Predicates on paths should respect link following option on Windows

[FrankHB]

ChezScheme/c/io.c

Lines 127 to 195 in c048ad8

	IBOOL S_file_existsp(const char *inpath, IBOOL followp) {
	#ifdef WIN32
	wchar_t *wpath; IBOOL res;
	WIN32_FILE_ATTRIBUTE_DATA filedata;
	if ((wpath = S_malloc_wide_pathname(inpath)) == NULL) {
	return 0;
	} else {
	res = GetFileAttributesExW(wpath, GetFileExInfoStandard, &filedata);
	free(wpath);
	return res;
	}
	#else /* WIN32 */
	struct STATBUF statbuf; char *path; IBOOL res;
	path = S_malloc_pathname(inpath);
	res = (followp ? STAT(path, &statbuf) : LSTAT(path, &statbuf)) == 0;
	free(path);
	return res;
	#endif /* WIN32 */
	}
	IBOOL S_file_regularp(const char *inpath, IBOOL followp) {
	#ifdef WIN32
	wchar_t *wpath; IBOOL res;
	WIN32_FILE_ATTRIBUTE_DATA filedata;
	if ((wpath = S_malloc_wide_pathname(inpath)) == NULL) {
	return 0;
	} else {
	res = GetFileAttributesExW(wpath, GetFileExInfoStandard, &filedata)
	&& (filedata.dwFileAttributes & (FILE_ATTRIBUTE_DEVICE | FILE_ATTRIBUTE_DIRECTORY | FILE_ATTRIBUTE_REPARSE_POINT)) == 0;
	free(wpath);
	return res;
	}
	#else /* WIN32 */
	struct STATBUF statbuf; char *path; IBOOL res;
	path = S_malloc_pathname(inpath);
	res = (followp ? STAT(path, &statbuf) : LSTAT(path, &statbuf)) == 0
	&& (statbuf.st_mode & S_IFMT) == S_IFREG;
	free(path);
	return res;
	#endif /* WIN32 */
	}
	IBOOL S_file_directoryp(const char *inpath, IBOOL followp) {
	#ifdef WIN32
	wchar_t *wpath; IBOOL res;
	WIN32_FILE_ATTRIBUTE_DATA filedata;
	if ((wpath = S_malloc_wide_pathname(inpath)) == NULL) {
	return 0;
	} else {
	res = GetFileAttributesExW(wpath, GetFileExInfoStandard, &filedata)
	&& filedata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
	free(wpath);
	return res;
	}
	#else /* WIN32 */
	struct STATBUF statbuf; char *path; IBOOL res;
	path = S_malloc_pathname(inpath);
	res = (followp ? STAT(path, &statbuf) : LSTAT(path, &statbuf)) == 0
	&& (statbuf.st_mode & S_IFMT) == S_IFDIR;
	free(path);
	return res;
	#endif /* WIN32 */
	}

In these implementations, followp is not used at all for Win32. This looks wrong, because Windows supports symbolic links similar enough to POSIX. There is no reason to keep the inconsistent behaviors. Further, the behavior is also not the default of POSIX, due to the fact that GetFileAttributesExW does not follow links (i.e. it is more like lstat but not stat). These gliches are not documented.

[burgerrg]

On Windows 11, I used mklink to create a symbolic link from foo.ss to bar.ss. In Chez Scheme 9.5.8, (file-exists? "bar.ss") returned #t. However, (load "bar.ss") failed with "no such file or directory".

This means that GetFileAttributesExW is following the link, but whatever Chez Scheme calls to open the file is not.

Do you know how to modify S_file_existsp to use followp on Windows?