Index: util.c
===================================================================
--- util.c	(revision 28992)
+++ util.c	(working copy)
@@ -3120,16 +3120,16 @@
 static char *
 nrv_alloc(const char *s, char **rve, size_t n)
 {
-    char *rv, *t;
+    char *rv;
 
-    t = rv = rv_alloc(n);
-    while ((*t = *s++) != 0) t++;
+    rv = rv_alloc(n);
+    memcpy(rv,s,n);
     if (rve)
-        *rve = t;
+        *rve = rv + n - 1;
     return rv;
 }
 
-#define rv_strdup(s, rve) nrv_alloc(s, rve, strlen(s)+1)
+#define rv_strdup(s, rve) nrv_alloc(s, rve, sizeof(s))
 
 #ifndef MULTIPLE_THREADS
 /* freedtoa(s) must be used to free values s returned by dtoa
@@ -3179,6 +3179,10 @@
  *     calculation.
  */
 
+#define	INFSTR	"Infinity"
+#define	NANSTR	"NaN"
+#define ZEROSTR "0"
+
 char *
 ruby_dtoa(double d_, int mode, int ndigits, int *decpt, int *sign, char **rve)
 {
@@ -3263,9 +3267,9 @@
         *decpt = 9999;
 #ifdef IEEE_Arith
         if (!word1(d) && !(word0(d) & 0xfffff))
-            return rv_strdup("Infinity", rve);
+            return rv_strdup(INFSTR, rve);
 #endif
-        return rv_strdup("NaN", rve);
+        return rv_strdup(NANSTR, rve);
     }
 #endif
 #ifdef IBM
@@ -3273,7 +3277,7 @@
 #endif
     if (!dval(d)) {
         *decpt = 1;
-        return rv_strdup("0", rve);
+        return rv_strdup(ZEROSTR, rve);
     }
 
 #ifdef SET_INEXACT
@@ -3897,8 +3901,6 @@
 
 #define	DBL_MANH_SIZE	20
 #define	DBL_MANL_SIZE	32
-#define	INFSTR	"Infinity"
-#define	NANSTR	"NaN"
 #define	DBL_ADJ	(DBL_MAX_EXP - 2)
 #define	SIGFIGS	((DBL_MANT_DIG + 3) / 4 + 1)
 #define dexp_get(u) ((int)(word0(u) >> Exp_shift) & ~Exp_msk1)
@@ -3951,15 +3953,15 @@
 
 	if (isinf(d)) { /* FP_INFINITE */
 	    *decpt = INT_MAX;
-	    return (nrv_alloc(INFSTR, rve, sizeof(INFSTR) - 1));
+	    return (rv_strdup(INFSTR, rve));
 	}
 	else if (isnan(d)) { /* FP_NAN */
 	    *decpt = INT_MAX;
-	    return (nrv_alloc(NANSTR, rve, sizeof(NANSTR) - 1));
+	    return (rv_strdup(NANSTR, rve));
 	}
 	else if (d == 0.0) { /* FP_ZERO */
 	    *decpt = 1;
-	    return (nrv_alloc("0", rve, 1));
+	    return (rv_strdup(ZEROSTR, rve));
 	}
 	else if (dexp_get(u)) { /* FP_NORMAL */
 	    *decpt = dexp_get(u) - DBL_ADJ;