configure.ac

#                                               -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.

AC_PREREQ([2.61])
AC_INIT([mosh], [1.4.0], [mosh-devel@mit.edu])
AM_INIT_AUTOMAKE([foreign std-options -Wall -Werror -Wno-portability])
m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
AC_CONFIG_SRCDIR([src/frontend/mosh-client.cc])
AC_CONFIG_MACRO_DIR([m4])
AC_CONFIG_HEADERS([src/include/config.h])
AC_LANG([C++])
AX_CODE_COVERAGE

# Checks for programs.
AC_PROG_CC([cc gcc clang])
AC_PROG_CXX([c++ g++ clang++])
AC_PROG_RANLIB
AC_PATH_PROG([PROTOC], [protoc], [])
AS_IF([test x"$PROTOC" = x],
  [AC_MSG_ERROR([cannot find protoc, the Protocol Buffers compiler])])

# automake 1.12 seems to require this, but automake 1.11 doesn't recognize it
m4_ifdef([AM_PROG_AR], [AM_PROG_AR])

# Protobuf transitively requires at least C++14, get ahead of the
# curve and require at least C++17.
AX_CXX_COMPILE_STDCXX([17])

WARNING_CXXFLAGS=""
PICKY_CXXFLAGS=""
DISTCHECK_CXXFLAGS=""
AC_ARG_ENABLE([compile-warnings],
  [AS_HELP_STRING([--enable-compile-warnings@<:@=no/yes/maximum/error/distcheck@:>@],
     [Turn on compiler warnings])],
  [case "$enableval" in
     no)
       ;;
     '' | yes)
       WARNING_CXXFLAGS="-Wall"
       ;;
     maximum)
       WARNING_CXXFLAGS="-Wall"
       PICKY_CXXFLAGS="-Wextra -pedantic -Wno-long-long -Weffc++ -Wmissing-declarations"
       ;;
     error)
       # remove -Wno-c++17-extensions once protocolbuffers/protobuf#9181 is
       # resolved
       # remove -Wno-unused-parameter once
       # protocolbuffers/protobuf#10357 is resolved       
       WARNING_CXXFLAGS="-Wall -Werror -Wno-c++17-extensions"
       PICKY_CXXFLAGS="-Wextra -pedantic -Wno-long-long -Weffc++ -Wmissing-declarations -Wno-unused-parameter"
       ;;
     distcheck)
       WARNING_CXXFLAGS="-Wall -Werror"
       PICKY_CXXFLAGS="-Wextra -pedantic -Wno-long-long -Weffc++ -Wmissing-declarations"
       AX_CHECK_COMPILE_FLAG([-Wno-error=unused-parameter],
         [PICKY_CXXFLAGS="$PICKY_CXXFLAGS -Wno-error=unused-parameter"], [], [-Werror])
       AX_CHECK_COMPILE_FLAG([-Wno-error=c++11-extensions],
         [PICKY_CXXFLAGS="$PICKY_CXXFLAGS -Wno-error=c++11-extensions"], [], [-Werror])
       AX_CHECK_COMPILE_FLAG([-Wno-error=deprecated-declarations],
         [PICKY_CXXFLAGS="$PICKY_CXXFLAGS -Wno-error=deprecated-declarations"], [], [-Werror])
       AX_CHECK_COMPILE_FLAG([-Wno-error=nested-anon-types],
         [PICKY_CXXFLAGS="$PICKY_CXXFLAGS -Wno-error=nested-anon-types"], [], [-Werror])
       ;;
     *)
       AC_MSG_ERROR([Unknown argument '$enableval' to --enable-compile-warnings])
       ;;
   esac],
  [WARNING_CXXFLAGS="-Wall"])
AC_SUBST([WARNING_CXXFLAGS])
AC_SUBST([PICKY_CXXFLAGS])

