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json-c v0.15 Release Notes

Release Date: 2020-07-26 // almost 2 years ago

  • 🚚 Deprecated and removed features:

    • Deprecate array_list_new() in favor of array_list_new2()
    • Remove the THIS_FUNCTION_IS_DEPRECATED define.
    • ✂ Remove config.h.win32

    🆕 New features

    • Add a JSON_TOKENER_ALLOW_TRAILING_CHARS flag to allow multiple objects to be parsed even when JSON_TOKENER_STRICT is set.
    • Add json_object_new_array_ext(int) and array_list_new_2(int) to allow arrays to be allocated with the exact size needed, when known.
    • Add json_object_array_shrink() (and array_list_shrink()) and use it in json_tokener to minimize the amount of memory used.
    • ➕ Add a json_parse binary, for use in testing changes (not installed, but available in the apps directory).

    🏗 Build changes

    • #639/#621 - Add symbol versions to all exported symbols
    • #508/#634 - Always enable -fPIC to allow use of the json-c static library in other libraries
    • 🏗 Build both static and shared libraries at the same time.
    • ⏪ #626 - Restore compatibility with cmake 2.8
    • #471 - Always create directories with mode 0755, regardless of umask.
    • 👍 #606/#604 - Improve support for OSes like AIX and IBM i, as well as for MINGW32 and old versions of MSVC
    • #451/#617 - Add a DISABLE_THREAD_LOCAL_STORAGE cmake option to disable the use of thread-local storage.

    🛠 Significant changes and bug fixes

    • Split the internal json_object structure into several sub-types, one for each json_type (json_object_object, json_object_string, etc...). This improves memory usage and speed, with the benchmark under bench/ report 5.8% faster test time and 6%(max RSS)-12%(peak heap) less memory usage. Memory used just for json_object structures decreased 27%, so use cases with fewer arrays and/or strings would benefit more.
    • Minimize memory usage in array handling in json_tokener by shrinking arrays to the exact number of elements parsed. On bench/ benchmark: 9% faster test time, 39%(max RSS)-50%(peak heap) less memory usage. Add json_object_array_shrink() and array_list_shrink() functions.
    • 📜 #616 - Parsing of surrogate pairs in unicode escapes now properly handles incremental parsing.
    • 🛠 Fix incremental parsing of numbers, especially those with exponents, e.g. so parsing "[0", "e+", "-]" now properly returns an error. Strict mode now rejects missing exponents ("0e").
    • Successfully return number objects at the top level even when they are followed by a "-", "." or "e". This makes parsing things like "123-45" behave consistently with things like "123xyz".

    Other changes

    • #589 - Detect broken RDRAND during initialization; also, fix segfault in the CPUID check.
    • ⏪ #592 - Fix integer overflows to prevert out of bounds write on large input.
    • Protect against division by zero in linkhash, when creaed with zero size.
    • 📜 #602 - Fix json_parse_uint64() internal error checking, leaving the retval untouched in more failure cases.
    • #614 - Prevent truncation when custom double formatters insert extra \0's

Previous changes from v0.14

  • 🚚 Deprecated and removed features:

    • 🚚 bits.h has been removed
    • 🚚 lh_abort() has been removed
    • lh_table_lookup() has been removed, use lh_table_lookup_ex() instead.
    • ✂ Remove TRUE and FALSE defines, use 1 and 0 instead.

    🏗 Build changes:

    🚚 Deprecated and removed features:

    • 🚚 bits.h has been removed
    • 🚚 lh_abort() has been removed
    • lh_table_lookup() has been removed, use lh_table_lookup_ex() instead.
    • ✂ Remove TRUE and FALSE defines, use 1 and 0 instead.
    • 👀 autoconf support, including autogen.sh, has been removed. See details about cmake, below.
    • With the addition of json_tokener_get_parse_end(), access to internal fields of json_tokener, as well as use of many other symbols and types in json_tokener.h, is deprecated now.
    • 🏗 The use of Android.configure.mk to build for Android no longer works, and it is unknown how (or if) the new cmake-based build machinery can be used.
      • Reports of success, or pull requests to correct issues are welcome.

