Correctly handle horizontal spans at the beginning of rows,

fixing an assertion failure found by jsg@ with afl(1).

While here, also drop printing of whitespace in tbl_data()
which makes no difference because column positioning code
in term_tbl() already takes care of that.

diff --git a/usr.bin/mandoc/tbl_term.c b/usr.bin/mandoc/tbl_term.c
index fbbebff..f707958 100644 (file)
--- a/usr.bin/mandoc/tbl_term.c
+++ b/usr.bin/mandoc/tbl_term.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tbl_term.c,v 1.43 2017/06/27 18:23:29 schwarze Exp $ */
+/*     $OpenBSD: tbl_term.c,v 1.44 2017/07/08 13:43:09 schwarze Exp $ */
 /*
  * Copyright (c) 2009, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2011,2012,2014,2015,2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -168,7 +168,8 @@ term_tbl(struct termp *tp, const struct tbl_span *sp)
                        if (dp == NULL)
                                continue;
                        spans = dp->spans;
-                       dp = dp->next;
+                       if (ic || sp->layout->first->pos != TBL_CELL_SPAN)
+                               dp = dp->next;
                }
 
                /* Set up a column for a right vertical frame. */
@@ -202,7 +203,8 @@ term_tbl(struct termp *tp, const struct tbl_span *sp)
                        if (dp == NULL)
                                continue;
                        spans = dp->spans;
-                       dp = dp->next;
+                       if (cp->pos != TBL_CELL_SPAN)
+                               dp = dp->next;
                }
                break;
        }
@@ -302,7 +304,9 @@ term_tbl(struct termp *tp, const struct tbl_span *sp)
                                }
                                if (dp != NULL) {
                                        spans = dp->spans;
-                                       dp = dp->next;
+                                       if (ic || sp->layout->first->pos
+                                           != TBL_CELL_SPAN)
+                                               dp = dp->next;
                                }
 
                                /*
@@ -512,14 +516,11 @@ tbl_data(struct termp *tp, const struct tbl_opts *opts,
                break;
        }
 
-       if (dp == NULL) {
-               tbl_char(tp, ASCII_NBRSP, col->width);
+       if (dp == NULL)
                return;
-       }
 
        switch (dp->pos) {
        case TBL_DATA_NONE:
-               tbl_char(tp, ASCII_NBRSP, col->width);
                return;
        case TBL_DATA_HORIZ:
        case TBL_DATA_NHORIZ:
@@ -544,7 +545,7 @@ tbl_data(struct termp *tp, const struct tbl_opts *opts,
                tbl_number(tp, opts, dp, col);
                break;
        case TBL_CELL_DOWN:
-               tbl_char(tp, ASCII_NBRSP, col->width);
+       case TBL_CELL_SPAN:
                break;
        default:
                abort();