Don't dereference NULL pointers when formatting missing denominators,

subscripts, superscripts, or "from" or "to" arguments.
Found by jsg@ with afl.

13 files changed, 77 insertions, 9 deletions

diff --git a/regress/usr.bin/mandoc/eqn/fromto/Makefile b/regress/usr.bin/mandoc/eqn/fromto/Makefile
index 5951f81cb67..a2012e8f932 100644
--- a/regress/usr.bin/mandoc/eqn/fromto/Makefile
+++ b/regress/usr.bin/mandoc/eqn/fromto/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.1 2015/01/01 12:53:46 schwarze Exp $
+# $OpenBSD: Makefile,v 1.2 2015/01/01 15:34:43 schwarze Exp $
 
-REGRESS_TARGETS	 = basic
-HTML_TARGETS	 = basic
+REGRESS_TARGETS	 = basic noarg
+HTML_TARGETS	 = basic noarg
 
 .include <bsd.regress.mk>
diff --git a/regress/usr.bin/mandoc/eqn/fromto/noarg.in b/regress/usr.bin/mandoc/eqn/fromto/noarg.in
new file mode 100644
index 00000000000..e37d2e93d0b
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/fromto/noarg.in
@@ -0,0 +1,12 @@
+.Dd January 1, 2015
+.Dt FROMTO-NOARG 1
+.Os OpenBSD
+.Sh NAME
+.Nm fromto-noarg
+.Nd vertical stacking lacks final argument
+.Sh DESCRIPTION
+initial text
+.EQ
+x from a to to
+.EN
+final text
diff --git a/regress/usr.bin/mandoc/eqn/fromto/noarg.out_ascii b/regress/usr.bin/mandoc/eqn/fromto/noarg.out_ascii
new file mode 100644
index 00000000000..06d2ae8167b
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/fromto/noarg.out_ascii
@@ -0,0 +1,9 @@
+FROMTO-NOARG(1)             General Commands Manual            FROMTO-NOARG(1)
+
+NNAAMMEE
+     ffrroommttoo--nnooaarrgg - vertical stacking lacks final argument
+
+DDEESSCCRRIIPPTTIIOONN
+     initial text x_a^^ final text
+
+OpenBSD                         January 1, 2015                        OpenBSD
diff --git a/regress/usr.bin/mandoc/eqn/fromto/noarg.out_html b/regress/usr.bin/mandoc/eqn/fromto/noarg.out_html
new file mode 100644
index 00000000000..1caf3a3d661
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/fromto/noarg.out_html
@@ -0,0 +1 @@
+<mrow><munderover><mi>x</mi><mover><mi>a</mi></mover></munderover></mrow>
diff --git a/regress/usr.bin/mandoc/eqn/over/Makefile b/regress/usr.bin/mandoc/eqn/over/Makefile
index a7a6e7ef02c..8b864c25c70 100644
--- a/regress/usr.bin/mandoc/eqn/over/Makefile
+++ b/regress/usr.bin/mandoc/eqn/over/Makefile
@@ -1,6 +1,7 @@
-# $OpenBSD: Makefile,v 1.1 2015/01/01 12:53:46 schwarze Exp $
+# $OpenBSD: Makefile,v 1.2 2015/01/01 15:34:43 schwarze Exp $
 
-REGRESS_TARGETS	 = precedence
-HTML_TARGETS	 = precedence
+REGRESS_TARGETS	 = noarg precedence
+HTML_TARGETS	 = noarg precedence
+LINT_TARGETS	 = noarg
 
