diff --git a/src/libString/s_alloc.c b/src/libString/s_alloc.c
new file mode 100644
index 0000000..34f8916
--- /dev/null
+++ b/src/libString/s_alloc.c
@@ -0,0 +1,86 @@
+#include <u.h>
+#include <libc.h>
+#include "libString.h"
+
+#define STRLEN 128
+
+extern void
+s_free(String *sp)
+{
+	if (sp == nil)
+		return;
+	lock(&sp->lk);
+	if(--(sp->ref) != 0){
+		unlock(&sp->lk);
+		return;
+	}
+	unlock(&sp->lk);
+
+	if(sp->fixed == 0 && sp->base != nil)
+		free(sp->base);
+	free(sp);
+}
+
+/* get another reference to a string */
+extern String *
+s_incref(String *sp)
+{
+	lock(&sp->lk);
+	sp->ref++;
+	unlock(&sp->lk);
+
+	return sp;
+}
+
+/* allocate a String head */
+extern String *
+_s_alloc(void)
+{
+	String *s;
+
+	s = mallocz(sizeof *s, 1);
+	if(s == nil)
+		return s;
+	s->ref = 1;
+	s->fixed = 0;
+	return s;
+}
+
+/* create a new `short' String */
+extern String *
+s_newalloc(int len)
+{
+	String *sp;
+
+	sp = _s_alloc();
+	if(sp == nil)
+		sysfatal("s_newalloc: %r");
+	setmalloctag(sp, getcallerpc(&len));
+	if(len < STRLEN)
+		len = STRLEN;
+	sp->base = sp->ptr = malloc(len);
+	if (sp->base == nil)
+		sysfatal("s_newalloc: %r");
+	setmalloctag(sp->base, getcallerpc(&len));
+
+	sp->end = sp->base + len;
+	s_terminate(sp);
+	return sp;
+}
+
+/* create a new `short' String */
+extern String *
+s_new(void)
+{
+	String *sp;
+
+	sp = _s_alloc();
+	if(sp == nil)
+		sysfatal("s_new: %r");
+	sp->base = sp->ptr = malloc(STRLEN);
+	if (sp->base == nil)
+		sysfatal("s_new: %r");
+	sp->end = sp->base + STRLEN;
+	s_terminate(sp);
+	return sp;
+}