The --default-symver linker option attaches a default version definition
(the SONAME) to every exported symbol. It is supported since at least
GNU binutils 2.22 in 2011 (older versions not tested).
With this version definition, newly-linked binaries that depend on the
jansson 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-c or json-glib if those libraries appear in
dependency search order before jansson, 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 parse_json() calls json_decref(). It does not affect
calls from external code into jansson, unless jansson was statically
linked into the external caller.
This change will also not prevent code that depends on json-c or
json-glib from finding jansson's symbols and crashing; to prevent
that, a corresponding change in json-c or json-glib would be needed.
Adding a symbol-version is a backwards-compatible change, but once
added, removing or changing the symbol-version would be an incompatible
change that requires a SONAME bump.
Resolves: https://github.com/akheron/jansson/issues/523
(when combined with an equivalent change to json-c).
Signed-off-by: Simon McVittie <smcv@collabora.com>
It was discovered fairly recently that JSON parsing libraries use
common pattern to name their exported symbols (they all use
json_ prefix). So eventually it happens that two symbols from two
different libraries have the same name. This will lead to cryptic
crashes (see [1] and [2]). Linking with -Bsymbolic-functions
prevents this.
1: https://gitlab.gnome.org/GNOME/json-glib/issues/33
2: https://groups.google.com/forum/#!topic/jansson-users/7Efx-RI45IU
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Recent versions of gcc have introduced compiler warnings for string
operations that could be truncated. This caused problems with -Werror.
src/error.c used strncpy to write "..." to a string, but skipped writing
the NUL terminator. Switch this to use memcpy. src/load.c produced
warnings from snprintf writing error strings that could be truncated.
Added code to autotools build to detect `-Wno-format-truncation', add it
to AM_CFLAGS if supported.
This is because it's really easy to get a name collission if compiling
Jansson as a subproject in a larger CMake project. If one project includes
several subprojects each having their own config.h, this will cause the
wrong file to be loaded.
The decimal point '.' is changed to locale's decimal point
before/after JSON conversion to make C standard library's
locale-specific string conversion functions work correctly.
All the tests now call setlocale(LC_ALL, "") on startup to use the
locale set in the environment.
Fixes GH-32.
json_int_t is typedef'd to long long if it's supported, or long
otherwise. There's also some supporting things, like the
JSON_INTEGER_FORMAT macro that expands to the printf() conversion
specifier that corresponds to json_int_t's actual type.
This is a backwards incompatible change.
