util: add a helper function to parse a "WIDTHxHEIGHT" property

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

src/libinput-util.c

@@ -234,3 +234,33 @@ parse_trackpoint_accel_property(const char *prop)
 
 	return accel;
 }
+
+/**
+ * Parses a simple dimension string in the form of "10x40". The two
+ * numbers must be positive integers in decimal notation.
+ * On success, the two numbers are stored in w and h. On failure, w and h
+ * are unmodified.
+ *
+ * @param prop The value of the property
+ * @param w Returns the first component of the dimension
+ * @param h Returns the second component of the dimension
+ * @return true on success, false otherwise
+ */
+bool
+parse_dimension_property(const char *prop, size_t *w, size_t *h)
+{
+	int x, y;
+
+	if (!prop)
+		return false;
+
+	if (sscanf(prop, "%dx%d", &x, &y) != 2)
+		return false;
+
+	if (x < 0 || y < 0)
+		return false;
+
+	*w = (size_t)x;
+	*h = (size_t)y;
+	return true;
+}

src/libinput-util.h

@@ -28,6 +28,7 @@
 #include <unistd.h>
 #include <math.h>
 #include <stdarg.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 #include <time.h>
@@ -296,6 +297,7 @@ enum ratelimit_state ratelimit_test(struct ratelimit *r);
 int parse_mouse_dpi_property(const char *prop);
 int parse_mouse_wheel_click_angle_property(const char *prop);
 double parse_trackpoint_accel_property(const char *prop);
+bool parse_dimension_property(const char *prop, size_t *width, size_t *height);
 
 static inline double
 vector_length(double x, double y)

test/misc.c

@@ -584,6 +584,52 @@ START_TEST(trackpoint_accel_parser)
 }
 END_TEST
 
+struct parser_test_dimension {
+	char *tag;
+	bool success;
+	int x, y;
+};
+
+START_TEST(dimension_prop_parser)
+{
+	struct parser_test_dimension tests[] = {
+		{ "10x10", true, 10, 10 },
+		{ "1x20", true, 1, 20 },
+		{ "1x8000", true, 1, 8000 },
+		{ "238492x428210", true, 238492, 428210 },
+		{ "0x0", true, 0, 0 },
+		{ "-10x10", false, 0, 0 },
+		{ "-1", false, 0, 0 },
+		{ "1x-99", false, 0, 0 },
+		{ "0", false, 0, 0 },
+		{ "100", false, 0, 0 },
+		{ "", false, 0, 0 },
+		{ "abd", false, 0, 0 },
+		{ "xabd", false, 0, 0 },
+		{ "0xaf", false, 0, 0 },
+		{ "0x0x", true, 0, 0 },
+		{ "x10", false, 0, 0 },
+		{ NULL, false, 0, 0 }
+	};
+	int i;
+	size_t x, y;
+	bool success;
+
+	for (i = 0; tests[i].tag != NULL; i++) {
+		x = y = 0xad;
+		success = parse_dimension_property(tests[i].tag, &x, &y);
+		ck_assert(success == tests[i].success);
+		if (success) {
+			ck_assert_int_eq(x, tests[i].x);
+			ck_assert_int_eq(y, tests[i].y);
+		} else {
+			ck_assert_int_eq(x, 0xad);
+			ck_assert_int_eq(y, 0xad);
+		}
+	}
+}
+END_TEST
+
 void
 litest_setup_tests(void)
 {
@@ -602,4 +648,5 @@ litest_setup_tests(void)
 	litest_add_no_device("misc:parser", dpi_parser);
 	litest_add_no_device("misc:parser", wheel_click_parser);
 	litest_add_no_device("misc:parser", trackpoint_accel_parser);
+	litest_add_no_device("misc:parser", dimension_prop_parser);
 }