fs: add uv_open_osfhandle

Adds uv_open_osfhandle to complete uv_get_osfhandle

Ref: nodejs/node#15433
Ref: nodejs/node-addon-api#304
PR-URL: #1927
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

docs/src/fs.rst

@@ -403,6 +403,15 @@ Helper functions
 
     .. versionadded:: 1.12.0
 
+.. c:function:: int uv_open_osfhandle(uv_os_fd_t os_fd)
+
+   For a OS-dependent handle, get the file descriptor in the C runtime.
+   On UNIX, returns the ``os_fd`` intact. On Windows, this calls `_open_osfhandle <https://msdn.microsoft.com/en-us/library/bdts1c9x.aspx>`_.
+   Note that the return value is still owned by the CRT,
+   any attempts to close it or to use it after closing the handle may lead to malfunction.
+
+    .. versionadded:: 1.23.0
+
 File open constants
 -------------------
 

include/uv.h

@@ -1065,6 +1065,7 @@ UV_EXTERN int uv_set_process_title(const char* title);
 UV_EXTERN int uv_resident_set_memory(size_t* rss);
 UV_EXTERN int uv_uptime(double* uptime);
 UV_EXTERN uv_os_fd_t uv_get_osfhandle(int fd);
+UV_EXTERN int uv_open_osfhandle(uv_os_fd_t os_fd);
 
 typedef struct {
   long tv_sec;

src/unix/core.c

@@ -1338,6 +1338,9 @@ uv_os_fd_t uv_get_osfhandle(int fd) {
   return fd;
 }
 
+int uv_open_osfhandle(uv_os_fd_t os_fd) {
+  return os_fd;
+}
 
 uv_pid_t uv_os_getpid(void) {
   return getpid();

src/win/handle.c

@@ -157,3 +157,7 @@ int uv_is_closing(const uv_handle_t* handle) {
 uv_os_fd_t uv_get_osfhandle(int fd) {
   return uv__get_osfhandle(fd);
 }
+
+int uv_open_osfhandle(uv_os_fd_t os_fd) {
+  return _open_osfhandle((intptr_t) os_fd, 0);
+}

test/test-fs.c

@@ -3069,6 +3069,52 @@ TEST_IMPL(get_osfhandle_valid_handle) {
   return 0;
 }
 
+TEST_IMPL(open_osfhandle_valid_handle) {
+  int r;
+  uv_os_fd_t handle;
+  int fd;
+
+  /* Setup. */
+  unlink("test_file");
+
+  loop = uv_default_loop();
+
+  r = uv_fs_open(NULL,
+                 &open_req1,
+                 "test_file",
+                 O_RDWR | O_CREAT,
+                 S_IWUSR | S_IRUSR,
+                 NULL);
+  ASSERT(r >= 0);
+  ASSERT(open_req1.result >= 0);
+  uv_fs_req_cleanup(&open_req1);
+
+  handle = uv_get_osfhandle(open_req1.result);
+#ifdef _WIN32
+  ASSERT(handle != INVALID_HANDLE_VALUE);
+#else
+  ASSERT(handle >= 0);
+#endif
+
+  fd = uv_open_osfhandle(handle);
+#ifdef _WIN32
+  ASSERT(fd > 0);
+#else
+  ASSERT(fd == open_req1.result);
+#endif
+
+  r = uv_fs_close(NULL, &close_req, open_req1.result, NULL);
+  ASSERT(r == 0);
+  ASSERT(close_req.result == 0);
+  uv_fs_req_cleanup(&close_req);
+
+  /* Cleanup. */
+  unlink("test_file");
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}
+
 TEST_IMPL(fs_file_pos_after_op_with_offset) {
   int r;
 

test/test-list.h

@@ -334,6 +334,7 @@ TEST_DECLARE   (fs_rename_to_existing_file)
 TEST_DECLARE   (fs_write_multiple_bufs)
 TEST_DECLARE   (fs_read_write_null_arguments)
 TEST_DECLARE   (get_osfhandle_valid_handle)
+TEST_DECLARE   (open_osfhandle_valid_handle)
 TEST_DECLARE   (fs_write_alotof_bufs)
 TEST_DECLARE   (fs_write_alotof_bufs_with_offset)
 TEST_DECLARE   (fs_file_pos_after_op_with_offset)
@@ -887,6 +888,7 @@ TASK_LIST_START
   TEST_ENTRY  (fs_fchmod_archive_readonly)
 #endif
   TEST_ENTRY  (get_osfhandle_valid_handle)
+  TEST_ENTRY  (open_osfhandle_valid_handle)
   TEST_ENTRY  (threadpool_queue_work_simple)
   TEST_ENTRY  (threadpool_queue_work_einval)
   TEST_ENTRY  (threadpool_multiple_event_loops)