3 files changed, 33 insertions, 185 deletions
diff --git a/configure.ac b/configure.ac
index 18321bc..a9f8b6e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -80,58 +80,53 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [[
 AC_MSG_RESULT([$CLANG])
 AS_IF([test "x$CLANG" == "xyes"], [CLANG_FLAGS=-Qunused-arguments])
-# We want to check for compiler flag support. Prior to clang v5.1, there was no way to make
+# We want to check for compiler flag support. Prior to clang v5.1, there was no
-# clang's "argument unused" warning fatal.  So we invoke the compiler through a
+# way to make clang's "argument unused" warning fatal.  So we invoke the
-# wrapper script that greps for this message.
+# compiler through a wrapper script that greps for this message.
 saved_CC="$CC"
 saved_LD="$LD"
 flag_wrap="$srcdir/scripts/wrap-compiler-for-flag-check"
 CC="$flag_wrap $CC"
 LD="$flag_wrap $LD"
-AC_DEFUN([check_cflag],
-        [AX_CHECK_COMPILE_FLAG([$1], [$2], [$3], [-Werror $4])])
-AC_DEFUN([check_ldflag],
-        [AX_CHECK_LINK_FLAG([$1], [$2], [$3], [-Werror $4])])
 AC_ARG_ENABLE([hardening],
-        [AS_HELP_STRING([--disable-hardening], [Disable options to frustrate memory corruption exploits])],
+        [AS_HELP_STRING([--disable-hardening],
-        [],
+                        [Disable options to frustrate memory corruption exploits])],
-        [enable_hardening=yes])
+        [], [enable_hardening=yes])
-HARDEN_CFLAGS=""
+AC_DEFUN([CHECK_CFLAG],
-HARDEN_LDFLAGS=""
+         [AC_LANG_ASSERT(C)
-AS_IF([test "x$enable_hardening" == "xyes"], [
+          AC_MSG_CHECKING([if $saved_CC supports "$1"])
+          old_cflags="$CFLAGS"
+          CFLAGS=[$1]
+          AC_TRY_LINK([#include <stdio.h>],
+                      [printf("Hello")],
+                      AC_MSG_RESULT([yes])
+                      HARDEN_CFLAGS="$HARDEN_CFLAGS [$1]",
+                      AC_MSG_RESULT([no])
+                      $2
+                      )
+          ])
+AS_IF([test "x$enable_hardening" == "xyes" -a "x$HOST_OS" != "xwin"], [
        # Tell GCC to NOT optimize based on signed arithmetic overflow
-        check_cflag([-fno-strict-overflow], [HARDEN_CFLAGS="$HARDEN_CFLAGS -fno-strict-overflow"])
+        CHECK_CFLAG([-fno-strict-overflow])
