implemented FileInfo struct

This struct is a wrapper around `uv_stat_t` to hide the stat information
inside `src/os/`.
The stat file attribute will be private after all refactorings concerning
file informations are done.

src/os/fs.c

@@ -237,3 +237,41 @@ int os_remove(const char *path)
   return result;
 }
 
+bool os_get_file_info(const char *path, FileInfo *file_info)
+{
+  if (os_stat((char_u *)path, &(file_info->stat)) == OK) {
+    return true;
+  }
+  return false;
+}
+
+bool os_get_file_info_link(const char *path, FileInfo *file_info)
+{
+  uv_fs_t request;
+  int result = uv_fs_lstat(uv_default_loop(), &request, path, NULL);
+  file_info->stat = request.statbuf;
+  uv_fs_req_cleanup(&request);
+  if (result == kLibuvSuccess) {
+    return true;
+  }
+  return false;
+}
+
+bool os_get_file_info_fd(int file_descriptor, FileInfo *file_info)
+{
+  uv_fs_t request;
+  int result = uv_fs_fstat(uv_default_loop(), &request, file_descriptor, NULL);
+  file_info->stat = request.statbuf;
+  uv_fs_req_cleanup(&request);
+  if (result == kLibuvSuccess) {
+    return true;
+  }
+  return false;
+}
+
+bool os_file_info_id_equal(FileInfo *file_info_1, FileInfo *file_info_2)
+{
+  return file_info_1->stat.st_ino == file_info_2->stat.st_ino
+         && file_info_1->stat.st_dev == file_info_2->stat.st_dev;
+}
+

src/os/os.h

@@ -111,4 +111,36 @@ char *os_get_user_directory(const char *name);
 /// @return OK on success, FAIL if an failure occured.
 int os_stat(const char_u *name, uv_stat_t *statbuf);
 
+/// Struct which encapsulates stat information.
+typedef struct {
+  // TODO(stefan991): make stat private
+  uv_stat_t stat;
+} FileInfo;
+
+/// Get the file information for a given path
+///
+/// @param file_descriptor File descriptor of the file.
+/// @param[out] file_info Pointer to a FileInfo to put the information in.
+/// @return `true` on sucess, `false` for failure.
+bool os_get_file_info(const char *path, FileInfo *file_info);
+
+/// Get the file information for a given path without following links
+///
+/// @param path Path to the file.
+/// @param[out] file_info Pointer to a FileInfo to put the information in.
+/// @return `true` on sucess, `false` for failure.
+bool os_get_file_info_link(const char *path, FileInfo *file_info);
+
+/// Get the file information for a given file descriptor
+///
+/// @param file_descriptor File descriptor of the file.
+/// @param[out] file_info Pointer to a FileInfo to put the information in.
+/// @return `true` on sucess, `false` for failure.
+bool os_get_file_info_fd(int file_descriptor, FileInfo *file_info);
+
+/// Compare the inodes of two FileInfos
+///
+/// @return `true` if the two FileInfos represent the same file.
+bool os_file_info_id_equal(FileInfo *file_info_1, FileInfo *file_info_2);
+
 #endif  // NEOVIM_OS_OS_H