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| -rw-r--r-- | ChangeLog | 6 | ||||
| -rw-r--r-- | manual/time.texi | 38 |
2 files changed, 27 insertions, 17 deletions
@@ -1,3 +1,9 @@ +2013-12-04 Paul Eggert <eggert@cs.ucla.edu> + + [BZ #926] + * manual/time.texi (Calendar Time): Clarify what timezone functions + use. + 2013-12-04 Adhemerval Zanella <azanella@linux.vnet.ibm.com> * sysdeps/powerpc/fpu/libm-test-ulps: Update. diff --git a/manual/time.texi b/manual/time.texi index ff31e284fd..1a5aaed032 100644 --- a/manual/time.texi +++ b/manual/time.texi @@ -687,9 +687,8 @@ The return value is the null pointer if @var{time} cannot be represented as a broken-down time; typically this is because the year cannot fit into an @code{int}. -Calling @code{localtime} has one other effect: it sets the variable -@code{tzname} with information about the current time zone. @xref{Time -Zone Functions}. +Calling @code{localtime} also sets the current time zone as if +@code{tzset} were called. @xref{Time Zone Functions}. @end deftypefun Using the @code{localtime} function is a big problem in multi-threaded @@ -739,25 +738,28 @@ object the result was written into, i.e., it returns @var{resultp}. @comment time.h @comment ISO @deftypefun time_t mktime (struct tm *@var{brokentime}) -The @code{mktime} function is used to convert a broken-down time structure -to a simple time representation. It also ``normalizes'' the contents of -the broken-down time structure, by filling in the day of week and day of -year based on the other date and time components. +The @code{mktime} function converts a broken-down time structure to a +simple time representation. It also normalizes the contents of the +broken-down time structure, and fills in some components based on the +values of the others. The @code{mktime} function ignores the specified contents of the -@code{tm_wday} and @code{tm_yday} members of the broken-down time +@code{tm_wday}, @code{tm_yday}, @code{tm_gmtoff}, and @code{tm_zone} +members of the broken-down time structure. It uses the values of the other components to determine the calendar time; it's permissible for these components to have unnormalized values outside their normal ranges. The last thing that @code{mktime} does is adjust the components of the @var{brokentime} -structure (including the @code{tm_wday} and @code{tm_yday}). +structure, including the members that were initally ignored. If the specified broken-down time cannot be represented as a simple time, @code{mktime} returns a value of @code{(time_t)(-1)} and does not modify the contents of @var{brokentime}. -Calling @code{mktime} also sets the variable @code{tzname} with -information about the current time zone. @xref{Time Zone Functions}. +Calling @code{mktime} also sets the current time zone as if +@code{tzset} were called; @code{mktime} uses this information instead +of @var{brokentime}'s initial @code{tm_gmtoff} and @code{tm_zone} +members. @xref{Time Zone Functions}. @end deftypefun @comment time.h @@ -1053,8 +1055,8 @@ rather than in broken-down local time format. It is equivalent to asctime (localtime (@var{time})) @end smallexample -@code{ctime} sets the variable @code{tzname}, because @code{localtime} -does so. @xref{Time Zone Functions}. +Calling @code{ctime} also sets the current time zone as if +@code{tzset} were called. @xref{Time Zone Functions}. @end deftypefun @comment time.h @@ -1081,7 +1083,8 @@ This function is similar to the @code{sprintf} function (@pxref{Formatted Input}), but the conversion specifications that can appear in the format template @var{template} are specialized for printing components of the date and time @var{brokentime} according to the locale currently specified for -time conversion (@pxref{Locales}). +time conversion (@pxref{Locales}) and the current time zone +(@pxref{Time Zone Functions}). Ordinary characters appearing in the @var{template} are copied to the output string @var{s}; this can include multibyte character sequences. @@ -1392,9 +1395,10 @@ if (len == 0 && buf[0] != '\0') If @var{s} is a null pointer, @code{strftime} does not actually write anything, but instead returns the number of characters it would have written. -According to POSIX.1 every call to @code{strftime} implies a call to -@code{tzset}. So the contents of the environment variable @code{TZ} -is examined before any output is produced. +Calling @code{strftime} also sets the current time zone as if +@code{tzset} were called; @code{strftime} uses this information +instead of @var{brokentime}'s @code{tm_gmtoff} and @code{tm_zone} +members. @xref{Time Zone Functions}. For an example of @code{strftime}, see @ref{Time Functions Example}. @end deftypefun |