        # _FORTIFY_SOURCE replaces builtin functions with safer versions.
-        check_cflag([-D_FORTIFY_SOURCE=2], 
+        CHECK_CFLAG([-D_FORTIFY_SOURCE=2])
-                [HARDEN_CFLAGS="$HARDEN_CFLAGS -D_FORTIFY_SOURCE=2"])
+        # Use stack-protector-strong if available; if not, fallback to
-        # Use stack-protector-strong if available; if not, fallback to stack-protector-all which
+        # stack-protector-all which is considered to be overkill
-        # is considered to be overkill
+        CHECK_CFLAG([-fstack-protector-strong],
-        check_cflag([-fstack-protector-strong], 
+                CHECK_CFLAG([-fstack-protector-all],
-                [STACK_PROTECT="-fstack-protector-strong"],
+                        AC_MSG_ERROR([compiler does appear to support stack protection
-                check_cflag([-fstack-protector-all],
+                          - use --disable-hardening to override])
-                        [STACK_PROTECT="-fstack-protector-all"],
-                        [AC_MSG_ERROR([compiler does not support stack protection - use --disable-hardening to override if you understand the risks])]
                )
        )
-        check_ldflag([$STACK_PROTECT],
-                [HARDEN_CFLAGS="$HARDEN_CFLAGS $STACK_PROTECT"
-                 check_cflag([-Wstack-protector], [HARDEN_CFLAGS="$HARDEN_CFLAGS -Wstack-protector"],
-                        [], [$STACK_PROTECT])
-                ],
-                [AC_MSG_ERROR([compiler supports stack protection but linker does not])]
-        )
        # Enable read only relocations
-        check_ldflag([-Wl,-z,relro],
+        CHECK_CFLAG([-Wl,-z,relro])
-                [HARDEN_LDFLAGS="$HARDEN_LDFLAGS -Wl,-z,relro"
+        CHECK_CFLAG([-Wl,-z,now])
-        check_ldflag([-Wl,-z,now], [HARDEN_LDFLAGS="$HARDEN_LDFLAGS -Wl,-z,now"])])
 ])
 # Restore CC, LD
diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
deleted file mode 100644
index 51df0c0..0000000
--- a/m4/ax_check_compile_flag.m4
+++ /dev/null
@@ -1,74 +0,0 @@
-# ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
-#
-# DESCRIPTION
-#
-#   Check whether the given FLAG works with the current language's compiler
-#   or gives an error.  (Warnings, however, are ignored)
-#
-#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
-#   success/failure.
-#
-#   If EXTRA-FLAGS is defined, it is added to the current language's default
-#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
-#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
-#   force the compiler to issue an error when a bad flag is given.
-#
-#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
-#
-#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
-#   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
-#
-# LICENSE
-#
-#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
-#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
-#
-#   This program is free software: you can redistribute it and/or modify it
-#   under the terms of the GNU General Public License as published by the
-#   Free Software Foundation, either version 3 of the License, or (at your
-#   option) any later version.
-#
-#   This program is distributed in the hope that it will be useful, but
-#   WITHOUT ANY WARRANTY; without even the implied warranty of
-#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
-#   Public License for more details.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <http://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
-#serial 3
-AC_DEFUN([AX_CHECK_COMPILE_FLAG],
-[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
-AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
-AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
-  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
-  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
-  AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
-    [AS_VAR_SET(CACHEVAR,[yes])],
-    [AS_VAR_SET(CACHEVAR,[no])])
-  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
-AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
-  [m4_default([$2], :)],
-  [m4_default([$3], :)])
-AS_VAR_POPDEF([CACHEVAR])dnl
-])dnl AX_CHECK_COMPILE_FLAGS
diff --git a/m4/ax_check_link_flag.m4 b/m4/ax_check_link_flag.m4
deleted file mode 100644
index db899dd..0000000
--- a/m4/ax_check_link_flag.m4
+++ /dev/null
@@ -1,73 +0,0 @@
-# ===========================================================================
-#    http://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
-#
-# DESCRIPTION
-#
-#   Check whether the given FLAG works with the linker or gives an error.
-#   (Warnings, however, are ignored)
-#
-#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
-#   success/failure.
-#
-#   If EXTRA-FLAGS is defined, it is added to the linker's default flags
-#   when the check is done.  The check is thus made with the flags: "LDFLAGS
-#   EXTRA-FLAGS FLAG".  This can for example be used to force the linker to
-#   issue an error when a bad flag is given.
-#
-#   INPUT gives an alternative input source to AC_LINK_IFELSE.
-#
-#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
-#   macro in sync with AX_CHECK_{PREPROC,COMPILE}_FLAG.
-#
-# LICENSE
-#
-#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
-#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
-#
-#   This program is free software: you can redistribute it and/or modify it
-#   under the terms of the GNU General Public License as published by the
-#   Free Software Foundation, either version 3 of the License, or (at your
-#   option) any later version.