# Check for fuzzing support before the flag wrapper, because if
# requested and missing the functionality is entirely nonexistent.
MISC_CXXFLAGS=""
AC_ARG_ENABLE([fuzzing],
  [AS_HELP_STRING([--enable-fuzzing],
    [Enable compiler and linker options to enable fuzz testing @<:@no/yes/libfuzzer@:>@])],
  [fuzzing="$enableval"
   case "$enableval" in
    no)
      ;;
    '' | yes | libfuzzer)
      AX_CHECK_COMPILE_FLAG([-fsanitize=fuzzer],
        [FUZZING_CFLAGS="$FUZZING_CFLAGS -fsanitize=fuzzer"], [
        AC_MSG_ERROR([Fuzzing requested, but compiler support not present])], [-Werror])
      ;;
    *)
     AC_MSG_ERROR(["Unknown argument '$enableval' to --enable-fuzzing])
     ;;
  esac],
  [fuzzing="no"])
AC_SUBST([FUZZING_CFLAGS])
AC_SUBST([MISC_CXXFLAGS])
AM_CONDITIONAL([ENABLE_FUZZING], [test x"$fuzzing" != xno])

AC_ARG_ENABLE([asan],
  [AS_HELP_STRING([--enable-asan],
    [Enable compiler and linker options to enable AddressSanitizer @<:@no@:>@])],
  [asan="$enableval"],
  [asan="no"])

AS_IF([test x"$asan" != x"no"], [
  AX_CHECK_COMPILE_FLAG([-fsanitize=address,leak],
  [MISC_CXXFLAGS="$MISC_CXXFLAGS -fsanitize=address,leak"], [
  AC_MSG_ERROR([ASAN requested, but compiler support not present])], [-Werror])
])
AC_SUBST([MISC_CXXFLAGS])

# We want to check for compiler flag support, but there is no way to make
# clang's "argument unused" warning fatal.  So we invoke the compiler through a
# wrapper script that greps for this message.

saved_CXX="$CXX"
saved_LD="$LD"
flag_wrap="$srcdir/scripts/wrap-compiler-for-flag-check"
CXX="$flag_wrap $CXX"
LD="$flag_wrap $LD"

AC_DEFUN([check_cxx_flag],
  [AX_CHECK_COMPILE_FLAG([$1], [$2], [$3], [-Werror $4])])
AC_DEFUN([check_link_flag],
  [AX_CHECK_LINK_FLAG([$1], [$2], [$3], [-Werror $4])])

AC_ARG_ENABLE([hardening],
  [AS_HELP_STRING([--enable-hardening],
    [Enable compiler and linker options to frustrate memory corruption exploits @<:@yes@:>@])],
  [hardening="$enableval"],
  [hardening="yes"])

HARDEN_CFLAGS=""
HARDEN_LDFLAGS=""
AS_IF([test x"$hardening" != x"no"], [
  check_cxx_flag([-fno-strict-overflow], [HARDEN_CFLAGS="$HARDEN_CFLAGS -fno-strict-overflow"])

  # This one will likely succeed, even on platforms where it does nothing.
  check_cxx_flag([-D_FORTIFY_SOURCE=2], [HARDEN_CFLAGS="$HARDEN_CFLAGS -D_FORTIFY_SOURCE=2"])

  check_link_flag([-fstack-protector-all],
   [HARDEN_CFLAGS="$HARDEN_CFLAGS -fstack-protector-all"
    check_cxx_flag([-Wstack-protector], [HARDEN_CFLAGS="$HARDEN_CFLAGS -Wstack-protector"],
      [], [-fstack-protector-all])
    check_cxx_flag([--param ssp-buffer-size=1], [HARDEN_CFLAGS="$HARDEN_CFLAGS --param ssp-buffer-size=1"],
      [], [-fstack-protector-all])])

  check_cxx_flag([-fPIE],
   [check_link_flag([-fPIE -pie],
     [HARDEN_CFLAGS="$HARDEN_CFLAGS -fPIE"
      HARDEN_LDFLAGS="$HARDEN_LDFLAGS -pie"],
     [check_link_flag([-fPIE -Wl,-pie],
       [HARDEN_CFLAGS="$HARDEN_CFLAGS -fPIE"
        HARDEN_LDFLAGS="$HARDEN_LDFLAGS -Wl,-pie"])])])

  check_link_flag([-Wl,-z,relro],
   [HARDEN_LDFLAGS="$HARDEN_LDFLAGS -Wl,-z,relro"
    check_link_flag([-Wl,-z,now], [HARDEN_LDFLAGS="$HARDEN_LDFLAGS -Wl,-z,now"])])])
AC_SUBST([HARDEN_CFLAGS])
AC_SUBST([HARDEN_LDFLAGS])

