fix(input): bail OSC code accumulation past 22 to prevent overflow

The numeric OSC code loop accumulated digits with no cap, so a long
digit run (e.g. ESC ] 9999...) would overflow the int accumulator.
Since 22 is the only code parse_osc accepts and the accumulator only
grows, bail with PARSE_ERR as soon as it passes 22.

Addresses review feedback from @dreyfus92 on #101.

Author: natemoo-re

src/input.c

@@ -632,6 +632,11 @@ static int parse_osc(struct InputState *st, struct InputEvent *ev) {
     if (code == -1)
       code = 0;
     code = code * 10 + (st->buf[i] - '0');
+    /* 22 is the only accepted code; the accumulator only grows as digits
+     * arrive, so once it passes 22 no valid completion exists. Bail here so a
+     * long digit run can never overflow `code`. */
+    if (code > 22)
+      return PARSE_ERR;
     i++;
   }
   if (i >= st->len)

test/input.test.ts

@@ -763,6 +763,15 @@ describe("input", () => {
       });
     });
 
+    it("rejects an unbounded digit run without overflowing", () => {
+      // A long run of digits must not overflow the code accumulator; anything
+      // that grows past 22 can never match, so it is dropped as an error.
+      let result = input.scan(str("\x1b]" + "9".repeat(64) + ";x\x1b\\"));
+      expect(
+        result.events.some((e) => e.type === "pointershape"),
+      ).toBe(false);
+    });
+
     it("parses a reply interleaved with other input", () => {
       let result = input.scan(str("a\x1b]22;default\x1b\\b"));
       expect(result.events.length).toBe(3);