src: fix uv_err_name memory leak

Author: theanarkh

src/util.cc

@@ -475,4 +475,13 @@ void SetConstructorFunction(Local<v8::Context> context,
   that->Set(context, name, tmpl->GetFunction(context).ToLocalChecked()).Check();
 }
 
+void freeUVErrorNameMemoryIfNeed(const char* name, int code) {
+  // See uv__unknown_err_code in uv-common.c
+  std::string buf("Unknown system error ");
+  buf.append(std::to_string(code));
+  if (strcmp(name, buf.c_str()) == 0) {
+    free(reinterpret_cast<void*>(const_cast<char*>(name)));
+  }
+}
+
 }  // namespace node

src/util.h

@@ -923,6 +923,8 @@ void SetConstructorFunction(v8::Local<v8::Context> context,
                             SetConstructorFunctionFlag flag =
                                 SetConstructorFunctionFlag::SET_CLASS_NAME);
 
+void freeUVErrorNameMemoryIfNeed(const char* name, int code);
+
 }  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

src/uv.cc

@@ -24,6 +24,7 @@
 #include "node.h"
 #include "node_external_reference.h"
 #include "node_process-inl.h"
+#include "util.h"
 
 namespace node {
 
@@ -75,6 +76,7 @@ void ErrName(const FunctionCallbackInfo<Value>& args) {
   CHECK_LT(err, 0);
   const char* name = uv_err_name(err);
   args.GetReturnValue().Set(OneByteString(env->isolate(), name));
+  freeUVErrorNameMemoryIfNeed(name, err);
 }
 
 void GetErrMap(const FunctionCallbackInfo<Value>& args) {

test/parallel/test-uv-errno.js

@@ -12,6 +12,8 @@ const { internalBinding } = require('internal/test/binding');
 const uv = internalBinding('uv');
 const keys = Object.keys(uv);
 
+assert.strictEqual(uv.errname(-111111), 'Unknown system error -111111');
+
 keys.forEach((key) => {
   if (!key.startsWith('UV_'))
     return;