Ignore empty XDG_*_DIRS env. variables

As the specification says we should.  GLib does this as well.

It is still possible to achieve an empty set by using ":",
which are two non-absolute paths that should be ignored.
GLib doesn't implement this.  Thus, we're now better than GLib.

CMakeLists.txt

@@ -4,9 +4,9 @@ cmake_minimum_required (VERSION 2.8.5)
 # Moar warnings
 if ("${CMAKE_C_COMPILER_ID}" MATCHES "GNU" OR CMAKE_COMPILER_IS_GNUCC)
 	# -Wunused-function is pretty annoying here, as everything is static
-	set (wdisabled "-Wno-unused-function -Wno-implicit-fallthrough")
+	set (wdisabled "-Wno-unused-function")
 	set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99 -Wall -Wextra ${wdisabled}")
-endif ("${CMAKE_C_COMPILER_ID}" MATCHES "GNU" OR CMAKE_COMPILER_IS_GNUCC)
+endif ()
 
 # Dependencies
 set (CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
@@ -16,11 +16,9 @@ find_package (PkgConfig REQUIRED)
 pkg_check_modules (libssl REQUIRED libssl libcrypto)
 
 if ("${CMAKE_SYSTEM_NAME}" MATCHES "BSD")
-	include_directories (/usr/local/include)
-	link_directories (/usr/local/lib)
 	# Our POSIX version macros make these undefined
 	add_definitions (-D__BSD_VISIBLE=1 -D_BSD_SOURCE=1)
-endif ("${CMAKE_SYSTEM_NAME}" MATCHES "BSD")
+endif ()
 
 set (common_libraries ${libssl_LIBRARIES})
 include_directories (${libssl_INCLUDE_DIRS})
@@ -32,8 +30,8 @@ foreach (extra iconv rt)
 	find_library (extra_lib_${extra} ${extra})
 	if (extra_lib_${extra})
 		list (APPEND common_libraries ${extra})
-	endif (extra_lib_${extra})
-endforeach (extra)
+	endif ()
+endforeach ()
 
 # Build some unit tests
 include_directories (${PROJECT_SOURCE_DIR})
@@ -43,4 +41,4 @@ foreach (name liberty proto)
 	add_threads (test-${name})
 	target_link_libraries (test-${name} ${common_libraries})
 	add_test (NAME test-${name} COMMAND test-${name})
-endforeach (name)
+endforeach ()

liberty.c

@@ -3247,7 +3247,7 @@ get_xdg_config_dirs (struct strv *out)
 	str_free (&config_home);
 
 	const char *xdg_config_dirs;
-	if (!(xdg_config_dirs = getenv ("XDG_CONFIG_DIRS")))
+	if (!(xdg_config_dirs = getenv ("XDG_CONFIG_DIRS")) || !*xdg_config_dirs)
 		xdg_config_dirs = "/etc/xdg";
 	cstr_split (xdg_config_dirs, ":", true, out);
 }
@@ -3272,7 +3272,7 @@ get_xdg_data_dirs (struct strv *out)
 	str_free (&data_home);
 
 	const char *xdg_data_dirs;
-	if (!(xdg_data_dirs = getenv ("XDG_DATA_DIRS")))
+	if (!(xdg_data_dirs = getenv ("XDG_DATA_DIRS")) || !*xdg_data_dirs)
 		xdg_data_dirs = "/usr/local/share/:/usr/share/";
 	cstr_split (xdg_data_dirs, ":", true, out);
 }
@@ -4708,13 +4708,15 @@ config_item_write_string (struct str *output, const struct str *s)
 	for (size_t i = 0; i < s->len; i++)
 	{
 		unsigned char c = s->str[i];
-		if      (c == '\n')  str_append        (output, "\\n");
-		else if (c == '\r')  str_append        (output, "\\r");
-		else if (c == '\t')  str_append        (output, "\\t");
-		else if (c == '\\')  str_append        (output, "\\\\");
-		else if (c == '"')   str_append        (output, "\\\"");
-		else if (c < 32)     str_append_printf (output, "\\x%02x", c);
-		else                 str_append_c      (output, c);
+		if      (c == '\n')  str_append (output, "\\n");
+		else if (c == '\r')  str_append (output, "\\r");
+		else if (c == '\t')  str_append (output, "\\t");
+		else if (c == '\\')  str_append (output, "\\\\");
+		else if (c == '"')   str_append (output, "\\\"");
+		else if (iscntrl_ascii (c))
+			str_append_printf (output, "\\x%02x", c);
+		else
+			str_append_c (output, c);
 	}
 	str_append_c (output, '"');
 }