libbio: add Breadn

1 files changed, 26 insertions, 0 deletions

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;
+}