[PATCH 2/2] BZ#10375: Configure magic to use -fno-stack-protector if needed.

[Roland McGrath <roland at hack dot frob dot com>]

---
 ChangeLog      |    9 ++++
 Makeconfig     |    2 +-
 config.make.in |    1 +
 configure      |  132 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.in   |   26 +++++++++++
 5 files changed, 169 insertions(+), 1 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 338b418..6180207 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,15 @@
 2012-05-07  Roland McGrath  <roland@hack.frob.com>
 
 	[BZ #10375]
+	* configure.in (NM): Add AC_CHECK_TOOL for it.
+	(libc_extra_cflags): New substituted variable.
+	Check for -fstack-protector being used implicitly.
+	* configure: Regenerated.
+	* config.make.in (config-extra-cflags): New variable,
+	gets @libc_extra_cflags@.
+	* Makeconfig (CFLAGS): Add $(config-extra-cflags) near the front.
+
+	[BZ #10375]
 	* configure.in: Check for _FORTIFY_SOURCE being predefined.
 	(CPPUNDEFS): New substituted variable; add -U_FORTIFY_SOURCE if needed.
 	* configure: Regenerated.
diff --git a/Makeconfig b/Makeconfig
index 5c78ee4..df020df 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -662,7 +662,7 @@ CPPFLAGS = $(CPPFLAGS-config) $($(subdir)-CPPFLAGS) $(+includes) $(defines) \
 	   $(foreach lib,$(libof-$(basename $(@F))) \
 			 $(libof-$(<F)) $(libof-$(@F)),$(CPPFLAGS-$(lib))) \
 	   $(CPPFLAGS-$(<F)) $(CPPFLAGS-$(@F)) $(CPPFLAGS-$(basename $(@F)))
-override CFLAGS	= -std=gnu99 $(gnu89-inline-CFLAGS) \
+override CFLAGS	= -std=gnu99 $(gnu89-inline-CFLAGS) $(config-extra-cflags) \
 		  $(filter-out %frame-pointer,$(+cflags)) $(+gccwarn-c) \
 		  $(sysdep-CFLAGS) $(CFLAGS-$(suffix $@)) $(CFLAGS-$(<F)) \
 		  $(CFLAGS-$(@F)) \
diff --git a/config.make.in b/config.make.in
index 3641fb2..83615c3 100644
--- a/config.make.in
+++ b/config.make.in
@@ -34,6 +34,7 @@ config-sysdirs = @sysnames@
 cflags-cpu = @libc_cv_cc_submachine@
 asflags-cpu = @libc_cv_cc_submachine@
 
+config-extra-cflags = @libc_extra_cflags@
 config-cflags-sse4 = @libc_cv_cc_sse4@
 config-cflags-avx = @libc_cv_cc_avx@
 config-cflags-sse2avx = @libc_cv_cc_sse2avx@
diff --git a/configure b/configure
index 8bea2e1..2ec5c44 100755
--- a/configure
+++ b/configure
@@ -666,6 +666,7 @@ libc_cv_gcc_static_libgcc
 CXX_SYSINCLUDES
 SYSINCLUDES
 AUTOCONF
+NM
 READELF
 SED
 MAKEINFO
@@ -5131,6 +5132,98 @@ else
   READELF="$ac_cv_prog_READELF"
 fi
 
+if test -n "$ac_tool_prefix"; then
+  # Extract the first word of "${ac_tool_prefix}nm", so it can be a program name with args.
+set dummy ${ac_tool_prefix}nm; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_NM+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$NM"; then
+  ac_cv_prog_NM="$NM" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_NM="${ac_tool_prefix}nm"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+NM=$ac_cv_prog_NM
+if test -n "$NM"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $NM" >&5
+$as_echo "$NM" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+fi
+if test -z "$ac_cv_prog_NM"; then
+  ac_ct_NM=$NM
+  # Extract the first word of "nm", so it can be a program name with args.
+set dummy nm; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_ac_ct_NM+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$ac_ct_NM"; then
+  ac_cv_prog_ac_ct_NM="$ac_ct_NM" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_ac_ct_NM="nm"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+ac_ct_NM=$ac_cv_prog_ac_ct_NM
+if test -n "$ac_ct_NM"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_NM" >&5
+$as_echo "$ac_ct_NM" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+  if test "x$ac_ct_NM" = x; then
+    NM="false"
+  else
+    case $cross_compiling:$ac_tool_warned in
+yes:)
+{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
+$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
+ac_tool_warned=yes ;;
+esac
+    NM=$ac_ct_NM
+  fi
+else
+  NM="$ac_cv_prog_NM"
+fi
+
 