# Also check for a few non-hardening-related flags.
AX_CHECK_COMPILE_FLAG([-fno-default-inline],
  [MISC_CXXFLAGS="$MISC_CXXFLAGS -fno-default-inline"], [], [-Werror])
AX_CHECK_COMPILE_FLAG([-pipe],
  [MISC_CXXFLAGS="$MISC_CXXFLAGS -pipe"], [], [-Werror])
AC_SUBST([MISC_CXXFLAGS])

# End of flag tests.
CXX="$saved_CXX"
LD="$saved_LD"

AC_ARG_ENABLE([client],
  [AS_HELP_STRING([--enable-client], [Build the mosh-client program @<:@yes@:>@])],
  [build_client="$enableval"],
  [build_client="yes"])
AM_CONDITIONAL([BUILD_CLIENT], [test x"$build_client" != xno])

AC_ARG_ENABLE([server],
  [AS_HELP_STRING([--enable-server], [Build the mosh-server program @<:@yes@:>@])],
  [build_server="$enableval"],
  [build_server="yes"])
AM_CONDITIONAL([BUILD_SERVER], [test x"$build_server" != xno])

AC_ARG_ENABLE([examples],
  [AS_HELP_STRING([--enable-examples], [Build the miscellaneous programs in src/examples @<:@no@:>@])],
  [build_examples="$enableval"],
  [build_examples="no"])
AM_CONDITIONAL([BUILD_EXAMPLES], [test x"$build_examples" != xno])

AC_ARG_ENABLE([ufw],
  [AS_HELP_STRING([--enable-ufw], [Install firewall profile for ufw (Uncomplicated Firewall) @<:@no@:>@])],
  [install_ufw="$enableval"],
  [install_ufw="no"])
AM_CONDITIONAL([INSTALL_UFW], [test x"$install_ufw" != xno])

AC_ARG_ENABLE([completion],
  [AS_HELP_STRING([--enable-completion], [Install bash_completion rule @<:@no@:>@])],
  [install_completion="$enableval"],
  [install_completion="no"])
AM_CONDITIONAL([INSTALL_COMPLETION], [test x"$install_completion" != xno])

AC_ARG_ENABLE([syslog],
  [AS_HELP_STRING([--enable-syslog], [Enable connection logging in mosh-server @<:@no@:>@])],
  [enable_syslog="$enableval"],
  [enable_syslog="no"])
AS_IF([test x"$enable_syslog" != xno],
  [AC_CHECK_HEADERS([syslog.h],
    [AC_DEFINE([HAVE_SYSLOG], [1], [Define if syslog is available.])],
    [AS_IF([test x"$enable_syslog" = xcheck],
      [AC_MSG_WARN([Unable to find syslog.h.])],
      [AC_MSG_ERROR([--enable-syslog was given but syslog.h was not found.])])])])

AC_ARG_ENABLE([agent-forwarding],
  [AS_HELP_STRING([--enable-agent-forwarding], [Enable support for SSH agent forwarding @<:@yes@:>@])],
  [enable_agent_forwarding="$enableval"],
  [enable_agent_forwarding="yes"])
AS_IF([test x"$enable_agent_forwarding" != xno],
  [AC_DEFINE([SUPPORT_AGENT_FORWARDING], [1], [Define to build support for SSH agent forwarding.])])

