configure.ac - external/github.com/google/hiba - Git at Google

 # Copyright (c) 2020 The HIBA Authors All rights reserved.
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 m4_define([MAJOR], 1)
 m4_define([MINOR], 2)

 AC_PREREQ([2.69])
 AC_INIT([HIBA], [MAJOR.MINOR], [hibassh@google.com])
 AC_CONFIG_SRCDIR([hiba.h])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_MACRO_DIRS([m4])
 AC_LANG([C])
 AC_PROG_CC([cc gcc clang])

 LT_INIT

 AM_INIT_AUTOMAKE([foreign no-dependencies])
 AM_SILENT_RULES([yes])

 # Values for SONAME. See -version-info for details.
 AC_SUBST(SONAME_CURRENT, 0)
 AC_SUBST(SONAME_REVISION, 0)
 AC_SUBST(SONAME_AGE, 0)

 save_CFLAGS="$CFLAGS"
 save_CPPFLAGS="$CPPFLAGS"
 save_LDFLAGS="$LDFLAGS"
 save_LIBS="$LIBS"

 # Check for required CFLAGS & CPPFLAGS availability
 for f in -fstack-protector-strong -fstack-protector-all -fstack-protector; do
 	AC_MSG_CHECKING(whether $CC supports $f options)
 	CFLAGS="$CFLAGS $extra_CFLAGS $f -Werror"
 	LDFLAGS="$LDFLAGS $extra_LDFLAGS $f"
 	AC_LINK_IFELSE(
 		[AC_LANG_PROGRAM()], [
 			extra_LDFLAGS="$extra_LDFLAGS $f"
 			extra_CFLAGS="$extra_CFLAGS $f"
 			AC_MSG_RESULT([yes])
 			break
 		], [AC_MSG_RESULT([no])],
 	)
 	# Restore CFLAGS & LDFLAGS in the loop as options are exclusive.
 	LDFLAGS="$save_LDFLAGS"
 	CFLAGS="$save_CFLAGS"
 done

 for f in -fpie -fPIE -fpic -fPIC; do
 	AC_MSG_CHECKING(whether compiler supports $f)
 	CFLAGS="$CFLAGS $extra_CFLAGS $f -Werror"
 	AC_COMPILE_IFELSE(
 		[AC_LANG_PROGRAM()], [
 			extra_CFLAGS="$extra_CFLAGS $f"
 			AC_MSG_RESULT([yes])
 			break
 		], [AC_MSG_RESULT([no])],
 	)
 	# Restore CFLAGS in the loop as options are exclusive.
 	CFLAGS="$save_CFLAGS"
 done

 for f in -ansi -Wall -Wextra -Werror -Wno-attributes -Wno-unused-parameter -Wformat-security -Wuninitialized; do
 	AC_MSG_CHECKING(whether $CC supports $f options)
 	CFLAGS="$CFLAGS $extra_CFLAGS $f"
 	AC_COMPILE_IFELSE(
 		[AC_LANG_PROGRAM()], [
 			extra_CFLAGS="$extra_CFLAGS $f"
 			AC_MSG_RESULT([yes])
 		], [AC_MSG_RESULT([no])],
 	)
 done
 CFLAGS="$save_CFLAGS"

 AC_MSG_CHECKING(whether preprocessor supports _DEFAULT_SOURCE)
 CPPFLAGS="$CPPFLAGS $extra_CPPFLAGS -D_DEFAULT_SOURCE"
 AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM()], [
 		extra_CPPFLAGS="$extra_CPPFLAGS -D_DEFAULT_SOURCE"
 		AC_MSG_RESULT([yes])
 	], [AC_MSG_ERROR([no])],
 )
 CPPFLAGS="$save_CPPFLAGS"

 AC_MSG_CHECKING(whether preprocessor supports _FORTIFY_SOURCE)
 CPPFLAGS="$CPPFLAGS $extra_CPPFLAGS -D_FORTIFY_SOURCE=2"
 AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM()], [
 		extra_CPPFLAGS="$extra_CPPFLAGS -D_FORTIFY_SOURCE=2"
 		AC_MSG_RESULT([yes])
 	], [AC_MSG_RESULT([no])],
 )
 CPPFLAGS="$save_CPPFLAGS"

 AC_MSG_CHECKING(whether compiler supports no-strict-aliasing option)
 CFLAGS="$CFLAGS $extra_CFLAGS -fno-strict-aliasing -Werror"
 AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM()], [
 		extra_CFLAGS="$extra_CFLAGS -fno-strict-aliasing"
 		AC_MSG_RESULT([yes])
 	], [AC_MSG_RESULT([no])],
 )
 CFLAGS="$save_CFLAGS"

