AC_DEFUN([CHECK_LIBC_COMPAT], [
# Check for libc headers
AC_CHECK_HEADERS([err.h readpassphrase.h])
# Check for general libc functions
AC_CHECK_FUNCS([asprintf inet_pton memmem readpassphrase reallocarray])
AC_CHECK_FUNCS([strlcat strlcpy strndup strnlen strsep strtonum])
AC_CHECK_FUNCS([timegm _mkgmtime])
AM_CONDITIONAL([HAVE_ASPRINTF], [test "x$ac_cv_func_asprintf" = xyes])
AM_CONDITIONAL([HAVE_INET_PTON], [test "x$ac_cv_func_inet_pton" = xyes])
AM_CONDITIONAL([HAVE_MEMMEM], [test "x$ac_cv_func_memmem" = xyes])
AM_CONDITIONAL([HAVE_READPASSPHRASE], [test "x$ac_cv_func_readpassphrase" = xyes])
AM_CONDITIONAL([HAVE_REALLOCARRAY], [test "x$ac_cv_func_reallocarray" = xyes])
AM_CONDITIONAL([HAVE_STRLCAT], [test "x$ac_cv_func_strlcat" = xyes])
AM_CONDITIONAL([HAVE_STRLCPY], [test "x$ac_cv_func_strlcpy" = xyes])
AM_CONDITIONAL([HAVE_STRNDUP], [test "x$ac_cv_func_strndup" = xyes])
AM_CONDITIONAL([HAVE_STRNLEN], [test "x$ac_cv_func_strnlen" = xyes])
AM_CONDITIONAL([HAVE_STRSEP], [test "x$ac_cv_func_strsep" = xyes])
AM_CONDITIONAL([HAVE_STRTONUM], [test "x$ac_cv_func_strtonum" = xyes])
AM_CONDITIONAL([HAVE_TIMEGM], [test "x$ac_cv_func_timegm" = xyes])
])

AC_DEFUN([CHECK_SYSCALL_COMPAT], [
AC_CHECK_FUNCS([accept4 pledge poll])
AM_CONDITIONAL([HAVE_ACCEPT4], [test "x$ac_cv_func_accept4" = xyes])
AM_CONDITIONAL([HAVE_PLEDGE], [test "x$ac_cv_func_pledge" = xyes])
AM_CONDITIONAL([HAVE_POLL], [test "x$ac_cv_func_poll" = xyes])
])

AC_DEFUN([CHECK_B64_NTOP], [
AC_SEARCH_LIBS([b64_ntop],[resolv])
AC_SEARCH_LIBS([__b64_ntop],[resolv])
AC_CACHE_CHECK([for b64_ntop], ac_cv_have_b64_ntop_arg, [
	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <resolv.h>
		]], [[ b64_ntop(NULL, 0, NULL, 0); ]])],
	[ ac_cv_have_b64_ntop_arg="yes" ],
	[ ac_cv_have_b64_ntop_arg="no"
	])
])
AM_CONDITIONAL([HAVE_B64_NTOP], [test "x$ac_cv_func_b64_ntop_arg" = xyes])
])

AC_DEFUN([CHECK_CRYPTO_COMPAT], [
# Check crypto-related libc functions and syscalls
AC_CHECK_FUNCS([arc4random arc4random_buf arc4random_uniform])
AC_CHECK_FUNCS([explicit_bzero getauxval getentropy])
AC_CHECK_FUNCS([timingsafe_bcmp timingsafe_memcmp])
AM_CONDITIONAL([HAVE_ARC4RANDOM], [test "x$ac_cv_func_arc4random" = xyes])
AM_CONDITIONAL([HAVE_ARC4RANDOM_BUF], [test "x$ac_cv_func_arc4random_buf" = xyes])
AM_CONDITIONAL([HAVE_ARC4RANDOM_UNIFORM], [test "x$ac_cv_func_arc4random_uniform" = xyes])
AM_CONDITIONAL([HAVE_EXPLICIT_BZERO], [test "x$ac_cv_func_explicit_bzero" = xyes])
AM_CONDITIONAL([HAVE_GETENTROPY], [test "x$ac_cv_func_getentropy" = xyes])
AM_CONDITIONAL([HAVE_TIMINGSAFE_BCMP], [test "x$ac_cv_func_timingsafe_bcmp" = xyes])
AM_CONDITIONAL([HAVE_TIMINGSAFE_MEMCMP], [test "x$ac_cv_func_timingsafe_memcmp" = xyes])

# Override arc4random_buf implementations with known issues
AM_CONDITIONAL([HAVE_ARC4RANDOM_BUF],
	[test "x$USE_BUILTIN_ARC4RANDOM" != xyes \
	   -a "x$ac_cv_func_arc4random_buf" = xyes])

# Check for getentropy fallback dependencies
AC_CHECK_FUNC([getauxval])
AC_SEARCH_LIBS([clock_gettime],[rt posix4])
AC_CHECK_FUNC([clock_gettime])
AC_SEARCH_LIBS([dl_iterate_phdr],[dl])
AC_CHECK_FUNC([dl_iterate_phdr])
])

AC_DEFUN([CHECK_VA_COPY], [
AC_CACHE_CHECK([whether va_copy exists], ac_cv_have_va_copy, [
	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
#include <stdarg.h>
va_list x,y;
		]], [[ va_copy(x,y); ]])],
	[ ac_cv_have_va_copy="yes" ],
	[ ac_cv_have_va_copy="no"
	])
])
if test "x$ac_cv_have_va_copy" = "xyes" ; then
	AC_DEFINE([HAVE_VA_COPY], [1], [Define if va_copy exists])
fi

AC_CACHE_CHECK([whether __va_copy exists], ac_cv_have___va_copy, [
	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
#include <stdarg.h>
va_list x,y;
		]], [[ __va_copy(x,y); ]])],
	[ ac_cv_have___va_copy="yes" ], [ ac_cv_have___va_copy="no"
	])
])
if test "x$ac_cv_have___va_copy" = "xyes" ; then
	AC_DEFINE([HAVE___VA_COPY], [1], [Define if __va_copy exists])
fi
])