suffix functions: leading dot is not delimiter

* stream.c (short_suffix, long_suffix): Do not treat the
starting dot of the last componet as a suffix delimiter.

* tests/018/path.tl: Test cases edited to reflect
requirements change; new tests added.

* txr.1: Updated.

1 files changed, 5 insertions, 2 deletions

diff --git a/stream.c b/stream.c
index 1c965c8c..ecd30ba6 100644
--- a/stream.c
+++ b/stream.c
@@ -5040,7 +5040,7 @@ val short_suffix(val name, val alt_in)
   const wchar_t *dot = wcsrchr(str, '.');
   const wchar_t *sl = if3(dot, wcspbrk(dot + 1, psc), 0);
 
-  if (!dot || (sl && sl[1])) {
+  if (!dot || (sl && sl[1]) || dot == str || wcschr(psc, dot[-1])) {
     return default_null_arg(alt_in);
   } else {
     wchar_t *suff = chk_strdup(dot + 1);
@@ -5063,7 +5063,10 @@ val long_suffix(val name, val alt_in)
     while (dot && (sl = wcspbrk(dot, psc)) && sl[1])
       dot = wcschr(sl + 1, '.');
 
-    if (!dot || (sl && sl[1])) {
+    if (dot && (dot == str || wcschr(psc, dot[-1])))
+      dot = wcschr(dot + 1, '.');
+
+    if (!dot || dot == str) {
       return default_null_arg(alt_in);
     } else {
       wchar_t *suff = chk_strdup(dot + 1);