fix(ext/node): implement uv.errname (#20785)

Fixes https://github.com/denoland/deno/issues/20617

2 files changed, 21 insertions, 0 deletions

diff --git a/cli/tests/unit_node/process_test.ts b/cli/tests/unit_node/process_test.ts
index bcb7a9767..78c5fcc97 100644
--- a/cli/tests/unit_node/process_test.ts
+++ b/cli/tests/unit_node/process_test.ts
@@ -786,3 +786,16 @@ Deno.test({
     worker.terminate();
   },
 });
+
+Deno.test({
+  name: "process.binding('uv').errname",
+  ignore: Deno.build.os === "windows",
+  fn() {
+    // @ts-ignore: untyped internal binding, not actually supposed to be
+    // used by userland modules in Node.js
+    const uv = process.binding("uv");
+    assert(uv.errname);
+    assert(typeof uv.errname === "function");
+    assertEquals(uv.errname(-1), "EPERM");
+  },
+});
diff --git a/ext/node/polyfills/internal_binding/uv.ts b/ext/node/polyfills/internal_binding/uv.ts
index c08d44565..3cb145d28 100644
--- a/ext/node/polyfills/internal_binding/uv.ts
+++ b/ext/node/polyfills/internal_binding/uv.ts
@@ -531,3 +531,11 @@ export const UV_EINVAL = codeMap.get("EINVAL")!;
 export const UV_ENOENT = codeMap.get("ENOENT");
 export const UV_ENOTSOCK = codeMap.get("ENOTSOCK")!;
 export const UV_UNKNOWN = codeMap.get("UNKNOWN")!;
+
+export function errname(errno: number): string {
+  const err = errorMap.get(errno);
+  if (err) {
+    return err[0];
+  }
+  return `UNKNOWN (${errno})`;
+}