 for ac_prog in autoconf
 do
@@ -7554,6 +7647,45 @@ if test $libc_cv_predef_fortify_source = yes; then
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC implicitly enables -fstack-protector" >&5
+$as_echo_n "checking whether $CC implicitly enables -fstack-protector... " >&6; }
+if ${libc_cv_predef_stack_protector+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+extern void foobar (char *);
+int
+main ()
+{
+char large_array[2048]; foobar (large_array);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+libc_undefs=`$NM -u conftest.o 2>&1 |
+  LC_ALL=C $AWK '$1 == "U" { print $2 | "sort -u"; next } { exit(1) }'` || {
+  as_fn_error $? "confusing output from $NM -u" "$LINENO" 5
+}
+echo >&5 "libc_undefs='$libc_undefs'"
+case "$libc_undefs" in
+foobar) libc_cv_predef_stack_protector=no ;;
+'__stack_chk_fail
+foobar') libc_cv_predef_stack_protector=yes ;;
+*) as_fn_error $? "unexpected symbols in test: $libc_undefs" "$LINENO" 5 ;;
+esac
+else
+  as_fn_error $? "test compilation failed" "$LINENO" 5
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_predef_stack_protector" >&5
+$as_echo "$libc_cv_predef_stack_protector" >&6; }
+
 ### End of automated tests.
 ### Now run sysdeps configure fragments.
 
diff --git a/configure.in b/configure.in
index 6f3e98e..b4452c6 100644
--- a/configure.in
+++ b/configure.in
@@ -911,6 +911,7 @@ AC_CHECK_PROG_VER(SED, sed, --version,
   SED=: aux_missing="$aux_missing sed")
 
 AC_CHECK_TOOL(READELF, readelf, false)
+AC_CHECK_TOOL(NM, nm, false)
 
 AC_CHECK_PROGS(AUTOCONF, autoconf, no)
 case "x$AUTOCONF" in
@@ -2034,6 +2035,31 @@ if test $libc_cv_predef_fortify_source = yes; then
 fi
 AC_SUBST(CPPUNDEFS)
 
+dnl Check for silly hacked compilers inserting -fstack-protector.
+AC_CACHE_CHECK([whether $CC implicitly enables -fstack-protector],
+	       libc_cv_predef_stack_protector, [
+AC_TRY_COMPILE([extern void foobar (char *);],
+	       [char large_array[2048]; foobar (large_array);], [
+libc_undefs=`$NM -u conftest.o |
+  LC_ALL=C $AWK '$1 == "U" { print $2 | "sort -u"; next } { exit(1) }' \
+    2>&AS_MESSAGE_LOG_FD` || {
+  AC_MSG_ERROR([confusing output from $NM -u])
+}
+echo >&AS_MESSAGE_LOG_FD "libc_undefs='$libc_undefs'"
+case "$libc_undefs" in
+foobar) libc_cv_predef_stack_protector=no ;;
+'__stack_chk_fail
+foobar') libc_cv_predef_stack_protector=yes ;;
+*) AC_MSG_ERROR([unexpected symbols in test: $libc_undefs]) ;;
+esac],
+	       [AC_MSG_ERROR([test compilation failed])])
+])
+libc_extra_cflags=
+if test $libc_cv_predef_stack_protector = yes; then
+  libc_extra_cflags=-fno-stack-protector
+fi
+AC_SUBST(libc_extra_cflags)
+
 ### End of automated tests.
 ### Now run sysdeps configure fragments.
 
-- 
1.7.7.3