-#
-#   This program is distributed in the hope that it will be useful, but
-#   WITHOUT ANY WARRANTY; without even the implied warranty of
-#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
-#   Public License for more details.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <http://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
-#serial 3
-AC_DEFUN([AX_CHECK_LINK_FLAG],
-[AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
-AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [
-  ax_check_save_flags=$LDFLAGS
-  LDFLAGS="$LDFLAGS $4 $1"
-  AC_LINK_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
-    [AS_VAR_SET(CACHEVAR,[yes])],
-    [AS_VAR_SET(CACHEVAR,[no])])
-  LDFLAGS=$ax_check_save_flags])
-AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
-  [m4_default([$2], :)],
-  [m4_default([$3], :)])
-AS_VAR_POPDEF([CACHEVAR])dnl
-])dnl AX_CHECK_LINK_FLAGS

diff --git a/configure.ac b/configure.ac index 18321bc..a9f8b6e 100644 --- a/configure.ac +++ b/configure.ac
@@ -80,58 +80,53 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [[
80	AC_MSG_RESULT([$CLANG])	80	AC_MSG_RESULT([$CLANG])
81	AS_IF([test "x$CLANG" == "xyes"], [CLANG_FLAGS=-Qunused-arguments])	81	AS_IF([test "x$CLANG" == "xyes"], [CLANG_FLAGS=-Qunused-arguments])
82		82
83	# We want to check for compiler flag support. Prior to clang v5.1, there was no way to make	83	# We want to check for compiler flag support. Prior to clang v5.1, there was no
84	# clang's "argument unused" warning fatal. So we invoke the compiler through a	84	# way to make clang's "argument unused" warning fatal. So we invoke the
85	# wrapper script that greps for this message.	85	# compiler through a wrapper script that greps for this message.
86	saved_CC="$CC"	86	saved_CC="$CC"
87	saved_LD="$LD"	87	saved_LD="$LD"
88	flag_wrap="$srcdir/scripts/wrap-compiler-for-flag-check"	88	flag_wrap="$srcdir/scripts/wrap-compiler-for-flag-check"
89	CC="$flag_wrap $CC"	89	CC="$flag_wrap $CC"
90	LD="$flag_wrap $LD"	90	LD="$flag_wrap $LD"
91		91
92	AC_DEFUN([check_cflag],
93	[AX_CHECK_COMPILE_FLAG([$1], [$2], [$3], [-Werror $4])])
94	AC_DEFUN([check_ldflag],
95	[AX_CHECK_LINK_FLAG([$1], [$2], [$3], [-Werror $4])])
96
97
98	AC_ARG_ENABLE([hardening],	92	AC_ARG_ENABLE([hardening],
99	[AS_HELP_STRING([--disable-hardening], [Disable options to frustrate memory corruption exploits])],	93	[AS_HELP_STRING([--disable-hardening],
100	[],	94	[Disable options to frustrate memory corruption exploits])],
101	[enable_hardening=yes])	95	[], [enable_hardening=yes])
102		96
103	HARDEN_CFLAGS=""	97	AC_DEFUN([CHECK_CFLAG],
104	HARDEN_LDFLAGS=""	98	[AC_LANG_ASSERT(C)
105	AS_IF([test "x$enable_hardening" == "xyes"], [	99	AC_MSG_CHECKING([if $saved_CC supports "$1"])
		100	old_cflags="$CFLAGS"
		101	CFLAGS=[$1]
		102	AC_TRY_LINK([#include <stdio.h>],
		103	[printf("Hello")],
		104	AC_MSG_RESULT([yes])
		105	HARDEN_CFLAGS="$HARDEN_CFLAGS [$1]",
		106	AC_MSG_RESULT([no])
		107	$2
		108	)
		109	])
		110
		111	AS_IF([test "x$enable_hardening" == "xyes" -a "x$HOST_OS" != "xwin"], [
106	# Tell GCC to NOT optimize based on signed arithmetic overflow	112	# Tell GCC to NOT optimize based on signed arithmetic overflow
107	check_cflag([-fno-strict-overflow], [HARDEN_CFLAGS="$HARDEN_CFLAGS -fno-strict-overflow"])	113	CHECK_CFLAG([-fno-strict-overflow])
108		114
109	# _FORTIFY_SOURCE replaces builtin functions with safer versions.	115	# _FORTIFY_SOURCE replaces builtin functions with safer versions.
