Add libString.

src/libString/s_read.c

@@ -0,0 +1,38 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include "libString.h"
+
+enum
+{
+	Minread=	256,
+};
+
+/* Append up to 'len' input bytes to the string 'to'.
+ *
+ * Returns the number of characters read.
+ */ 
+extern int
+s_read(Biobuf *fp, String *to, int len)
+{
+	int rv;
+	int n;
+
+	if(to->ref > 1)
+		sysfatal("can't s_read a shared string");
+	for(rv = 0; rv < len; rv += n){
+		n = to->end - to->ptr;
+		if(n < Minread){
+			s_grow(to, Minread);
+			n = to->end - to->ptr;
+		}
+		if(n > len - rv)
+			n = len - rv;
+		n = Bread(fp, to->ptr, n);
+		if(n <= 0)
+			break;
+		to->ptr += n;
+	}
+	s_terminate(to);
+	return rv;
+}