path: safely cast path calculation

src/path.c

@@ -160,7 +160,13 @@ int git_path_dirname_r(git_buf *buffer, const char *path)
 	while (endp > path && *endp == '/')
 		endp--;
 
-	if ((len = win32_prefix_length(path, endp - path + 1)) > 0) {
+	if (endp - path + 1 > INT_MAX) {
+		git_error_set(GIT_ERROR_INVALID, "path too long");
+		len = -1;
+		goto Exit;
+	}
+
+	if ((len = win32_prefix_length(path, (int)(endp - path + 1))) > 0) {
 		is_prefix = 1;
 		goto Exit;
 	}
@@ -180,7 +186,13 @@ int git_path_dirname_r(git_buf *buffer, const char *path)
 		endp--;
 	} while (endp > path && *endp == '/');
 
-	if ((len = win32_prefix_length(path, endp - path + 1)) > 0) {
+	if (endp - path + 1 > INT_MAX) {
+		git_error_set(GIT_ERROR_INVALID, "path too long");
+		len = -1;
+		goto Exit;
+	}
+
+	if ((len = win32_prefix_length(path, (int)(endp - path + 1))) > 0) {
 		is_prefix = 1;
 		goto Exit;
 	}