Let roff_getname() end the roff identifier at a tab character

and audit all its callers whether termination is handled correctly.

Resulting improvements:
* An escape or tab ending the macro name in a macro invocation
is discarded, and argument processing is started after it.
* An escape or tab ending a name in ".if d" and ".if r" is preserved.
* An escape ending a name in ".ds" causes the whole request to be ignored.
* A tab ending a name in ".ds" becomes part of the string.
* An escape or tab ending a name in ".rm"
causes the rest of the line to be ignored.
* An escape or tab ending the first name in ".als", ".rn", or ".nr"
causes the whole request to be ignored.

Kurt Jaeger <pi at FreeBSD> made me aware of
  https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=235456#c0
and in that bug report, comment 0 item (3) is a special case
of this class of issues.

Yes, the "mh" manual pages are no doubt among the worst on the planet.

4 files changed, 30 insertions, 6 deletions

diff --git a/regress/roff/cond/register.in b/regress/roff/cond/register.in
index 44c53a84..879c573c 100644
--- a/regress/roff/cond/register.in
+++ b/regress/roff/cond/register.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: register.in,v 1.2 2017/07/04 14:53:26 schwarze Exp $
-.TH REGISTER 1 "May 31, 2015"
+.\" $OpenBSD: register.in,v 1.3 2019/02/06 20:54:28 schwarze Exp $
+.TH REGISTER 1 "February 6, 2019"
 .SH NAME
 register \- conditional testing whether a register is defined
 .SH DESCRIPTION
@@ -10,3 +10,11 @@ register \- conditional testing whether a register is defined
 .ie rmyreg now defined
 .el OOPS
 .if !rmyreg OOPS
+.PP
+identifier + identifier:
+.ie rmyreg	myreg is defined
+.el OOPS
+.PP
+escape sequence after identifier:
+.ie rmyreg\(enmyreg is defined
+.el OOPS
diff --git a/regress/roff/cond/register.out_ascii b/regress/roff/cond/register.out_ascii
index acd0f724..0799c5e7 100644
--- a/regress/roff/cond/register.out_ascii
+++ b/regress/roff/cond/register.out_ascii
@@ -9,6 +9,10 @@ DDEESSCCRRIIPPTTIIOONN
        not yet defined
        now defined
 
+       identifier + identifier:      myreg is defined
 
+       escape sequence after identifier: -myreg is defined
 
-OpenBSD                          May 31, 2015                      REGISTER(1)
+
+
+OpenBSD                        February 6, 2019                    REGISTER(1)
diff --git a/regress/roff/cond/string.in b/regress/roff/cond/string.in
index b3bf14b4..273984be 100644
--- a/regress/roff/cond/string.in
+++ b/regress/roff/cond/string.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: string.in,v 1.3 2017/07/04 14:53:26 schwarze Exp $
-.TH STRING 1 "June 14, 2017"
+.\" $OpenBSD: string.in,v 1.4 2019/02/06 20:54:28 schwarze Exp $
+.TH STRING 1 "February 6, 2019"
 .SH NAME
 string \- conditional testing whether a string is defined
 .SH DESCRIPTION
@@ -32,3 +32,11 @@ mymacval
 standard macro is
 .ie d PP defined
 .el not defined \(em OOPS
+.PP
+identifier and tab:
+.ie d mystr	mystr is defined
+.el OOPS
+.PP
+escape sequence after identifier:
+.ie d mystr\(enmystr is defined
+.el OOPS
diff --git a/regress/roff/cond/string.out_ascii b/regress/roff/cond/string.out_ascii
index b5075d21..b01e072a 100644
--- a/regress/roff/cond/string.out_ascii
+++ b/regress/roff/cond/string.out_ascii
@@ -17,6 +17,10 @@ DDEESSCCRRIIPPTTIIOONN
 
        standard macro is defined
 
+       identifier and tab:      mystr is defined
 
+       escape sequence after identifier: -mystr is defined
 
-OpenBSD                          June 14, 2017                       STRING(1)
+
+
+OpenBSD                        February 6, 2019                      STRING(1)