refactor(sandbox): share bind parsing and host-path policy checks

src/agents/sandbox/bind-spec.ts

@@ -0,0 +1,34 @@
+type SplitBindSpec = {
+  host: string;
+  container: string;
+  options: string;
+};
+
+export function splitSandboxBindSpec(spec: string): SplitBindSpec | null {
+  const separator = getHostContainerSeparatorIndex(spec);
+  if (separator === -1) {
+    return null;
+  }
+
+  const host = spec.slice(0, separator);
+  const rest = spec.slice(separator + 1);
+  const optionsStart = rest.indexOf(":");
+  if (optionsStart === -1) {
+    return { host, container: rest, options: "" };
+  }
+  return {
+    host,
+    container: rest.slice(0, optionsStart),
+    options: rest.slice(optionsStart + 1),
+  };
+}
+
+function getHostContainerSeparatorIndex(spec: string): number {
+  const hasDriveLetterPrefix = /^[A-Za-z]:[\\/]/.test(spec);
+  for (let i = hasDriveLetterPrefix ? 2 : 0; i < spec.length; i += 1) {
+    if (spec[i] === ":") {
+      return i;
+    }
+  }
+  return -1;
+}