libs/protoutil/src/ProtoOutputStream.cpp

/*
 * Copyright (C) 2017 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 "libprotoutil"

#include <android/util/protobuf.h>
#include <android/util/ProtoOutputStream.h>
#include <cutils/log.h>
#include <cstring>

namespace android {
namespace util {

/**
 * Position of the field type in a (long long) fieldId.
 */
const uint64_t FIELD_TYPE_SHIFT = 32;

/**
 * Mask for the field types stored in a fieldId.  Leaves a whole
 * byte for future expansion, even though there are currently only 17 types.
 */
const uint64_t FIELD_TYPE_MASK = 0x0ffULL << FIELD_TYPE_SHIFT;

const uint64_t FIELD_TYPE_UNKNOWN  = 0;
const uint64_t TYPE_DOUBLE         = 1ULL << FIELD_TYPE_SHIFT;   // double, exactly eight bytes on the wire.
const uint64_t TYPE_FLOAT          = 2ULL << FIELD_TYPE_SHIFT;   // float, exactly four bytes on the wire.
const uint64_t TYPE_INT64          = 3ULL << FIELD_TYPE_SHIFT;   // int64, varint on the wire.  Negative numbers
                                                                 // take 10 bytes.  Use TYPE_SINT64 if negative
                                                                 // values are likely.
const uint64_t TYPE_UINT64         = 4ULL << FIELD_TYPE_SHIFT;   // uint64, varint on the wire.
const uint64_t TYPE_INT32          = 5ULL << FIELD_TYPE_SHIFT;   // int32, varint on the wire.  Negative numbers
                                                                 // take 10 bytes.  Use TYPE_SINT32 if negative
                                                                 // values are likely.
const uint64_t TYPE_FIXED64        = 6ULL << FIELD_TYPE_SHIFT;   // uint64, exactly eight bytes on the wire.
const uint64_t TYPE_FIXED32        = 7ULL << FIELD_TYPE_SHIFT;   // uint32, exactly four bytes on the wire.
const uint64_t TYPE_BOOL           = 8ULL << FIELD_TYPE_SHIFT;   // bool, varint on the wire.
const uint64_t TYPE_STRING         = 9ULL << FIELD_TYPE_SHIFT;   // UTF-8 text.
const uint64_t TYPE_GROUP          = 10ULL << FIELD_TYPE_SHIFT;  // Tag-delimited message.  Deprecated.
const uint64_t TYPE_MESSAGE        = 11ULL << FIELD_TYPE_SHIFT;  // Length-delimited message.

const uint64_t TYPE_BYTES          = 12ULL << FIELD_TYPE_SHIFT;  // Arbitrary byte array.
const uint64_t TYPE_UINT32         = 13ULL << FIELD_TYPE_SHIFT;  // uint32, varint on the wire
const uint64_t TYPE_ENUM           = 14ULL << FIELD_TYPE_SHIFT;  // Enum, varint on the wire
const uint64_t TYPE_SFIXED32       = 15ULL << FIELD_TYPE_SHIFT;  // int32, exactly four bytes on the wire
const uint64_t TYPE_SFIXED64       = 16ULL << FIELD_TYPE_SHIFT;  // int64, exactly eight bytes on the wire
const uint64_t TYPE_SINT32         = 17ULL << FIELD_TYPE_SHIFT;  // int32, ZigZag-encoded varint on the wire
const uint64_t TYPE_SINT64         = 18ULL << FIELD_TYPE_SHIFT;  // int64, ZigZag-encoded varint on the wire

//
// FieldId flags for whether the field is single, repeated or packed.
// TODO: packed is not supported yet.
//
const uint64_t FIELD_COUNT_SHIFT = 40;
const uint64_t FIELD_COUNT_MASK = 0x0fULL << FIELD_COUNT_SHIFT;
const uint64_t FIELD_COUNT_UNKNOWN = 0;
const uint64_t FIELD_COUNT_SINGLE = 1ULL << FIELD_COUNT_SHIFT;
const uint64_t FIELD_COUNT_REPEATED = 2ULL << FIELD_COUNT_SHIFT;
const uint64_t FIELD_COUNT_PACKED = 4ULL << FIELD_COUNT_SHIFT;

ProtoOutputStream::ProtoOutputStream()
        :mBuffer(),
         mCopyBegin(0),
         mCompact(false),
         mDepth(0),
         mObjectId(0),
         mExpectedObjectToken(0LL)
{
}

