March 1994 - tz - lists.iana.org

Re: Does anyone have the source for this function?
by myersn＠roguewave.com March 22, 1994

March 22, 1994

> Does anyone have a UNIX function for converting a time from timezoneX > to timezoneY? I know how to write this by mucking with char** environ > and by calling tzset(), but I'm interested in a more elegant solution > (perhaps using fields in the tm structure). > > convert(timezoneX, timezoneY, inputTime, outputTime) > > The char** environ solution seems to me to be inelegant because > > 1) I have to reread a file whenever I call tzset() (I think), > and > > 2) while I'm doing the conversion the call to tzset() has a > global effect on my process. If I'm interrupted by a > signal handler that displays the time it will be in a > foreign timezone. My current best solution is to use the Rogue Wave Tools.h++ library class RWZone. Nathan Myers myersn(a)roguewave.com

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Does anyone have the source for this function?
by aaron＠lehman.com March 22, 1994

March 22, 1994

Does anyone have a UNIX function for converting a time from timezoneX to timezoneY? I know how to write this by mucking with char** environ and by calling tzset(), but I'm interested in a more elegant solution (perhaps using fields in the tm structure). convert(timezoneX, timezoneY, inputTime, outputTime) The char** environ solution seems to me to be inelegant because 1) I have to reread a file whenever I call tzset() (I think), and 2) while I'm doing the conversion the call to tzset() has a global effect on my process. If I'm interrupted by a signal handler that displays the time it will be in a foreign timezone. aaron(a)lehman.com

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Time Conversoin Question [forwarded with permission]
by ado March 21, 1994

March 21, 1994

> From aaron(a)lehman.com Thu Mar 17 16:49:11 1994 > Return-Path: <aaron(a)lehman.com> > Received: from lehman.com by elsie.nci.nih.gov (4.1/SMI-4.1) > id AA28619; Thu, 17 Mar 94 16:49:08 EST > Received: from relay.lehman.com by lehman.com (8.6.4/LB 0.1) > id QAA19119; Thu, 17 Mar 1994 16:48:58 -0500 > Received: from killer.lehman.com by relay.lehman.com (4.1/LB-0.6) > id AA04769; Thu, 17 Mar 94 16:48:51 EST > Received: from yen.lehman.com by killer.lehman.com (5.0/SMI-SVR4) > id AA29096; Thu, 17 Mar 1994 16:48:48 +0500 > Date: Thu, 17 Mar 1994 16:48:48 +0500 > From: aaron(a)lehman.com (Aaron Akman) > Message-Id: <9403172148.AA29096(a)killer.lehman.com> > Received: by yen.lehman.com (4.1/SMI-4.1) > id AA03187; Thu, 17 Mar 94 16:48:45 EST > To: ado(a)elsie.nci.nih.gov > Subject: Time Conversion Question > Content-Length: 1037 > Status: RO > > Arthur, > > I've downloaded your timezone stuff (got pointers from Arnold Robbins > and Don Libes), and have a question: > > I'm looking to convert from GMT to one of a few timezones, or from one > timezone to another. I'm concerned about setting TZ and calling > tzset() because I think it changes some global state associated with > the process. If I were interrupted before setting TZ back and > re-calling tzset(), I could have an interrupt function that doesn't > have the right local TZ setting. I.e. > > get_other_local_time(char* tzsetting) > { > oldsetting = temporarily_set_TZ(tzsetting); > tzset(); > > do_time_stuff_with_alternate_TZ(); > > /* i could get interrupted here by a signal handler > that needs the real local time!! */ > > set_TZ_back(oldsetting); > tzset(); > } > > Is there a better way? Is it true the effect of tzset() global? I > haven't gone through the .c files in depth yet. > > It seems like this should be a common problem for a globally > distributed system. > > Thanks in advance for any advice, > Aaron Akman > aaron(a)lehman.com > 212 464 3978

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