mingw: support renaming symlinks

Older MSVCRT's `_wrename()` function cannot rename symlinks over
existing files: it returns success without doing anything. Newer
MSVCR*.dll versions probably do not share this problem: according to CRT
sources, they just call `MoveFileEx()` with the `MOVEFILE_COPY_ALLOWED`
flag.

Avoid the `_wrename()` call, and go with directly calling
`MoveFileEx()`, with proper error handling of course.

Signed-off-by: Karsten Blees <[email protected]>
Signed-off-by: Johannes Schindelin <[email protected]>

Author: kblees

compat/mingw.c

@@ -2275,7 +2275,7 @@ int mingw_accept(int sockfd1, struct sockaddr *sa, socklen_t *sz)
 int mingw_rename(const char *pold, const char *pnew)
 {
 	static int supports_file_rename_info_ex = 1;
-	DWORD attrs, gle;
+	DWORD attrs = INVALID_FILE_ATTRIBUTES, gle;
 	int tries = 0;
 	wchar_t wpold[MAX_PATH], wpnew[MAX_PATH];
 	int wpnew_len;
@@ -2286,15 +2286,6 @@ int mingw_rename(const char *pold, const char *pnew)
 	if (wpnew_len < 0)
 		return -1;
 
-	/*
-	 * Try native rename() first to get errno right.
-	 * It is based on MoveFile(), which cannot overwrite existing files.
-	 */
-	if (!_wrename(wpold, wpnew))
-		return 0;
-	if (errno != EEXIST)
-		return -1;
-
 repeat:
 	if (supports_file_rename_info_ex) {
 		/*
@@ -2370,13 +2361,22 @@ int mingw_rename(const char *pold, const char *pnew)
 		 * to retry.
 		 */
 	} else {
-		if (MoveFileExW(wpold, wpnew, MOVEFILE_REPLACE_EXISTING))
+		if (MoveFileExW(wpold, wpnew,
+				MOVEFILE_REPLACE_EXISTING | MOVEFILE_COPY_ALLOWED))
 			return 0;
 		gle = GetLastError();
 	}
 
-	/* TODO: translate more errors */
-	if (gle == ERROR_ACCESS_DENIED &&
+	/* revert file attributes on failure */
+	if (attrs != INVALID_FILE_ATTRIBUTES)
+		SetFileAttributesW(wpnew, attrs);
+
+	if (!is_file_in_use_error(gle)) {
+		errno = err_win_to_posix(gle);
+		return -1;
+	}
+
+	if (attrs == INVALID_FILE_ATTRIBUTES &&
 	    (attrs = GetFileAttributesW(wpnew)) != INVALID_FILE_ATTRIBUTES) {
 		if (attrs & FILE_ATTRIBUTE_DIRECTORY) {
 			DWORD attrsold = GetFileAttributesW(wpold);
@@ -2388,16 +2388,10 @@ int mingw_rename(const char *pold, const char *pnew)
 			return -1;
 		}
 		if ((attrs & FILE_ATTRIBUTE_READONLY) &&
-		    SetFileAttributesW(wpnew, attrs & ~FILE_ATTRIBUTE_READONLY)) {
-			if (MoveFileExW(wpold, wpnew, MOVEFILE_REPLACE_EXISTING))
-				return 0;
-			gle = GetLastError();
-			/* revert file attributes on failure */
-			SetFileAttributesW(wpnew, attrs);
-		}
+		    SetFileAttributesW(wpnew, attrs & ~FILE_ATTRIBUTE_READONLY))
+			goto repeat;
 	}
-	if (gle == ERROR_ACCESS_DENIED &&
-	       retry_ask_yes_no(&tries, "Rename from '%s' to '%s' failed. "
+	if (retry_ask_yes_no(&tries, "Rename from '%s' to '%s' failed. "
 		       "Should I try again?", pold, pnew))
 		goto repeat;