mSize + WINDOW_ALLOCATION_SIZE;
-        while (size > (newSize - allocated)) {
-            newSize += WINDOW_ALLOCATION_SIZE;
-            if (newSize > mMaxSize) {
-                LOGE("Attempting to grow window beyond max size (%d)", mMaxSize);
-                return 0;
-            }
-        }
-LOG_WINDOW("found size %d", newSize);
-        mSize = newSize;
+    uint32_t offset = mHeader->freeOffset + padding;
+    uint32_t nextFreeOffset = offset + size;
+    if (nextFreeOffset > mSize) {
+        LOGE("Window is full: requested allocation %d bytes, "
+                "free space %d bytes, window size %d bytes",
+                size, freeSpace(), mSize);
+        return 0;
     }
 
-    uint32_t offset = mFreeOffset + padding;
-    mFreeOffset += size;
+    mHeader->freeOffset = nextFreeOffset;
     return offset;
 }
 
-row_slot_t * CursorWindow::getRowSlot(int row)
-{
-    LOG_WINDOW("enter getRowSlot current row num %d, this row %d", mHeader->numRows, row);
-    int chunkNum = row / ROW_SLOT_CHUNK_NUM_ROWS;
-    int chunkPos = row % ROW_SLOT_CHUNK_NUM_ROWS;
-    int chunkPtrOffset = sizeof(window_header_t) + ROW_SLOT_CHUNK_SIZE - sizeof(uint32_t);
-    uint8_t * rowChunk = mData + sizeof(window_header_t);
-    for (int i = 0; i < chunkNum; i++) {
-        rowChunk = offsetToPtr(*((uint32_t *)(mData + chunkPtrOffset)));
-        chunkPtrOffset = rowChunk - mData + (ROW_SLOT_CHUNK_NUM_ROWS * sizeof(row_slot_t));
+CursorWindow::RowSlot* CursorWindow::getRowSlot(uint32_t row) {
+    uint32_t chunkPos = row;
+    RowSlotChunk* chunk = static_cast<RowSlotChunk*>(
+            offsetToPtr(mHeader->firstChunkOffset));
+    while (chunkPos >= ROW_SLOT_CHUNK_NUM_ROWS) {
+        chunk = static_cast<RowSlotChunk*>(offsetToPtr(chunk->nextChunkOffset));
+        chunkPos -= ROW_SLOT_CHUNK_NUM_ROWS;
     }
-    return (row_slot_t *)(rowChunk + (chunkPos * sizeof(row_slot_t)));
-    LOG_WINDOW("exit getRowSlot current row num %d, this row %d", mHeader->numRows, row);    
+    return &chunk->slots[chunkPos];
 }
 
-row_slot_t * CursorWindow::allocRowSlot()
-{
-    int chunkNum = mHeader->numRows / ROW_SLOT_CHUNK_NUM_ROWS;
-    int chunkPos = mHeader->numRows % ROW_SLOT_CHUNK_NUM_ROWS;
-    int chunkPtrOffset = sizeof(window_header_t) + ROW_SLOT_CHUNK_SIZE - sizeof(uint32_t);
-    uint8_t * rowChunk = mData + sizeof(window_header_t);
-LOG_WINDOW("Allocating row slot, mHeader->numRows is %d, chunkNum is %d, chunkPos is %d", mHeader->numRows, chunkNum, chunkPos);
-    for (int i = 0; i < chunkNum; i++) {
-        uint32_t nextChunkOffset = *((uint32_t *)(mData + chunkPtrOffset));
-LOG_WINDOW("nextChunkOffset is %d", nextChunkOffset);
-        if (nextChunkOffset == 0) {
-            // Allocate a new row chunk
-            nextChunkOffset = alloc(ROW_SLOT_CHUNK_SIZE, true);
-            if (nextChunkOffset == 0) {
+CursorWindow::RowSlot* CursorWindow::allocRowSlot() {
+    uint32_t chunkPos = mHeader->numRows;
+    RowSlotChunk* chunk = static_cast<RowSlotChunk*>(
+            offsetToPtr(mHeader->firstChunkOffset));
+    while (chunkPos > ROW_SLOT_CHUNK_NUM_ROWS) {
+        chunk = static_cast<RowSlotChunk*>(offsetToPtr(chunk->nextChunkOffset));
+        chunkPos -= ROW_SLOT_CHUNK_NUM_ROWS;
+    }
+    if (chunkPos == ROW_SLOT_CHUNK_NUM_ROWS) {
+        if (!chunk->nextChunkOffset) {
+            chunk->nextChunkOffset = alloc(sizeof(RowSlotChunk), true /*aligned*/);
+            if (!chunk->nextChunkOffset) {
                 return NULL;
             }
-            rowChunk = offsetToPtr(nextChunkOffset);
-LOG_WINDOW("allocated new chunk at %d, rowChunk = %p", nextChunkOffset, rowChunk);
-            *((uint32_t *)(mData + chunkPtrOffset)) = rowChunk - mData;
-            // Mark the new chunk's next 'pointer' as null
-            *((uint32_t *)(rowChunk + ROW_SLOT_CHUNK_SIZE - sizeof(uint32_t))) = 0;
-        } else {
-LOG_WINDOW("follwing 'pointer' to next chunk, offset of next pointer is %d", chunkPtrOffset);
-            rowChunk = offsetToPtr(nextChunkOffset);
-            chunkPtrOffset = rowChunk - mData + (ROW_SLOT_CHUNK_NUM_ROWS * sizeof(row_slot_t));
         }
+        chunk = static_cast<RowSlotChunk*>(offsetToPtr(chunk->nextChunkOffset));
+        chunk->nextChunkOffset = 0;
+        chunkPos = 0;
     }
-    mHeader->numRows++;
-
-    return (row_slot_t *)(rowChunk + (chunkPos * sizeof(row_slot_t)));
+    mHeader->numRows += 1;
+    return &chunk->slots[chunkPos];
 }
 