 AC_MSG_CHECKING(whether compiler supports hardening options)
 CPPFLAGS="$CPPFLAGS $extra_CPPFLAGS -Wa,--noexecstack -Werror"
 AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM()], [
 		extra_CPPFLAGS="$extra_CPPFLAGS -Wa,--noexecstack"
 		AC_MSG_RESULT([yes])
 	], [AC_MSG_RESULT([no])],
 )
 CPPFLAGS="$save_CPPFLAGS"

 # Check for required LDFLAGS availability
 AC_MSG_CHECKING(whether linker supports hardening options)
 LDFLAGS="$LDFLAGS $extra_LDFLAGS -Wl,-z,relro,-z,now"
 AC_LINK_IFELSE(
 	[AC_LANG_PROGRAM()], [
 		extra_LDFLAGS="$extra_LDFLAGS -Wl,-z,relro,-z,now"
 		AC_MSG_RESULT([yes])
 	], [AC_MSG_RESULT([no])],
 )
 LDFLAGS="$save_LDFLAGS"

 # Check for definition of max hostname length
 AC_CHECK_DECL(
 	[HOST_NAME_MAX], [], [AC_DEFINE([HOST_NAME_MAX], [64], [
 		Maximum supported hostname size if not already defined by OS.
 	])], [#include <limits.h>],
 )

 # Update flags.
 CFLAGS="$CFLAGS $extra_CFLAGS"
 CPPFLAGS="$CPPFLAGS $extra_CPPFLAGS"
 LDFLAGS="$LDFLAGS $extra_LDFLAGS"

 case "$host" in
 *-*-cygwin*)
 	# We can't generate dynamic libraries on cygwin since openssh only builds a static libssh.
 	AS_VAR_IF([enable_shared], [yes], [
 		AC_DISABLE_SHARED AC_MSG_WARN([Only static libraries can be buit using cygwin])
 		], [],
 	)
   ;;
 esac

 # Checks for OpenSSH sources
 AC_ARG_WITH(
 	[opensshdir], [AS_HELP_STRING(
 		[--with-opensshdir=DIR], [OpenSSH source directory],
 	)], [opensshdir=$withval], [AC_MSG_ERROR([
 		unable to find the OpenSSH sources. Set --with-opensshdir=<path to OpenSSH sources>
 	])],
 )

 # Update flags with OpenSSH location
 CFLAGS="$CFLAGS -I$opensshdir"
 LDFLAGS="$LDFLAGS -L$opensshdir -L$opensshdir/openbsd-compat"

 # Check for OpenSSH use of OpenSSL
 AC_MSG_CHECKING(whether OpenSSH is configured with OpenSSL)
 AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM([
 		#include "$opensshdir/config.h"
 	], [
 		#ifdef WITH_OPENSSL
 		#if WITH_OPENSSL != 0
 		#error 1
 		#endif
 		#endif
 	])], [
 		need_openssl=false
 		AC_MSG_RESULT([no])
 	], [
 		need_openssl=true
 		AC_MSG_RESULT([yes])
 	],
 )
 AM_CONDITIONAL([NEED_OPENSSL], [test "x$need_openssl" = xtrue])

 # Checks for optional OpenSSL sources
 AC_ARG_WITH(
 	[openssldir], [AS_HELP_STRING(
 		[--with-openssldir=DIR], [OpenSSL source directory],
 	)], [openssldir=$withval], [],
 )
 AM_CONDITIONAL([OPENSSLDIR], [test "x$openssldir" != x])

 # Maybe checks for OpenSSL library.
 # First in openssldir if provided, then in sysroot.
 AM_COND_IF(
 	[NEED_OPENSSL], [
 		# Check whether user specified a custom location:
 		AC_MSG_CHECKING(whether custom OpenSSL folder is set)
 		AM_COND_IF(
 			[OPENSSLDIR], [
 				CFLAGS="$CFLAGS -I$openssldir/include"
 				LDFLAGS="$LDFLAGS -L$openssldir"
 				AC_MSG_RESULT(yes)
 			], [
 				AC_MSG_RESULT(no)
 			],
 		)
 		# In case of static libcrypto, we need explicit linking.
 		AC_MSG_CHECKING(whether OpenSSL requires explicit linking)
 		for l in '' '-ldl' '-lpthread' '-ldl -lpthread'; do
 			LIBS="-lcrypto $l"
 			AC_LINK_IFELSE(
 				[AC_LANG_CALL([], [RSA_new])], [
 					libcrypto_LIBS=$l
 					break
 				], [],
 			)
 		done
 		LIBS="$save_LIBS"

 		if test "x$libcrypto_LIBS" = x; then
 			AC_MSG_RESULT(no)
 		else
 			AC_MSG_RESULT($libcrypto_LIBS)
 		fi

