I think you can mention you are talking on UTC (Every one know UTC). May be something like: "As UTC do not use daylight savings time and with accords to POSIX, disable the use of daylight savings by setting tm_isdst to 0".
Feel free to find a better syntax. Or just copy the 2 lines from the POSIX (2004 Edition) https://pubs.opengroup.org/onlinepubs/009695399/functions/mktime.html "A positive or 0 value for tm_isdst shall cause mktime() to presume initially that Daylight Savings Time, respectively, is or is not in effect for the specified time. A negative value for tm_isdst shall cause mktime() to attempt to determine whether Daylight Savings Time is in effect for the specified time." Are you sure it was added in POSIX 2017? I do not think you need to be that precise which version of POSIX you use, they usually do not change much. Only enhance functionality or improve description. Last thought: We are software engineers, not poets. Do not be hard on yourself. Just use something short, clear that describe the problem and the fix. A message that if you read it in 2 years from now, you understand what was it. Erez -----Original Message----- From: Lars Munch <l...@segv.dk> Sent: Friday, 14 May 2021 19:30 To: Geva, Erez (ext) (DI PA DCP R&D 3) <erez.geva....@siemens.com> Cc: linuxptp-devel@lists.sourceforge.net Subject: Re: [Linuxptp-devel] [PATCH 1/4] ts2phc: Fix uninitialized variable in nmea_scan_rmc So how about the following simple explanation? According to POSIX.1-2017 tm_isdst must be set to 0 to indicate that Daylight Savings Time is not in effect for the specified time. On Fri, May 14, 2021 at 6:28 PM Geva, Erez <erez.geva....@siemens.com> wrote: > > One of my hardest bug was one a single bit. > Do not measure bugs by code. Measure by complexity. > > Erez > > -----Original Message----- > From: Lars Munch <l...@segv.dk> > Sent: Friday, 14 May 2021 18:14 > To: Geva, Erez (ext) (DI PA DCP R&D 3) <erez.geva....@siemens.com> > Cc: linuxptp-devel@lists.sourceforge.net > Subject: Re: [Linuxptp-devel] [PATCH 1/4] ts2phc: Fix uninitialized > variable in nmea_scan_rmc > > So much work for a one-liner. I see If I can come up with a better > explanation. > > On Fri, May 14, 2021 at 4:34 PM Geva, Erez <erez.geva....@siemens.com> wrote: > > > > Hi, > > > > > > > > I think it is better to use a short explanation how does mktime() use the > > tm_isdst flag, and why should it be set to 0. > > > > For me the problem is that we did not comply with proper use of mktime(). > > > > Fixing glibc only revealed the bug in linuxptp. > > > > So we fix linuxptp, not trying to comply with a specific glibc! > > > > > > > > The choice of libc is up to the user, as long as it comply to the standards > > (ISO C or POSIX). > > > > I do not see the purpose of links to bugs in glibc. > > > > It is also does not helps the Developers to understand, why do we need the > > patch (which we do need). > > > > > > > > We are a source project, not a binary one > > > > > > > > Erez > > > > > > > > -----Original Message----- > > From: Lars Munch <l...@segv.dk> > > Sent: Friday, 14 May 2021 13:34 > > To: linuxptp-devel@lists.sourceforge.net > > Subject: [Linuxptp-devel] [PATCH 1/4] ts2phc: Fix uninitialized > > variable in nmea_scan_rmc > > > > > > > > tm_isdst needs to be initialized to make sure mktime does not fail > > on recent versions of glibc > > > > > > > > See: > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbu > > gzilla.redhat.com%2Fshow_bug.cgi%3Fid%3D1653340&data=04%7C01%7Ce > > rez.geva.ext%40siemens.com%7C9d2a2f4353c0403194bc08d916fdfdd6%7C38ae > > 3bcd95794fd4addab42e1495d55a%7C1%7C0%7C637566103157490221%7CUnknown% > > 7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLC > > JXVCI6Mn0%3D%7C3000&sdata=BkgCRqVecfkCb4ug8zYUpNz%2By6Lum%2FIm4y > > ZiZj8Hsw4%3D&reserved=0 > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fso > > urceware.org%2Fbugzilla%2Fshow_bug.cgi%3Fid%3D24630&data=04%7C01 > > %7Cerez.geva.ext%40siemens.com%7C9d2a2f4353c0403194bc08d916fdfdd6%7C > > 38ae3bcd95794fd4addab42e1495d55a%7C1%7C0%7C637566103157500214%7CUnkn > > own%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haW > > wiLCJXVCI6Mn0%3D%7C3000&sdata=%2FFscYQHQqnvekRr%2Fkmf2H4FL96HsT2 > > EbDqEF%2F2f1qHw%3D&reserved=0 > > > > > > > > Signed-off-by: Lars Munch <l...@segv.dk> > > > > --- > > > > 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_scan_rmc(struct nmea_parser *np, > > struct nmea_rmc *result) > > > > } > > > > tm.tm_year += 100; > > > > tm.tm_mon--; > > > > + tm.tm_isdst = 0; > > > > result->ts.tv_sec = mktime(&tm); > > > > result->ts.tv_nsec = msec * 1000000UL; > > > > result->fix_valid = status == 'A' ? true : false; > > > > -- > > > > 2.25.1 > > > > > > > > > > > > > > > > _______________________________________________ > > > > Linuxptp-devel mailing list > > > > Linuxptp-devel@lists.sourceforge.net > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fli > > sts.sourceforge.net%2Flists%2Flistinfo%2Flinuxptp-devel&data=04% > > 7C01%7Cerez.geva.ext%40siemens.com%7C9d2a2f4353c0403194bc08d916fdfdd > > 6%7C38ae3bcd95794fd4addab42e1495d55a%7C1%7C0%7C637566103157500214%7C > > Unknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik > > 1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=%2FVBUVBAwqnX4zjGxzwRCxGsLRIWc > > xP2lUuVN%2B%2FYtwGI%3D&reserved=0 _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
