#268: update json-c from 0.12 to 0.13.1

[patrikjuvonen]

GitHub issue:
Resolves #268

Summary:

• Contains performance improvements and bug fixes
• Not many changes required to our code - the following changes have been made:
  1. Removal in our code: is_error() -> a simple NULL check is the way to go now
  2. Change in our code: "Use size_t for array length and size." -> we need to change any affected parts to use unsigned ints instead of signed ints to avoid compiler warnings. In our case this only affects a couple for loops int -> uint.
  3. Change in json-c code (double precision): json-c has changed it a few times, by default it is at %.17g but we've had it at %.16g so it has to be edited (due to backwards compatibility reasons) in the source code at json_object.c:808 (issue: https://bugs.mtasa.com/view.php?id=8853) (commit: 4cc6fda)
  4. Change in json-c code (pretty mode improvements): See @qaisjp's commit here: e5b1c3f
• Couldn't find any other commits related to json-c that we should take into account: https://github.com/multitheftauto/mtasa-blue/commits/master/vendor/json-c
• It is good to update while we select and upgrade out of json-c to some other json library. The upgrade is unlikely to happen before 1.6, so it doesn't hurt to update now for whatever it's worth.
• Changelog: https://github.com/json-c/json-c/blob/master/ChangeLog
• Releases: 0.12.1, 0.13, 0.13.1

Performance test:

function doToJSONAndFromJSONTestAndPushDurationToResults(amount, times, results)
	if (not results) then
		amount = amount or 25e4
		times = times or 20
		results = {}

		print(("="):rep(62))
		print("Running toJSON + fromJSON test [" .. amount .. "] x [" .. times .. "] times.")
		print(("="):rep(62))
	end

	local startTickCount = getTickCount()
	for i = 1, amount do
		local json = toJSON({
			255,
			255,
			255,
			{
				id = 128,
				name = "test name goes here",
				available = false
			},
			nil,
			192.000000001,
			127.000000001,
			false,
			true,
			"Some text over here",
			{ 1, 2, true }
		})
		local tb = fromJSON(json)
	end
	local endTickCount = getTickCount() - startTickCount

	results[#results + 1] = endTickCount
	print("Test: [" .. #results .. "/" .. times .. "]; Duration: [" .. endTickCount .. "ms]")

	if (#results == times) then
		local totalDuration = 0

		for _, duration in pairs(results) do
			totalDuration = totalDuration + duration
		end

		print(("="):rep(62))
		print("Total duration: [" .. totalDuration .. "ms]")
		print("Average duration: [" .. totalDuration / #results .. "ms]")
		print("Tests completed: [" .. #results .. "/" .. times .. "]")
		print(("="):rep(62))
	else
		testTimer = setTimer(doToJSONAndFromJSONTestAndPushDurationToResults, 50, 1, amount, times, results)
	end
end
setTimer(doToJSONAndFromJSONTestAndPushDurationToResults, 500, 1)

Results (250,000 toJSON + fromJSON executions, 20 times):

• json-c 0.12 (MTA:SA r13816 client-side): 194195ms
• json-c 0.12 (MTA:SA r13816 server-side): 246032ms
• json-c 0.13.1 (MTA:SA 8c3cddd client-side): 179426ms (7.61% improvement)
• json-c 0.13.1 (MTA:SA 8c3cddd server-side): 210169ms (14.58% improvement)

Copy of changelog:

Build changes:
--------------

0.13.1 (up to commit 0f814e5, 2018/03/04)
=========================================

* Bump the major version of the .so library generated up to 4.0 to avoid 
  conflicts because some downstream packagers of json-c had already done
  their own bump to ".so.3" for a much older 0.12 release.
* Add const size_t json_c_object_sizeof()
* Avoid invalid free (and thus a segfault) when ref_count gets < 0
* PR#394: fix handling of custom double formats that include a ".0"
* Avoid uninitialized variable warnings in json_object_object_foreach
* Issue #396: fix build for certain uClibc based systems.
* Add a top level fuzz directory for fuzzers run by OSS-Fuzz


0.13 (up to commit 5dae561, 2017/11/29)
=================================

This release, being three and a half years after the 0.12 branch (f84d9c),
   has quite a number of changes included.  The following is a sampling of
   the most significant ones.

Since the 0.12 release, 250 issues and pull requests have been closed.
See issues_closed_for_0.13.md for a complete list.


Deprecated and removed features:
--------------------------------
* All internal use of bits.h has been eliminated.  The file will be removed.
	Do not use: hexdigit(), error_ptr(), error_descrition() and it_error() 
* lh_abort() is deprecated.  It will be removed.

Behavior changes:
-----------------
* Tighten the number parsing algorithm to raise errors instead of truncating
     the results.  For example 12.3.4 or 2015-01-15, which now return null.
	 See commit 99d8fc

* Use size_t for array length and size.  Platforms where sizeof(size_t) != sizeof(int) may not be backwards compatible
	See commits 45c56b, 92e9a5 and others.

