Rename mandoc_getarg() to roff_getarg() and pass it the roff parser

struct as an argument such that after copy-in, it can call roff_expand()
once again, which used to be called roff_res() before this.  This
fixes a subtle low-level roff(7) parsing bug reported by Fabio
Scotoni <fabio at esse dot ch> in the 4.4BSD-Lite2 mdoc.samples(7)
manual page, because that page used an escaped escape sequence in
a macro argument.

To expand escaped escape sequences in quoted mdoc(7) arguments, too,
stop bypassing the call to roff_getarg() in mdoc_argv.c, function args()
for this case.  This does not solve the case of escaped escape sequences
in quoted .Bl -column phrases yet.

Because roff_expand() can make the string longer, roff_getarg() can no
longer operate in-place but needs to malloc(3) the returned string.
In the high-level parsers, free(3) that string after processing it.

5 files changed, 75 insertions, 2 deletions

diff --git a/regress/mdoc/Eo/Makefile b/regress/mdoc/Eo/Makefile
index 0034e271..1e101ace 100644
--- a/regress/mdoc/Eo/Makefile
+++ b/regress/mdoc/Eo/Makefile
@@ -1,6 +1,7 @@
-# $OpenBSD: Makefile,v 1.4 2015/02/11 14:14:53 schwarze Exp $
+# $OpenBSD: Makefile,v 1.8 2018/12/21 16:58:49 schwarze Exp $
 
-REGRESS_TARGETS	 = break empty obsolete unclosed
+REGRESS_TARGETS	 = arg break empty obsolete unclosed
+UTF8_TARGETS	 = arg
 LINT_TARGETS	 = break obsolete unclosed
 
 # groff-1.22.3 defect:
diff --git a/regress/mdoc/Eo/arg.in b/regress/mdoc/Eo/arg.in
new file mode 100644
index 00000000..ecb30ed2
--- /dev/null
+++ b/regress/mdoc/Eo/arg.in
@@ -0,0 +1,25 @@
+.\" $OpenBSD: arg.in,v 1.1 2018/12/21 16:58:49 schwarze Exp $
+.Dd $Mdocdate$
+.Dt EO-ARG 1
+.Os
+.Sh NAME
+.Nm Eo-arg
+.Nd escapes in arguments of enclosure macros
+.Sh DESCRIPTION
+.ds o \(Fo
+.ds c \(Fc
+.Eo \*o
+unquoted unescaped
+.Ec \*c
+.Pp
+.Eo "\*o"
+quoted unescaped
+.Ec "\*c"
+.Pp
+.Eo \\*o
+unquoted escaped
+.Ec \\*c
+.Pp
+.Eo "\\*o"
+quoted escaped
+.Ec "\\*c"
diff --git a/regress/mdoc/Eo/arg.out_ascii b/regress/mdoc/Eo/arg.out_ascii
new file mode 100644
index 00000000..004c3fe5
--- /dev/null
+++ b/regress/mdoc/Eo/arg.out_ascii
@@ -0,0 +1,15 @@
+EO-ARG(1)                   General Commands Manual                  EO-ARG(1)
+
+NNAAMMEE
+     EEoo--aarrgg - escapes in arguments of enclosure macros
+
+DDEESSCCRRIIPPTTIIOONN
+     <<unquoted unescaped>>
+
+     <<quoted unescaped>>
+
+     <<unquoted escaped>>
+
+     <<quoted escaped>>
+
+OpenBSD                        December 21, 2018                       OpenBSD
diff --git a/regress/mdoc/Eo/arg.out_markdown b/regress/mdoc/Eo/arg.out_markdown
new file mode 100644
index 00000000..9da6ff4f
--- /dev/null
+++ b/regress/mdoc/Eo/arg.out_markdown
@@ -0,0 +1,17 @@
+EO-ARG(1) - General Commands Manual
+
+# NAME
+
+**Eo-arg** - escapes in arguments of enclosure macros
+
+# DESCRIPTION
+
+&#171;unquoted unescaped&#187;
+
+&#171;quoted unescaped&#187;
+
+&#171;unquoted escaped&#187;
+
+&#171;quoted escaped&#187;
+
+OpenBSD - December 21, 2018
diff --git a/regress/mdoc/Eo/arg.out_utf8 b/regress/mdoc/Eo/arg.out_utf8
new file mode 100644
index 00000000..3b4a30bd
--- /dev/null
+++ b/regress/mdoc/Eo/arg.out_utf8
@@ -0,0 +1,15 @@
+EO-ARG(1)                   General Commands Manual                  EO-ARG(1)
+
+NNAAMMEE
+     EEoo--aarrgg – escapes in arguments of enclosure macros
+
+DDEESSCCRRIIPPTTIIOONN
+     «unquoted unescaped»
+
+     «quoted unescaped»
+
+     «unquoted escaped»
+
+     «quoted escaped»
+
+OpenBSD                        December 21, 2018                       OpenBSD