From the Go release: Bfdopen().

Notes:
Thu Dec 15 13:58:56 EST 2011 geoff
    apparently no longer needed.


Reference: /n/sources/patch/sorry/bio-bfdopen
Date: Sat Aug  6 07:50:17 CES 2011
Signed-off-by: lucio@proxima.alt.za
Reviewed-by: geoff

--- /sys/include/bio.h	Sat Aug  6 07:49:27 2011
+++ /sys/include/bio.h	Sat Aug  6 07:49:20 2011
@@ -48,6 +48,7 @@
 #define	BFILDES(bp)	Bfildes(bp)
 
 int	Bbuffered(Biobufhdr*);
+Biobuf*	Bfdopen(int, int);
 int	Bfildes(Biobufhdr*);
 int	Bflush(Biobufhdr*);
 int	Bgetc(Biobufhdr*);
--- /sys/src/libbio/binit.c	Sat Aug  6 07:49:39 2011
+++ /sys/src/libbio/binit.c	Sat Aug  6 07:49:32 2011
@@ -94,6 +94,19 @@
 }
 
 Biobuf*
+Bfdopen(int f, int mode)
+{
+	Biobuf *bp;
+
+	bp = malloc(sizeof(Biobuf));
+	if(bp == 0)
+		return 0;
+	Binits(bp, f, mode, bp->b, sizeof(bp->b));
+	bp->flag = Bmagic;
+	return bp;
+}
+
+Biobuf*
 Bopen(char *name, int mode)
 {
 	Biobuf *bp;