Add libString.

src/libString/s_grow.c

@@ -0,0 +1,34 @@
+#include <u.h>
+#include <libc.h>
+#include "libString.h"
+
+/* grow a String's allocation by at least `incr' bytes */
+extern String*
+s_grow(String *s, int incr)	
+{
+	char *cp;
+	int size;
+
+	if(s->fixed)
+		sysfatal("s_grow of constant string");
+	s = s_unique(s);
+
+	/*
+	 *  take a larger increment to avoid mallocing too often
+	 */
+	size = s->end-s->base;
+	if(size/2 < incr)
+		size += incr;
+	else
+		size += size/2;
+
+	cp = realloc(s->base, size);
+	if (cp == 0)
+		sysfatal("s_grow: %r");
+	s->ptr = (s->ptr - s->base) + cp;
+	s->end = cp + size;
+	s->base = cp;
+
+	return s;
+}
+