Arrange to install a "posixrules" entry in our timezone database, so that

POSIX-style timezone specs that don't exactly match any database entry will
be treated as having correct USA DST rules.  Also, document that this can
be changed if you want to use some other DST rules with a POSIX zone spec.

We could consider changing localtime.c's TZDEFRULESTRING, but since that
facility can only deal with one DST transition rule, it seems fairly useless
now; might as well just plan to override it using a "posixrules" entry.

Backpatch as far as 8.0.  There isn't much we can do in 7.x ... either your
libc gets it right, or it doesn't.

diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 9dc09cd6047066a126dbbd2ad9fab29e808291f2..73a1431cd6da5acac00082b3e448ed8d10b17f78 100644 (file)
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -2194,12 +2194,13 @@ January 8 04:05:06 1999 PST
         were not already a recognized zone name, it would be accepted and would
         be functionally equivalent to USA East Coast time.  When a
         daylight-savings zone name is present, it is assumed to be used
-        according to USA time zone rules, so this feature is of limited use
-        outside North America.  One should also be wary that this provision can
-        lead to silently accepting bogus input, since there is no check on the
-        reasonableness of the zone abbreviations.  For example, <literal>SET
-        TIMEZONE TO FOOBAR0</> will work, leaving the system effectively using
-        a rather peculiar abbreviation for GMT.
+        according to the same daylight-savings transition rules used in the
+        <literal>zic</> time zone database's <filename>posixrules</> entry.
+        In a standard <productname>PostgreSQL</productname> installation,
+        <filename>posixrules</> is the same as <literal>US/Eastern</>, so
+        that POSIX-style time zone specifications follow USA daylight-savings
+        rules.  If needed, you can adjust this behavior by replacing the
+        <filename>posixrules</> file.
        </para>
       </listitem>
      </itemizedlist>
@@ -2210,6 +2211,14 @@ January 8 04:05:06 1999 PST
      rule and so have two possible UTC offsets.
     </para>
 
+    <para>
+     One should be wary that the POSIX-style time zone feature can
+     lead to silently accepting bogus input, since there is no check on the
+     reasonableness of the zone abbreviations.  For example, <literal>SET
+     TIMEZONE TO FOOBAR0</> will work, leaving the system effectively using
+     a rather peculiar abbreviation for UTC.
+    </para>
+
     <para>
      In all cases, timezone names are recognized case-insensitively.
      (This is a change from <productname>PostgreSQL</productname> versions

diff --git a/src/timezone/Makefile b/src/timezone/Makefile
index cc9fac987ab7cdbfde4a51f4aa2cd80d2a0c37c4..e2d48460e30de5058cc0bfa387950b8d630cbbf1 100644 (file)
--- a/src/timezone/Makefile
+++ b/src/timezone/Makefile
@@ -25,6 +25,10 @@ TZDATA := africa antarctica asia australasia europe northamerica southamerica \
        pacificnew etcetera factory backward systemv solar87 solar88 solar89
 TZDATAFILES := $(TZDATA:%=$(srcdir)/data/%)
 
+# which zone should determine the DST rules (not the specific UTC offset!)
+# for POSIX-style timezone specs
+POSIXRULES = US/Eastern
+
 all: SUBSYS.o submake-libpgport zic
 
 SUBSYS.o: $(OBJS)
@@ -34,7 +38,7 @@ zic: $(ZICOBJS)
        $(CC) $(CFLAGS) $(ZICOBJS) $(LDFLAGS) $(LIBS) -o $@$(X)
 
 install: all installdirs
-       ./zic -d '$(DESTDIR)$(datadir)/timezone' $(TZDATAFILES)
+       ./zic -d '$(DESTDIR)$(datadir)/timezone' -p '$(POSIXRULES)' $(TZDATAFILES)
        $(MAKE) -C tznames $@
 
 installdirs: