Add optional compile-time depth limit for reader

[akx]

Idea based on the patch in orjson.

When no limit is compiled in, there is no performance impact.

I didn't add a test case (seemed pretty hairy to do so while keeping the rest of the tests intact, but let me know if there's a neat way to do that), but there's an "experiment" file you can run:

Use e.g.

cmake -B cmake-build-limit . -D YYJSON_BUILD_MISC=true -D YYJSON_BUILD_TESTS=false -D YYJSON_READER_DEPTH_LIMIT=50
cmake --build cmake-build-limit
./cmake-build-limit/experiment_depth_limit

to see this in action:

Parsing: [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[8]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]], depth limit = 50
=> Error code: 15
Parsing: {"a":{"b":{"c":{"d":{"e":{"f":{"g":{"h":{"i":{"j":{"k":{"l":{"m":{"n":{"o":{"p":{"q":{"r":{"s":{"t":{"u":{"v":{"w":{"x":{"y":{"z":{"a":{"b":{"c":{"d":{"e":{"f":{"g":{"h":{"i":{"j":{"k":{"l":{"m":{"n":{"o":{"p":{"q":{"r":{"s":{"t":{"u":{"v":{"w":{"x":{"y":8}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}, depth limit = 50
=> Error code: 15

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.34%. Comparing base (351b5d7) to head (395e0f2).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
src/yyjson.c	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #235      +/-   ##
==========================================
- Coverage   98.53%   98.34%   -0.20%     
==========================================
  Files           2        2              
  Lines        9098     9102       +4     
==========================================
- Hits         8965     8951      -14     
- Misses        133      151      +18     

Flag	Coverage Δ
unittests	98.34% <0.00%> (-0.20%)	⬇️

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[akx]

windows_msvc seems to be complaining about "warning C4702: unreachable code"... I guess that'd be the bail-out goto targets that can't be reached unless a limit is compiled in. Should I make the warning be ignored for those lines, or those goto targets also be conditionally compiled in?

[ibireme]

windows_msvc seems to be complaining about "warning C4702: unreachable code"... I guess that'd be the bail-out goto targets that can't be reached unless a limit is compiled in. Should I make the warning be ignored for those lines, or those goto targets also be conditionally compiled in?

Since we already have several warning suppressions, I'm okay with using #pragma warning(disable:4702) for this.

[akx]

Since we already have several warning suppressions, I'm okay with using #pragma warning(disable:4702) for this.

Alright. Would you prefer warning(push)/warning(disable:4702)/warning(pop) around the 4 bail-out sections, or globally in the file?

[ibireme]

Could add here globally:

yyjson/src/yyjson.c

Lines 44 to 50 in 351b5d7

	#elif defined(_MSC_VER)
	# pragma warning(disable:4100) /* unreferenced formal parameter */
	# pragma warning(disable:4101) /* unreferenced variable */
	# pragma warning(disable:4102) /* unreferenced label */
	# pragma warning(disable:4127) /* conditional expression is constant */
	# pragma warning(disable:4706) /* assignment within conditional expression */
	#endif

[akx]

Added the pragma – sorry for the delay, didn't get a notification of your reply.