On Wed, Jul 6, 2016 at 9:33 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
> Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx> writes:
>
>> clang -Wabsolute-value on IA-32 architecture complains that "absolute
>> value function 'labs' given an argument of type 'intmax_t' (aka 'long
>> long') but has parameter of type 'long' which may cause truncation of
>> value". Very unlikely for this code though. Nevertheless, add an
>> explicit check for truncation to shut clang up and error out.
>
> Thanks. It however makes me wonder if it is a better approach to
> avoid downcasting intmax_t to long by using imaxabs()?
I think the tricky part is detect overflow. WIth uval being a
potentially signed number, i'm not sure how to catch it. The (uval >
max || labs(val) > uval) was written with unsigned number in mind, I
think.
>
>>
>> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
>> ---
>> config.c | 10 ++++++++--
>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/config.c b/config.c
>> index d7ce34b..880bd4a 100644
>> --- a/config.c
>> +++ b/config.c
>> @@ -503,6 +503,7 @@ static int git_parse_signed(const char *value, intmax_t *ret, intmax_t max)
>> intmax_t val;
>> uintmax_t uval;
>> uintmax_t factor = 1;
>> + long int lival;
>>
>> errno = 0;
>> val = strtoimax(value, &end, 0);
>> @@ -512,9 +513,14 @@ static int git_parse_signed(const char *value, intmax_t *ret, intmax_t max)
>> errno = EINVAL;
>> return 0;
>> }
>> - uval = labs(val);
>> + lival = (long int)val;
>> + if (lival != val) {
>> + errno = ERANGE;
>> + return 0;
>> + }
>> + uval = labs(lival);
>> uval *= factor;
>> - if (uval > max || labs(val) > uval) {
>> + if (uval > max || labs(lival) > uval) {
>> errno = ERANGE;
>> return 0;
>> }
--
Duy
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