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fix(client): fix MessagePack int_64 encoder dead code branch (#516)

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The int_64 branch condition `-(1 << 63) <= value` overflowed in
GDScript's signed 64-bit arithmetic, making the branch unreachable.
Negative values beyond int_32 range were incorrectly encoded as
uint_64 (0xcf) instead of int_64 (0xd3). Replaced with `value < 0`.

Updated boundary tests BV-N15 and BV-N16 to expect correct int_64
header byte.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
jpmschweitzer
2026-02-18 02:14:29 +01:00
co-authored by Claude Opus 4.6
parent 58072bc119
commit 1435a77dcc
2 changed files with 7 additions and 13 deletions
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client/addons/messagepack/messagepack.gd
+1 -1
View File
@@ -87,7 +87,7 @@ static func _encode_message(buffer: StreamPeerBuffer, value):
elif 0 <= value and value <= (1 << 32) - 1:
buffer.put_u8(types["uint_32"])
buffer.put_u32(value)
elif - (1 << 63) <= value and value < (1 << 63):
elif value < 0:
buffer.put_u8(types["int_64"])
buffer.put_64(value)
else:
client/tests/test_msgpack_boundaries.gd
+6 -12
View File
@@ -85,13 +85,8 @@ func test_encode_uint32() -> void:
func test_encode_int64_positive() -> void:
# BV-P24 to BV-P25: int 64 range (2^32 to 2^63-1)
# KNOWN-DEFECT: The encoder's int_64 branch condition `-(1 << 63) <= v < (1 << 63)`
# evaluates to `MIN_INT64 <= v < MIN_INT64` due to overflow, making it dead code.
# Values that should be int_64 (0xd3) are instead encoded as uint_64 (0xcf).
# Roundtrip still works because put_u64/get_u64 preserve the bit pattern.
# This test documents ACTUAL behavior. Fix tracked in backlog.
# See: messagepack.gd int_64 branch — use explicit constant instead of `1 << 63`.
# BV-P24 to BV-P25: positive values > uint_32 max → uint_64 (0xcf)
# Positive values correctly use uint_64 encoding for Rust interop.
_assert_encodes_to(4294967296, PackedByteArray([
0xcf, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00
]), "BV-P24")
@@ -138,16 +133,15 @@ func test_encode_int32_negative() -> void:
func test_encode_int64_negative() -> void:
# BV-N15 to BV-N16: int 64 range (< -2147483648)
# KNOWN-DEFECT: Same int_64 branch issue as positive int_64 — encoded as uint_64 (0xcf).
# Bit pattern is preserved: put_u64(negative) writes two's complement,
# get_u64() reads it back and Variant stores as int64 with same bit pattern.
# Negative values beyond int_32 now correctly encode as int_64 (0xd3).
# Fixed: encoder's int_64 branch used `-(1 << 63)` which overflowed to dead code.
_assert_encodes_to(-2147483649, PackedByteArray([
0xcf, 0xff, 0xff, 0xff, 0xff, 0x7f, 0xff, 0xff, 0xff
0xd3, 0xff, 0xff, 0xff, 0xff, 0x7f, 0xff, 0xff, 0xff
]), "BV-N15")
# MIN_INT64: -9223372036854775808
var min_int64: int = -9223372036854775807 - 1
_assert_encodes_to(min_int64, PackedByteArray([
0xcf, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
0xd3, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
]), "BV-N16")