-field_slot_t * CursorWindow::getFieldSlotWithCheck(int row, int column)
-{
-  if (row < 0 || row >= mHeader->numRows || column < 0 || column >= mHeader->numColumns) {
-      LOGE("Failed to read row# %d, column# from a CursorWindow which has %d rows, %d columns.",
-              row, column, mHeader->numRows, mHeader->numColumns);
-      return NULL;
-  }        
-  row_slot_t * rowSlot = getRowSlot(row);
-  if (!rowSlot) {
-      LOGE("Failed to find rowSlot for row %d", row);
-      return NULL;
-  }
-  if (rowSlot->offset == 0 || rowSlot->offset >= mSize) {
-      LOGE("Invalid rowSlot, offset = %d", rowSlot->offset);
-      return NULL;
-  }  
-  int fieldDirOffset = rowSlot->offset;
-  return ((field_slot_t *)offsetToPtr(fieldDirOffset)) + column;  
+CursorWindow::FieldSlot* CursorWindow::getFieldSlot(uint32_t row, uint32_t column) {
+    if (row >= mHeader->numRows || column >= mHeader->numColumns) {
+        LOGE("Failed to read row %d, column %d from a CursorWindow which "
+                "has %d rows, %d columns.",
+                row, column, mHeader->numRows, mHeader->numColumns);
+        return NULL;
+    }
+    RowSlot* rowSlot = getRowSlot(row);
+    if (!rowSlot) {
+        LOGE("Failed to find rowSlot for row %d.", row);
+        return NULL;
+    }
+    FieldSlot* fieldDir = static_cast<FieldSlot*>(offsetToPtr(rowSlot->offset));
+    return &fieldDir[column];
 }
 
-void CursorWindow::copyIn(uint32_t offset, uint8_t const * data, size_t size)
-{
-    assert(offset + size <= mSize);    
-    memcpy(mData + offset, data, size);
+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);
 }
 
-void CursorWindow::copyIn(uint32_t offset, int64_t data)
-{
-    assert(offset + sizeof(int64_t) <= mSize);
-    memcpy(mData + offset, (uint8_t *)&data, sizeof(int64_t));
+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);
 }
 
-void CursorWindow::copyIn(uint32_t offset, double data)
-{
-    assert(offset + sizeof(double) <= mSize);
-    memcpy(mData + offset, (uint8_t *)&data, sizeof(double));
-}
+status_t CursorWindow::putBlobOrString(uint32_t row, uint32_t column,
+        const void* value, size_t size, int32_t type) {
+    if (mReadOnly) {
+        return INVALID_OPERATION;
+    }
 
