+2017-05-09 Bruno Haible <bruno@clisp.org>
+
+ tzset: Expand comment about TZ problem on native Windows.
+ * lib/tzset.c (tzset): Elaborate comment, based on explanations by
+ Paul Eggert.
+ * lib/ctime.c (rpl_ctime): Likewise.
+ * lib/localtime.c (rpl_localtime): Likewise.
+ * lib/mktime.c (mktime): Likewise.
+ * lib/strftime-fixes.c (rpl_strftime): Likewise.
+ * lib/wcsftime.c (rpl_wcsftime): Likewise.
+
2017-05-08 Paul Eggert <eggert@cs.ucla.edu>
intprops: don’t depend on ‘verify’
rpl_ctime (const time_t *tp)
{
#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
- /* If the environment variable TZ has been set by Cygwin, neutralize it.
- The Microsoft CRT interprets TZ differently than Cygwin and produces
- incorrect results if TZ has the syntax used by Cygwin. */
+ /* Rectify the value of the environment variable TZ.
+ There are four possible kinds of such values:
+ - Traditional US time zone names, e.g. "PST8PDT". Syntax: see
+ <https://msdn.microsoft.com/en-us/library/90s5c885.aspx>
+ - Time zone names based on geography, that contain one or more
+ slashes, e.g. "Europe/Moscow".
+ - Time zone names based on geography, without slashes, e.g.
+ "Singapore".
+ - Time zone names that contain explicit DST rules. Syntax: see
+ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>
+ The Microsoft CRT understands only the first kind. It produces incorrect
+ results if the value of TZ is of the other kinds.
+ But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value
+ of the second kind for most geographies, or of the first kind in a few
+ other geographies. If it is of the second kind, neutralize it. For the
+ Microsoft CRT, an absent or empty TZ means the time zone that the user
+ has set in the Windows Control Panel.
+ If the value of TZ is of the third or fourth kind -- Cygwin programs
+ understand these syntaxes as well --, it does not matter whether we
+ neutralize it or not, since these values occur only when a Cygwin user
+ has set TZ explicitly; this case is 1. rare and 2. under the user's
+ responsibility. */
const char *tz = getenv ("TZ");
if (tz != NULL && strchr (tz, '/') != NULL)
_putenv ("TZ=");
rpl_localtime (const time_t *tp)
{
# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
- /* If the environment variable TZ has been set by Cygwin, neutralize it.
- The Microsoft CRT interprets TZ differently than Cygwin and produces
- incorrect results if TZ has the syntax used by Cygwin. */
+ /* Rectify the value of the environment variable TZ.
+ There are four possible kinds of such values:
+ - Traditional US time zone names, e.g. "PST8PDT". Syntax: see
+ <https://msdn.microsoft.com/en-us/library/90s5c885.aspx>
+ - Time zone names based on geography, that contain one or more
+ slashes, e.g. "Europe/Moscow".
+ - Time zone names based on geography, without slashes, e.g.
+ "Singapore".
+ - Time zone names that contain explicit DST rules. Syntax: see
+ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>
+ The Microsoft CRT understands only the first kind. It produces incorrect
+ results if the value of TZ is of the other kinds.
+ But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value
+ of the second kind for most geographies, or of the first kind in a few
+ other geographies. If it is of the second kind, neutralize it. For the
+ Microsoft CRT, an absent or empty TZ means the time zone that the user
+ has set in the Windows Control Panel.
+ If the value of TZ is of the third or fourth kind -- Cygwin programs
+ understand these syntaxes as well --, it does not matter whether we
+ neutralize it or not, since these values occur only when a Cygwin user
+ has set TZ explicitly; this case is 1. rare and 2. under the user's
+ responsibility. */
const char *tz = getenv ("TZ");
if (tz != NULL && strchr (tz, '/') != NULL)
_putenv ("TZ=");
mktime (struct tm *tp)
{
# if NEED_MKTIME_WINDOWS
- /* If the environment variable TZ has been set by Cygwin, neutralize it.
- The Microsoft CRT interprets TZ differently than Cygwin and produces
- incorrect results if TZ has the syntax used by Cygwin. */
+ /* Rectify the value of the environment variable TZ.
+ There are four possible kinds of such values:
+ - Traditional US time zone names, e.g. "PST8PDT". Syntax: see
+ <https://msdn.microsoft.com/en-us/library/90s5c885.aspx>
+ - Time zone names based on geography, that contain one or more
+ slashes, e.g. "Europe/Moscow".
+ - Time zone names based on geography, without slashes, e.g.
+ "Singapore".
+ - Time zone names that contain explicit DST rules. Syntax: see
+ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>
+ The Microsoft CRT understands only the first kind. It produces incorrect
+ results if the value of TZ is of the other kinds.
+ But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value
+ of the second kind for most geographies, or of the first kind in a few
+ other geographies. If it is of the second kind, neutralize it. For the
+ Microsoft CRT, an absent or empty TZ means the time zone that the user
+ has set in the Windows Control Panel.
