diff --git a/sofort/cfgtest/cfgtest.sh b/sofort/cfgtest/cfgtest.sh
new file mode 100644
index 0000000..ab5d2ab
--- /dev/null
+++ b/sofort/cfgtest/cfgtest.sh
@@ -0,0 +1,551 @@
+# cfgtest.sh: sofort's config test framework,
+# for use from within a project's custom cfgdefs.sh.
+
+# this file is covered by COPYING.SOFORT.
+
+# in the common scenario, host-specific tests are preceded
+# by a single invocation of cfgtest_host_section, whereas
+# native (build) system tests are preceded by the invocation
+# of cfgtest_native_section.
+
+# cfgdefs fraework variables:
+# mb_cfgtest_cc:      the compiler used for the current test
+# mb_cfgtest_cflags:  the compiler flags used for the current test
+# mb_cfgtest_cfgtype: the type of the current test (host/native)
+# mb_cfgtest_makevar: the make variable affected by the current test
+# mb_cfgtest_headers: headers for ad-hoc inclusion with the current test
+
+
+cfgtest_newline()
+{
+	printf '\n' >> $mb_pwd/cfgdefs.mk
+}
+
+
+cfgtest_comment()
+{
+	mb_internal_str='#'
+
+	for mb_internal_arg ; do
+		mb_internal_str="$mb_internal_str $mb_internal_arg"
+	done
+
+	printf '%s\n' "$mb_internal_str" >> $mb_pwd/cfgdefs.mk
+}
+
+
+cfgtest_host_section()
+{
+	mb_cfgtest_cc="$ccenv_host_cc"
+	mb_cfgtest_cfgtype='host'
+	mb_cfgtest_cflags=$(${mb_make} -n -f "$mb_pwd/Makefile.tmp" .cflags-host)
+	mb_cfgtest_cflags="${mb_cfgtest_cflags#*: }"
+
+	mb_cfgtest_ldflags="$mb_ldflags_cmdline"
+	mb_cfgtest_ldflags="$mb_cfgtest_ldflags $mb_ldflags_debug"
+	mb_cfgtest_ldflags="$mb_cfgtest_ldflags $mb_ldflags_common"
+	mb_cfgtest_ldflags="$mb_cfgtest_ldflags $mb_ldflags_strict"
+	mb_cfgtest_ldflags="$mb_cfgtest_ldflags $mb_ldflags_config"
+	mb_cfgtest_ldflags="$mb_cfgtest_ldflags $mb_ldflags_sysroot"
+	mb_cfgtest_ldflags="$mb_cfgtest_ldflags $mb_ldflags_path"
+	mb_cfgtest_ldflags="$mb_cfgtest_ldflags $mb_ldflags_last"
+
+	cfgtest_comment 'host-specific tests'
+}
+
+
+cfgtest_native_section()
+{
+	mb_cfgtest_cc="$mb_native_cc"
+	mb_cfgtest_cfgtype='native'
+	mb_cfgtest_cflags=$(${mb_make} -n -f "$mb_pwd/Makefile.tmp" .cflags-native)
+	mb_cfgtest_cflags="${mb_cfgtest_cflags#*: }"
+	mb_cfgtest_ldflags="$mb_native_ldflags"
+
+	cfgtest_comment 'native system tests'
+}
+
+
+cfgtest_prolog()
+{
+	cfgtest_line_dots='.......................'
+	cfgtest_line_dots="${cfgtest_line_dots}${cfgtest_line_dots}"
+	cfgtest_tool_desc=" == trying ${mb_cfgtest_cfgtype} ${1}: ${2}"
+	cfgtest_tool_dlen="${#cfgtest_line_dots}"
+
+	printf '\n%s\n' '________________________' >&3
+	printf "cfgtest: probing for ${mb_cfgtest_cfgtype} ${1}: ${2}\n\n" >&3
+	printf "%${cfgtest_tool_dlen}.${cfgtest_tool_dlen}s" \
+		"${cfgtest_tool_desc}  ${mb_line_dots}"
+}
+
+
+cfgtest_epilog()
+{
+	cfgtest_line_dots='.......................'