    Notable improvements and new features

    📚 Builds and documentation

    • 🏗 Build machinery has been switched to CMake. See README.md for details about how to build.
      • TL;DR: mkdir build ; cd build ; cmake -DCMAKE_INSTALL_PREFIX=/some/path ../json-c ; make all test install
      • To ease the transition, there is a cmake-configure wrapper that emulates the old autoconf-based configure script.
      • This has enabled improvements to the build on Windows system; also all public functions have been fixed to be properly exported. For best results, use Visual Studio 2015 or newer.
    • 💅 The json-c style guide has been updated to specify the use of clang-format, and all code has been reformatted.
      • Since many lines of code have trivial changes now, when using git blame, be sure to specify -w
    • 📚 Numerous improvements have been made to the documentation including function effects on refcounts, when passing a NULL is safe, and so on.

    json_tokener changes

    • Added a json_tokener_get_parse_end() function to replace direct access of tok->char_offset.
      • The char_offset field, and the rest of the json_tokener structure remain exposed for now, but expect a future release to hide it like is done with json_object_private.h
    • json_tokener_parse_ex() now accepts a new JSON_TOKENER_VALIDATE_UTF8 flag to validate that input is UTF8.
      • If validation fails, json_tokener_get_error(tok) will return json_tokener_error_parse_utf8_string (see enum json_tokener_error).

    Other changes and additions

    • ➕ Add support for unsigned 64-bit integers, uint64_t, to gain one extra bit of magnitude for positive ints.
      • json_tokener will now parse values up to UINT64_MAX (18446744073709551615)
      • Existing methods returning int32_t or int64_t will cap out-of-range values at INT32_MAX or INT64_MAX, preserving existing behavior.
      • The implementation includes the possibility of easily extending this to larger sizes in the future.
    • A total of 7 new functions were added:
      • json_object_get_uint64 ( struct json_object const* jso )
      • json_object_new_uint64 ( uint64_t i )
      • json_object_set_uint64 ( struct json_object* jso, uint64_t new_value )
      • json_parse_uint64 ( char const* buf, uint64_t* retval )
        • See description of uint64 support, above.
      • json_tokener_get_parse_end ( struct json_tokener* tok )
        • See details under "json_tokener changes", above.
      • json_object_from_fd_ex ( int fd, int in_depth )
        • Allows the max nesting depth to be specified.
      • json_object_new_null ( )
        • Simply returns NULL. Its use is not recommended.
    • The size of struct json_object has decreased from 96 bytes to 88 bytes.

    ✅ Testing

    • ⚡️ Many updates were made to test cases, increasing code coverage.
    • ✅ There is now a quick way (JSONC_TEST_TRACE=1) to turn on shell tracing in tests.
    • ✅ To run tests, use make test; the old "check" target no longer exists.

    🛠 Significant bug fixes

    For the full list of issues and pull requests since the previous release, please see issues_closed_for_0.14.md

    • Issue #389: Add an assert to explicitly crash when _ref_count is corrupted, instead of a later "double free" error.
    • 📜 Issue #407: fix incorrect casts in calls to ctype functions (isdigit and isspace) so we don't crash when asserts are enabled on certain platforms and characters > 128 are parsed.
    • Issue #418: Fix docs for json_util_from_fd and json_util_from_file to say that they return NULL on failures.
    • Issue #422: json_object.c:set errno in json_object_get_double() when called on a json_type_string object with bad content.
    • Issue #453: Fixed misalignment in JSON serialization when JSON_C_TO_STRING_SPACED and JSON_C_TO_STRING_PRETTY are used together.
    • Issue #463: fix newlocale() call to use LC_NUMERIC_MASK instead of LC_NUMERIC, and remove incorrect comment.
    • Issue #486: append a missing ".0" to negative double values to ensure they are serialized as floating point numbers.
    • 🏁 Issue #488: use JSON_EXPORT on functions so they are properly exported on Windows.
    • Issue #539: use an internal-only serializer function in json_object_new_double_s() to avoid potential conflicts with user code that uses the json_object_userdata_to_json_string serializer.