Handle infinite explicitly in createStringObjectFromLongLong().

src/object.c

@@ -111,18 +111,30 @@ robj *createStringObjectFromLongLong(long long value) {
 
 /* Create a string object from a long double. If humanfriendly is non-zero
  * it does not use exponential format and trims trailing zeroes at the end,
- * however this result in loss of precision. Otherwise exp format is used
- * and the output of snprintf() is not modified. */
+ * however this results in loss of precision. Otherwise exp format is used
+ * and the output of snprintf() is not modified.
+ *
+ * The 'humanfriendly' option is used for INCRBYFLOAT and HINCRBYFLOAT. */
 robj *createStringObjectFromLongDouble(long double value, int humanfriendly) {
     char buf[256];
     int len;
 
-    /* We use 17 digits precision since with 128 bit floats that precision
-     * after rounding is able to represent most small decimal numbers in a way
-     * that is "non surprising" for the user (that is, most small decimal
-     * numbers will be represented in a way that when converted back into
-     * a string are exactly the same as what the user typed.) */
-    if (humanfriendly) {
+    if (isinf(value)) {
+        /* Libc in odd systems (Hi Solaris!) will format infinite in a
+         * different way, so better to handle it in an explicit way. */
+        if (value > 0) {
+            memcpy(buf,"inf",3);
+            len = 3;
+        } else {
+            memcpy(buf,"-inf",4);
+            len = 4;
+        }
+    } else if (humanfriendly) {
+        /* We use 17 digits precision since with 128 bit floats that precision
+         * after rounding is able to represent most small decimal numbers in a
+         * way that is "non surprising" for the user (that is, most small
+         * decimal numbers will be represented in a way that when converted
+         * back into a string are exactly the same as what the user typed.) */
         len = snprintf(buf,sizeof(buf),"%.17Lf", value);
         /* Now remove trailing zeroes after the '.' */
         if (strchr(buf,'.') != NULL) {