Add is_utf8_fixed_width_buf_flags() and use it

This encodes a simple pattern that may not be immediately obvious to
someone needing it.  If you have a fixed-size buffer that is full of
purportedly UTF-8 bytes, is it valid or not?  It's easy to do, as shown
in this commit.  The file test operators -T and -B can be simpified by
using this function.

1 files changed, 2 insertions, 6 deletions

diff --git a/pp_sys.c b/pp_sys.c
index a198d4e525..3c8e985df6 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -3556,14 +3556,10 @@ PP(pp_fttext)
 
     assert(len);
     if (! is_utf8_invariant_string((U8 *) s, len)) {
-        const U8 *ep;
 
         /* Here contains a variant under UTF-8 .  See if the entire string is
-         * UTF-8.  But the buffer may end in a partial character, so if it
-         * failed, see if the failure was due just to that */
-        if (   is_utf8_string_loc((U8 *) s, len, &ep)
-            || is_utf8_valid_partial_char(ep, (U8 *) s + len))
-        {
+         * UTF-8. */
+        if (is_utf8_fixed_width_buf_flags((U8 *) s, len, 0)) {
             if (PL_op->op_type == OP_FTTEXT) {
                 FT_RETURNYES;
             }