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Add a check for the -Bsymbolic-functions linker flag

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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.
This commit is contained in:
Emmanuele Bassi
2013-09-17 13:08:14 +01:00
parent 06450206c4
commit 311686f63e
2 changed files with 28 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
Makefile.am
View File

@@ -36,10 +36,10 @@ libjson_cinclude_HEADERS = \
#libjsonx_include_HEADERS = \ #libjsonx_include_HEADERS = \
# json_config.h # 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 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. # Temporary libjson library. This will be removed after one release.
libjson_la_LIBADD = -ljson-c libjson_la_LIBADD = -ljson-c

26
configure.in
View File

@@ -57,6 +57,32 @@ AC_LANG_POP([C])
AM_PROG_LIBTOOL 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([ AC_CONFIG_FILES([
Makefile Makefile
json.pc json.pc