Import libbio Bfdopen function from plan9port.
Notes:
Thu Dec 15 13:59:08 EST 2011 geoff
    apparently no longer needed.


Reference: /n/sources/patch/sorry/libbio-bfdopen
Date: Tue Nov 15 10:03:16 CET 2011
Signed-off-by: djc@9grid.fr
Reviewed-by: geoff

--- /sys/src/libbio/binit.c	Tue Nov 15 10:01:44 2011
+++ /sys/src/libbio/binit.c	Tue Nov 15 10:01:38 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;
@@ -112,9 +125,9 @@
 	}
 	if(f < 0)
 		return 0;
-	bp = malloc(sizeof(Biobuf));
-	Binits(bp, f, mode, bp->b, sizeof(bp->b));
-	bp->flag = Bmagic;			/* mark bp open & malloced */
+	bp = Bfdopen(f, mode);
+	if(bp == 0)
+		close(f);
 	return bp;
 }
 
--- /sys/include/bio.h	Tue Nov 15 10:01:53 2011
+++ /sys/include/bio.h	Tue Nov 15 10:01:49 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/man/2/bio	Tue Nov 15 10:02:02 2011
+++ /sys/man/2/bio	Tue Nov 15 10:01:57 2011
@@ -1,6 +1,6 @@
 .TH BIO 2
 .SH NAME
-Bopen, Binit, Binits, Brdline, Brdstr, Bgetc, Bgetrune, Bgetd, Bungetc, Bungetrune, Bread, Bseek, Boffset, Bfildes, Blinelen, Bputc, Bputrune, Bprint, Bvprint, Bwrite, Bflush, Bterm, Bbuffered \- buffered input/output
+Bopen, Bfdopen, Binit, Binits, Brdline, Brdstr, Bgetc, Bgetrune, Bgetd, Bungetc, Bungetrune, Bread, Bseek, Boffset, Bfildes, Blinelen, Bputc, Bputrune, Bprint, Bvprint, Bwrite, Bflush, Bterm, Bbuffered \- buffered input/output
 .SH SYNOPSIS
 .ta \w'Biobuf* 'u
 .B #include <u.h>
@@ -10,7 +10,10 @@
 .B #include <bio.h>
 .PP
 .B
-Biobuf* Bopen(char *file, int mode)
+Biobuf*	Bopen(char *file, int mode)
+.PP
+.B
+Biobuf*	Bfdopen(int fd, int mode)
 .PP
 .B
 int	Binit(Biobuf *bp, int fd, int mode)
@@ -88,6 +91,17 @@
 for mode
 .B OREAD
 or creates for mode
+.BR OWRITE .
+It calls
+.IR malloc (2)
+to allocate a buffer.
+.PP
+.I Bfdopen
+allocates a buffer for the already-open file descriptor
+.I fd
+for mode
+.B OREAD
+or
 .BR OWRITE .
 It calls
 .IR malloc (2)