+	cfgtest_tool_dlen="$((${#cfgtest_line_dots} - ${#2}))"
+
+	printf "%${cfgtest_tool_dlen}.${cfgtest_tool_dlen}s  %s.\n" \
+		"${cfgtest_line_dots}" "${2}"
+
+	if [ "${1}" = 'snippet' ] && [ -f = 'a.out' ]; then
+		rm -f 'a.out'
+	fi
+
+	if [ "${1}" = 'snippet' ] && [ "${2}" = '(error)' ]; then
+		printf '\n\ncfgtest: the %s compiler %s %s.\n' \
+			"$mb_cfgtest_cfgtype"                 \
+			'failed to compile the above code'   \
+			"${1}" >&3
+		printf '%s\n' '------------------------' >&3
+		return 1
+	fi
+
+	if [ "${2}" = '-----' ]; then
+		printf '\n\ncfgtest: %s %s is missing or cannot be found.\n' "${1}" "${3}" >&3
+		printf '%s\n' '------------------------' >&3
+		return 1
+	elif [ "${1}" = 'size-of-type' ] && [ "${2}" = '(error)' ]; then
+		printf '\n\ncfgtest: could not determine size of type `%s.\n' "${3}'" >&3
+		printf '%s\n' '------------------------' >&3
+		return 1
+	elif [ "${2}" = '(error)' ]; then
+		printf '\n\ncfgtest: %s `%s is not defined or cannot be used.\n' "${1}" "${3}'" >&3
+		printf '%s\n' '------------------------' >&3
+		return 1
+	fi
+}
+
+
+cfgtest_entity_size_prolog()
+{
+	cfgtest_line_dots='.......................'
+	cfgtest_line_dots="${cfgtest_line_dots}${cfgtest_line_dots}"
+	cfgtest_tool_desc=" == checking size of ${mb_cfgtest_cfgtype} type: ${@}"
+	cfgtest_tool_dlen="${#cfgtest_line_dots}"
+
+	printf '\n%s\n' '________________________' >&3
+	printf "cfgtest: checking size of ${mb_cfgtest_cfgtype} type: ${@}\n\n" >&3
+
+	printf "%${cfgtest_tool_dlen}.${cfgtest_tool_dlen}s" \
+		"${cfgtest_tool_desc}  ${mb_line_dots}"
+}
+
+
+cfgtest_makevar_append()
+{
+	mb_internal_str='+='
+
+	for mb_internal_arg ; do
+		if ! [ -z "$mb_internal_arg" ]; then
+			mb_internal_str="$mb_internal_str $mb_internal_arg"
+		fi
+	done
+
+	printf '%-24s%s\n' "$mb_cfgtest_makevar" "$mb_internal_str" \
+		>> $mb_pwd/cfgdefs.mk
+
+	unset cfgtest_internal_unit_test
+}
+
+
+cfgtest_cflags_append()
+{
+	if [ $mb_cfgtest_cfgtype = 'host' ]; then
+		mb_internal_makevar='CFLAGS_CONFIG'
+	else
+		mb_internal_makevar='NATIVE_CFLAGS'
+	fi
+
+	mb_cfgtest_makevar_saved=$mb_cfgtest_makevar
+	mb_cfgtest_makevar=$mb_internal_makevar
+
+	cfgtest_makevar_append "$@"
+	mb_cfgtest_makevar=$mb_cfgtest_makevar_saved
+}
+
+
+cfgtest_ldflags_append()
+{
+	if [ $mb_cfgtest_cfgtype = 'host' ]; then
+		mb_internal_makevar='LDFLAGS_CONFIG'
+	else
+		mb_internal_makevar='NATIVE_LDFLAGS'
+	fi
+
+	mb_cfgtest_makevar_saved=$mb_cfgtest_makevar
+	mb_cfgtest_makevar=$mb_internal_makevar
+
+	cfgtest_makevar_append "$@"
+	mb_cfgtest_makevar=$mb_cfgtest_makevar_saved
+}
+
+
+cfgtest_common_init()
+{
+	# cfgtest variables
+	if [ "${1:-}" = 'asm' ]; then
+		cfgtest_fmt='%s -c -xc - -o a.out'
+	elif [ "${1:-}" = 'lib' ]; then
+		cfgtest_fmt='%s -xc - -o a.out'
+	else
+		cfgtest_fmt='%s -S -xc - -o -'
+	fi
+
+	if [ "${1:-}" = 'lib' ]; then
+		cfgtest_cmd=$(printf "$cfgtest_fmt %s %s %s" \
+			"$mb_cfgtest_cc"                     \
+			"$mb_cfgtest_cflags"                 \
+			"$mb_cfgtest_ldflags"                \
+			"$cfgtest_libs")
+	else
+		cfgtest_cmd=$(printf "$cfgtest_fmt %s" \
+			"$mb_cfgtest_cc"               \
+			"$mb_cfgtest_cflags")
+	fi
+
+	if [ -z "$mb_cfgtest_headers" ] || [ "${1:-}" = 'lib' ]; then
+		cfgtest_inc=
+		cfgtest_src="$cfgtest_code_snippet"
+	else
+		cfgtest_inc=$(printf '#include <%s>\n' $mb_cfgtest_headers)
+		cfgtest_src=$(printf '%s\n_\n' "$cfgtest_inc" \
+			| m4 -D_="$cfgtest_code_snippet")
+	fi
+
+	# config.log
+	printf "$cfgtest_fmt" "$mb_cfgtest_cc" >&3
+
+	for cfgtest_cflag in $mb_cfgtest_cflags; do
+		printf ' \\\n\t%s' "$cfgtest_cflag" >&3
+	done
+
+	if [ "${1:-}" = 'lib' ]; then
+		for cfgtest_lib in $cfgtest_libs; do
+			printf ' \\\n\t%s' "$cfgtest_lib" >&3
+		done
+	fi
+
+	printf ' \\\n'                           >&3
+	printf '<< _SRCEOF\n%s\n' "$cfgtest_src" >&3
+	printf '_SRCEOF \n\n\n'                  >&3
+}
+
+
+cfgtest_header_presence()
+{
+	#init
+	cfgtest_prolog 'header' "${1}"
+
+	cfgtest_code_snippet=$(printf '#include <%s>\n' "${1}")
+
+	cfgtest_common_init
+
+	# execute
+	printf '%s' "$cfgtest_src"                  \
+		| eval $(printf '%s' "$cfgtest_cmd") \
+		> /dev/null 2>&3                      \
+	|| cfgtest_epilog 'header' '-----' "<${1}>"    \
+	|| return
+
+	# result
+	mb_internal_str=$(printf '%s%s' '-DHAVE_' "${1}"  \
+			| sed -e 's/\./_/g' -e 's@/@_@g'  \
+			| tr "[:lower:]" "[:upper:]")
+
+	if [ -z ${cfgtest_internal_unit_test:-} ]; then
+		cfgtest_cflags_append "$mb_internal_str"
+	else
+		cfgtest_makevar_append "$mb_internal_str"
+	fi
+
+	printf 'cfgtest: %s header <%s> was found and may be included.\n' \
+		"$mb_cfgtest_cfgtype" "${1}" >&3
+	printf '%s\n' '------------------------' >&3
+
+	cfgtest_epilog 'header' "${1}"
+}
+
+
+cfgtest_header_absence()
+{
+	#init
+	cfgtest_prolog 'header absence' "${1}"
+
+	cfgtest_code_snippet=$(printf '#include <%s>\n' "${1}")
+
+	cfgtest_common_init
+
+	# execute
+	printf '%s' "$cfgtest_src"                  \
+		| eval $(printf '%s' "$cfgtest_cmd") \
+		> /dev/null 2>&3                      \
+	&& printf 'cfgtest: %s header <%s>: no error.' \
+		"$mb_cfgtest_cfgtype" "${1}" >&3        \
+	&& cfgtest_epilog 'header' "${1}"                \
+	&& return
+
+	# result
+	mb_internal_str=$(printf '%s%s' '-DHAVE_NO_' "$@" \
+			| sed -e 's/\./_/g' -e 's@/@_@g'  \
+			| tr "[:lower:]" "[:upper:]")
+
+	if [ -z ${cfgtest_internal_unit_test:-} ]; then
+		cfgtest_cflags_append "$mb_internal_str"
+	else
+		cfgtest_makevar_append "$mb_internal_str"
+	fi
+
+	printf 'cfgtest: %s header <%s> may not be included.\n' \
+		"$mb_cfgtest_cfgtype" "${1}" >&3