+ If the value of TZ is of the third or fourth kind -- Cygwin programs
+ understand these syntaxes as well --, it does not matter whether we
+ neutralize it or not, since these values occur only when a Cygwin user
+ has set TZ explicitly; this case is 1. rare and 2. under the user's
+ responsibility. */
const char *tz = getenv ("TZ");
if (tz != NULL && strchr (tz, '/') != NULL)
_putenv ("TZ=");
rpl_strftime (char *buf, size_t bufsize, const char *format, const struct tm *tp)
{
#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
- /* If the environment variable TZ has been set by Cygwin, neutralize it.
- The Microsoft CRT interprets TZ differently than Cygwin and produces
- incorrect results if TZ has the syntax used by Cygwin. */
+ /* Rectify the value of the environment variable TZ.
+ There are four possible kinds of such values:
+ - Traditional US time zone names, e.g. "PST8PDT". Syntax: see
+ <https://msdn.microsoft.com/en-us/library/90s5c885.aspx>
+ - Time zone names based on geography, that contain one or more
+ slashes, e.g. "Europe/Moscow".
+ - Time zone names based on geography, without slashes, e.g.
+ "Singapore".
+ - Time zone names that contain explicit DST rules. Syntax: see
+ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>
+ The Microsoft CRT understands only the first kind. It produces incorrect
+ results if the value of TZ is of the other kinds.
+ But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value
+ of the second kind for most geographies, or of the first kind in a few
+ other geographies. If it is of the second kind, neutralize it. For the
+ Microsoft CRT, an absent or empty TZ means the time zone that the user
+ has set in the Windows Control Panel.
+ If the value of TZ is of the third or fourth kind -- Cygwin programs
+ understand these syntaxes as well --, it does not matter whether we
+ neutralize it or not, since these values occur only when a Cygwin user
+ has set TZ explicitly; this case is 1. rare and 2. under the user's
+ responsibility. */
const char *tz = getenv ("TZ");
if (tz != NULL && strchr (tz, '/') != NULL)
_putenv ("TZ=");
#endif
#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
- /* If the environment variable TZ has been set by Cygwin, neutralize it.
- The Microsoft CRT interprets TZ differently than Cygwin and produces
- incorrect results if TZ has the syntax used by Cygwin. */
+ /* Rectify the value of the environment variable TZ.
+ There are four possible kinds of such values:
+ - Traditional US time zone names, e.g. "PST8PDT". Syntax: see
+ <https://msdn.microsoft.com/en-us/library/90s5c885.aspx>
+ - Time zone names based on geography, that contain one or more
+ slashes, e.g. "Europe/Moscow".
+ - Time zone names based on geography, without slashes, e.g.
+ "Singapore".
+ - Time zone names that contain explicit DST rules. Syntax: see
+ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>
+ The Microsoft CRT understands only the first kind. It produces incorrect
+ results if the value of TZ is of the other kinds.
+ But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value
+ of the second kind for most geographies, or of the first kind in a few
+ other geographies. If it is of the second kind, neutralize it. For the
+ Microsoft CRT, an absent or empty TZ means the time zone that the user
+ has set in the Windows Control Panel.
+ If the value of TZ is of the third or fourth kind -- Cygwin programs
+ understand these syntaxes as well --, it does not matter whether we
+ neutralize it or not, since these values occur only when a Cygwin user
+ has set TZ explicitly; this case is 1. rare and 2. under the user's
+ responsibility. */
const char *tz = getenv ("TZ");
if (tz != NULL && strchr (tz, '/') != NULL)
_putenv ("TZ=");
rpl_wcsftime (wchar_t *buf, size_t bufsize, const wchar_t *format, const struct tm *tp)
{
#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
- /* If the environment variable TZ has been set by Cygwin, neutralize it.
- The Microsoft CRT interprets TZ differently than Cygwin and produces
- incorrect results if TZ has the syntax used by Cygwin. */
+ /* Rectify the value of the environment variable TZ.
+ There are four possible kinds of such values:
+ - Traditional US time zone names, e.g. "PST8PDT". Syntax: see
+ <https://msdn.microsoft.com/en-us/library/90s5c885.aspx>
+ - Time zone names based on geography, that contain one or more
+ slashes, e.g. "Europe/Moscow".
+ - Time zone names based on geography, without slashes, e.g.
+ "Singapore".
+ - Time zone names that contain explicit DST rules. Syntax: see
+ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>
+ The Microsoft CRT understands only the first kind. It produces incorrect
+ results if the value of TZ is of the other kinds.
+ But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value
+ of the second kind for most geographies, or of the first kind in a few
+ other geographies. If it is of the second kind, neutralize it. For the
+ Microsoft CRT, an absent or empty TZ means the time zone that the user
+ has set in the Windows Control Panel.
+ If the value of TZ is of the third or fourth kind -- Cygwin programs
+ understand these syntaxes as well --, it does not matter whether we
+ neutralize it or not, since these values occur only when a Cygwin user
+ has set TZ explicitly; this case is 1. rare and 2. under the user's
+ responsibility. */
const char *tz = getenv ("TZ");
if (tz != NULL && strchr (tz, '/') != NULL)
_putenv ("TZ=");