1 files changed, 92 insertions, 0 deletions
diff --git a/runtime/rt/40_write_file.js b/runtime/rt/40_write_file.js
new file mode 100644
index 000000000..7a9cb1f40
--- /dev/null
+++ b/runtime/rt/40_write_file.js
@@ -0,0 +1,92 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+((window) => {
+  const { stat, statSync, chmod, chmodSync } = window.__bootstrap.fs;
+  const { open, openSync } = window.__bootstrap.files;
+  const { writeAll, writeAllSync } = window.__bootstrap.buffer;
+  const { build } = window.__bootstrap.build;
+
+  function writeFileSync(
+    path,
+    data,
+    options = {},
+  ) {
+    if (options.create !== undefined) {
+      const create = !!options.create;
+      if (!create) {
+        // verify that file exists
+        statSync(path);
+      }
+    }
+
+    const openOptions = options.append
+      ? { write: true, create: true, append: true }
+      : { write: true, create: true, truncate: true };
+    const file = openSync(path, openOptions);
+
+    if (
+      options.mode !== undefined &&
+      options.mode !== null &&
+      build.os !== "windows"
+    ) {
+      chmodSync(path, options.mode);
+    }
+
+    writeAllSync(file, data);
+    file.close();
+  }
+
+  async function writeFile(
+    path,
+    data,
+    options = {},
+  ) {
+    if (options.create !== undefined) {
+      const create = !!options.create;
+      if (!create) {
+        // verify that file exists
+        await stat(path);
+      }
+    }
+
+    const openOptions = options.append
+      ? { write: true, create: true, append: true }
+      : { write: true, create: true, truncate: true };
+    const file = await open(path, openOptions);
+
+    if (
+      options.mode !== undefined &&
+      options.mode !== null &&
+      build.os !== "windows"
+    ) {
+      await chmod(path, options.mode);
+    }
+
+    await writeAll(file, data);
+    file.close();
+  }
+
+  function writeTextFileSync(
+    path,
+    data,
+    options = {},
+  ) {
+    const encoder = new TextEncoder();
+    return writeFileSync(path, encoder.encode(data), options);
+  }
+
+  function writeTextFile(
+    path,
+    data,
+    options = {},
+  ) {
+    const encoder = new TextEncoder();
+    return writeFile(path, encoder.encode(data), options);
+  }
+
+  window.__bootstrap.writeFile = {
+    writeTextFile,
+    writeTextFileSync,
+    writeFile,
+    writeFileSync,
+  };
+})(this);