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/*
* Copyright (C) 2026 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <wtf/Compiler.h>
#include <wtf/Platform.h>
#if ENABLE(WEBASSEMBLY)
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
#include <array>
#include <wtf/text/WTFString.h>
namespace JSC {
namespace Wasm {
// FIXME: This parser has no WebAssembly-specific dependencies and could potentially be moved to WTF
// if other subsystems need GDB protocol support. Note: This is a simplified implementation that
// doesn't support escape sequences ('}' character) or run-length encoding ('*' character). This is
// sufficient for typical LLDB/WASM debugger communication where all data is hex-encoded, but may
// not handle all possible GDB protocol packets.
// GDB Remote Serial Protocol packet parser
// Implements byte-by-byte state machine parsing for packets of the form: $<data>#<checksum>
// Also handles special interrupt character (0x03 / Ctrl+C)
class JS_EXPORT_PRIVATE GDBPacketParser {
public:
enum class ParseResult : uint8_t {
Incomplete, // Continue accumulating bytes
CompletePacket, // Full packet received and validated (includes interrupt 0x03)
Error, // Parse error - check getError() for details
};
enum class ErrorReason : uint8_t {
None,
BufferOverflow,
InvalidHexInChecksum,
ChecksumMismatch,
};
GDBPacketParser() = default;
ParseResult processByte(uint8_t byte);
StringView getCompletedPacket() const;
void reset();
bool isIdle() const { return m_phase == ReceivePhase::Idle; }
ErrorReason getError() const { return m_errorReason; }
void dump(PrintStream&) const;
static void dumpBuffer(std::span<const uint8_t> buffer);
private:
enum class ReceivePhase : uint8_t {
Idle, // Waiting for '$' or interrupt (0x03)
Payload, // Reading packet content until '#'
Checksum, // Reading 2-byte checksum
};
enum class IncludeInChecksum : bool { No, Yes };
static constexpr size_t bufferSize = 4096;
template<IncludeInChecksum includeInChecksum = IncludeInChecksum::No>
bool pushByte(uint8_t byte)
{
if (m_bufferIndex >= bufferSize) {
m_errorReason = ErrorReason::BufferOverflow;
return false;
}
m_buffer[m_bufferIndex++] = byte;
if constexpr (includeInChecksum == IncludeInChecksum::Yes)
m_checksum += byte;
return true;
}
std::array<uint8_t, bufferSize> m_buffer;
size_t m_bufferIndex { 0 };
uint8_t m_checksum { 0 };
ReceivePhase m_phase { ReceivePhase::Idle };
uint8_t m_checksumBytesRead { 0 };
ErrorReason m_errorReason { ErrorReason::None };
};
} // namespace Wasm
} // namespace JSC
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
#endif // ENABLE(WEBASSEMBLY)
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