# Checks for libraries.
AC_ARG_ENABLE([static-libraries],
  [AS_HELP_STRING([--enable-static-libraries], [Enable all static linking options below @<:@no@:>@])])

AC_ARG_ENABLE([static-libstdc++],
  [AS_HELP_STRING([--enable-static-libstdc++], [Link libstdc++ statically @<:@no@:>@])],
  [], [enable_static_libstdc__="$enable_static_libraries"])
AS_IF([test "$enable_static_libstdc__" = yes],
  [LDFLAGS="$LDFLAGS -static-libstdc++"])

AC_ARG_ENABLE([static-libgcc],
  [AS_HELP_STRING([--enable-static-libgcc], [Link libgcc statically @<:@no@:>@])],
  [], [enable_static_libgcc="$enable_static_libraries"])
AS_IF([test "$enable_static_libgcc" = yes],
  [LDFLAGS="$LDFLAGS -static-libgcc"])

AC_ARG_WITH([utempter],
  [AS_HELP_STRING([--with-utempter], [write utmp entries using libutempter @<:@check@:>@])],
  [with_utempter="$withval"],
  [with_utempter="check"])
AC_ARG_ENABLE([static-utempter],
  [AS_HELP_STRING([--enable-static-utempter], [Link utempter statically @<:@no@:>@])],
  [], [enable_static_utempter="$enable_static_libraries"])
AS_IF([test x"$with_utempter" != xno],
  [AC_CHECK_LIB([utempter], [utempter_remove_record],
    [UTEMPTER_LIBS=-lutempter
     AS_IF([test "$enable_static_utempter" = yes],
       [UTEMPTER_LIBS="-Wl,-Bstatic $UTEMPTER_LIBS -Wl,-Bdynamic"])
     LIBS="$UTEMPTER_LIBS $LIBS"
     AC_DEFINE([HAVE_UTEMPTER], [1], [Define if libutempter is available.])],
    [AS_IF([test x"$with_utempter" = xcheck],
      [AC_MSG_WARN([Unable to find libutempter; utmp entries will not be made.])],
      [AC_MSG_ERROR([--with-utempter was given but libutempter was not found.])])])])

AC_ARG_ENABLE([static-zlib],
  [AS_HELP_STRING([--enable-static-zlib], [Link zlib statically @<:@no@:>@])],
  [], [enable_static_zlib="$enable_static_libraries"])
AC_CHECK_LIB([z], [compress],
  [ZLIB_LIBS=-lz
   AS_IF([test "$enable_static_zlib" = yes],
     [ZLIB_LIBS="-Wl,-Bstatic $ZLIB_LIBS -Wl,-Bdynamic"])
   LIBS="$ZLIB_LIBS $LIBS"],
  [AC_MSG_ERROR([Unable to find zlib.])])

AC_SEARCH_LIBS([socket], [socket network])
AC_SEARCH_LIBS([inet_addr], [nsl])

AC_SEARCH_LIBS([clock_gettime], [rt])

# Checks for header files.
AC_CHECK_HEADERS(m4_normalize([
  errno.h
  fcntl.h
  langinfo.h
  limits.h
  locale.h
  netdb.h
  netinet/in.h
  stddef.h
  stdint.h
  inttypes.h
  stdlib.h
  string.h
  sys/ioctl.h
  sys/resource.h
  sys/socket.h
  sys/stat.h
  sys/time.h
  termios.h
  unistd.h
  wchar.h
  wctype.h
  ]), [], [AC_MSG_ERROR([Missing required header file.])])

