Blob.cpp

/*
 * MIT License
 *
 * Copyright (c) 2025 Adriano dos Santos Fernandes
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to do so, subject to the
 * following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
 
#include "Blob.h"
#include "Attachment.h"
#include "Client.h"
#include "Transaction.h"
#include "firebird/impl/inf_pub.h"
#include <cstdint>
#include <cstring>
#include <limits>
#include <vector>
 
using namespace fbcpp;
using namespace fbcpp::impl;
 
Blob::Blob(Attachment& attachment, Transaction& transaction, const BlobOptions& options)
    : attachment{attachment},
      transaction{transaction},
      statusWrapper{attachment.getClient()}
{
    assert(attachment.isValid());
    assert(transaction.isValid());
 
    const auto preparedBpb = prepareBpb(options);
 
    handle.reset(attachment.getHandle()->createBlob(&statusWrapper, transaction.getHandle().get(), &id.id,
        static_cast<unsigned>(preparedBpb.size()), preparedBpb.data()));
}
 
Blob::Blob(Attachment& attachment, Transaction& transaction, const BlobId& blobId, const BlobOptions& options)
    : attachment{attachment},
      transaction{transaction},
      id{blobId},
      statusWrapper{attachment.getClient()}
{
    assert(attachment.isValid());
    assert(transaction.isValid());
 
    const auto preparedBpb = prepareBpb(options);
 
    handle.reset(attachment.getHandle()->openBlob(&statusWrapper, transaction.getHandle().get(), &id.id,
        static_cast<unsigned>(preparedBpb.size()), preparedBpb.data()));
}
 
std::vector<std::uint8_t> Blob::prepareBpb(const BlobOptions& options)
{
    // IXpbBuilder::BPB only exists since Firebird 4, so the BPB is built by hand to work with Firebird 3 clients.
 
    const auto& userBpb = options.getBpb();
    std::vector<std::uint8_t> bpb(userBpb.begin(), userBpb.end());
 
    const auto addInt = [&](std::uint8_t tag, int value)
    {
        if (bpb.empty())
            bpb.push_back(isc_bpb_version1);
 
        const auto unsignedValue = static_cast<unsigned>(value);
 
        bpb.push_back(tag);
        bpb.push_back(4u);
 
        for (unsigned shift = 0u; shift < 32u; shift += 8u)
            bpb.push_back(static_cast<std::uint8_t>((unsignedValue >> shift) & 0xFFu));
    };
 
    if (const auto type = options.getType(); type.has_value())
        addInt(isc_bpb_type, static_cast<int>(type.value()));
 
    if (const auto sourceType = options.getSourceType(); sourceType.has_value())
        addInt(isc_bpb_source_type, static_cast<int>(sourceType.value()));
 
    if (const auto targetType = options.getTargetType(); targetType.has_value())
        addInt(isc_bpb_target_type, static_cast<int>(targetType.value()));
 
    if (const auto sourceCharSet = options.getSourceCharSet(); sourceCharSet.has_value())
        addInt(isc_bpb_source_interp, static_cast<int>(sourceCharSet.value()));
 
    if (const auto targetCharSet = options.getTargetCharSet(); targetCharSet.has_value())
        addInt(isc_bpb_target_interp, static_cast<int>(targetCharSet.value()));
 
    if (const auto storage = options.getStorage(); storage.has_value())
        addInt(isc_bpb_storage, static_cast<int>(storage.value()));
 
    return bpb;
}
 
unsigned Blob::getLength()
{
    assert(isValid());
 
    const std::uint8_t items[] = {isc_info_blob_total_length};
    std::uint8_t buffer[16]{};
 
    handle->getInfo(&statusWrapper, sizeof(items), items, sizeof(buffer), buffer);
 
    const auto* ptr = buffer;
    const auto* end = buffer + sizeof(buffer);
 
    while (ptr < end)
    {
        const auto item = *ptr++;
 
        if (item == isc_info_end)
            break;
 
        if (item == isc_info_truncated)
            throw FbCppException("Blob::getLength truncated response");
 
        if (item == isc_info_error)
            throw FbCppException("Blob::getLength error response");
 
        if (ptr + 2 > end)
            throw FbCppException("Blob::getLength malformed response");
 
        const auto itemLength = static_cast<std::uint16_t>((ptr[0]) | (ptr[1] << 8));
        ptr += 2;
 
        if (ptr + itemLength > end)
            throw FbCppException("Blob::getLength invalid length");
 
        if (item == isc_info_blob_total_length)
        {
            unsigned result = 0;
 
            for (std::uint16_t i = 0; i < itemLength; ++i)
                result |= static_cast<unsigned>(ptr[i]) << (8u * i);
 
            return result;
        }
 
        ptr += itemLength;
    }
 
    throw FbCppException("Blob::getLength value not found");
}
 
unsigned Blob::read(std::span<std::byte> buffer)
{
    assert(isValid());
 
    unsigned totalRead = 0;
    const unsigned maxChunkSize = std::numeric_limits<std::uint16_t>::max();
 
    while (!buffer.empty())
    {
        const auto chunkSize = buffer.size() < maxChunkSize ? buffer.size() : maxChunkSize;
        const auto chunk = buffer.first(chunkSize);
        const auto readNow = readSegment(chunk);
 
        if (readNow == 0)
            break;
 
        totalRead += readNow;
        buffer = buffer.subspan(readNow);
    }
 
    return totalRead;
}
 
unsigned Blob::readSegment(std::span<std::byte> buffer)
{
    assert(isValid());
 
    if (buffer.empty())
        return 0;
 
    unsigned segmentLength = 0;
    const auto result =
        handle->getSegment(&statusWrapper, static_cast<unsigned>(buffer.size()), buffer.data(), &segmentLength);
 
    switch (result)
    {
        case fb::IStatus::RESULT_OK:
        case fb::IStatus::RESULT_SEGMENT:
            return segmentLength;
 
        case fb::IStatus::RESULT_NO_DATA:
            return 0;
 
        default:
            return 0;
    }
}
 
void Blob::write(std::span<const std::byte> buffer)
{
    assert(isValid());
 
    const unsigned maxChunkSize = std::numeric_limits<std::uint16_t>::max();
 
    while (!buffer.empty())
    {
        const auto chunkSize = buffer.size() < maxChunkSize ? buffer.size() : maxChunkSize;
        const auto chunk = buffer.first(chunkSize);
        writeSegment(chunk);
        buffer = buffer.subspan(chunkSize);
    }
}
 
void Blob::writeSegment(std::span<const std::byte> buffer)
{
    assert(isValid());
 
    if (buffer.empty())
        return;
 
    if (buffer.size() > std::numeric_limits<unsigned>::max())
        throw FbCppException("Segment too large");
 
    handle->putSegment(&statusWrapper, static_cast<unsigned>(buffer.size()), buffer.data());
}
 
int Blob::seek(BlobSeekMode mode, int offset)
{
    assert(isValid());
    return handle->seek(&statusWrapper, static_cast<int>(mode), offset);
}
 
void Blob::cancel()
{
    assert(isValid());
 
    handle->cancel(&statusWrapper);
    handle.release();
}
 
void Blob::close()
{
    assert(isValid());
 
    handle->close(&statusWrapper);
    handle.release();
}