110	check_cflag([-D_FORTIFY_SOURCE=2],	116	CHECK_CFLAG([-D_FORTIFY_SOURCE=2])
111	[HARDEN_CFLAGS="$HARDEN_CFLAGS -D_FORTIFY_SOURCE=2"])	117
112		118	# Use stack-protector-strong if available; if not, fallback to
113	# Use stack-protector-strong if available; if not, fallback to stack-protector-all which	119	# stack-protector-all which is considered to be overkill
114	# is considered to be overkill	120	CHECK_CFLAG([-fstack-protector-strong],
115	check_cflag([-fstack-protector-strong],	121	CHECK_CFLAG([-fstack-protector-all],
116	[STACK_PROTECT="-fstack-protector-strong"],	122	AC_MSG_ERROR([compiler does appear to support stack protection
117	check_cflag([-fstack-protector-all],	123	- use --disable-hardening to override])
118	[STACK_PROTECT="-fstack-protector-all"],
119	[AC_MSG_ERROR([compiler does not support stack protection - use --disable-hardening to override if you understand the risks])]
120	)	124	)
121	)	125	)
122		126
123	check_ldflag([$STACK_PROTECT],
124	[HARDEN_CFLAGS="$HARDEN_CFLAGS $STACK_PROTECT"
125	check_cflag([-Wstack-protector], [HARDEN_CFLAGS="$HARDEN_CFLAGS -Wstack-protector"],
126	[], [$STACK_PROTECT])
127	],
128	[AC_MSG_ERROR([compiler supports stack protection but linker does not])]
129	)
130
131	# Enable read only relocations	127	# Enable read only relocations
132	check_ldflag([-Wl,-z,relro],	128	CHECK_CFLAG([-Wl,-z,relro])
133	[HARDEN_LDFLAGS="$HARDEN_LDFLAGS -Wl,-z,relro"	129	CHECK_CFLAG([-Wl,-z,now])
134	check_ldflag([-Wl,-z,now], [HARDEN_LDFLAGS="$HARDEN_LDFLAGS -Wl,-z,now"])])
135	])	130	])
136		131
137	# Restore CC, LD	132	# Restore CC, LD


diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4 deleted file mode 100644 index 51df0c0..0000000 --- a/m4/ax_check_compile_flag.m4 +++ /dev/null
@@ -1,74 +0,0 @@
1	# ===========================================================================
2	# http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
3	# ===========================================================================
4	#
5	# SYNOPSIS
6	#
7	# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
8	#
9	# DESCRIPTION
10	#
11	# Check whether the given FLAG works with the current language's compiler
12	# or gives an error. (Warnings, however, are ignored)
13	#
14	# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
15	# success/failure.
16	#
17	# If EXTRA-FLAGS is defined, it is added to the current language's default
18	# flags (e.g. CFLAGS) when the check is done. The check is thus made with
19	# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to
20	# force the compiler to issue an error when a bad flag is given.
21	#
22	# INPUT gives an alternative input source to AC_COMPILE_IFELSE.
23	#
24	# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
25	# macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
26	#
27	# LICENSE
28	#
29	# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
30	# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
31	#
32	# This program is free software: you can redistribute it and/or modify it
33	# under the terms of the GNU General Public License as published by the
34	# Free Software Foundation, either version 3 of the License, or (at your
35	# option) any later version.
36	#
37	# This program is distributed in the hope that it will be useful, but
38	# WITHOUT ANY WARRANTY; without even the implied warranty of
39	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
40	# Public License for more details.
41	#
42	# You should have received a copy of the GNU General Public License along
43	# with this program. If not, see <http://www.gnu.org/licenses/>.
44	#
45	# As a special exception, the respective Autoconf Macro's copyright owner
46	# gives unlimited permission to copy, distribute and modify the configure
47	# scripts that are the output of Autoconf when processing the Macro. You
48	# need not follow the terms of the GNU General Public License when using
49	# or distributing such scripts, even though portions of the text of the
50	# Macro appear in them. The GNU General Public License (GPL) does govern
51	# all other use of the material that constitutes the Autoconf Macro.