-void CursorWindow::copyOut(uint32_t offset, uint8_t * data, size_t size)
-{
-    assert(offset + size <= mSize);
-    memcpy(data, mData + offset, size);
-}
-
-int64_t CursorWindow::copyOutLong(uint32_t offset)
-{
-    int64_t value;
-    assert(offset + sizeof(int64_t) <= mSize);
-    memcpy(&value, mData + offset, sizeof(int64_t));
-    return value;
-}
-
-double CursorWindow::copyOutDouble(uint32_t offset)
-{
-    double value;
-    assert(offset + sizeof(double) <= mSize);
-    memcpy(&value, mData + offset, sizeof(double));
-    return value;
-}
-
-bool CursorWindow::putLong(unsigned int row, unsigned int col, int64_t value)
-{
-    field_slot_t * fieldSlot = getFieldSlotWithCheck(row, col);
+    FieldSlot* fieldSlot = getFieldSlot(row, column);
     if (!fieldSlot) {
-        return false;
+        return BAD_VALUE;
     }
 
-#if WINDOW_STORAGE_INLINE_NUMERICS
-    fieldSlot->data.l = value;
-#else
-    int offset = alloc(sizeof(int64_t));
+    uint32_t offset = alloc(size);
     if (!offset) {
-        return false;
+        return NO_MEMORY;
     }
 
-    copyIn(offset, value);
+    memcpy(offsetToPtr(offset), value, size);
 
+    fieldSlot->type = type;
     fieldSlot->data.buffer.offset = offset;
-    fieldSlot->data.buffer.size = sizeof(int64_t);
-#endif
+    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;
-    return true;
+    fieldSlot->data.l = value;
+    return OK;
 }
 
-bool CursorWindow::putDouble(unsigned int row, unsigned int col, double value)
-{
-    field_slot_t * fieldSlot = getFieldSlotWithCheck(row, col);
+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 false;
+        return BAD_VALUE;
     }
 
-#if WINDOW_STORAGE_INLINE_NUMERICS
-    fieldSlot->data.d = value;
-#else
-    int offset = alloc(sizeof(int64_t));
-    if (!offset) {
-        return false;
-    }
-
-    copyIn(offset, value);
-
-    fieldSlot->data.buffer.offset = offset;
-    fieldSlot->data.buffer.size = sizeof(double);
-#endif
     fieldSlot->type = FIELD_TYPE_FLOAT;
-    return true;
+    fieldSlot->data.d = value;
+    return OK;
 }
 
-bool CursorWindow::putNull(unsigned int row, unsigned int col)
-{
-    field_slot_t * fieldSlot = getFieldSlotWithCheck(row, col);
+status_t CursorWindow::putNull(uint32_t row, uint32_t column) {
+    if (mReadOnly) {
+        return INVALID_OPERATION;
+    }
+
+    FieldSlot* fieldSlot = getFieldSlot(row, column);
     if (!fieldSlot) {
-        return false;
+        return BAD_VALUE;
     }
 
     fieldSlot->type = FIELD_TYPE_NULL;
     fieldSlot->data.buffer.offset = 0;
     fieldSlot->data.buffer.size = 0;
-    return true;
-}
-
-bool CursorWindow::getLong(unsigned int row, unsigned int col, int64_t * valueOut)
-{
-    field_slot_t * fieldSlot = getFieldSlotWithCheck(row, col);
-    if (!fieldSlot || fieldSlot->type != FIELD_TYPE_INTEGER) {
-        return false;
-    }
-
-    *valueOut = getFieldSlotValueLong(fieldSlot);
-    return true;
-}
-
-bool CursorWindow::getDouble(unsigned int row, unsigned int col, double * valueOut)
-{
-    field_slot_t * fieldSlot = getFieldSlotWithCheck(row, col);
-    if (!fieldSlot || fieldSlot->type != FIELD_TYPE_FLOAT) {
-        return false;
-    }
-
-    *valueOut = getFieldSlotValueDouble(fieldSlot);
-    return true;
-}
-
-bool CursorWindow::getNull(unsigned int row, unsigned int col, bool * valueOut)
-{
-    field_slot_t * fieldSlot = getFieldSlotWithCheck(row, col);
-    if (!fieldSlot) {
-        return false;
-    }
-    
-    if (fieldSlot->type != FIELD_TYPE_NULL) {
-        *valueOut = false;
-    } else {
-        *valueOut = true;
-    }
-    return true;
+    return OK;
 }
 
 }; // namespace android