 		# Add the OpenSSL library.
 		AC_SEARCH_LIBS(
 			[RSA_new], [crypto], [], [
 				AC_MSG_ERROR([unable to find a working OpenSSL library])
 			], [$libcrypto_LIBS])
 		LIBS="$LIBS $libcrypto_LIBS"
 	], [],
 )

 # Checks for Zlib library
 AC_ARG_ENABLE(
 	[extension-compression], [AS_HELP_STRING(
 		[--enable-extension-compression], [enable extension compression support],
 	)], [zlib=$enableval], [zlib=yes])
 AM_CONDITIONAL([WANT_ZLIB], [test "x$zlib" = xyes])

 AC_ARG_WITH(
 	[zlibdir], [AS_HELP_STRING(
 		[--with-zlibdir=DIR], [path to source directory],
 	)], [zlibdir=$withval], [zlibdir=])
 AM_CONDITIONAL([CUSTOM_ZLIB], [test "x$zlibdir" != x])

 # If we want Zlib, we need to sources and libraries available
 AC_MSG_CHECKING(for compressed extensions support)
 AM_COND_IF(
 	[WANT_ZLIB], [
 		AC_DEFINE([WITH_EXTENSION_COMPRESSION], [1], [
 			Define to 1 if you have support for extension compression.
 		])
 		AC_MSG_RESULT(yes)
 		AM_COND_IF(
 			[CUSTOM_ZLIB], [
 				LIBS="$LIBS -lz"
 				CFLAGS="$CFLAGS -I$zlibdir"
 				LDFLAGS="$LDFLAGS -L$zlibdir"

 				AC_MSG_CHECKING(for zlib.h)
 				AC_COMPILE_IFELSE(
 					[AC_LANG_PROGRAM([#include "zlib.h"], [])], [
 						AC_MSG_RESULT([yes])
 					], [
 						AC_MSG_ERROR([missing from custom directory $zlibdir])])

 				AC_MSG_CHECKING(for library containing inflate)
 				AC_LINK_IFELSE(
 					[AC_LANG_CALL([], [inflate])], [
 						AC_MSG_RESULT(yes)
 					], [
 						AC_MSG_ERROR([no, make sure to compile it in $zlibdir])
 					])
 			], [
 				AC_CHECK_HEADER([zlib.h], , [
 					AC_MSG_ERROR([Missing zlib.h, please install it to sysroot or use --with-zlibdir=path]),
 				])
 				AC_SEARCH_LIBS(
 					[inflate], [z], [], [
 						AC_MSG_ERROR([unable to find a working zlib library])
 					])
 			],
 		)
 	], [
 		AC_MSG_RESULT(no)
 	])

 # Checks for OpenBSD compat library (part of OpenSSH).
 AC_SEARCH_LIBS([ssh_get_progname], [openbsd-compat], [], [
 	AC_MSG_ERROR([/!\ Make sure to configure and build OpenSSH before HIBA.])],
 )

 # Checks for OpenSSH compat library.
 AC_SEARCH_LIBS([sshbuf_new], [ssh], [], [
 	AC_MSG_ERROR([/!\ Make sure to configure and build OpenSSH before HIBA.])],
 )
 AC_SUBST([extra_LIBS], [$LIBS])
 LIBS="$save_LIBS"

 # Checks for header files.
 AC_CHECK_HEADERS([inttypes.h limits.h stdint.h stdlib.h string.h sys/types.h unistd.h])

 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_INLINE
 AC_TYPE_SIZE_T

 # Checks for library functions.
 AC_CHECK_FUNCS([gethostname memset strdup strerror strspn strtol])

 AC_CONFIG_FILES([Makefile])
 AC_OUTPUT

 # Print configuration summary
 echo ""
 echo "HIBA has been configure with the following options:"
 echo ""
 echo "              Host: $host"
 echo "          Compiler: $CC"
 echo "    Compiler flags: $CFLAGS"
 echo "Preprocessor flags: $CPPFLAGS"
 echo "            Linker: $LD"
 echo "      Linker flags: $LDFLAGS"
 echo "         Libraries: $LIBS $extra_LIBS"
 echo "    Shared library: $enable_shared"
 echo "    Static library: $enable_static"
	# Copyright (c) 2020 The HIBA Authors All rights reserved.
	# Use of this source code is governed by a BSD-style
	# license that can be found in the LICENSE file.
	m4_define([MAJOR], 1)
	m4_define([MINOR], 2)