AC_CHECK_HEADERS([pty.h util.h libutil.h paths.h])
AC_CHECK_HEADERS([endian.h sys/endian.h])
AC_CHECK_HEADERS([utmpx.h])
AC_CHECK_HEADERS([termio.h])
AC_CHECK_HEADERS([sys/uio.h])
AC_CHECK_HEADERS([sys/un.h])
AC_CHECK_HEADERS([sys/types.h])
AC_CHECK_HEADERS([memory tr1/memory])

# Checks for typedefs, structures, and compiler characteristics.
AC_C_INLINE
AC_TYPE_INT64_T
AC_TYPE_PID_T
AC_C_RESTRICT
AC_TYPE_SIZE_T
AC_TYPE_SSIZE_T
AC_TYPE_UINT16_T
AC_TYPE_UINT32_T
AC_TYPE_UINT64_T
AC_TYPE_UINT8_T
AC_TYPE_UINTPTR_T

# Checks for library functions.
AC_CHECK_FUNCS(m4_normalize([
  gettimeofday
  posix_memalign
  cfmakeraw
  pselect
  pledge
  ]))

# Start by trying to find the needed tinfo parts by pkg-config
PKG_CHECK_MODULES([TINFO], [tinfo],
  [AC_DEFINE([HAVE_CURSES_H], [1], [Define to 1 if <curses.h> is present])],
  [PKG_CHECK_MODULES([TINFO], [ncurses],
    [AC_DEFINE([HAVE_CURSES_H], [1], [Define to 1 if <curses.h> is present])],
    [AX_CHECK_LIBRARY([TINFO], [curses.h], [tinfo],
      [AC_DEFINE([HAVE_CURSES_H], [1], [Define to 1 if <curses.h> is present])
        AC_SUBST([TINFO_CFLAGS], ["$TINFO_CPPFLAGS"])
        AC_SUBST([TINFO_LIBS], ["$TINFO_LDFLAGS -ltinfo"])],)])])

# Then try to find it in a specific install dir
AC_ARG_WITH(curses, [AS_HELP_STRING([--with-curses=DIR], [Where curses is installed])],
    [if test $withval != yes; then
        cv_curses=$withval
    fi
    if test x$cv_curses != x/usr; then
        CURSES_LDFLAGS="-L${cv_curses}/lib"
        CURSES_CPPFLAGS="-I${cv_curses}/include"
    fi])

if test "x$ax_cv_have_TINFO" = xno ; then
    # save away old LDFLAGS/CPPFLAGS and check for curses with cv_curses
    old_LDFLAGS="$LDFLAGS"
    old_CPPFLAGS="$CPPFLAGS"
    LDFLAGS="$LDFLAGS $CURSES_LDFLAGS"
    CPPFLAGS="$CPPFLAGS $CURSES_CPPFLAGS"

    AX_WITH_CURSES
    # restore old LDFLAGS/CPPFLAGS
    LDFLAGS="$old_LDFLAGS"
    CPPFLAGS="$old_CPPFLAGS"

    if test "x$ax_cv_curses_which" = xno ; then
        AC_MSG_ERROR([requires either tinfo, NcursesW or Ncurses library])
    else
        AC_SUBST([TINFO_LIBS], ["$CURSES_LDFLAGS $CURSES_LIB"])
        AC_SUBST([TINFO_CFLAGS], ["$CURSES_CPPFLAGS"])
    fi
fi

AC_ARG_ENABLE([static-curses],
  [AS_HELP_STRING([--enable-static-curses], [Link curses statically @<:@no@:>@])],
  [], [enable_static_curses="$enable_static_libraries"])
AS_IF([test "$enable_static_curses" = yes],
  [TINFO_LIBS="-Wl,-Bstatic $TINFO_LIBS -Wl,-Bdynamic"])

dnl Default to OpenSSL, or OS X crypto library if found
AC_CHECK_HEADERS([CommonCrypto/CommonCrypto.h],
  [default_crypto_library="apple-common-crypto"],
  [default_crypto_library="openssl"]
)

dnl Allow user to select over the default.
AC_ARG_WITH(
  [crypto-library],
  [AS_HELP_STRING([--with-crypto-library=library], [build with the given crypto library, TYPE=openssl|nettle|apple-common-crypto @<:@default=openssl@:>@])],
  [
    case "${withval}" in
      openssl|openssl-with-internal-ocb|openssl-with-openssl-ocb|nettle|apple-common-crypto) ;;
      *) AC_MSG_ERROR([bad value ${withval} for --with-crypto-library]) ;;
    esac
  ],
  [with_crypto_library="$default_crypto_library"]
)