ProtoOutputStream::~ProtoOutputStream()
{
}

bool
ProtoOutputStream::write(uint64_t fieldId, double val)
{
    if (mCompact) return false;
    const uint32_t id = (uint32_t)fieldId;
    switch (fieldId & FIELD_TYPE_MASK) {
        case TYPE_DOUBLE:   writeDoubleImpl(id, (double)val);           break;
        case TYPE_FLOAT:    writeFloatImpl(id, (float)val);             break;
        case TYPE_INT64:    writeInt64Impl(id, (long long)val);         break;
        case TYPE_UINT64:   writeUint64Impl(id, (uint64_t)val);         break;
        case TYPE_INT32:    writeInt32Impl(id, (int)val);               break;
        case TYPE_FIXED64:  writeFixed64Impl(id, (uint64_t)val);        break;
        case TYPE_FIXED32:  writeFixed32Impl(id, (uint32_t)val);        break;
        case TYPE_UINT32:   writeUint32Impl(id, (uint32_t)val);         break;
        case TYPE_SFIXED32: writeSFixed32Impl(id, (int)val);            break;
        case TYPE_SFIXED64: writeSFixed64Impl(id, (long long)val);      break;
        case TYPE_SINT32:   writeZigzagInt32Impl(id, (int)val);         break;
        case TYPE_SINT64:   writeZigzagInt64Impl(id, (long long)val);   break;
        default:
            ALOGW("Field type %d is not supported when writing double val.",
                    (int)((fieldId & FIELD_TYPE_MASK) >> FIELD_TYPE_SHIFT));
            return false;
    }
    return true;
}

bool
ProtoOutputStream::write(uint64_t fieldId, float val)
{
    if (mCompact) return false;
    const uint32_t id = (uint32_t)fieldId;
    switch (fieldId & FIELD_TYPE_MASK) {
        case TYPE_DOUBLE:   writeDoubleImpl(id, (double)val);           break;
        case TYPE_FLOAT:    writeFloatImpl(id, (float)val);             break;
        case TYPE_INT64:    writeInt64Impl(id, (long long)val);         break;
        case TYPE_UINT64:   writeUint64Impl(id, (uint64_t)val);         break;
        case TYPE_INT32:    writeInt32Impl(id, (int)val);               break;
        case TYPE_FIXED64:  writeFixed64Impl(id, (uint64_t)val);        break;
        case TYPE_FIXED32:  writeFixed32Impl(id, (uint32_t)val);        break;
        case TYPE_UINT32:   writeUint32Impl(id, (uint32_t)val);         break;
        case TYPE_SFIXED32: writeSFixed32Impl(id, (int)val);            break;
        case TYPE_SFIXED64: writeSFixed64Impl(id, (long long)val);      break;
        case TYPE_SINT32:   writeZigzagInt32Impl(id, (int)val);         break;
        case TYPE_SINT64:   writeZigzagInt64Impl(id, (long long)val);   break;
        default:
            ALOGW("Field type %d is not supported when writing float val.",
                    (int)((fieldId & FIELD_TYPE_MASK) >> FIELD_TYPE_SHIFT));
            return false;
    }
    return true;
}

bool
ProtoOutputStream::write(uint64_t fieldId, int val)
{
    if (mCompact) return false;
    const uint32_t id = (uint32_t)fieldId;
    switch (fieldId & FIELD_TYPE_MASK) {
        case TYPE_DOUBLE:   writeDoubleImpl(id, (double)val);           break;
        case TYPE_FLOAT:    writeFloatImpl(id, (float)val);             break;
        case TYPE_INT64:    writeInt64Impl(id, (long long)val);         break;
        case TYPE_UINT64:   writeUint64Impl(id, (uint64_t)val);         break;
        case TYPE_INT32:    writeInt32Impl(id, (int)val);               break;
        case TYPE_FIXED64:  writeFixed64Impl(id, (uint64_t)val);        break;
        case TYPE_FIXED32:  writeFixed32Impl(id, (uint32_t)val);        break;
        case TYPE_UINT32:   writeUint32Impl(id, (uint32_t)val);         break;
        case TYPE_SFIXED32: writeSFixed32Impl(id, (int)val);            break;
        case TYPE_SFIXED64: writeSFixed64Impl(id, (long long)val);      break;
        case TYPE_SINT32:   writeZigzagInt32Impl(id, (int)val);         break;
        case TYPE_SINT64:   writeZigzagInt64Impl(id, (long long)val);   break;
        case TYPE_ENUM:     writeEnumImpl(id, (int)val);                break;
        case TYPE_BOOL:     writeBoolImpl(id, val != 0);                break;
        default:
            ALOGW("Field type %d is not supported when writing int val.",
                    (int)((fieldId & FIELD_TYPE_MASK) >> FIELD_TYPE_SHIFT));
            return false;
    }
    return true;
}

