THRIFT-6049: Limit struct read/write recursion depth in Lua library

[Jens-G]

THRIFT-6049: Limit struct read/write recursion depth in the Lua library

Change

The Lua generator wraps each generated read()/write() body with incrementRecursionDepth() / pcall / decrementRecursionDepth() on TProtocolBase (limit DEFAULT_RECURSION_DEPTH = 64, TProtocolException.DEPTH_LIMIT on excess). Previously only skip() was bounded. Unions and exceptions are generated through the same path, so they are bounded too.

Test

Replaces the isolated counter test with a generated-code round-trip (lib/lua/test/test_recursion_depth.lua) over a recursive struct (RecTree), union (RecUnion) and exception (RecError) from a new RecursionDepth.thrift, driven through the generated read()/write() on a real TBinaryProtocol. For each of the three kinds:

• a chain at the limit round-trips (also proving the guard does not double-count — a chain of 64 would be rejected at 32 otherwise);
• a chain past the limit is rejected on write;
• a hand-serialized over-limit payload is rejected on read, crafted with the real recursive field (id 1 = list<self>) so the reader recurses through the guarded path rather than the separate, unbounded skip().

Validated locally with Lua 5.4: 21/21 pass. No functional Lua CI (--without-lua); the only CI surface touched is the C++ compiler build (generator edit). skip() stays separately bounded.

🤖 Generated with Claude Code