✨feature: Initial MVP

src/Support/AtomicWriter.php

@@ -0,0 +1,51 @@
+<?php
+// phpcs:disable PEAR.Commenting.FileComment,PEAR.Commenting.ClassComment
+
+/**
+ * Atomic file writing support.
+ */
+
+declare(strict_types=1);
+
+namespace IronKanban\Support;
+
+/**
+ * Writes files using a temporary file swap.
+ */
+final class AtomicWriter
+{
+    /**
+     * Atomically write contents to a file.
+     *
+     * @param string $path     Destination path.
+     * @param string $contents File contents.
+     *
+     * @return void
+     */
+    public static function write(string $path, string $contents): void
+    {
+        ensure_directory(dirname($path));
+
+        $tmpPath = $path . '.tmp-' . bin2hex(random_bytes(4));
+        $handle = fopen($tmpPath, 'wb');
+
+        if ($handle === false) {
+            throw new \RuntimeException('Unable to open temp file: ' . $tmpPath);
+        }
+
+        try {
+            if (fwrite($handle, $contents) === false) {
+                throw new \RuntimeException('Unable to write temp file: ' . $tmpPath);
+            }
+
+            fflush($handle);
+        } finally {
+            fclose($handle);
+        }
+
+        if (!rename($tmpPath, $path)) {
+            @unlink($tmpPath);
+            throw new \RuntimeException('Unable to move temp file into place: ' . $path);
+        }
+    }
+}