app/main.js

@@ -10,6 +10,8 @@ const FILE_MODE_PRIVATE = 0o600;
 const DIR_MODE_PRIVATE = 0o700;
 const DEFAULT_CODEX_TIMEOUT_MS = 30 * 60 * 1000;
 const DEFAULT_OUTPUT_LIMIT_BYTES = 1024 * 1024;
+const TEMP_DIR_PREFIX = ".codex-action-";
+const OUTPUT_DELIMITER_PREFIX = "CODEX_OUTPUT_";
 
 class TempFileRegistry {
   constructor() {
@@ -92,7 +94,7 @@ function cleanup() {
 }
 
 function makeTempDir(dir) {
-  const tempDir = fs.mkdtempSync(path.join(dir, ".codex-action-"));
+  const tempDir = fs.mkdtempSync(path.join(dir, TEMP_DIR_PREFIX));
   fs.chmodSync(tempDir, DIR_MODE_PRIVATE);
   tempFiles.trackDir(tempDir);
   return tempDir;
@@ -115,7 +117,7 @@ function appendGithubOutput(status, output) {
 
   let delimiter;
   do {
-    delimiter = `CODEX_OUTPUT_${crypto.randomBytes(12).toString("hex")}`;
+    delimiter = `${OUTPUT_DELIMITER_PREFIX}${crypto.randomBytes(12).toString("hex")}`;
   } while (output.includes(delimiter));
 
   fs.appendFileSync(
@@ -132,22 +134,27 @@ function fail(message, code = 1) {
   process.exit(code);
 }
 
-function normalizeBase64(value) {
-  return value.replace(/\s+/g, "").replace(/=+$/, "");
+function compactBase64(value) {
+  return value.replace(/\s+/g, "");
+}
+
+function isBase64(value) {
+  const normalized = compactBase64(value);
+  const paddingIndex = normalized.indexOf("=");
+
+  if (!normalized || normalized.length % 4 === 1 || !/^[A-Za-z0-9+/]*={0,2}$/.test(normalized)) {
+    return false;
+  }
+
+  return paddingIndex === -1 || /^=+$/.test(normalized.slice(paddingIndex));
 }
 
 function validateAuth(encodedAuth, authFile) {
-  const decoded = Buffer.from(encodedAuth, "base64");
-  const normalizedDecoded = normalizeBase64(decoded.toString("base64"));
-  const normalizedInput = normalizeBase64(encodedAuth);
-
-  if (decoded.length === 0 && normalizedInput.length > 0) {
+  if (!isBase64(encodedAuth)) {
     fail("OAUTH must be valid base64 encoded Codex auth.json.");
   }
 
-  if (normalizedDecoded !== normalizedInput) {
-    fail("OAUTH must be valid base64 encoded Codex auth.json.");
-  }
+  const decoded = Buffer.from(compactBase64(encodedAuth), "base64");
 
   fs.writeFileSync(authFile, decoded, { mode: FILE_MODE_PRIVATE });
 
@@ -168,26 +175,33 @@ function parsePositiveInteger(value, fallback) {
   return Number.isFinite(parsed) && parsed > 0 ? parsed : fallback;
 }
 
+function readExecutionConfig() {
+  return {
+    timeoutMs: parsePositiveInteger(process.env.CODEX_TIMEOUT_MS, DEFAULT_CODEX_TIMEOUT_MS),
+    outputLimitBytes: parsePositiveInteger(process.env.CODEX_OUTPUT_LIMIT_BYTES, DEFAULT_OUTPUT_LIMIT_BYTES),
+    workspace: process.env.GITHUB_WORKSPACE || process.cwd(),
+  };
+}
+
+function codexExecArgs(model, prompt) {
+  return [
+    "exec",
+    "--dangerously-bypass-approvals-and-sandbox",
+    "--skip-git-repo-check",
+    "--model",
+    model,
+    prompt,
+  ];
+}
+
 function runCodex(model, prompt) {
   return new Promise((resolve) => {
-    const timeoutMs = parsePositiveInteger(process.env.CODEX_TIMEOUT_MS, DEFAULT_CODEX_TIMEOUT_MS);
-    const outputLimitBytes = parsePositiveInteger(process.env.CODEX_OUTPUT_LIMIT_BYTES, DEFAULT_OUTPUT_LIMIT_BYTES);
-    const workspace = process.env.GITHUB_WORKSPACE || process.cwd();
+    const { timeoutMs, outputLimitBytes, workspace } = readExecutionConfig();
+    const args = codexExecArgs(model, prompt);
 
     // This Docker Action runs inside an ephemeral CI container where Codex must be
     // able to edit the checked-out workspace without interactive approvals.
-    const child = spawn(
-      "codex",
-      [
-        "exec",
-        "--dangerously-bypass-approvals-and-sandbox",
-        "--skip-git-repo-check",
-        "--model",
-        model,
-        prompt,
-      ],
-      { cwd: workspace, stdio: ["ignore", "pipe", "pipe"] },
-    );
+    const child = spawn("codex", args, { cwd: workspace, stdio: ["ignore", "pipe", "pipe"] });
 
     const output = new OutputCollector(outputLimitBytes);
 
@@ -255,6 +269,19 @@ function readConfig() {
   return { oauth, model, codexHome, prompt };
 }
 
+function createAuthLock(codexHome) {
+  const lockName = crypto.createHash("sha256").update(codexHome).digest("hex");
+  const lockPath = path.join(codexHome, `.codex-auth-${lockName}.lock`);
+
+  try {
+    const lockHandle = fs.openSync(lockPath, "wx", FILE_MODE_PRIVATE);
+    tempFiles.trackFile(lockPath);
+    return lockHandle;
+  } catch {
+    fail("Unable to lock Codex auth.json.");
+  }
+}
+
 function setupAuth(oauth, codexHome) {
   try {
     fs.mkdirSync(codexHome, { recursive: true, mode: DIR_MODE_PRIVATE });
@@ -267,16 +294,7 @@ function setupAuth(oauth, codexHome) {
   const tempDir = makeTempDir(codexHome);
   const authFile = makeTempFile(tempDir, "auth");
   const authPath = path.join(codexHome, "auth.json");
-  const lockName = crypto.createHash("sha256").update(codexHome).digest("hex");
-  const lockPath = path.join(codexHome, `.codex-auth-${lockName}.lock`);
-
-  let lockHandle;
-  try {
-    lockHandle = fs.openSync(lockPath, "wx", FILE_MODE_PRIVATE);
-    tempFiles.trackFile(lockPath);
-  } catch {
-    fail("Unable to lock Codex auth.json.");
-  }
+  const lockHandle = createAuthLock(codexHome);
 
   validateAuth(oauth, authFile);