dnl Checks for chosen crypto library
PKG_CHECK_MODULES([OpenSSL], [openssl],
  [have_openssl=yes
    AC_CHECK_LIB([crypto], [AES_encrypt], [have_deprecated_openssl_aes=yes])
    AC_CHECK_LIB([crypto], [EVP_aes_128_ocb], [have_evp_aes_ocb=yes])],
  [:])
PKG_CHECK_MODULES([Nettle], [nettle], [have_nettle=yes], [:])
AS_CASE([$with_crypto_library],
  [openssl*],
    [AS_IF([test "x$have_openssl" != xyes],
       [AC_MSG_ERROR([OpenSSL crypto library not found])])
     AC_DEFINE([USE_OPENSSL_AES], [1], [Use OpenSSL library])
     AC_SUBST([CRYPTO_CFLAGS], ["$OpenSSL_CFLAGS"])
     AC_SUBST([CRYPTO_LIBS], ["$OpenSSL_LIBS -lcrypto"])])
case "${with_crypto_library}" in
  openssl|openssl-with-internal-ocb)
    AS_IF([test "x$have_deprecated_openssl_aes" != xyes],
      [AC_MSG_ERROR([found OpenSSL without AES support])])
    AM_CONDITIONAL([USE_AES_OCB_FROM_OPENSSL], [false])
    human_readable_cryptography_description='internal OCB, OpenSSL AES'
    ;;
  openssl-with-openssl-ocb)
    AS_IF([test "x$have_evp_aes_ocb" != xyes],
      [AC_MSG_ERROR([found OpenSSL without AES-OCB support])])
    AM_CONDITIONAL([USE_AES_OCB_FROM_OPENSSL], [true])
    human_readable_cryptography_description='OpenSSL OCB, OpenSSL AES'
    ;;
  nettle)
    AS_IF([test "x$have_nettle" != xyes],
      [AC_MSG_ERROR([Nettle crypto library not found])])
    AC_DEFINE([USE_NETTLE_AES], [1], [Use Nettle library])
    AC_SUBST([CRYPTO_CFLAGS], ["$Nettle_CFLAGS"])
    AC_SUBST([CRYPTO_LIBS], ["$Nettle_LIBS"])
    AM_CONDITIONAL([USE_AES_OCB_FROM_OPENSSL], [false])
    human_readable_cryptography_description='internal OCB, Nettle AES'
    ;;
  apple-common-crypto)
    AS_IF([test "x$ac_cv_header_CommonCrypto_CommonCrypto_h" != xyes],
      [AC_MSG_ERROR([Apple Common Crypto header not found])])
    AC_DEFINE([USE_APPLE_COMMON_CRYPTO_AES], [1], [Use Apple Common Crypto library])
    AM_CONDITIONAL([USE_AES_OCB_FROM_OPENSSL], [false])
    human_readable_cryptography_description='internal OCB, Apple Common Crypto AES'
    ;;
esac

AC_ARG_ENABLE([static-crypto],
  [AS_HELP_STRING([--enable-static-crypto], [Link crypto library statically @<:@no@:>@])],
  [], [enable_static_crypto="$enable_static_libraries"])
AS_IF([test "$enable_static_crypto" = yes],
  [CRYPTO_LIBS="-Wl,-Bstatic $CRYPTO_LIBS -Wl,-Bdynamic"])

AC_CHECK_DECL([forkpty],
  [AC_DEFINE([FORKPTY_IN_LIBUTIL], [1],
     [Define if libutil.h necessary for forkpty().])],
  , [[#include <sys/types.h>
#include <libutil.h>]])

AC_SEARCH_LIBS([forkpty], [util bsd], [
  AC_DEFINE([HAVE_FORKPTY],, [Define if you have forkpty().])
])

