fix(multibyte): handle backspace of wide clusters in replace mode

Make utf_head_off more robust against invalid sequences
and embedded NUL chars

1 files changed, 9 insertions, 13 deletions

diff --git a/src/nvim/change.c b/src/nvim/change.c
index 47a9f0ce92..51a13b80e7 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -756,10 +756,8 @@ void ins_char_bytes(char *buf, size_t charlen)
     // put back when BS is used.  The bytes of a multi-byte character are
     // done the other way around, so that the first byte is popped off
     // first (it tells the byte length of the character).
-    replace_push(NUL);
-    for (size_t i = 0; i < oldlen; i++) {
-      i += (size_t)replace_push_mb(oldp + col + i) - 1;
-    }
+    replace_push_nul();
+    replace_push(oldp + col, oldlen);
   }
 
   char *newp = xmalloc(linelen + newlen - oldlen);
@@ -1137,12 +1135,10 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
     // on the line onto the replace stack.  We'll push any other characters
     // that might be replaced at the start of the next line (due to
     // autoindent etc) a bit later.
-    replace_push(NUL);      // Call twice because BS over NL expects it
-    replace_push(NUL);
+    replace_push_nul();      // Call twice because BS over NL expects it
+    replace_push_nul();
     p = saved_line + curwin->w_cursor.col;
-    while (*p != NUL) {
-      p += replace_push_mb(p);
-    }
+    replace_push(p, strlen(p));
     saved_line[curwin->w_cursor.col] = NUL;
   }
 
@@ -1691,13 +1687,13 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
     // stack, preceded by a NUL, so they can be put back when a BS is
     // entered.
     if (REPLACE_NORMAL(State)) {
-      replace_push(NUL);            // end of extra blanks
+      replace_push_nul();            // end of extra blanks
     }
     if (curbuf->b_p_ai || (flags & OPENLINE_DELSPACES)) {
       while ((*p_extra == ' ' || *p_extra == '\t')
              && !utf_iscomposing_first(utf_ptr2char(p_extra + 1))) {
         if (REPLACE_NORMAL(State)) {
-          replace_push(*p_extra);
+          replace_push(p_extra, 1);  // always ascii, len = 1
         }
         p_extra++;
         less_cols_off++;
@@ -1794,7 +1790,7 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
     // must be a NUL on the replace stack, for when it is deleted with BS
     if (REPLACE_NORMAL(State)) {
       for (colnr_T n = 0; n < curwin->w_cursor.col; n++) {
-        replace_push(NUL);
+        replace_push_nul();
       }
     }
     newcol += curwin->w_cursor.col;
@@ -1808,7 +1804,7 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
   // must be a NUL on the replace stack, for when it is deleted with BS.
   if (REPLACE_NORMAL(State)) {
     while (lead_len-- > 0) {
-      replace_push(NUL);
+      replace_push_nul();
     }
   }