From c0c9a9927f413e70f59158a10c460b1927985f44 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@centraldogma>
Date: Thu, 6 Oct 2011 00:39:05 +0200
Subject: [PATCH] libbio: add Breadn

---
 sys/include/bio.h       |  1 +
 sys/man/2/bio           | 12 +++++++++++-
 sys/src/libbio/breadn.c | 26 ++++++++++++++++++++++++++
 sys/src/libbio/mkfile   |  1 +
 4 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 sys/src/libbio/breadn.c

diff --git a/sys/include/bio.h b/sys/include/bio.h
index f358c962c..fabc2b7c8 100644
--- a/sys/include/bio.h
+++ b/sys/include/bio.h
@@ -66,6 +66,7 @@ int	Bputrune(Biobufhdr*, long);
 void*	Brdline(Biobufhdr*, int);
 char*	Brdstr(Biobufhdr*, int, int);
 long	Bread(Biobufhdr*, void*, long);
+long	Breadn(Biobufhdr*, void*, long);
 vlong	Bseek(Biobufhdr*, vlong, int);
 int	Bterm(Biobufhdr*);
 int	Bungetc(Biobufhdr*);
diff --git a/sys/man/2/bio b/sys/man/2/bio
index a059f1cf4..ebb17c840 100644
--- a/sys/man/2/bio
+++ b/sys/man/2/bio
@@ -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, Blethal \- buffered input/output
+Bopen, Binit, Binits, Brdline, Brdstr, Bgetc, Bgetrune, Bgetd, Bungetc, Bungetrune, Bread, Breadn, Bseek, Boffset, Bfildes, Blinelen, Bputc, Bputrune, Bprint, Bvprint, Bwrite, Bflush, Bterm, Bbuffered, Blethal \- buffered input/output
 .SH SYNOPSIS
 .ta \w'Biobuf* 'u
 .B #include <u.h>
@@ -70,6 +70,9 @@ int	Bputrune(Biobufhdr *bp, long c)
 long	Bread(Biobufhdr *bp, void *addr, long nbytes)
 .PP
 .B
+long	Breadn(Biobufhdr *bp, void *addr, long nbytes)
+.PP
+.B
 long	Bwrite(Biobufhdr *bp, void *addr, long nbytes)
 .PP
 .B
@@ -236,6 +239,13 @@ into memory starting at
 The number of bytes read is returned on success
 and a negative value is returned if a read error occurred.
 .PP
+.I Breadn
+is like
+.I Bread
+but continues reading until
+.I nbytes
+have been read into the buffer.
+.PP
 .I Bseek
 applies
 .IR seek (2)
diff --git a/sys/src/libbio/breadn.c b/sys/src/libbio/breadn.c
new file mode 100644
index 000000000..fa335873f
--- /dev/null
+++ b/sys/src/libbio/breadn.c
@@ -0,0 +1,26 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+
+long
+Breadn(Biobufhdr *bp, void *data, long len)
+{
+	char *e, *p;
+	int n;
+
+	p = data;
+	e = p + len;
+	if(e < p){
+		Berror(bp, "invalid read length");
+		return -1;
+	}
+	while(p < e){
+		if((n = Bread(bp, p, e - p)) <= 0){
+			if(n < 0 && p == data)
+				return -1;
+			break;
+		}
+		p += n;
+	}
+	return p - (char*)data;
+}
diff --git a/sys/src/libbio/mkfile b/sys/src/libbio/mkfile
index 3b40fd25c..cae6e4850 100644
--- a/sys/src/libbio/mkfile
+++ b/sys/src/libbio/mkfile
@@ -17,6 +17,7 @@ OFILES=\
 	brdline.$O\
 	brdstr.$O\
 	bread.$O\
+	breadn.$O\
 	bseek.$O\
 	bwrite.$O\
 	bvprint.$O\