feat: support createNew in Deno.writeFile (#17023)

cli/tests/unit/write_file_test.ts

@@ -96,6 +96,20 @@ Deno.test(
   },
 );
 
+Deno.test(
+  { permissions: { read: true, write: true } },
+  function writeFileSyncCreateNew() {
+    const enc = new TextEncoder();
+    const data = enc.encode("Hello");
+    const filename = Deno.makeTempDirSync() + "/test.txt";
+    Deno.writeFileSync(filename, data, { createNew: true });
+
+    assertThrows(() => {
+      Deno.writeFileSync(filename, data, { createNew: true });
+    }, Deno.errors.AlreadyExists);
+  },
+);
+
 Deno.test(
   { permissions: { read: true, write: true } },
   function writeFileSyncAppend() {
@@ -216,6 +230,19 @@ Deno.test(
   },
 );
 
+Deno.test(
+  { permissions: { read: true, write: true } },
+  async function writeFileCreateNew() {
+    const enc = new TextEncoder();
+    const data = enc.encode("Hello");
+    const filename = Deno.makeTempDirSync() + "/test.txt";
+    await Deno.writeFile(filename, data, { createNew: true });
+    await assertRejects(async () => {
+      await Deno.writeFile(filename, data, { createNew: true });
+    }, Deno.errors.AlreadyExists);
+  },
+);
+
 Deno.test(
   { permissions: { read: true, write: true } },
   async function writeFileAppend() {

cli/tsc/dts/lib.deno.ns.d.ts

@@ -3296,6 +3296,10 @@ declare namespace Deno {
     /** Sets the option to allow creating a new file, if one doesn't already
      * exist at the specified path (defaults to `true`). */
     create?: boolean;
+    /** Defaults to `false`. If set to `true`, no file, directory, or symlink is
+     * allowed to exist at the target location. When createNew is set to `true`,
+     * `create` is ignored. */
+    createNew?: boolean;
     /** Permissions always applied to file. */
     mode?: number;
     /** An abort signal to allow cancellation of the file write operation.

runtime/js/40_write_file.js

@@ -17,6 +17,7 @@
       options.mode,
       options.append ?? false,
       options.create ?? true,
+      options.createNew ?? false,
       data,
     );
   }
@@ -41,6 +42,7 @@
         options.mode,
         options.append ?? false,
         options.create ?? true,
+        options.createNew ?? false,
         data,
         cancelRid,
       );

runtime/ops/fs.rs

@@ -222,14 +222,18 @@ async fn op_open_async(
 }
 
 #[inline]
-fn write_open_options(create: bool, append: bool) -> OpenOptions {
+fn write_open_options(
+  create: bool,
+  append: bool,
+  create_new: bool,
+) -> OpenOptions {
   OpenOptions {
     read: false,
     write: true,
     create,
     truncate: !append,
     append,
-    create_new: false,
+    create_new,
   }
 }
 
@@ -240,13 +244,14 @@ fn op_write_file_sync(
   mode: Option<u32>,
   append: bool,
   create: bool,
+  create_new: bool,
   data: ZeroCopyBuf,
 ) -> Result<(), AnyError> {
   let (path, open_options) = open_helper(
     state,
     &path,
     mode,
-    Some(&write_open_options(create, append)),
+    Some(&write_open_options(create, append, create_new)),
     "Deno.writeFileSync()",
   )?;
   write_file(&path, open_options, mode, data)
@@ -259,6 +264,7 @@ async fn op_write_file_async(
   mode: Option<u32>,
   append: bool,
   create: bool,
+  create_new: bool,
   data: ZeroCopyBuf,
   cancel_rid: Option<ResourceId>,
 ) -> Result<(), AnyError> {
@@ -274,7 +280,7 @@ async fn op_write_file_async(
     &mut state.borrow_mut(),
     &path,
     mode,
-    Some(&write_open_options(create, append)),
+    Some(&write_open_options(create, append, create_new)),
     "Deno.writeFile()",
   )?;
   let write_future = tokio::task::spawn_blocking(move || {