AC_MSG_CHECKING([whether FD_ISSET() argument is const])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/select.h>
class T {
public:
  fd_set fds;
  bool Fun( void ) const { return FD_ISSET( 0, &fds ); } };]],
[[T x = T(); return x.Fun();]])],
  [AC_DEFINE([FD_ISSET_IS_CONST], [1],
     [Define if FD_ISSET() fd_set argument is const.])
   AC_MSG_RESULT([yes])],
  [AC_MSG_RESULT([no])])

AC_MSG_CHECKING([whether std::shared_ptr is available])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <memory>
class T {
public:
  std::shared_ptr<int> Fun( void ) { return std::shared_ptr<int>( new int ( 0 ) ); } };]],
[[T x; return !!x.Fun();]])],
  [AC_DEFINE([HAVE_STD_SHARED_PTR], [1],
     [Define if std::shared_ptr is available.])
   AC_MSG_RESULT([yes])],
  [AC_MSG_RESULT([no])])

AC_MSG_CHECKING([whether std::tr1::shared_ptr is available])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <tr1/memory>
class T {
public:
  std::tr1::shared_ptr<int> Fun( void ) { return std::tr1::shared_ptr<int>( new int ( 0 ) ); } };]],
[[T x; return !!x.Fun();]])],
  [AC_DEFINE([HAVE_STD_TR1_SHARED_PTR], [1],
     [Define if std::tr1::shared_ptr is available.])
   AC_MSG_RESULT([yes])],
  [AC_MSG_RESULT([no])])

AC_MSG_CHECKING([whether clock_gettime() is supported])
AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <time.h>
struct timespec ts;
]], [[return clock_gettime(CLOCK_MONOTONIC, &ts);]])],
  [AC_DEFINE([HAVE_CLOCK_GETTIME], [1],
     [Define if clock_gettime() is available.])
   AC_MSG_RESULT([yes])],
  [AC_MSG_RESULT([no])])

AC_CHECK_DECL([mach_absolute_time],
  [AC_DEFINE([HAVE_MACH_ABSOLUTE_TIME], [1],
     [Define if mach_absolute_time is available.])],
  , [[#include <mach/mach_time.h>]])


AC_CHECK_DECLS([__builtin_ctz])

AC_CHECK_DECLS([ffs], [], [],
  [[#include <strings.h>]])

AC_CHECK_DECLS([be64toh, betoh64, bswap64, __builtin_bswap64], [], [],
  [[#if defined(HAVE_ENDIAN_H)
#include <endian.h>
#elif defined(HAVE_SYS_ENDIAN_H)
#include <sys/types.h>
#include <sys/endian.h>
#endif]])

AS_IF([test x"$ac_cv_have_decl_be64toh" != xyes &&
       test x"$ac_cv_have_decl_betoh64" != xyes],
  [AC_CHECK_DECL([OSSwapHostToBigInt64],
     [AC_DEFINE([HAVE_OSX_SWAP], [1],
        [Define if OSSwapHostToBigInt64 and friends exist.])],
     [AC_MSG_WARN([Unable to find byte swapping functions; using built-in routines.])],
     [[#include <libkern/OSByteOrder.h>]])])

AC_CHECK_DECL([IP_MTU_DISCOVER],
  [AC_DEFINE([HAVE_IP_MTU_DISCOVER], [1],
     [Define if IP_MTU_DISCOVER is a valid sockopt.])],
  , [[#include <netinet/in.h>]])

AC_CHECK_DECL([IP_RECVTOS],
  [AC_DEFINE([HAVE_IP_RECVTOS], [1],
     [Define if IP_RECVTOS is a valid sockopt.])],
  , [[#include <netinet/in.h>]])

AC_CHECK_DECL([__STDC_ISO_10646__],
  [],
  [AC_MSG_WARN([C library doesn't advertise wchar_t is Unicode (OS X works anyway with workaround).])],
  [[#include <wchar.h>]])

AC_CHECK_DECL([IUTF8],
  [AC_DEFINE([HAVE_IUTF8], [1],
     [Define if IUTF8 is a defined termios mode.])],
  [AC_MSG_WARN([No IUTF8 termios mode; character-erase of multibyte character sequence probably does not work properly in canonical mode on this platform.])],
  [[#include <termios.h>]])

