I think that no matter what any particular implementation might do, we are
relying on undefined behavior which is at best unsafe. I wonder if maybe
we shouldn't consider initializing the entire structure (and all others?)
after it is allocated. The performance price feels small and the safety
gua
Sorry for the noise. In my previous example I had by accident pasted a huge
number into the example. New example:
#include
#include
#include
int main()
{
struct tm t;
time_t now = time((void*)0);
localtime_r(&now, &t);
setenv("TZ", "UTC", 1);
t.tm_isdst = 1;
printf("%ld
Indeed, any positive random number in tm.tm_isdst will set DST in effect it
seems.
On my stripped down ARM system with no timezone information, it will simply
return -1.
On Tue, Apr 20, 2021 at 4:26 PM Michael Galassi wrote:
> Somewhere lies a bug. The following code snippet:
> #include
> #in
Ok, so mktime is forced to return in time UTC time scale earlier in the
code:
#include
#include
#include
int main()
{
struct tm t;
time_t now = time((void*)0);
localtime_r(&now, &t);
setenv("TZ", "UTC", 1);
t.tm_isdst = 41;
printf("%ld\n", mktime(&t));
t.tm_
Somewhere lies a bug. The following code snippet:
#include
#include
int main()
{
struct tm t;
time_t now = time((void*)0);
localtime_r(&now, &t);
t.tm_isdst = 1;
printf("%ld\n", mktime(&t));
t.tm_isdst = 0;
printf("%ld\n", mktime(&t));
t.tm_isdst = -1;
printf(
On Tue, Apr 20, 2021 at 11:44:06AM +0200, Lars Munch wrote:
> tm_isdst needs to be initialized to make sure mktime does not fail
> or calculates the wrong time.
No, take a look at the mktime(3) man page. There you will read the
following.
The mktime() function modifies the fields of the
port.twoStepFlag.
When -1, inherit the global twoStepFlag value, otherwise enable two-step mode
for sync messages on port basis. One-step mode can be used only with hardware
time stamping. The default is -1 (as global twoStepFlag value).
---
config.c | 1 +
port.c | 40
tm_isdst needs to be initialized to make sure mktime does not fail
or calculates the wrong time.
Signed-off-by: Lars Munch
---
nmea.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/nmea.c b/nmea.c
index dc865d0..44c7c01 100644
--- a/nmea.c
+++ b/nmea.c
@@ -157,6 +157,7 @@ static int nmea_sc
