From: Torsten Bögershausen <tboegi@xxxxxx>
When setting
DEVELOPER = 1
DEVOPTS = extra-all
"gcc (Raspbian 6.3.0-18+rpi1+deb9u1) 6.3.0 20170516" errors out with
"comparison is always false due to limited range of data type"
"[-Werror=type-limits]"
It turns out that the function xcurl_off_t() has 2 flavours:
- It gives a warning 32 bit systems, like Linux
- It takes the signed ssize_t as a paramter, but the only caller is using
a size_t (which is typically unsigned these days)
The original motivation of this function is to make sure that sizes > 2GiB
are handled correctly. The curl documentation says:
"For any given platform/compiler curl_off_t must be typedef'ed to a 64-bit
wide signed integral data type"
On a 32 bit system "size_t" can be promoted into a 64 bit signed value
without loss of data, and therefore we may see the
"comparison is always false" warning.
On a 64 bit system it may happen, at least in theory, that size_t is > 2^63,
and then the promotion from an unsigned "size_t" into a signed "curl_off_t"
may be a problem.
One solution to suppress a possible compiler warning could be to remove
the function xcurl_off_t().
However, to be on the very safe side, we keep it and improve it:
- The len parameter is changed from ssize_t to size_t
- A temporally variable "size" is used, promoted int uintmax_t and the comopared
with "maximum_signed_value_of_type(curl_off_t)".
Thanks to Junio C Hamano for this hint.
Signed-off-by: Torsten Bögershausen <tboegi@xxxxxx>
---
remote-curl.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/remote-curl.c b/remote-curl.c
index 762a55a75f..1220dffcdc 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -617,10 +617,11 @@ static int probe_rpc(struct rpc_state *rpc, struct slot_results *results)
return err;
}
-static curl_off_t xcurl_off_t(ssize_t len) {
- if (len > maximum_signed_value_of_type(curl_off_t))
+static curl_off_t xcurl_off_t(size_t len) {
+ uintmax_t size = len;
+ if (size > maximum_signed_value_of_type(curl_off_t))
die("cannot handle pushes this big");
- return (curl_off_t) len;
+ return (curl_off_t)size;
}
static int post_rpc(struct rpc_state *rpc)
--
2.19.0.271.gfe8321ec05
