sync with plan 9

1 files changed, 11 insertions, 5 deletions

diff --git a/libbio/bgetrune.c b/libbio/bgetrune.c
index ed216379..13b02bec 100644
--- a/libbio/bgetrune.c
+++ b/libbio/bgetrune.c
@@ -6,7 +6,7 @@ Bgetrune(Biobuf *bp)
 {
 	int c, i;
 	Rune rune;
-	char str[4];
+	char str[UTFmax];
 
 	c = Bgetc(bp);
 	if(c < Runeself) {		/* one char */
@@ -14,19 +14,25 @@ Bgetrune(Biobuf *bp)
 		return c;
 	}
 	str[0] = c;
+	bp->runesize = 0;
 
 	for(i=1;;) {
 		c = Bgetc(bp);
 		if(c < 0)
 			return c;
+		if (i >= sizeof str)
+			return Runeerror;
 		str[i++] = c;
 
 		if(fullrune(str, i)) {
+			/* utf is long enough to be a rune, but could be bad. */
 			bp->runesize = chartorune(&rune, str);
-			while(i > bp->runesize) {
-				Bungetc(bp);
-				i--;
-			}
+			if (rune == Runeerror)
+				bp->runesize = 0;	/* push back nothing */
+			else
+				/* push back bytes unconsumed by chartorune */
+				for(; i > bp->runesize; i--)
+					Bungetc(bp);
 			return rune;
 		}
 	}