bool
ProtoOutputStream::write(uint64_t fieldId, long long val)
{
    if (mCompact) return false;
    const uint32_t id = (uint32_t)fieldId;
    switch (fieldId & FIELD_TYPE_MASK) {
        case TYPE_DOUBLE:   writeDoubleImpl(id, (double)val);           break;
        case TYPE_FLOAT:    writeFloatImpl(id, (float)val);             break;
        case TYPE_INT64:    writeInt64Impl(id, (long long)val);         break;
        case TYPE_UINT64:   writeUint64Impl(id, (uint64_t)val);         break;
        case TYPE_INT32:    writeInt32Impl(id, (int)val);               break;
        case TYPE_FIXED64:  writeFixed64Impl(id, (uint64_t)val);        break;
        case TYPE_FIXED32:  writeFixed32Impl(id, (uint32_t)val);        break;
        case TYPE_UINT32:   writeUint32Impl(id, (uint32_t)val);         break;
        case TYPE_SFIXED32: writeSFixed32Impl(id, (int)val);            break;
        case TYPE_SFIXED64: writeSFixed64Impl(id, (long long)val);      break;
        case TYPE_SINT32:   writeZigzagInt32Impl(id, (int)val);         break;
        case TYPE_SINT64:   writeZigzagInt64Impl(id, (long long)val);   break;
        case TYPE_ENUM:     writeEnumImpl(id, (int)val);                break;
        case TYPE_BOOL:     writeBoolImpl(id, val != 0);                break;
        default:
            ALOGW("Field type %d is not supported when writing long long val.",
                    (int)((fieldId & FIELD_TYPE_MASK) >> FIELD_TYPE_SHIFT));
            return false;
    }
    return true;
}

bool
ProtoOutputStream::write(uint64_t fieldId, bool val)
{
    if (mCompact) return false;
    const uint32_t id = (uint32_t)fieldId;
    switch (fieldId & FIELD_TYPE_MASK) {
        case TYPE_BOOL:
            writeBoolImpl(id, val);
            return true;
        default:
            ALOGW("Field type %d is not supported when writing bool val.",
                    (int)((fieldId & FIELD_TYPE_MASK) >> FIELD_TYPE_SHIFT));
            return false;
    }
}

bool
ProtoOutputStream::write(uint64_t fieldId, string val)
{
    if (mCompact) return false;
    const uint32_t id = (uint32_t)fieldId;
    switch (fieldId & FIELD_TYPE_MASK) {
        case TYPE_STRING:
            writeUtf8StringImpl(id, val.c_str(), val.size());
            return true;
        default:
            ALOGW("Field type %d is not supported when writing string val.",
                    (int)((fieldId & FIELD_TYPE_MASK) >> FIELD_TYPE_SHIFT));
            return false;
    }
}

bool
ProtoOutputStream::write(uint64_t fieldId, const char* val, size_t size)
{
    if (mCompact) return false;
    const uint32_t id = (uint32_t)fieldId;
    switch (fieldId & FIELD_TYPE_MASK) {
        case TYPE_STRING:
        case TYPE_BYTES:
            writeUtf8StringImpl(id, val, size);
            return true;
        default:
            ALOGW("Field type %d is not supported when writing char[] val.",
                    (int)((fieldId & FIELD_TYPE_MASK) >> FIELD_TYPE_SHIFT));
            return false;
    }
}

/**
 * Make a token.
 *  Bits 61-63 - tag size (So we can go backwards later if the object had not data)
 *                - 3 bits, max value 7, max value needed 5
 *  Bit  60    - true if the object is repeated
 *  Bits 59-51 - depth (For error checking)
 *                - 9 bits, max value 512, when checking, value is masked (if we really
 *                  are more than 512 levels deep)
 *  Bits 32-50 - objectId (For error checking)
 *                - 19 bits, max value 524,288. that's a lot of objects. IDs will wrap
 *                  because of the overflow, and only the tokens are compared.
 *  Bits  0-31 - offset of the first size field in the buffer.
 */
long long
makeToken(int tagSize, bool repeated, int depth, int objectId, int sizePos) {
    return ((0x07L & (long long)tagSize) << 61)
            | (repeated ? (1LL << 60) : 0)
            | (0x01ffL & (long long)depth) << 51
            | (0x07ffffL & (long long)objectId) << 32
            | (0x0ffffffffL & (long long)sizePos);
}

