Fix expansion of escape sequences with incomplete arguments.

* For \* and \n, discard the incomplete arg, expand to empty string.
* For \B, discard the incomplete arg, expand to the digit 0.
* For \w, use the incomplete arg (behaviour unchanged).

1 files changed, 14 insertions, 7 deletions

diff --git a/roff.c b/roff.c
index 4712297e..5fd29f71 100644
--- a/roff.c
+++ b/roff.c
@@ -500,7 +500,7 @@ roff_res(struct roff *r, char **bufp, size_t *szp, int ln, int pos)
 	size_t		 naml;	/* actual length of the escape name */
 	int		 expand_count;	/* to avoid infinite loops */
 	int		 npos;	/* position in numeric expression */
-	int		 irc;	/* return code from roff_evalnum() */
+	int		 arg_complete; /* argument not interrupted by eol */
 	char		 term;	/* character terminating the escape */
 
 	expand_count = 0;
@@ -585,10 +585,12 @@ roff_res(struct roff *r, char **bufp, size_t *szp, int ln, int pos)
 
 		/* Advance to the end of the name. */
 
+		arg_complete = 1;
 		for (naml = 0; 0 == maxl || naml < maxl; naml++, cp++) {
 			if ('\0' == *cp) {
 				mandoc_msg(MANDOCERR_BADESCAPE, r->parse,
 				    ln, (int)(stesc - *bufp), NULL);
+				arg_complete = 0;
 				break;
 			}
 			if (0 == maxl && *cp == term) {
@@ -604,20 +606,25 @@ roff_res(struct roff *r, char **bufp, size_t *szp, int ln, int pos)
 
 		switch (stesc[1]) {
 		case '*':
-			res = roff_getstrn(r, stnam, naml);
+			if (arg_complete)
+				res = roff_getstrn(r, stnam, naml);
 			break;
 		case 'B':
 			npos = 0;
-			irc = roff_evalnum(stnam, &npos, NULL, 0);
-			ubuf[0] = irc && stnam + npos + 1 == cp
-			    ? '1' : '0';
+			ubuf[0] = arg_complete &&
+			    roff_evalnum(stnam, &npos, NULL, 0) &&
+			    stnam + npos + 1 == cp ? '1' : '0';
 			ubuf[1] = '\0';
 			break;
 		case 'n':
-			(void)snprintf(ubuf, sizeof(ubuf), "%d",
-			    roff_getregn(r, stnam, naml));
+			if (arg_complete)
+				(void)snprintf(ubuf, sizeof(ubuf), "%d",
+				    roff_getregn(r, stnam, naml));
+			else
+				ubuf[0] = '\0';
 			break;
 		case 'w':
+			/* use even incomplete args */
 			(void)snprintf(ubuf, sizeof(ubuf), "%d",
 			    24 * (int)naml);
 			break;