* Check for failue when allocating memory, returning NULL and errno=ENOMEM.
	 See commit 2149a04.

* Change json_object_object_add() return type from void to int, and will return -1 on failures, instead of exiting. (Note: this is not an ABI change)

New features:
-------------
* We're aiming to follow RFC 7159 now.

* Add a couple of additional option to json_object_to_json_string_ext:
	JSON_C_TO_STRING_PRETTY_TAB
	JSON_C_TO_STRING_NOSLASHESCAPE

* Add a json_object_object_add_ex() function to allow for performance
	improvements when certain constraints are known to be true.

* Make serialization format of doubles configurable, in two different ways:
	Call json_object_set_serializer with json_object_double_to_json_string and a custom
	 format on each double object, or
	Call json_c_set_serialization_double_format() to set a global or thread-wide format.

* Add utility function for comparing json_objects - json_object_equal()

* Add a way to copy entire object trees: json_object_deep_copy()
* Add json_object_set_<type> function to modify the value of existing json_object's
 without the need to recreate them.  Also add a json_object_int_inc function to
 adjust an int's value.
* Add support for JSON pointer, RFC 6901.  See json_pointer.h
* Add a json_util_get_last_err() function to retrieve the string describing the
 cause of errors, instead of printing to stderr.
* Add perllike hash function for strings, and json_global_set_string_hash() 8f8d03d
* Add a json_c_visit() function to provide a way to iterate over a tree of json-c objects.

Notable bug fixes and other improvements:
-----------------------------------------
* Make reference increment and decrement atomic to allow passing json objects between threads.
* Fix json_object_object_foreach to avoid uninitialized variable warnings.
* Improve performance by removing unneeded data items from hashtable code and reducing duplicate hash computation.
* Improve performance by storing small strings inside json_object
* Improve performance of json_object_to_json_string by removing variadic printf. commit 9ff0f49
* Issue #371: fix parsing of "-Infinity", and avoid needlessly copying the input when doing so.
* Fix stack buffer overflow in json_object_double_to_json_string_format() - commit 2c2deb87
* Fix various potential null ptr deref and int32 overflows
* Issue #332: fix a long-standing bug in array_list_put_idx() where it would attempt to free previously free'd entries due to not checking the current array length.
* Issue #195: use uselocale() instead of setlocale() in json_tokener to behave better in threaded environments.
* Issue #275: fix out of bounds read when handling unicode surrogate pairs.
* Ensure doubles that happen to be a whole number are emitted with ".0" - commit ca7a19
* PR#331: for Visual Studio, use a snprintf/vsnprintf wrapper that ensures the string is terminated.
* Fix double to int cast overflow in json_object_get_int64.
* Clamp double to int32 when narrowing in json_object_get_int.
* Use strtoll() to parse ints - instead of sscanf
* Miscellaneous smaller changes, including removing unused variables, fixing warning
 about uninitialized variables adding const qualifiers, reformatting code, etc...

Build changes:
--------------
* Add Appveyor and Travis build support
* Switch to using CMake when building on Windows with Visual Studio.
	A dynamic .dll is generated instead of a .lib
	config.h is now generated, config.h.win32 should no longer be manually copied
* Add support for MacOS through CMake too.
* Enable silent build by default
* Link against libm when needed
* Add support for building with AddressSanitizer
* Add support for building with Clang
* Add a --enable-threading configure option, and only use the (slower) __sync_add_and_fetch()/__sync_sub_and_fetch() function when it is specified.

List of new functions added:
----------------------------
### json_object.h
* array_list_bsearch()
* array_list_del_idx()
* json_object_to_json_string_length()
* json_object_get_userdata()
* json_object_set_userdata()
* json_object_object_add_ex()
* json_object_array_bsearch()
* json_object_array_del_idx()
* json_object_set_boolean()
* json_object_set_int()
* json_object_int_inc()
* json_object_set_int64()
* json_c_set_serialization_double_format()
* json_object_double_to_json_string()
* json_object_set_double()
* json_object_set_string()
* json_object_set_string_len()
* json_object_equal()
* json_object_deep_copy()

### json_pointer.h
* json_pointer_get()
* json_pointer_getf()
* json_pointer_set()
* json_pointer_setf()

### json_util.h
* json_object_from_fd()
* json_object_to_fd()
* json_util_get_last_err()

### json_visit.h
* json_c_visit()

### linkhash.h
* json_global_set_string_hash()
* lh_table_resize()

### printbuf.h
* printbuf_strappend()


0.12.1
======

  * Minimal changes to address compile issues.

[Pirulax]

Are there any new functions at Lua side?
Or still just the good ol' to/fromJSON?

[patrikjuvonen]

No new functionality. It is just a vendor update.

[ghost]

Nice work!

[qaisjp]

👍Thank you!

• Checked this tree against 0.13.1 and it's pretty much identical except for our changes.
• Checked the current master against 0.12 and there are some other changes here and there but it should be fine.