/**
 * Get the encoded tag size from the token.
 */
static int getTagSizeFromToken(long long token) {
    return (int)(0x7 & (token >> 61));
}

/**
 * Get the nesting depth of startObject calls from the token.
 */
static int getDepthFromToken(long long token) {
    return (int)(0x01ff & (token >> 51));
}

/**
 * Get the location of the childRawSize (the first 32 bit size field) in this object.
 */
static int getSizePosFromToken(long long token) {
    return (int)token;
}

long long
ProtoOutputStream::start(uint64_t fieldId)
{
    if ((fieldId & FIELD_TYPE_MASK) != TYPE_MESSAGE) {
        ALOGE("Can't call start for non-message type field: 0x%llx", (long long)fieldId);
        return 0;
    }

    uint32_t id = (uint32_t)fieldId;
    mBuffer.writeHeader(id, WIRE_TYPE_LENGTH_DELIMITED);

    size_t sizePos = mBuffer.wp()->pos();

    mDepth++;
    mObjectId++;
    mBuffer.writeRawFixed64(mExpectedObjectToken); // push previous token into stack.

    mExpectedObjectToken = makeToken(get_varint_size(id),
        (bool)(fieldId & FIELD_COUNT_REPEATED), mDepth, mObjectId, sizePos);
    return mExpectedObjectToken;
}

void
ProtoOutputStream::end(long long token)
{
    if (token != mExpectedObjectToken) {
        ALOGE("Unexpected token: 0x%llx, should be 0x%llx", token, mExpectedObjectToken);
        return;
    }

    int depth = getDepthFromToken(token);
    if (depth != (mDepth & 0x01ff)) {
        ALOGE("Unexpected depth: %d, should be %d", depth, mDepth);
        return;
    }
    mDepth--;

    int sizePos = getSizePosFromToken(token);
    // number of bytes written in this start-end session.
    int childRawSize = mBuffer.wp()->pos() - sizePos - 8;

    // retrieve the old token from stack.
    mBuffer.ep()->rewind()->move(sizePos);
    mExpectedObjectToken = mBuffer.readRawFixed64();

    // If raw size is larger than 0, write the negative value here to indicate a compact is needed.
    if (childRawSize > 0) {
        mBuffer.editRawFixed32(sizePos, -childRawSize);
        mBuffer.editRawFixed32(sizePos+4, -1);
    } else {
        // reset wp which erase the header tag of the message when its size is 0.
        mBuffer.wp()->rewind()->move(sizePos - getTagSizeFromToken(token));
    }
}

bool
ProtoOutputStream::compact() {
    if (mCompact) return true;
    if (mDepth != 0) {
        ALOGE("Can't compact when depth(%d) is not zero. Missing calls to end.", mDepth);
        return false;
    }
    // record the size of the original buffer.
    size_t rawBufferSize = mBuffer.size();
    if (rawBufferSize == 0) return true; // nothing to do if the buffer is empty;

    // reset edit pointer and recursively compute encoded size of messages.
    mBuffer.ep()->rewind();
    if (editEncodedSize(rawBufferSize) == 0) {
        ALOGE("Failed to editEncodedSize.");
        return false;
    }

    // reset both edit pointer and write pointer, and compact recursively.
    mBuffer.ep()->rewind();
    mBuffer.wp()->rewind();
    if (!compactSize(rawBufferSize)) {
        ALOGE("Failed to compactSize.");
        return false;
    }
    // copy the reset to the buffer.
    if (mCopyBegin < rawBufferSize) {
        mBuffer.copy(mCopyBegin, rawBufferSize - mCopyBegin);
    }

    // mark true means it is not legal to write to this ProtoOutputStream anymore
    mCompact = true;
    return true;
}