	AC_PREREQ([2.69])
	AC_INIT([HIBA], [MAJOR.MINOR], [hibassh@google.com])
	AC_CONFIG_SRCDIR([hiba.h])
	AC_CONFIG_HEADERS([config.h])
	AC_CONFIG_MACRO_DIRS([m4])
	AC_LANG([C])
	AC_PROG_CC([cc gcc clang])

	LT_INIT

	AM_INIT_AUTOMAKE([foreign no-dependencies])
	AM_SILENT_RULES([yes])

	# Values for SONAME. See -version-info for details.
	AC_SUBST(SONAME_CURRENT, 0)
	AC_SUBST(SONAME_REVISION, 0)
	AC_SUBST(SONAME_AGE, 0)

	save_CFLAGS="$CFLAGS"
	save_CPPFLAGS="$CPPFLAGS"
	save_LDFLAGS="$LDFLAGS"
	save_LIBS="$LIBS"

	# Check for required CFLAGS & CPPFLAGS availability
	for f in -fstack-protector-strong -fstack-protector-all -fstack-protector; do
	AC_MSG_CHECKING(whether $CC supports $f options)
	CFLAGS="$CFLAGS $extra_CFLAGS $f -Werror"
	LDFLAGS="$LDFLAGS $extra_LDFLAGS $f"
	AC_LINK_IFELSE(
	[AC_LANG_PROGRAM()], [
	extra_LDFLAGS="$extra_LDFLAGS $f"
	extra_CFLAGS="$extra_CFLAGS $f"
	AC_MSG_RESULT([yes])
	break
	], [AC_MSG_RESULT([no])],
	)
	# Restore CFLAGS & LDFLAGS in the loop as options are exclusive.
	LDFLAGS="$save_LDFLAGS"
	CFLAGS="$save_CFLAGS"
	done

	for f in -fpie -fPIE -fpic -fPIC; do
	AC_MSG_CHECKING(whether compiler supports $f)
	CFLAGS="$CFLAGS $extra_CFLAGS $f -Werror"
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM()], [
	extra_CFLAGS="$extra_CFLAGS $f"
	AC_MSG_RESULT([yes])
	break
	], [AC_MSG_RESULT([no])],
	)
	# Restore CFLAGS in the loop as options are exclusive.
	CFLAGS="$save_CFLAGS"
	done

	for f in -ansi -Wall -Wextra -Werror -Wno-attributes -Wno-unused-parameter -Wformat-security -Wuninitialized; do
	AC_MSG_CHECKING(whether $CC supports $f options)
	CFLAGS="$CFLAGS $extra_CFLAGS $f"
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM()], [
	extra_CFLAGS="$extra_CFLAGS $f"
	AC_MSG_RESULT([yes])
	], [AC_MSG_RESULT([no])],
	)
	done
	CFLAGS="$save_CFLAGS"

	AC_MSG_CHECKING(whether preprocessor supports _DEFAULT_SOURCE)
	CPPFLAGS="$CPPFLAGS $extra_CPPFLAGS -D_DEFAULT_SOURCE"
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM()], [
	extra_CPPFLAGS="$extra_CPPFLAGS -D_DEFAULT_SOURCE"
	AC_MSG_RESULT([yes])
	], [AC_MSG_ERROR([no])],
	)
	CPPFLAGS="$save_CPPFLAGS"

	AC_MSG_CHECKING(whether preprocessor supports _FORTIFY_SOURCE)
	CPPFLAGS="$CPPFLAGS $extra_CPPFLAGS -D_FORTIFY_SOURCE=2"
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM()], [
	extra_CPPFLAGS="$extra_CPPFLAGS -D_FORTIFY_SOURCE=2"
	AC_MSG_RESULT([yes])
	], [AC_MSG_RESULT([no])],
	)
	CPPFLAGS="$save_CPPFLAGS"

