fix(terminal): correct SGR direct color parsing

src/terminal/sgr.zig

@@ -189,11 +189,20 @@ pub const Parser = struct {
                 .@"8_fg" = @enumFromInt(slice[0] - 30),
             },
 
-            38 => if (slice.len >= 5 and slice[1] == 2) {
+            38 => if (slice.len >= 2) switch (slice[1]) {
+                // `2` indicates direct-color (r, g, b).
+                // We need at least 3 more params for this to make sense.
+                2 => if (slice.len >= 5) {
                     self.idx += 4;
-
+                    // When a colon separator is used, there may or may not be
-                // In the 6-len form, ignore the 3rd param.
+                    // a color space identifier as the third param, which we
-                const rgb = slice[2..5];
+                    // need to ignore (it has no standardized behavior).
+                    const rgb = if (slice.len == 5 or !self.colon)
+                        slice[2..5]
+                    else rgb: {
+                        self.idx += 1;
+                        break :rgb slice[3..6];
+                    };
 
                     // We use @truncate because the value should be 0 to 255. If
                     // it isn't, the behavior is undefined so we just... truncate it.
@@ -204,12 +213,16 @@ pub const Parser = struct {
                             .b = @truncate(rgb[2]),
                         },
                     };
-            } else if (slice.len >= 3 and slice[1] == 5) {
+                },
+                // `5` indicates indexed color.
+                5 => if (slice.len >= 3) {
                     self.idx += 2;
                     return Attribute{
                         .@"256_fg" = @truncate(slice[2]),
                     };
                 },
+                else => {},
+            },
 
             39 => return Attribute{ .reset_fg = {} },
 
@@ -217,11 +230,20 @@ pub const Parser = struct {
                 .@"8_bg" = @enumFromInt(slice[0] - 40),
             },
 
-            48 => if (slice.len >= 5 and slice[1] == 2) {
+            48 => if (slice.len >= 2) switch (slice[1]) {
+                // `2` indicates direct-color (r, g, b).
+                // We need at least 3 more params for this to make sense.
+                2 => if (slice.len >= 5) {
                     self.idx += 4;
-
+                    // When a colon separator is used, there may or may not be
-                // We only support the 5-len form.
+                    // a color space identifier as the third param, which we
-                const rgb = slice[2..5];
+                    // need to ignore (it has no standardized behavior).
+                    const rgb = if (slice.len == 5 or !self.colon)
+                        slice[2..5]
+                    else rgb: {
+                        self.idx += 1;
+                        break :rgb slice[3..6];
+                    };
 
                     // We use @truncate because the value should be 0 to 255. If
                     // it isn't, the behavior is undefined so we just... truncate it.
@@ -232,24 +254,33 @@ pub const Parser = struct {
                             .b = @truncate(rgb[2]),
                         },
                     };
-            } else if (slice.len >= 3 and slice[1] == 5) {
+                },
+                // `5` indicates indexed color.
+                5 => if (slice.len >= 3) {
                     self.idx += 2;
                     return Attribute{
                         .@"256_bg" = @truncate(slice[2]),
                     };
                 },
+                else => {},
+            },
 
             49 => return Attribute{ .reset_bg = {} },
 
             53 => return Attribute{ .overline = {} },
             55 => return Attribute{ .reset_overline = {} },
 
-            58 => if (slice.len >= 5 and slice[1] == 2) {
+            58 => if (slice.len >= 2) switch (slice[1]) {
+                // `2` indicates direct-color (r, g, b).
+                // We need at least 3 more params for this to make sense.
+                2 => if (slice.len >= 5) {
                     self.idx += 4;
-
+                    // When a colon separator is used, there may or may not be
-                // In the 6-len form, ignore the 3rd param. Otherwise, use it.
+                    // a color space identifier as the third param, which we
-                const rgb = if (slice.len == 5) slice[2..5] else rgb: {
+                    // need to ignore (it has no standardized behavior).
-                    // Consume one more element
+                    const rgb = if (slice.len == 5 or !self.colon)
+                        slice[2..5]
+                    else rgb: {
                         self.idx += 1;
                         break :rgb slice[3..6];
                     };
@@ -263,12 +294,16 @@ pub const Parser = struct {
                             .b = @truncate(rgb[2]),
                         },
                     };
-            } else if (slice.len >= 3 and slice[1] == 5) {
+                },
+                // `5` indicates indexed color.
+                5 => if (slice.len >= 3) {
                     self.idx += 2;
                     return Attribute{
                         .@"256_underline_color" = @truncate(slice[2]),
                     };
                 },
+                else => {},
+            },
 
             59 => return Attribute{ .reset_underline_color = {} },