unix,win: add uv_translate_sys_error() public API

uv_translate_sys_error() was a private function for Windows.
This commit adds an equivalent function on other platforms, and
exposes it as public API.

Exposing this is useful in scenarios where the application uses
both libuv functions and platform-specific system calls and wants
to report errors uniformly as libuv errors.

Fixes: https://github.com/libuv/libuv/issues/79
PR-URL: https://github.com/libuv/libuv/pull/1060
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>

docs/src/errors.rst

@@ -332,3 +332,13 @@ API
 
     Returns the error name for the given error code.  Leaks a few bytes
     of memory when you call it with an unknown error code.
+
+.. c:function:: int uv_translate_sys_error(int sys_errno)
+
+   Returns the libuv error code equivalent to the given platform dependent error
+   code: POSIX error codes on Unix (the ones stored in `errno`), and Win32 error
+   codes on Windows (those returned by `GetLastError()` or `WSAGetLastError()`).
+
+   If `sys_errno` is already a libuv error, it is simply returned.
+
+   .. versionchanged:: 1.10.0 function declared public.

include/uv.h

@@ -363,6 +363,8 @@ typedef enum {
 } uv_membership;
 
 
+UV_EXTERN int uv_translate_sys_error(int sys_errno);
+
 UV_EXTERN const char* uv_strerror(int err);
 UV_EXTERN const char* uv_err_name(int err);
 

src/unix/core.c

@@ -1236,3 +1236,9 @@ void uv_os_free_passwd(uv_passwd_t* pwd) {
 int uv_os_get_passwd(uv_passwd_t* pwd) {
   return uv__getpwuid_r(pwd);
 }
+
+
+int uv_translate_sys_error(int sys_errno) {
+  /* If < 0 then it's already a libuv error. */
+  return sys_errno <= 0 ? sys_errno : -sys_errno;
+}

test/test-error.c

@@ -48,3 +48,22 @@ TEST_IMPL(error_message) {
 
   return 0;
 }
+
+
+TEST_IMPL(sys_error) {
+#if defined(_WIN32)
+  ASSERT(uv_translate_sys_error(ERROR_NOACCESS) == UV_EACCES);
+  ASSERT(uv_translate_sys_error(WSAEADDRINUSE) == UV_EADDRINUSE);
+  ASSERT(uv_translate_sys_error(ERROR_BAD_PIPE) == UV_EPIPE);
+#else
+  ASSERT(uv_translate_sys_error(EPERM) == UV_EPERM);
+  ASSERT(uv_translate_sys_error(EPIPE) == UV_EPIPE);
+  ASSERT(uv_translate_sys_error(EINVAL) == UV_EINVAL);
+#endif
+  ASSERT(uv_translate_sys_error(UV_EINVAL) == UV_EINVAL);
+  ASSERT(uv_translate_sys_error(UV_ERANGE) == UV_ERANGE);
+  ASSERT(uv_translate_sys_error(UV_EACCES) == UV_EACCES);
+  ASSERT(uv_translate_sys_error(0) == 0);
+
+  return 0;
+}

test/test-list.h

@@ -152,6 +152,7 @@ TEST_DECLARE   (shutdown_eof)
 TEST_DECLARE   (shutdown_twice)
 TEST_DECLARE   (callback_stack)
 TEST_DECLARE   (error_message)
+TEST_DECLARE   (sys_error)
 TEST_DECLARE   (timer)
 TEST_DECLARE   (timer_init)
 TEST_DECLARE   (timer_again)
@@ -542,6 +543,7 @@ TASK_LIST_START
   TEST_HELPER (callback_stack, tcp4_echo_server)
 
   TEST_ENTRY  (error_message)
+  TEST_ENTRY  (sys_error)
 
   TEST_ENTRY  (timer)
   TEST_ENTRY  (timer_init)