Re: [PATCH 4/4] cygwin: Use native Win32 API for stat

> Despite all efforts to make the fast implementation as robust as possible,
> it may not work well for some very rare situations. I am aware only one
> situation: use Cygwin mount to bind unrelated paths inside repository
> together.  Therefore, the core.cygwinnativestat configuration option is
> provided, which controls whether native or Cygwin version of stat is used.

> +static int do_stat(const char *file_name, struct stat *buf, stat_fn_t cygstat)
> +{
> +	WIN32_FILE_ATTRIBUTE_DATA fdata;
> +
> +	if (file_name[0] == '/')
> +		return cygstat (file_name, buf);
> +
> +	if (!(errno = get_file_attr(file_name, &fdata))) {
> +		/*
> +		 * If the system attribute is set and it is not a directory then
> +		 * it could be a symbol link created in the nowinsymlinks mode.
> +		 * Normally, Cygwin works in the winsymlinks mode, so this situation
> +		 * is very unlikely. For the sake of simplicity of our code, let's
> +		 * Cygwin to handle it.
> +		 */
> +		if ((fdata.dwFileAttributes & FILE_ATTRIBUTE_SYSTEM) &&
> +		    !(fdata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY))
> +			return cygstat (file_name, buf);

> +
> +		/* fill out the stat structure */
> +		buf->st_dev = buf->st_rdev = 0; /* not used by Git */
> +		buf->st_ino = 0;
> +		buf->st_mode = file_attr_to_st_mode (fdata.dwFileAttributes);
> +		buf->st_nlink = 1;
> +		buf->st_uid = buf->st_gid = 0;
> +#ifdef __CYGWIN_USE_BIG_TYPES__
> +		buf->st_size = ((_off64_t)fdata.nFileSizeHigh << 32) +
> +			fdata.nFileSizeLow;
> +#else
> +		buf->st_size = (off_t)fdata.nFileSizeLow;
> +#endif
> +		buf->st_blocks = size_to_blocks(buf->st_size);
> +		filetime_to_timespec(&fdata.ftLastAccessTime, &buf->st_atim);
> +		filetime_to_timespec(&fdata.ftLastWriteTime, &buf->st_mtim);
> +		filetime_to_timespec(&fdata.ftCreationTime, &buf->st_ctim);
> +		return 0;
> +	} else if (errno == ENOENT) {
> +		/*
> +		 * In the winsymlinks mode (which is the default), Cygwin
> +		 * emulates symbol links using Windows shortcut files. These
> +		 * files are formed by adding .lnk extension. So, if we have
> +		 * not found the specified file name, it could be that it is
> +		 * a symbol link. Let's Cygwin to deal with that.
> +		 */
> +		return cygstat (file_name, buf);
> +	}
> +	return -1;
> +}