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libctf: try several possibilities for linker versioning flags

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Checking for linker versioning by just grepping ld --help output for
mentions of --version-script is inadequate now that Solaris 11.4
implements a --version-script with different semantics.  Try linking a
test program with a small wildcard-using version script with each
supported set of flags in turn, to make sure that linker versioning is
not only advertised but actually works.

The Solaris "GNU-compatible" linker versioning is not quite
GNU-compatible enough, but we can work around the differences by
generating a new version script that removes the comments from the
original (Solaris ld requires #-style comments), and making another
version script for libctf-nonbfd in particular which doesn't mention any
of the symbols that appear in libctf.la, to avoid Solaris ld introducing
corresponding new NOTYPE symbols to match the version script.

libctf/ChangeLog
2021-09-27  Nick Alcock  <nick.alcock@oracle.com>

	PR libctf/27967
	* configure.ac (VERSION_FLAGS): Replace with...
	(ac_cv_libctf_version_script): ... this multiple test.
	(VERSION_FLAGS_NOBFD): Substitute this too.
	* Makefile.am (libctf_nobfd_la_LDFLAGS): Use it.  Split out...
	(libctf_ldflags_nover): ... non-versioning flags here.
	(libctf_la_LDFLAGS): Use it.
	* libctf.ver: Give every symbol not in libctf-nobfd a comment on
	the same line noting as much.
This commit is contained in:
Nick Alcock 2021-09-27 20:31:21 +01:00
parent bef9ef8ca0
commit ea9c200911
4 changed files with 62 additions and 11 deletions
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46
libctf/configure.ac
View file

@ -219,11 +219,51 @@ fi`
AM_CONDITIONAL(TCL_TRY, test "${ac_cv_libctf_tcl_try}" = yes)
# Use a version script, if possible, or an -export-symbols-regex otherwise.
VERSION_FLAGS='-export-symbols-regex ctf_.*'
if $LD --help 2>&1 | grep -- --version-script >/dev/null; then
VERSION_FLAGS="-Wl,--version-script='$srcdir/libctf.ver'"
decommented_version_script=
AC_CACHE_CHECK([for linker versioning flags], [ac_cv_libctf_version_script],
[echo 'FOO { global: mai*; local: ctf_fo*; };' > conftest.ver
old_LDFLAGS="$LDFLAGS"
old_CFLAGS="$CFLAGS"
LDFLAGS="$LDFLAGS -shared -Wl,--version-script=conftest.ver"
CFLAGS="$CFLAGS -fPIC"
AC_LINK_IFELSE([AC_LANG_SOURCE([[int ctf_foo (void) { return 0; }
int main (void) { return ctf_foo(); }]])],
[ac_cv_libctf_version_script="-Wl,--version-script='$srcdir/libctf.ver'"],
[])
LDFLAGS="$old_LDFLAGS"
if test -z "$ac_cv_libctf_version_script"; then
LDFLAGS="$LDFLAGS -shared -Wl,-B,local -Wl,-z,gnu-version-script=conftest.ver"
AC_LINK_IFELSE([AC_LANG_SOURCE([[int ctf_foo (void) { return 0; }
int main (void) { return ctf_foo(); }]])],
[ac_cv_libctf_version_script="-Wl,-B,local -Wl,-z,gnu-version-script"
decommented_version_script=t],
[])
LDFLAGS="$old_LDFLAGS"
fi
CFLAGS="$old_CFLAGS"
if test -z "$ac_cv_libctf_version_script"; then
ac_cv_libctf_version_script='-export-symbols-regex ctf_.*'
fi
rm -f conftest.ver])
if test -n "$decommented_version_script"; then
# Solaris's version scripts use shell-style comments rather than the C-style
# used by GNU ld. Use cpp to strip the comments out. (cpp exists under this
# name on all platforms that support ld -z gnu-version-script.)
# Also ensure that no symbols exist in the version script for libctf-nobfd.so
# that do not exist in the shared library itself, since some linkers add such
# symbols with type NOTYPE.
/lib/cpp < $srcdir/libctf.ver > libctf-decommented.ver
grep -v 'libctf only' $srcdir/libctf.ver | /lib/cpp > libctf-nobfd-decommented.ver
VERSION_FLAGS="$ac_cv_libctf_version_script='libctf-decommented.ver'"
VERSION_FLAGS_NOBFD="$ac_cv_libctf_version_script='libctf-nobfd-decommented.ver'"
else
VERSION_FLAGS="$ac_cv_libctf_version_script"
VERSION_FLAGS_NOBFD="$ac_cv_libctf_version_script"
fi
AC_SUBST(VERSION_FLAGS)
AC_SUBST(VERSION_FLAGS_NOBFD)
AC_CONFIG_FILES(Makefile)
AC_CONFIG_HEADERS(config.h)