/**
 * First compaction pass.  Iterate through the data, and fill in the
 * nested object sizes so the next pass can compact them.
 */
size_t
ProtoOutputStream::editEncodedSize(size_t rawSize)
{
    size_t objectStart = mBuffer.ep()->pos();
    size_t objectEnd = objectStart + rawSize;
    size_t encodedSize = 0;
    int childRawSize, childEncodedSize;
    size_t childEncodedSizePos;

    while (mBuffer.ep()->pos() < objectEnd) {
        uint32_t tag = (uint32_t)mBuffer.readRawVarint();
        encodedSize += get_varint_size(tag);
        switch (read_wire_type(tag)) {
            case WIRE_TYPE_VARINT:
                do {
                    encodedSize++;
                } while ((mBuffer.readRawByte() & 0x80) != 0);
                break;
            case WIRE_TYPE_FIXED64:
                encodedSize += 8;
                mBuffer.ep()->move(8);
                break;
            case WIRE_TYPE_LENGTH_DELIMITED:
                childRawSize = (int)mBuffer.readRawFixed32();
                childEncodedSizePos = mBuffer.ep()->pos();
                childEncodedSize = (int)mBuffer.readRawFixed32();
                if (childRawSize >= 0 && childRawSize == childEncodedSize) {
                    mBuffer.ep()->move(childRawSize);
                } else if (childRawSize < 0 && childEncodedSize == -1){
                    childEncodedSize = editEncodedSize(-childRawSize);
                    mBuffer.editRawFixed32(childEncodedSizePos, childEncodedSize);
                } else {
                    ALOGE("Bad raw or encoded values: raw=%d, encoded=%d at %zu",
                            childRawSize, childEncodedSize, childEncodedSizePos);
                    return 0;
                }
                encodedSize += get_varint_size(childEncodedSize) + childEncodedSize;
                break;
            case WIRE_TYPE_FIXED32:
                encodedSize += 4;
                mBuffer.ep()->move(4);
                break;
            default:
                ALOGE("Unexpected wire type %d in editEncodedSize at [%zu, %zu]",
                        read_wire_type(tag), objectStart, objectEnd);
                return 0;
        }
    }
    return encodedSize;
}

/**
 * Second compaction pass.  Iterate through the data, and copy the data
 * forward in the buffer, converting the pairs of uint32s into a single
 * unsigned varint of the size.
 */
bool
ProtoOutputStream::compactSize(size_t rawSize)
{
    size_t objectStart = mBuffer.ep()->pos();
    size_t objectEnd = objectStart + rawSize;
    int childRawSize, childEncodedSize;

    while (mBuffer.ep()->pos() < objectEnd) {
        uint32_t tag = (uint32_t)mBuffer.readRawVarint();
        switch (read_wire_type(tag)) {
            case WIRE_TYPE_VARINT:
                while ((mBuffer.readRawByte() & 0x80) != 0) {}
                break;
            case WIRE_TYPE_FIXED64:
                mBuffer.ep()->move(8);
                break;
            case WIRE_TYPE_LENGTH_DELIMITED:
                mBuffer.copy(mCopyBegin, mBuffer.ep()->pos() - mCopyBegin);

                childRawSize = (int)mBuffer.readRawFixed32();
                childEncodedSize = (int)mBuffer.readRawFixed32();
                mCopyBegin = mBuffer.ep()->pos();

                // write encoded size to buffer.
                mBuffer.writeRawVarint32(childEncodedSize);
                if (childRawSize >= 0 && childRawSize == childEncodedSize) {
                    mBuffer.ep()->move(childEncodedSize);
                } else if (childRawSize < 0){
                    if (!compactSize(-childRawSize)) return false;
                } else {
                    ALOGE("Bad raw or encoded values: raw=%d, encoded=%d",
                            childRawSize, childEncodedSize);
                    return false;
                }
                break;
            case WIRE_TYPE_FIXED32:
                mBuffer.ep()->move(4);
                break;
            default:
                ALOGE("Unexpected wire type %d in compactSize at [%zu, %zu]",
                        read_wire_type(tag), objectStart, objectEnd);
                return false;
        }
    }
    return true;
}

size_t
ProtoOutputStream::size()
{
    compact();
    return mBuffer.size();
}

static bool write_all(int fd, uint8_t const* buf, size_t size)
{
    while (size > 0) {
        ssize_t amt = ::write(fd, buf, size);
        if (amt < 0) {
            return false;
        }
        size -= amt;
        buf += amt;
    }
    return true;
}

bool
ProtoOutputStream::flush(int fd)
{
    if (fd < 0) return false;
    if (!compact()) return false;

