parse_color: return success + drop fallback color

This is the first in a series of commits to refactor the color handling
in sway. This changes parse_color to return whether it was success and
no longer uses 0xFFFFFFFF as the fallback color. This also verifies that
the string actually contains a valid hexadecimal number along with
the length checks.

In the process of altering the calls to parse_color, I also took the
opportunity to heavily refactor swaybar's ipc_parse_colors function.
This allowed for several lines of duplicated code to be removed.

1 files changed, 10 insertions, 9 deletions

diff --git a/common/util.c b/common/util.c
index c0324b2f..84ebab99 100644
--- a/common/util.c
+++ b/common/util.c
@@ -1,4 +1,5 @@
 #define _POSIX_C_SOURCE 200809L
+#include <ctype.h>
 #include <float.h>
 #include <fcntl.h>
 #include <math.h>
@@ -13,21 +14,21 @@ int wrap(int i, int max) {
         return ((i % max) + max) % max;
 }
 
-uint32_t parse_color(const char *color) {
+bool parse_color(const char *color, uint32_t *result) {
         if (color[0] == '#') {
                 ++color;
         }
-
         int len = strlen(color);
-        if (len != 6 && len != 8) {
-                sway_log(SWAY_DEBUG, "Invalid color %s, defaulting to color 0xFFFFFFFF", color);
-                return 0xFFFFFFFF;
+        if ((len != 6 && len != 8) || !isxdigit(color[0]) || !isxdigit(color[1])) {
+                return false;
         }
-        uint32_t res = (uint32_t)strtoul(color, NULL, 16);
-        if (strlen(color) == 6) {
-                res = (res << 8) | 0xFF;
+        char *ptr;
+        uint32_t parsed = strtoul(color, &ptr, 16);
+        if (*ptr != '\0') {
+                return false;
         }
-        return res;
+        *result = len == 6 ? ((parsed << 8) | 0xFF) : parsed;
+        return true;
 }
 
 bool parse_boolean(const char *boolean, bool current) {