gitea forge bundle: name the parent the forge used, match protection rules as the forge does, bound a commit's size and a search's time (issue 539)

The forge's contents and diffpatch endpoints take a branch, never a commit to
build on, so the parent is read from the commit the forge made, and a branch
that moved under the commit is said. Blobs are read at the commit read first,
not at the branch name. Protection rules match as Gitea 1.27 matches them
([...], {a,b}, escapes, a plain name in any case), in the Go bundle and in
guard.ts alike. One commit carries at most 4 MiB per file or patch and 16 MiB
together; code search stops at its deadline and says so. The HTTP client the
two Go bundles copied is one package, internal/forgehttp.

modules/gitea/guard.ts

@@ -164,21 +164,89 @@ export function judgeApiCall(method: string, rawPath: string, body: unknown): Ap
   };
 }
 
-/** Whether a protection rule's name — a branch, or a glob of them (`*`, `**`) — covers a branch. */
+/**
+ * Whether a protection rule's name covers a branch, as the forge itself decides it (Gitea 1.27,
+ * models/git/protected_branch.go Match and modules/glob; novox/hq issue 539): a name without a glob character
+ * covers the branch of that name in any case; any other name is a glob with `/` as its separator — `*` any run
+ * within a segment, `**` any run across them, `?` one character of a segment, `[abc]`, `[a-z]` and `[!abc]` one
+ * character, `{a,b}` either, `\` the next character itself — matched case-sensitively; a glob the forge cannot
+ * compile covers its own text exactly. The forge bundle's ruleCovers (cmd/forge/rules.go) is the same rule.
+ */
 export function ruleCovers(rule: string, branch: string): boolean {
-  if (rule === branch) return true;
-  if (!/[*?[]/.test(rule)) return false;
-  let re = "";
-  for (let i = 0; i < rule.length; i++) {
-    const c = rule[i];
-    if (c === "*" && rule[i + 1] === "*") {
-      re += ".*";
-      i++;
-    } else if (c === "*") re += "[^/]*";
-    else if (c === "?") re += "[^/]";
-    else re += c.replace(/[.+^${}()|[\]\\]/g, "\\$&");
+  if (!/[*?\\[\]{}]/.test(rule)) return rule.toLowerCase() === branch.toLowerCase();
+  const re = globRegExp(rule);
+  return re ? re.test(branch) : rule === branch;
+}
+
+/** The forge's glob as a regular expression, compiled as its modules/glob compiles it with `/` as separator. */
+function globRegExp(glob: string): RegExp | null {
+  const g = Array.from(glob);
+  let out = "";
+  let pos = 0;
+  const lit = (c: string) => c.replace(/[.*+?^${}()|[\]\\/]/g, "\\$&");
+  const chars = (): boolean => {
+    out += "[";
+    if (g[pos] === "!") {
+      pos++;
+      out += "^";
+    }
+    while (pos < g.length) {
+      const c = g[pos++];
+      if (c === "]") {
+        out += "]";
+        return true;
+      }
+      if (c === "\\") {
+        if (pos >= g.length) return false;
+        out += "\\" + g[pos++];
+      } else out += c === "[" ? "\\[" : c;
+    }
+    return false;
+  };
+  const compile = (sub: boolean): boolean => {
+    while (pos < g.length) {
+      const c = g[pos++];
+      if (sub && c === "}") {
+        out += ")";
+        return true;
+      }
+      switch (c) {
+        case "*":
+          if (g[pos] === "*") {
+            pos++;
+            out += ".*";
+          } else out += "[^/]*";
+          break;
+        case "?":
+          out += "[^/]";
+          break;
+        case "[":
+          if (!chars()) return false;
+          break;
+        case "{":
+          out += "(";
+          if (!compile(true)) return false;
+          break;
+        case ",":
+          out += sub ? "|" : ",";
+          break;
+        case "\\":
+          if (pos >= g.length) return false;
+          out += lit(g[pos++]);
+          break;
+        default:
+          out += lit(c);
+      }
+    }
+    // An alternative left open is a glob the forge cannot compile.
+    return !sub;
+  };
+  if (!compile(false)) return null;
+  try {
+    return new RegExp(`^${out}$`, "u");
+  } catch {
+    return null;
   }
-  return new RegExp(`^${re}$`).test(branch);
 }
 
 /** Refuses a file written to the default branch or to a branch a protection rule names. */