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.

2 files changed, 6 insertions, 4 deletions

diff --git a/include/swaybar/i3bar.h b/include/swaybar/i3bar.h
index 5b6001ce..0b3bee21 100644
--- a/include/swaybar/i3bar.h
+++ b/include/swaybar/i3bar.h
@@ -9,7 +9,8 @@ struct i3bar_block {
         int ref_count;
         char *full_text, *short_text, *align, *min_width_str;
         bool urgent;
-        uint32_t *color;
+        uint32_t color;
+        bool color_set;
         int min_width;
         char *name, *instance;
         bool separator;
diff --git a/include/util.h b/include/util.h
index 3cba49f0..931ac691 100644
--- a/include/util.h
+++ b/include/util.h
@@ -11,10 +11,11 @@
 int wrap(int i, int max);
 
 /**
- * Given a string that represents an RGB(A) color, return a uint32_t
- * version of the color.
+ * Given a string that represents an RGB(A) color, result will be set to a
+ * uint32_t version of the color, as long as it is valid. If it is invalid,
+ * then false will be returned and result will be untouched.
  */
-uint32_t parse_color(const char *color);
+bool parse_color(const char *color, uint32_t *result);
 
 /**
  * Given a string that represents a boolean, return the boolean value. This