# Checks for protobuf
PKG_CHECK_MODULES([protobuf], [protobuf])

# On Debian Sid 2016-03-16ish at least, "pkgconfig --libs protobuf"
# gives us the bogus "-lprotobuf -pthread -lpthread"; remove
# "-lpthread" which misconfigures compile, causing a segfault in
# mosh-server.
AS_IF([echo "$protobuf_LIBS" | grep -q -- -pthread],
  [protobuf_LIBS="`echo $protobuf_LIBS | sed 's/-lpthread//g'`"])

AC_ARG_ENABLE([static-protobuf],
  [AS_HELP_STRING([--enable-static-protobuf], [Link protobuf statically @<:@no@:>@])],
  [], [enable_static_protobuf="$enable_static_libraries"])
AS_IF([test "$enable_static_protobuf" = yes],
  [protobuf_LIBS="-Wl,-Bstatic $protobuf_LIBS -Wl,-Bdynamic"],
  [AS_IF([test "$enable_static_libstdc__" = yes],
     [AC_MSG_ERROR([--enable-static-libstdc++ requires --enable-static-protobuf])])
   AS_IF([test "$enable_static_libgcc" = yes],
     [AC_MSG_ERROR([--enable-static-libgcc requires --enable-static-protobuf])])])

AC_MSG_CHECKING([whether protoc matches protobuf])
cat > conftest.proto <<'EOF'
syntax = "proto2";
option optimize_for = LITE_RUNTIME;
EOF
AS_IF([$PROTOC --cpp_out=. conftest.proto],
  [old_CPPFLAGS="$CPPFLAGS"
   CPPFLAGS="$CPPFLAGS $protobuf_CFLAGS"
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include "conftest.pb.h"]], [[]])],
    [AC_MSG_RESULT([yes])],
    [AC_MSG_RESULT([no])
     cat conftest.err
     AC_MSG_FAILURE([Could not build output generated by protoc ($PROTOC).
Check that protoc matches the installed protobuf headers and libraries.])])
   CPPFLAGS="$old_CPPFLAGS"],
  [AC_MSG_RESULT([no])
   AC_MSG_ERROR([Could not run protoc ($PROTOC).])])

# Bash completion needs to ask where it goes if >= 2.0 is installed.
AS_IF([test "$install_completion" != no],
  [PKG_CHECK_MODULES([BASH_COMPLETION], [bash-completion >= 2.0],
     [if test "$prefix" = "NONE"; then
        completions="`pkg-config --variable=completionsdir bash-completion`"
      else
        completions="`pkg-config --define-variable=prefix=$prefix --variable=completionsdir bash-completion`"
      fi],
     [completions="${sysconfdir}/bash_completion.d"])
   AC_SUBST([completions])])

AC_CONFIG_FILES([
  Makefile
  src/Makefile
  src/crypto/Makefile
  src/frontend/Makefile
  src/fuzz/Makefile
  src/include/Makefile
  src/network/Makefile
  src/protobufs/Makefile
  src/statesync/Makefile
  src/terminal/Makefile
  src/agent/Makefile
  src/util/Makefile
  scripts/Makefile
  src/examples/Makefile
  src/tests/Makefile
  man/Makefile
  conf/Makefile
])
AC_OUTPUT

AC_MSG_NOTICE([ === Configuration results ===])
AC_MSG_NOTICE([Version:             $PACKAGE_VERSION])
AC_MSG_NOTICE([c++ compiler:        $CXX])
AC_MSG_NOTICE([Warning CXXFLAGS:    $WARNING_CXXFLAGS])
AC_MSG_NOTICE([Picky CXXFLAGS:      $PICKY_CXXFLAGS])
AC_MSG_NOTICE([Harden CFLAGS:       $HARDEN_CFLAGS])
AC_MSG_NOTICE([Cryptography:        $human_readable_cryptography_description])
AC_MSG_NOTICE([ =============================])