opt/helpers: fix out-of-range check in opt_set_floatval()

[ccan] / ccan / opt / helpers.c

diff --git a/ccan/opt/helpers.c b/ccan/opt/helpers.c
index 43b86d7ca2ad953665522cf37f449b8046ffd3b7..f247301cd7a2ba236871f8327c56a79ea144509f 100644 (file)
--- a/ccan/opt/helpers.c
+++ b/ccan/opt/helpers.c
@@ -9,6 +9,7 @@
 #include <stdio.h>
 #include <limits.h>
 #include "private.h"
+#include <float.h>
 
 /* Upper bound to sprintf this simple type?  Each 3 bits < 1 digit. */
 #define CHAR_SIZE(type) (((sizeof(type)*CHAR_BIT + 2) / 3) + 1)
@@ -126,8 +127,14 @@ char *opt_set_floatval(const char *arg, float *f)
                return err;
 
        *f = d;
-       if (*f != d)
-               return arg_bad("'%s' is out of range", arg);
+
+       /*allow true infinity via --foo=INF, while avoiding isinf() from math.h
+         because it wasn't standard 25 years ago.*/
+       double inf = 1e300 * 1e300; /*direct 1e600 annoys -Woverflow*/
+       if ((d > FLT_MAX || d < -FLT_MAX) && d != inf && d != -inf)
+               return arg_bad("'%s' is out of range for a 32 bit float", arg);
+       if (d != 0 && *f == 0)
+               return arg_bad("'%s' is out of range (truncated to zero)", arg);
 
        return NULL;
 }