	AC_MSG_CHECKING(whether compiler supports no-strict-aliasing option)
	CFLAGS="$CFLAGS $extra_CFLAGS -fno-strict-aliasing -Werror"
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM()], [
	extra_CFLAGS="$extra_CFLAGS -fno-strict-aliasing"
	AC_MSG_RESULT([yes])
	], [AC_MSG_RESULT([no])],
	)
	CFLAGS="$save_CFLAGS"

	AC_MSG_CHECKING(whether compiler supports hardening options)
	CPPFLAGS="$CPPFLAGS $extra_CPPFLAGS -Wa,--noexecstack -Werror"
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM()], [
	extra_CPPFLAGS="$extra_CPPFLAGS -Wa,--noexecstack"
	AC_MSG_RESULT([yes])
	], [AC_MSG_RESULT([no])],
	)
	CPPFLAGS="$save_CPPFLAGS"

	# Check for required LDFLAGS availability
	AC_MSG_CHECKING(whether linker supports hardening options)
	LDFLAGS="$LDFLAGS $extra_LDFLAGS -Wl,-z,relro,-z,now"
	AC_LINK_IFELSE(
	[AC_LANG_PROGRAM()], [
	extra_LDFLAGS="$extra_LDFLAGS -Wl,-z,relro,-z,now"
	AC_MSG_RESULT([yes])
	], [AC_MSG_RESULT([no])],
	)
	LDFLAGS="$save_LDFLAGS"

	# Check for definition of max hostname length
	AC_CHECK_DECL(
	[HOST_NAME_MAX], [], [AC_DEFINE([HOST_NAME_MAX], [64], [
	Maximum supported hostname size if not already defined by OS.
	])], [#include <limits.h>],
	)

	# Update flags.
	CFLAGS="$CFLAGS $extra_CFLAGS"
	CPPFLAGS="$CPPFLAGS $extra_CPPFLAGS"
	LDFLAGS="$LDFLAGS $extra_LDFLAGS"

	case "$host" in
	--cygwin*)
	# We can't generate dynamic libraries on cygwin since openssh only builds a static libssh.
	AS_VAR_IF([enable_shared], [yes], [
	AC_DISABLE_SHARED AC_MSG_WARN([Only static libraries can be buit using cygwin])
	], [],
	)
	;;
	esac

	# Checks for OpenSSH sources
	AC_ARG_WITH(
	[opensshdir], [AS_HELP_STRING(
	[--with-opensshdir=DIR], [OpenSSH source directory],
	)], [opensshdir=$withval], [AC_MSG_ERROR([
	unable to find the OpenSSH sources. Set --with-opensshdir=<path to OpenSSH sources>
	])],
	)

	# Update flags with OpenSSH location
	CFLAGS="$CFLAGS -I$opensshdir"
	LDFLAGS="$LDFLAGS -L$opensshdir -L$opensshdir/openbsd-compat"

	# Check for OpenSSH use of OpenSSL
	AC_MSG_CHECKING(whether OpenSSH is configured with OpenSSL)
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM([
	#include "$opensshdir/config.h"
	], [
	#ifdef WITH_OPENSSL
	#if WITH_OPENSSL != 0
	#error 1
	#endif
	#endif
	])], [
	need_openssl=false
	AC_MSG_RESULT([no])
	], [
	need_openssl=true
	AC_MSG_RESULT([yes])
	],
	)
	AM_CONDITIONAL([NEED_OPENSSL], [test "x$need_openssl" = xtrue])

	# Checks for optional OpenSSL sources
	AC_ARG_WITH(
	[openssldir], [AS_HELP_STRING(
	[--with-openssldir=DIR], [OpenSSL source directory],
	)], [openssldir=$withval], [],
	)
	AM_CONDITIONAL([OPENSSLDIR], [test "x$openssldir" != x])

	# Maybe checks for OpenSSL library.
	# First in openssldir if provided, then in sysroot.
	AM_COND_IF(
	[NEED_OPENSSL], [
	# Check whether user specified a custom location:
	AC_MSG_CHECKING(whether custom OpenSSL folder is set)
	AM_COND_IF(
	[OPENSSLDIR], [
	CFLAGS="$CFLAGS -I$openssldir/include"
	LDFLAGS="$LDFLAGS -L$openssldir"
	AC_MSG_RESULT(yes)
	], [
	AC_MSG_RESULT(no)
	],
	)
	# In case of static libcrypto, we need explicit linking.
	AC_MSG_CHECKING(whether OpenSSL requires explicit linking)
	for l in '' '-ldl' '-lpthread' '-ldl -lpthread'; do
	LIBS="-lcrypto $l"
	AC_LINK_IFELSE(
	[AC_LANG_CALL([], [RSA_new])], [
	libcrypto_LIBS=$l
	break
	], [],
	)
	done
	LIBS="$save_LIBS"

	if test "x$libcrypto_LIBS" = x; then
	AC_MSG_RESULT(no)
	else
	AC_MSG_RESULT($libcrypto_LIBS)
	fi