+	printf '%s\n' '------------------------' >&3
+
+	cfgtest_epilog 'header' '-----'
+}
+
+
+cfgtest_interface_presence()
+{
+	# init
+	cfgtest_prolog 'interface' "${1}"
+
+	cfgtest_code_snippet=$(printf 'void * addr = &%s;\n' "${1}")
+
+	cfgtest_common_init
+
+	# execute
+	printf '%s' "$cfgtest_src"                    \
+		| eval $(printf '%s' "$cfgtest_cmd")   \
+		> /dev/null 2>&3                        \
+	|| cfgtest_epilog 'interface' '(error)' "${1}"   \
+	|| return
+
+	# result
+	mb_internal_str=$(printf '%s%s' '-DHAVE_' "$@"  \
+			| sed -e 's/\./_/g'             \
+			| tr "[:lower:]" "[:upper:]")
+
+	if [ -z ${cfgtest_internal_unit_test:-} ]; then
+		cfgtest_cflags_append "$mb_internal_str"
+	else
+		cfgtest_makevar_append "$mb_internal_str"
+	fi
+
+	printf 'cfgtest: %s interface `%s'"'"' is available.\n' \
+		"$mb_cfgtest_cfgtype" "${1}" >&3
+	printf '%s\n' '------------------------' >&3
+
+	cfgtest_epilog 'interface' "${1}"
+
+	return 0
+}
+
+
+cfgtest_decl_presence()
+{
+	# init
+	cfgtest_prolog 'decl' "${1}"
+
+	cfgtest_code_snippet=$(printf 'void * any = (void *)(%s);' "${1}")
+
+	cfgtest_common_init
+
+	# execute
+	printf '%s' "$cfgtest_src"                  \
+		| eval $(printf '%s' "$cfgtest_cmd") \
+		> /dev/null 2>&3                      \
+	|| cfgtest_epilog 'decl' '(error)' "${1}"      \
+	|| return
+
+	# does the argument solely consist of the macro or enum member name?
+	mb_internal_str=$(printf '%s' "$@" | tr -d '[a-z][A-Z][0-9][_]')
+
+	if [ -n "$mb_internal_str" ]; then
+		cfgtest_epilog 'decl' '(defined)'
+		return 0
+	fi
+
+	# result
+	mb_internal_str=$(printf '%s%s' '-DHAVE_DECL_' "$@"  \
+			| sed -e 's/\./_/g'                  \
+			| tr "[:lower:]" "[:upper:]")
+
+	if [ -z ${cfgtest_internal_unit_test:-} ]; then
+		cfgtest_cflags_append "$mb_internal_str"
+	else
+		cfgtest_makevar_append "$mb_internal_str"
+	fi
+
+	printf 'cfgtest: `%s'"'"' is defined for the %s system.\n' \
+		"${1}" "$mb_cfgtest_cfgtype" >&3
+	printf '%s\n' '------------------------' >&3
+
+	cfgtest_epilog 'decl' '(defined)'
+
+	return 0
+}
+
+
+cfgtest_type_size()
+{
+	cfgtest_entity_size_prolog "$@"
+
+	mb_internal_size=''
+	mb_internal_test='char x[(sizeof(%s) == %s) ? 1 : -1];'
+
+	for mb_internal_guess in 8 4 2 1 16 32 64 128; do
+		if [ -z $mb_internal_size ]; then
+			printf '# guess %s ===>\n' "$mb_internal_guess" >&3
+
+			mb_internal_type="$@"
+
+			cfgtest_code_snippet=$(printf "$mb_internal_test" \
+				"$mb_internal_type" "$mb_internal_guess")
+
+			cfgtest_common_init
+
+			printf '%s' "$cfgtest_src"                  \
+				| eval $(printf '%s' "$cfgtest_cmd") \
+				> /dev/null 2>&3                      \
+			&& mb_internal_size=$mb_internal_guess
+
+			printf '\n' >&3
+		fi
+	done
+
+	# unrecognized type, or type size not within range