52	#
53	# This special exception to the GPL applies to versions of the Autoconf
54	# Macro released by the Autoconf Archive. When you make and distribute a
55	# modified version of the Autoconf Macro, you may extend this special
56	# exception to the GPL to apply to your modified version as well.
57
58	#serial 3
59
60	AC_DEFUN([AX_CHECK_COMPILE_FLAG],
61	[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
62	AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
63	AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
64	ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
65	_AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
66	AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
67	[AS_VAR_SET(CACHEVAR,[yes])],
68	[AS_VAR_SET(CACHEVAR,[no])])
69	_AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
70	AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
71	[m4_default([$2], :)],
72	[m4_default([$3], :)])
73	AS_VAR_POPDEF([CACHEVAR])dnl
74	])dnl AX_CHECK_COMPILE_FLAGS


diff --git a/m4/ax_check_link_flag.m4 b/m4/ax_check_link_flag.m4 deleted file mode 100644 index db899dd..0000000 --- a/m4/ax_check_link_flag.m4 +++ /dev/null
@@ -1,73 +0,0 @@
1	# ===========================================================================
2	# http://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html
3	# ===========================================================================
4	#
5	# SYNOPSIS
6	#
7	# AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
8	#
9	# DESCRIPTION
10	#
11	# Check whether the given FLAG works with the linker or gives an error.
12	# (Warnings, however, are ignored)
13	#
14	# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
15	# success/failure.
16	#
17	# If EXTRA-FLAGS is defined, it is added to the linker's default flags
18	# when the check is done. The check is thus made with the flags: "LDFLAGS
19	# EXTRA-FLAGS FLAG". This can for example be used to force the linker to
20	# issue an error when a bad flag is given.
21	#
22	# INPUT gives an alternative input source to AC_LINK_IFELSE.
23	#
24	# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
25	# macro in sync with AX_CHECK_{PREPROC,COMPILE}_FLAG.
26	#
27	# LICENSE
28	#
29	# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
30	# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
31	#
32	# This program is free software: you can redistribute it and/or modify it
33	# under the terms of the GNU General Public License as published by the
34	# Free Software Foundation, either version 3 of the License, or (at your
35	# option) any later version.
36	#
37	# This program is distributed in the hope that it will be useful, but
38	# WITHOUT ANY WARRANTY; without even the implied warranty of
39	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
40	# Public License for more details.
41	#
42	# You should have received a copy of the GNU General Public License along
43	# with this program. If not, see <http://www.gnu.org/licenses/>.
44	#
45	# As a special exception, the respective Autoconf Macro's copyright owner
46	# gives unlimited permission to copy, distribute and modify the configure
47	# scripts that are the output of Autoconf when processing the Macro. You
48	# need not follow the terms of the GNU General Public License when using
49	# or distributing such scripts, even though portions of the text of the
50	# Macro appear in them. The GNU General Public License (GPL) does govern
51	# all other use of the material that constitutes the Autoconf Macro.
52	#
53	# This special exception to the GPL applies to versions of the Autoconf
54	# Macro released by the Autoconf Archive. When you make and distribute a
55	# modified version of the Autoconf Macro, you may extend this special
56	# exception to the GPL to apply to your modified version as well.
57
58	#serial 3
59
60	AC_DEFUN([AX_CHECK_LINK_FLAG],
61	[AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
62	AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [
63	ax_check_save_flags=$LDFLAGS
64	LDFLAGS="$LDFLAGS $4 $1"
65	AC_LINK_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
66	[AS_VAR_SET(CACHEVAR,[yes])],
67	[AS_VAR_SET(CACHEVAR,[no])])
68	LDFLAGS=$ax_check_save_flags])
69	AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
70	[m4_default([$2], :)],
71	[m4_default([$3], :)])
72	AS_VAR_POPDEF([CACHEVAR])dnl
73	])dnl AX_CHECK_LINK_FLAGS