[PATCH iproute2] get_rate: detect 32bit overflows

[Eric Dumazet <eric.dumazet@gmail.com>]

Current rate limit is 34.359.738.360 bit per second, and
unfortunately 40Gbps links are above it.

overflows in get_rate() are currently not detected, and some
users are confused. Let's detect this and complain.

Note that some qdisc are ready to get extended range, but this will
need additional attributes and new iproute2

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 tc/tc_util.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/tc/tc_util.c b/tc/tc_util.c
index 8e62a01..0a25250 100644
--- a/tc/tc_util.c
+++ b/tc/tc_util.c
@@ -146,21 +146,26 @@ static const struct rate_suffix {
 int get_rate(unsigned *rate, const char *str)
 {
 	char *p;
-	double bps = strtod(str, &p);
+	long long bps = strtoll(str, &p, 0);
 	const struct rate_suffix *s;
 
 	if (p == str)
 		return -1;
 
+	bps /= 8; /* -> bytes per second */
 	if (*p == '\0') {
-		*rate = bps / 8.;	/* assume bits/sec */
+common:
+		*rate = bps;
+		/* detect if an overflow happened */
+		if (*rate != bps)
+			return -1;
 		return 0;
 	}
 
 	for (s = suffixes; s->name; ++s) {
 		if (strcasecmp(s->name, p) == 0) {
-			*rate = (bps * s->scale) / 8.;
-			return 0;
+			bps *= s->scale;
+			goto common;
 		}
 	}