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| author | Emmanuele Bassi <ebassi@gnome.org> | 2013-09-17 13:08:14 +0100 |
|---|---|---|
| committer | Emmanuele Bassi <ebassi@gnome.org> | 2013-09-17 13:08:14 +0100 |
| commit | 311686f63ed26e510c50808977c31883fe7bc23d (patch) | |
| tree | 951723742c4aaaefc7dd73b784420e3de974fb80 | |
| parent | 06450206c4f3de4af8d81bb6d93e9db1d5fedec1 (diff) | |
| download | json-c-311686f63ed26e510c50808977c31883fe7bc23d.tar.gz | |
Add a check for the -Bsymbolic-functions linker flag
The -Bsymbolic-functions linker flag reduces the amount of PLT jumps in
a shared object, and has a side effect of preventing symbol collisions
in libraries and applications linking against two different shared
objects exposing the same symbol.
While the former is (generally) a performance win, the latter is less
rare than expected. For instance, PulseAudio started linking against
json-c a while ago; now, every project linking against PulseAudio is
leaking json-c symbols. In the GNOME platform, this means that projects
linking against PulseAudio cannot be safely linked against other
libraries depending on the GLib-based JSON parsing libraries JSON-GLib,
because of a symbol conflict. Nominally, this conflict would not be an
issue: libraries and applications do not need to depend on two different
JSON parsing libraries; the symbol leakage, though, ends up causing
either segmentation faults, or weird errors. For further reference,
please see: https://bugzilla.gnome.org/show_bug.cgi?id=703734
JSON-GLib already switched to using -Bsymbolic-functions, but it would
be safe if json-c did the same, wherever the linker flag is available.
| -rw-r--r-- | Makefile.am | 4 | ||||
| -rw-r--r-- | configure.in | 26 |
2 files changed, 28 insertions, 2 deletions
diff --git a/Makefile.am b/Makefile.am index 73e8116..cc6f005 100644 --- a/Makefile.am +++ b/Makefile.am @@ -36,10 +36,10 @@ libjson_cinclude_HEADERS = \ #libjsonx_include_HEADERS = \ # json_config.h -libjson_c_la_LDFLAGS = -version-info 2:0:0 -no-undefined +libjson_c_la_LDFLAGS = -version-info 2:0:0 -no-undefined @JSON_BSYMBOLIC_LDFLAGS@ if ENABLE_OLDNAME_COMPAT -libjson_la_LDFLAGS = -version-info 1:0:1 -no-undefined -ljson-c +libjson_la_LDFLAGS = -version-info 1:0:1 -no-undefined -ljson-c @JSON_BSYMBOLIC_LDFLAGS@ # Temporary libjson library. This will be removed after one release. libjson_la_LIBADD = -ljson-c diff --git a/configure.in b/configure.in index 64f9cbe..7697be5 100644 --- a/configure.in +++ b/configure.in @@ -57,6 +57,32 @@ AC_LANG_POP([C]) AM_PROG_LIBTOOL +# Check for the -Bsymbolic-functions linker flag +AC_ARG_ENABLE([Bsymbolic], + [AS_HELP_STRING([--disable-Bsymbolic], [Avoid linking with -Bsymbolic-function])], + [], + [enable_Bsymbolic=check]) + +AS_IF([test "x$enable_Bsymbolic" = "xcheck"], + [ + saved_LDFLAGS="${LDFLAGS}" + AC_MSG_CHECKING([for -Bsymbolic-functions linker flag]) + LDFLAGS=-Wl,-Bsymbolic-functions + AC_TRY_LINK([], [int main (void) { return 0; }], + [ + AC_MSG_RESULT([yes]) + enable_Bsymbolic=yes + ], + [ + AC_MSG_RESULT([no]) + enable_Bsymbolic=no + ]) + LDFLAGS="${saved_LDFLAGS}" + ]) + +AS_IF([test "x$enable_Bsymbolic" = "xyes"], [JSON_BSYMBOLIC_LDFLAGS=-Wl[,]-Bsymbolic-functions]) +AC_SUBST(JSON_BSYMBOLIC_LDFLAGS) + AC_CONFIG_FILES([ Makefile json.pc |