Resolves https://github.com/json-c/json-c/issues/654

Also, create a _json_object_get_string_len() for internal use when we know
for sure the object we're dealing with is a json_type_string.

Make the documentation build reproducibly

Whilst working on the Reproducible Builds effort [0] I noticed that
json-c could not be built reproducibly.

This is because it used the full, absolute path name as an (sanitised)
input to a filename, resulting in some binary package containing, for
example:

  /usr/share/doc/libjson-c-dev/html/md__build_1st_json-c-0_815_issues_closed_for_0_813.html
                                        ^^^^^^^^^^^^^^^^^^^^^^
or

  /usr/share/doc/libjson-c-dev/html/md__build_2_json-c-0_815_2nd_issues_closed_for_0_813.html
                                        ^^^^^^^^^^^^^^^^^^^^^^^^

These differing values are based on the path in which json-c is built. This was
originally filed in Debian as #966657 [1].

 [0] https://reproducible-builds.org/
 [1] https://bugs.debian.org/966657

Getrandom

Lower overhead than opening & reading from /dev/urandom, and works
in chroots and other situtations where /dev/urandom is not available.
Falls back to existing methods when kernel doesn't support the syscall.

README: fix spelling errors

Signed-off-by: Jakov Smolic <jakov.smolic@sartura.hr>

Fix "may be used uninitialized" Release build failure

Fixes https://github.com/json-c/json-c/issues/647

Example:
mkdir build && cd build
cmake -DOVERRIDE_GET_RANDOM_SEED='do { extern uint32_t getMsTicks(void); int ms = getMsTicks() * 433494437; return ms; } while(0)' ..

Cast to unsigned char instead of int when calling tolower (Fixes #645)

See also PR #639 and issue #621

build: Add a symbol version to all exported symbols

With this version script, newly-linked binaries that depend on the
json-c shared library will refer to its symbols in a versioned form,
preventing their references from being resolved to a symbol of the same
name exported by json-glib or libjansson if those libraries appear in
dependency search order before json-c, which will usually result in
a crash. This is necessary because ELF symbol resolution normally uses
a single flat namespace, not a tree like Windows symbol resolution.
At least one symbol (json_object_iter_next()) is exported by all three
JSON libraries.

Linking with -Bsymbolic is not enough to have this effect in all cases,
because -Bsymbolic only affects symbol lookup within a shared object,
for example when json_object_set_serializer() calls
json_object_set_userdata(). It does not affect calls from external
code into json-c, unless json-c was statically linked into the
external caller.

This change will also not prevent code that depends on json-glib or
libjansson from finding json-c's symbols and crashing; to prevent
that, a corresponding change in json-glib or libjansson would be needed.

Adding a symbol-version is a backwards-compatible change, but once
added, removing or changing the symbol-version on a symbol would be an
incompatible change that requires a SONAME bump.

Resolves: https://github.com/json-c/json-c/issues/621
(when combined with an equivalent change to libjansson).

Signed-off-by: Simon McVittie <smcv@collabora.com>

In practice, the sizes of the signed and unsigned integer types will
almost cetainly be the same, but this is more correct.
Pointed out in issue #638.

This causes previously failing strings like "123-456" to return a valid json_object with the appropriate value.  If you care about the trailing content, call json_tokener_parse_ex() and check the parse end point with json_tokener_get_parse_end().

Deprecate the json_parse_double() function from json_util.h

Add an optional way to use an incremental chunk size ($TEST_PARSE_CHUNKSIZE)
for all of the single_basic_parse tests, in additional to the regular way.

While here, drop the utf8_replacement_char that is unnecesarily added if we run out of input in the middle of a unicode escape.  No other functional changes (yet).

fix issue 616: support the surrogate pair in split file.

Also add the json_object_new_array_ext, array_list_new2, and array_list_shrink functions.