    EncodedBuffer::iterator it = mBuffer.begin();
    while (it.readBuffer() != NULL) {
        if (!write_all(fd, it.readBuffer(), it.currentToRead())) return false;
        it.rp()->move(it.currentToRead());
    }
    return true;
}

EncodedBuffer::iterator
ProtoOutputStream::data()
{
    compact();
    return mBuffer.begin();
}

void
ProtoOutputStream::writeRawVarint(uint64_t varint)
{
    mBuffer.writeRawVarint64(varint);
}

void
ProtoOutputStream::writeLengthDelimitedHeader(uint32_t id, size_t size)
{
    mBuffer.writeHeader(id, WIRE_TYPE_LENGTH_DELIMITED);
    // reserves 64 bits for length delimited fields, if first field is negative, compact it.
    mBuffer.writeRawFixed32(size);
    mBuffer.writeRawFixed32(size);
}

void
ProtoOutputStream::writeRawByte(uint8_t byte)
{
    mBuffer.writeRawByte(byte);
}


// =========================================================================
// Private functions

/**
 * bit_cast
 */
template <class From, class To>
inline To bit_cast(From const &from) {
    To to;
    memcpy(&to, &from, sizeof(to));
    return to;
}

inline void
ProtoOutputStream::writeDoubleImpl(uint32_t id, double val)
{
    if (val == 0.0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_FIXED64);
    mBuffer.writeRawFixed64(bit_cast<double, uint64_t>(val));
}

inline void
ProtoOutputStream::writeFloatImpl(uint32_t id, float val)
{
    if (val == 0.0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_FIXED32);
    mBuffer.writeRawFixed32(bit_cast<float, uint32_t>(val));
}

inline void
ProtoOutputStream::writeInt64Impl(uint32_t id, long long val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_VARINT);
    mBuffer.writeRawVarint64((uint64_t)val);
}

inline void
ProtoOutputStream::writeInt32Impl(uint32_t id, int val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_VARINT);
    mBuffer.writeRawVarint32((uint32_t)val);
}

inline void
ProtoOutputStream::writeUint64Impl(uint32_t id, uint64_t val)
{
   if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_VARINT);
    mBuffer.writeRawVarint64(val);
}

inline void
ProtoOutputStream::writeUint32Impl(uint32_t id, uint32_t val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_VARINT);
    mBuffer.writeRawVarint32(val);
}

inline void
ProtoOutputStream::writeFixed64Impl(uint32_t id, uint64_t val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_FIXED64);
    mBuffer.writeRawFixed64(val);
}

inline void
ProtoOutputStream::writeFixed32Impl(uint32_t id, uint32_t val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_FIXED32);
    mBuffer.writeRawFixed32(val);
}

inline void
ProtoOutputStream::writeSFixed64Impl(uint32_t id, long long val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_FIXED64);
    mBuffer.writeRawFixed64((uint64_t)val);
}

inline void
ProtoOutputStream::writeSFixed32Impl(uint32_t id, int val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_FIXED32);
    mBuffer.writeRawFixed32((uint32_t)val);
}

inline void
ProtoOutputStream::writeZigzagInt64Impl(uint32_t id, long long val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_VARINT);
    mBuffer.writeRawVarint64((val << 1) ^ (val >> 63));
}

inline void
ProtoOutputStream::writeZigzagInt32Impl(uint32_t id, int val)
{
    if (val == 0) return;
    mBuffer.writeHeader(id, WIRE_TYPE_VARINT);
    mBuffer.writeRawVarint32((val << 1) ^ (val >> 31));
}

inline void
ProtoOutputStream::writeEnumImpl(uint32_t id, int val)
{
    mBuffer.writeHeader(id, WIRE_TYPE_VARINT);
    mBuffer.writeRawVarint32((uint32_t) val);
}

inline void
ProtoOutputStream::writeBoolImpl(uint32_t id, bool val)
{
    if (!val) return;
    mBuffer.writeHeader(id, WIRE_TYPE_VARINT);
    mBuffer.writeRawVarint32(val ? 1 : 0);
}

inline void
ProtoOutputStream::writeUtf8StringImpl(uint32_t id, const char* val, size_t size)
{
    if (val == NULL || size == 0) return;
    writeLengthDelimitedHeader(id, size);
    for (size_t i=0; i<size; i++) {
        mBuffer.writeRawByte((uint8_t)val[i]);
    }
}

} // util
} // android