 .include <bsd.regress.mk>
diff --git a/regress/usr.bin/mandoc/eqn/over/noarg.in b/regress/usr.bin/mandoc/eqn/over/noarg.in
new file mode 100644
index 00000000000..ac93fccac98
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/over/noarg.in
@@ -0,0 +1,12 @@
+.Dd January 1, 2015
+.Dt OVER-NOARG 1
+.Os OpenBSD
+.Sh NAME
+.Nm over-noarg
+.Nd fraction operator without arguments
+.Sh DESCRIPTION
+initial text
+.EQ
+over over
+.EN
+final text
diff --git a/regress/usr.bin/mandoc/eqn/over/noarg.out_ascii b/regress/usr.bin/mandoc/eqn/over/noarg.out_ascii
new file mode 100644
index 00000000000..4057f6bd9b5
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/over/noarg.out_ascii
@@ -0,0 +1,9 @@
+OVER-NOARG(1)               General Commands Manual              OVER-NOARG(1)
+
+NNAAMMEE
+     oovveerr--nnooaarrgg - fraction operator without arguments
+
+DDEESSCCRRIIPPTTIIOONN
+     initial text // final text
+
+OpenBSD                         January 1, 2015                        OpenBSD
diff --git a/regress/usr.bin/mandoc/eqn/over/noarg.out_html b/regress/usr.bin/mandoc/eqn/over/noarg.out_html
new file mode 100644
index 00000000000..565b988c129
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/over/noarg.out_html
@@ -0,0 +1 @@
+<mrow><mfrac><mfrac><mi></mi></mfrac></mfrac></mrow>
diff --git a/regress/usr.bin/mandoc/eqn/over/noarg.out_lint b/regress/usr.bin/mandoc/eqn/over/noarg.out_lint
new file mode 100644
index 00000000000..aabfc30b394
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/over/noarg.out_lint
@@ -0,0 +1 @@
+mandoc: noarg.in:9:1: WARNING: missing eqn box, using "": over
diff --git a/regress/usr.bin/mandoc/eqn/subsup/Makefile b/regress/usr.bin/mandoc/eqn/subsup/Makefile
index e3f92c881fb..4e11b33d5c5 100644
--- a/regress/usr.bin/mandoc/eqn/subsup/Makefile
+++ b/regress/usr.bin/mandoc/eqn/subsup/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.1 2015/01/01 12:53:46 schwarze Exp $
+# $OpenBSD: Makefile,v 1.2 2015/01/01 15:34:43 schwarze Exp $
 
-REGRESS_TARGETS	 = combine sub_group
-HTML_TARGETS	 = combine sub_group
+REGRESS_TARGETS	 = combine noarg sub_group
+HTML_TARGETS	 = combine noarg sub_group
 
 .include <bsd.regress.mk>
diff --git a/regress/usr.bin/mandoc/eqn/subsup/noarg.in b/regress/usr.bin/mandoc/eqn/subsup/noarg.in
new file mode 100644
index 00000000000..adc32d8f5e3
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/subsup/noarg.in
@@ -0,0 +1,12 @@
+.Dd January 1, 2015
+.Dt SUBSUP-NOARG 1
+.Os OpenBSD
+.Sh NAME
+.Nm subsup-noarg
+.Nd empty subscripts and superscripts
+.Sh DESCRIPTION
+initial text
+.EQ
+x sub 1 sup sup
+.EN
+final text
diff --git a/regress/usr.bin/mandoc/eqn/subsup/noarg.out_ascii b/regress/usr.bin/mandoc/eqn/subsup/noarg.out_ascii
new file mode 100644
index 00000000000..ad99680b060
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/subsup/noarg.out_ascii
@@ -0,0 +1,9 @@
+SUBSUP-NOARG(1)             General Commands Manual            SUBSUP-NOARG(1)
+
+NNAAMMEE
+     ssuubbssuupp--nnooaarrgg - empty subscripts and superscripts
+
+DDEESSCCRRIIPPTTIIOONN
+     initial text x_1^^ final text
+
+OpenBSD                         January 1, 2015                        OpenBSD
diff --git a/regress/usr.bin/mandoc/eqn/subsup/noarg.out_html b/regress/usr.bin/mandoc/eqn/subsup/noarg.out_html
new file mode 100644
index 00000000000..0741689120d
--- /dev/null
+++ b/regress/usr.bin/mandoc/eqn/subsup/noarg.out_html
@@ -0,0 +1 @@
+<mrow><msubsup><mi>x</mi><msup><mi>1</mi></msup></msubsup></mrow>