Provide a new function roff_req_or_macro() to parse and handle a request

or macro, including context-dependent error handling inside tbl(7) code
and inside .ce/.rj blocks.  Use it both in the top level roff(7) parser
and inside conditional blocks.

This fixes an assertion failure triggered by ".if 1 .ce" inside tbl(7)
code, found by tb@ using afl(1).

As a side benefit for readability, only one place remains in the
code that calls the main handler functions for the various roff(7)
requests.  This patch also improves column numbers in some error
messages and various comments.

1 files changed, 24 insertions, 0 deletions

diff --git a/regress/roff/ce/break.out_ascii b/regress/roff/ce/break.out_ascii
new file mode 100644
index 00000000..8572cc0a
--- /dev/null
+++ b/regress/roff/ce/break.out_ascii
@@ -0,0 +1,24 @@
+CE-BREAK(1)                 General Commands Manual                CE-BREAK(1)
+
+NNAAMMEE
+       ce-break - centering requests broken by high-level macros
+
+DDEESSCCRRIIPPTTIIOONN
+       initial text
+                        Text centered with the .ce request is
+       _n_o_t filled.
+                                             Text adjusted to the right margin
+                                             works in just the same way and is
+       _n_o_t filled either.
+                     High-level macros break centering even in a
+       _c_o_n_d_i_t_i_o_n_a_l block.
+
+       Now entering
+       explicit no-fill mode.
+                                    Text is still
+       _n_o_t
+       filled.
+
+       final text in fill mode
+
+OpenBSD                         April 30, 2022                     CE-BREAK(1)