Using an undefined string or macro will cause it to be defined as empty.

Observed by Werner Lemberg on Nov 14, 2011
and rotting on my TODO list ever since.

1 files changed, 82 insertions, 43 deletions

diff --git a/usr.bin/mandoc/roff.c b/usr.bin/mandoc/roff.c
index dfaf843c7c1..ab371c9d8d0 100644
--- a/usr.bin/mandoc/roff.c
+++ b/usr.bin/mandoc/roff.c
@@ -1,7 +1,7 @@
-/*	$OpenBSD: roff.c,v 1.196 2017/07/14 17:16:13 schwarze Exp $ */
+/*	$OpenBSD: roff.c,v 1.197 2018/04/09 02:31:37 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2010-2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2010-2015, 2017, 2018 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -44,6 +44,7 @@
 #define	ROFFDEF_STD	(1 << 4)  /* mdoc(7) or man(7) macro. */
 #define	ROFFDEF_ANY	(ROFFDEF_USER | ROFFDEF_PRE | \
 			 ROFFDEF_REN | ROFFDEF_STD)
+#define	ROFFDEF_UNDEF	(1 << 5)  /* Completely undefined. */
 
 /* --- data types --------------------------------------------------------- */
 
@@ -183,7 +184,7 @@ static	int		 roff_getregn(const struct roff *,
 				const char *, size_t);
 static	int		 roff_getregro(const struct roff *,
 				const char *name);
-static	const char	*roff_getstrn(const struct roff *,
+static	const char	*roff_getstrn(struct roff *,
 				const char *, size_t, int *);
 static	int		 roff_hasregn(const struct roff *,
 				const char *, size_t);
@@ -1637,6 +1638,11 @@ roff_parse(struct roff *r, char *buf, int *pos, int ln, int ppos)
 	}
 	if (t != TOKEN_NONE)
 		*pos = cp - buf;
+	else if (deftype == ROFFDEF_UNDEF) {
+		/* Using an undefined macro defines it to be empty. */
+		roff_setstrn(&r->strtab, mac, maclen, "", 0, 0);
+		roff_setstrn(&r->rentab, mac, maclen, NULL, 0, 0);
+	}
 	return t;
 }
 
@@ -3535,62 +3541,95 @@ roff_setstrn(struct roffkv **r, const char *name, size_t namesz,
 }
 
 static const char *
-roff_getstrn(const struct roff *r, const char *name, size_t len,
+roff_getstrn(struct roff *r, const char *name, size_t len,
     int *deftype)
 {
 	const struct roffkv	*n;
-	int			 i;
+	int			 found, i;
 	enum roff_tok		 tok;
 
-	if (*deftype & ROFFDEF_USER) {
-		for (n = r->strtab; n != NULL; n = n->next) {
-			if (strncmp(name, n->key.p, len) == 0 &&
-			    n->key.p[len] == '\0' &&
-			    n->val.p != NULL) {
-				*deftype = ROFFDEF_USER;
-				return n->val.p;
-			}
+	found = 0;
+	for (n = r->strtab; n != NULL; n = n->next) {
+		if (strncmp(name, n->key.p, len) != 0 ||
+		    n->key.p[len] != '\0' || n->val.p == NULL)
+			continue;
+		if (*deftype & ROFFDEF_USER) {
+			*deftype = ROFFDEF_USER;
+			return n->val.p;
+		} else {
+			found = 1;
+			break;
 		}
 	}
-	if (*deftype & ROFFDEF_PRE) {
-		for (i = 0; i < PREDEFS_MAX; i++) {
-			if (strncmp(name, predefs[i].name, len) == 0 &&
-			    predefs[i].name[len] == '\0') {
-				*deftype = ROFFDEF_PRE;
-				return predefs[i].str;
-			}
+	for (n = r->rentab; n != NULL; n = n->next) {
+		if (strncmp(name, n->key.p, len) != 0 ||
+		    n->key.p[len] != '\0' || n->val.p == NULL)
+			continue;
+		if (*deftype & ROFFDEF_REN) {
+			*deftype = ROFFDEF_REN;
+			return n->val.p;
+		} else {
+			found = 1;
+			break;
 		}
 	}
-	if (*deftype & ROFFDEF_REN) {
-		for (n = r->rentab; n != NULL; n = n->next) {
-			if (strncmp(name, n->key.p, len) == 0 &&
-			    n->key.p[len] == '\0' &&
-			    n->val.p != NULL) {
-				*deftype = ROFFDEF_REN;
-				return n->val.p;
-			}
+	for (i = 0; i < PREDEFS_MAX; i++) {
+		if (strncmp(name, predefs[i].name, len) != 0 ||
+		    predefs[i].name[len] != '\0')
+			continue;
+		if (*deftype & ROFFDEF_PRE) {
+			*deftype = ROFFDEF_PRE;
+			return predefs[i].str;
+		} else {
+			found = 1;
+			break;
 		}
 	}
-	if (*deftype & ROFFDEF_STD) {
-		if (r->man->macroset != MACROSET_MAN) {
-			for (tok = MDOC_Dd; tok < MDOC_MAX; tok++) {
-				if (strncmp(name, roff_name[tok], len) == 0 &&
-				    roff_name[tok][len] == '\0') {
-					*deftype = ROFFDEF_STD;
-					return NULL;
-				}
+	if (r->man->macroset != MACROSET_MAN) {
+		for (tok = MDOC_Dd; tok < MDOC_MAX; tok++) {
+			if (strncmp(name, roff_name[tok], len) != 0 ||
+			    roff_name[tok][len] != '\0')
+				continue;
+			if (*deftype & ROFFDEF_STD) {
+				*deftype = ROFFDEF_STD;
+				return NULL;
+			} else {
+				found = 1;
+				break;
 			}
 		}
-		if (r->man->macroset != MACROSET_MDOC) {
-			for (tok = MAN_TH; tok < MAN_MAX; tok++) {
-				if (strncmp(name, roff_name[tok], len) == 0 &&
-				    roff_name[tok][len] == '\0') {
-					*deftype = ROFFDEF_STD;
-					return NULL;
-				}
+	}
+	if (r->man->macroset != MACROSET_MDOC) {
+		for (tok = MAN_TH; tok < MAN_MAX; tok++) {
+			if (strncmp(name, roff_name[tok], len) != 0 ||
+			    roff_name[tok][len] != '\0')
+				continue;
+			if (*deftype & ROFFDEF_STD) {
+				*deftype = ROFFDEF_STD;
+				return NULL;
+			} else {
+				found = 1;
+				break;
 			}
 		}
 	}
+
+	if (found == 0 && *deftype != ROFFDEF_ANY) {
+		if (*deftype & ROFFDEF_REN) {
+			/*
+			 * This might still be a request,
+			 * so do not treat it as undefined yet.
+			 */
+			*deftype = ROFFDEF_UNDEF;
+			return NULL;
+		}
+
+		/* Using an undefined string defines it to be empty. */
+
+		roff_setstrn(&r->strtab, name, len, "", 0, 0);
+		roff_setstrn(&r->rentab, name, len, NULL, 0, 0);
+	}
+
 	*deftype = 0;
 	return NULL;
 }