From 02b74edba1ab97e782f7fe0baaeecf2d447bd18d Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sun, 3 Aug 2014 18:51:25 +0200
Subject: [PATCH] implement fdreadn

---
 README |  5 +++++
 fd.c   | 16 ++++++++++++++++
 task.h |  1 +
 3 files changed, 22 insertions(+)

diff --git a/README b/README
index 9c61468..4f50a3a 100644
--- a/README
+++ b/README
@@ -98,6 +98,11 @@ int fdread(int, void*, int);
 	Like regular read(), but puts task to sleep while waiting for
 	data instead of blocking the whole program.
 
+int fdreadn(int, void*, int);
+
+	Like fdread(), but does successive read calls until n bytes have
+	been read, or a read system call returns a non-positive count.
+
 int fdwrite(int, void*, int);
 
 	Like regular write(), but puts task to sleep while waiting to
diff --git a/fd.c b/fd.c
index 4a7d51d..5b4f579 100644
--- a/fd.c
+++ b/fd.c
@@ -290,6 +290,22 @@ fdread(int fd, void *buf, int n)
 	return m;
 }
 
+int
+fdreadn(int fd, void *buf, int n)
+{
+	int m, tot;
+
+	for(tot=0; tot<n; tot+=m){
+		m = fdread(fd, (char*)buf+tot, n-tot);
+		if(m < 0)
+			return m;
+		if(m == 0)
+			break;
+	}
+
+	return tot;
+}
+
 int
 fdwrite(int fd, void *buf, int n)
 {
diff --git a/task.h b/task.h
index b710dfa..533bdc1 100644
--- a/task.h
+++ b/task.h
@@ -154,6 +154,7 @@ int		chansendul(Channel *c, unsigned long v);
  */
 int		fdread(int, void*, int);
 int		fdread1(int, void*, int);	/* always uses fdwait */
+int		fdreadn(int, void*, int);
 int		fdwrite(int, void*, int);
 void		fdwait(int, int);
 int		fdnoblock(int);