	# Add the OpenSSL library.
	AC_SEARCH_LIBS(
	[RSA_new], [crypto], [], [
	AC_MSG_ERROR([unable to find a working OpenSSL library])
	], [$libcrypto_LIBS])
	LIBS="$LIBS $libcrypto_LIBS"
	], [],
	)

	# Checks for Zlib library
	AC_ARG_ENABLE(
	[extension-compression], [AS_HELP_STRING(
	[--enable-extension-compression], [enable extension compression support],
	)], [zlib=$enableval], [zlib=yes])
	AM_CONDITIONAL([WANT_ZLIB], [test "x$zlib" = xyes])

	AC_ARG_WITH(
	[zlibdir], [AS_HELP_STRING(
	[--with-zlibdir=DIR], [path to source directory],
	)], [zlibdir=$withval], [zlibdir=])
	AM_CONDITIONAL([CUSTOM_ZLIB], [test "x$zlibdir" != x])

	# If we want Zlib, we need to sources and libraries available
	AC_MSG_CHECKING(for compressed extensions support)
	AM_COND_IF(
	[WANT_ZLIB], [
	AC_DEFINE([WITH_EXTENSION_COMPRESSION], [1], [
	Define to 1 if you have support for extension compression.
	])
	AC_MSG_RESULT(yes)
	AM_COND_IF(
	[CUSTOM_ZLIB], [
	LIBS="$LIBS -lz"
	CFLAGS="$CFLAGS -I$zlibdir"
	LDFLAGS="$LDFLAGS -L$zlibdir"

	AC_MSG_CHECKING(for zlib.h)
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM([#include "zlib.h"], [])], [
	AC_MSG_RESULT([yes])
	], [
	AC_MSG_ERROR([missing from custom directory $zlibdir])])

	AC_MSG_CHECKING(for library containing inflate)
	AC_LINK_IFELSE(
	[AC_LANG_CALL([], [inflate])], [
	AC_MSG_RESULT(yes)
	], [
	AC_MSG_ERROR([no, make sure to compile it in $zlibdir])
	])
	], [
	AC_CHECK_HEADER([zlib.h], , [
	AC_MSG_ERROR([Missing zlib.h, please install it to sysroot or use --with-zlibdir=path]),
	])
	AC_SEARCH_LIBS(
	[inflate], [z], [], [
	AC_MSG_ERROR([unable to find a working zlib library])
	])
	],
	)
	], [
	AC_MSG_RESULT(no)
	])

	# Checks for OpenBSD compat library (part of OpenSSH).
	AC_SEARCH_LIBS([ssh_get_progname], [openbsd-compat], [], [
	AC_MSG_ERROR([/!\ Make sure to configure and build OpenSSH before HIBA.])],
	)

	# Checks for OpenSSH compat library.
	AC_SEARCH_LIBS([sshbuf_new], [ssh], [], [
	AC_MSG_ERROR([/!\ Make sure to configure and build OpenSSH before HIBA.])],
	)
	AC_SUBST([extra_LIBS], [$LIBS])
	LIBS="$save_LIBS"

	# Checks for header files.
	AC_CHECK_HEADERS([inttypes.h limits.h stdint.h stdlib.h string.h sys/types.h unistd.h])

	# Checks for typedefs, structures, and compiler characteristics.
	AC_C_INLINE
	AC_TYPE_SIZE_T

	# Checks for library functions.
	AC_CHECK_FUNCS([gethostname memset strdup strerror strspn strtol])

	AC_CONFIG_FILES([Makefile])
	AC_OUTPUT

	# Print configuration summary
	echo ""
	echo "HIBA has been configure with the following options:"
	echo ""
	echo " Host: $host"
	echo " Compiler: $CC"
	echo " Compiler flags: $CFLAGS"
	echo "Preprocessor flags: $CPPFLAGS"
	echo " Linker: $LD"
	echo " Linker flags: $LDFLAGS"
	echo " Libraries: $LIBS $extra_LIBS"
	echo " Shared library: $enable_shared"
	echo " Static library: $enable_static"