+	if [ -z $mb_internal_size ]; then
+		cfgtest_epilog 'size-of-type' '(error)' "@"
+		return 1
+	fi
+
+	# -DSIZEOF_TYPE=SIZE
+	mb_internal_str=$(printf '%s%s=%s' '-DSIZEOF_'        \
+				"$mb_internal_type"           \
+				"$mb_internal_size"           \
+			| sed -e 's/\ /_/g' -e 's/*/P/g'      \
+			| tr "[:lower:]" "[:upper:]")
+
+	if [ -z ${cfgtest_internal_unit_test:-} ]; then
+		cfgtest_cflags_append "$mb_internal_str"
+	else
+		cfgtest_makevar_append "$mb_internal_str"
+	fi
+
+	printf 'cfgtest: size of type `%s'"'"' determined to be %s\n' \
+		"${@}" "$mb_internal_size" >&3
+	printf '%s\n' '------------------------' >&3
+
+	cfgtest_epilog 'size-of-type' "$mb_internal_size"
+
+	return 0
+}
+
+
+cfgtest_code_snippet_asm()
+{
+	# init
+	cfgtest_prolog 'support of code snippet' '<...>'
+
+	cfgtest_code_snippet="$@"
+
+	cfgtest_common_init 'asm'
+
+	# execute
+	cfgtest_ret=1
+
+	printf '%s' "$cfgtest_src"                  \
+		| eval $(printf '%s' "$cfgtest_cmd") \
+		> /dev/null 2>&3                      \
+	|| cfgtest_epilog 'snippet' '(error)'          \
+	|| return
+
+	# result
+	cfgtest_ret=0
+
+	printf 'cfgtest: %s compiler: above code snippet compiled successfully.\n\n' \
+		"$mb_cfgtest_cfgtype" >&3
+
+	cfgtest_epilog 'snippet' '(ok)'
+
+	return 0
+}
+
+
+cfgtest_library_presence()
+{
+	# init
+	cfgtest_libs=
+	cfgtest_spc=
+
+	for cfgtest_lib in ${@}; do
+		cfgtest_libs="$cfgtest_libs$cfgtest_spc$cfgtest_lib"
+		cfgtest_spc=' '
+	done
+
+	if [ "${1}" = "$cfgtest_libs" ]; then
+		cfgtest_prolog 'library' "${1#*-l}"
+	else
+		cfgtest_prolog 'lib module' '(see config.log)'
+	fi
+
+	cfgtest_code_snippet='int main(void){return 0;}'
+
+	cfgtest_common_init 'lib'
+
+	# execute
+	printf '%s' "$cfgtest_src"                  \
+		| eval $(printf '%s' "$cfgtest_cmd") \
+		> /dev/null 2>&3                      \
+	|| cfgtest_epilog 'library' '-----' "$@"       \
+	|| return 1
+
+	# result
+	printf 'cfgtest: `%s'"'"' was accepted by the linker driver.\n' \
+		"$cfgtest_libs" >&3
+	printf '%s\n' '------------------------' >&3
+
+	cfgtest_epilog 'library' '(present)'
+
+	return 0
+}
+
+
+cfgtest_unit_header_presence()
+{
+	cfgtest_internal_unit_test='unit_test'
+	cfgtest_header_presence "$@" || return 1
+	return 0
+}
+
+
+cfgtest_unit_header_absence()
+{
+	cfgtest_internal_unit_test='unit_test'
+	cfgtest_header_absence "$@" || return 1
+	return 0
+}
+
+
+cfgtest_unit_interface_presence()
+{
+	cfgtest_internal_unit_test='unit_test'
+	cfgtest_interface_presence "$@" || return 1
+	return 0
+}
+
+
+cfgtest_unit_decl_presence()
+{
+	cfgtest_internal_unit_test='unit_test'
+	cfgtest_decl_presence "$@" || return 1
+	return 0
+}
+
+
+cfgtest_unit_type_size()
+{
+	cfgtest_internal_unit_test='unit_test'
+	cfgtest_type_size "$@" || return 1
+	return 0
+}