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json-c v0.16 Release Notes

Release Date: 2022-04-13 // about 2 years ago

  • 🚚 Deprecated and removed features:

    • JSON_C_OBJECT_KEY_IS_CONSTANT is deprecated in favor of JSON_C_OBJECT_ADD_CONSTANT_KEY
    • Direct access to lh_table and lh_entry structure members is deprecated.
      Use access functions instead, lh_table_head(), lh_entry_next(), etc...
    • ⬇️ Drop REFCOUNT_DEBUG code.

    🆕 New features

    • 🚀 The 0.16 release introduces no new features

    🏗 Build changes

    • Add a DISABLE_EXTRA_LIBS option to skip using libbsd
    • Add a DISABLE_JSON_POINTER option to skip compiling in json_pointer support.

    🛠 Significant changes and bug fixes

    • Cap string length at INT_MAX to avoid various issues with very long strings.
    • json_object_deep_copy: fix deep copy of strings containing '\0'
    • 🛠 Fix read past end of buffer in the "json_parse" command
    • 🖨 Avoid out of memory accesses in the locally provided vasprintf() function (for those platforms that use it)
    • Handle allocation failure in json_tokener_new_ex
    • Fix use-after-free in json_tokener_new_ex() in the event of printbuf_new() returning NULL
    • 🖨 printbuf_memset(): set gaps to zero - areas within the print buffer which have not been initialized by using printbuf_memset
    • 🖨 printbuf: return -1 on invalid arguments (len < 0 or total buffer > INT_MAX)
    • 🖨 sprintbuf(): propagate printbuf_memappend errors back to the caller

    Optimizations

    • 📜 Speed up parsing by replacing ctype functions with simplified, faster non-locale-sensitive ones in json_tokener and json_object_to_json_string.
    • Neither vertical tab nor formfeed are considered whitespace per the JSON spec
    • json_object: speed up creation of objects, calloc() -> malloc() + set fields
    • Avoid needless extra strlen() call in json_c_shallow_copy_default() and json_object_equal() when the object is known to be a json_type_string.

    Other changes

    • Validate size arguments in arraylist functions.
    • 👉 Use getrandom() if available; with GRND_NONBLOCK to allow use of json-c very early during boot, such as part of cryptsetup.
    • 👉 Use arc4random() if it's available.
    • 👀 random_seed: on error, continue to next method instead of exiting the process
    • Close file when unable to read from /dev/urandom in get_dev_random_seed()

Previous changes from v0.15

  • 🚚 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 created 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