The post_nm() validation function crashed when the first .Nm child node

was a non-text node.  Fix this by rewriting post_nm() to always set
the meta name to UNKNOWN when the name is missing or unusable.
While here, make MANDOCERR_NONAME an ERROR, as it usually renders
the page content unintelligible.

Bug reported by Maxim <Belooussov at gmail dot com>, thanks.
OpenBSD rev. 1.105

3 files changed, 19 insertions, 14 deletions

diff --git a/mandoc.h b/mandoc.h
index 5aaac54c..79807423 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -61,7 +61,6 @@ enum	mandocerr {
 	MANDOCERR_SO, /* .so is fragile, better use ln(1) */
 	MANDOCERR_NAMESECFIRST, /* NAME section must come first */
 	MANDOCERR_BADNAMESEC, /* bad NAME section contents */
-	MANDOCERR_NONAME, /* manual name not yet set */
 	MANDOCERR_SECOOO, /* sections out of conventional order */
 	MANDOCERR_SECREP, /* duplicate section name */
 	MANDOCERR_SECMSEC, /* section not in conventional manual section */
@@ -129,6 +128,7 @@ enum	mandocerr {
 	MANDOCERR_ROFFLOOP, /* input stack limit exceeded, infinite loop? */
 	MANDOCERR_BADCHAR, /* skipping bad character */
 	MANDOCERR_NAMESC, /* escaped character not allowed in a name */
+	MANDOCERR_NONAME, /* manual name not yet set */
 	MANDOCERR_NOTEXT, /* skipping text before the first section header */
 	MANDOCERR_MACRO, /* skipping unknown macro */
 	MANDOCERR_REQUEST, /* NOT IMPLEMENTED: skipping request */
diff --git a/mdoc_validate.c b/mdoc_validate.c
index 49d6f780..e8218d82 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -1123,24 +1123,29 @@ post_nm(POST_ARGS)
 	char		 buf[BUFSIZ];
 	int		 c;
 
-	/* If no child specified, make sure we have the meta name. */
-
-	if (NULL == mdoc->last->child && NULL == mdoc->meta.name) {
-		mdoc_nmsg(mdoc, mdoc->last, MANDOCERR_NONAME);
-		return(1);
-	} else if (mdoc->meta.name)
+	if (NULL != mdoc->meta.name)
 		return(1);
 
-	/* If no meta name, set it from the child. */
+	/* Try to use our children for setting the meta name. */
 
-	buf[0] = '\0';
-	if (-1 == (c = concat(buf, mdoc->last->child, BUFSIZ))) {
+	if (NULL != mdoc->last->child) {
+		buf[0] = '\0';
+		c = concat(buf, mdoc->last->child, BUFSIZ);
+	} else
+		c = 0;
+
+	switch (c) {
+	case (-1):
 		mdoc_nmsg(mdoc, mdoc->last->child, MANDOCERR_MEM);
 		return(0);
+	case (0):
+		mdoc_nmsg(mdoc, mdoc->last, MANDOCERR_NONAME);
+		mdoc->meta.name = mandoc_strdup("UNKNOWN");
+		break;
+	default:
+		mdoc->meta.name = mandoc_strdup(buf);
+		break;
 	}
-
-	assert(c);
-	mdoc->meta.name = mandoc_strdup(buf);
 	return(1);
 }
 
diff --git a/read.c b/read.c
index 390b2978..84c35363 100644
--- a/read.c
+++ b/read.c
@@ -106,7 +106,6 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	".so is fragile, better use ln(1)",
 	"NAME section must come first",
 	"bad NAME section contents",
-	"manual name not yet set",
 	"sections out of conventional order",
 	"duplicate section name",
 	"section not in conventional manual section",
@@ -174,6 +173,7 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	"input stack limit exceeded, infinite loop?",
 	"skipping bad character",
 	"escaped character not allowed in a name",
+	"manual name not yet set",
 	"skipping text before the first section header",
 	"skipping unknown macro",
 	"NOT IMPLEMENTED, please use groff: skipping request",