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| -rw-r--r-- | winsup/doc/faq-api.xml | 40 |
1 files changed, 35 insertions, 5 deletions
diff --git a/winsup/doc/faq-api.xml b/winsup/doc/faq-api.xml index 829e4d7..6283fb6 100644 --- a/winsup/doc/faq-api.xml +++ b/winsup/doc/faq-api.xml @@ -385,13 +385,43 @@ Cygwin version number details, check out the </answer></qandaentry> <qandaentry id="faq.api.timezone"> -<question><para>Why isn't timezone set correctly?</para></question> +<question><para>Why isn't my time (or zone) set correctly?</para></question> <answer> -<para><emphasis role='bold'>(Please note: This section has not yet been updated for the latest net release.)</emphasis> -</para> -<para>Did you explicitly call tzset() before checking the value of timezone? -If not, you must do so. +<para>Daylight saving (Summer time) and other time zone changes are +decided on by politicians, and announced by government officials, +sometimes with short or no notice, so time zone updates are released at +least a few, and sometimes several, times a year. +Details of changes are not known until they are announced publicly by +officials, often in foreign languages. +Those details then have to be noticed, possibly translated, passed to, +picked up, and applied by the official <filename>tzdata</filename> +source package maintainers. +That information has to be compiled, checked, and released publicly in +an update to the official <filename>tzdata</filename> source package. +Then those changes have to be picked up and applied to the Cygwin +<filename>tzdata</filename> package, which has to be updated, built, +tested, and released publicly. +</para> +<para>Time zone settings are updates to the daylight saving (Summer +time) rules for dates of changes, hour offsets from UTC of time zones, +and the geographic regions to which those rules and offsets apply, +provided in the <filename>tzdata</filename> package included in all +Cygwin installations. +Have you run the Cygwin Setup program recently to update at least +the <filename>tzdata</filename> package? +</para> +<para>Are you developing applications using times which may be affected +by time zones? +Since the <literal>ctime()</literal>, <literal>localtime()</literal>, +<literal>mktime()</literal>, and <literal>strftime()</literal> functions +are required to set time zone information as if by calling +<literal>tzset()</literal>, there is no need for an explicit +<literal>tzset()</literal> call before using these functions. +However, if none of the above functions are called first, applications +should ensure <literal>tzset()</literal> is called explicitly before +using any other time functions, or checking or using time zone +information. </para> </answer></qandaentry> |