archival: add "extended-timestamp" extra block for zip archives (issue3600)

Before this patch, zip archives created by "hg archive" are extracted
with unexpected timestamp, if TZ is not configured as GMT.

This patch adds "extended-timestamp" extra block to zip archives, and
unzip will extract such archives with timestamp specified in added
extra block, even though TZ is not configured as GMT.

Please see documents below for detail about specification of zip file
format and "extended-timestamp" extra block:

  http://www.pkware.com/documents/casestudies/APPNOTE.TXT
  http://www.opensource.apple.com/source/zip/zip-6/unzip/unzip/proginfo/extra.fld

Original implementation of this patch was suggested by "Jun Omae
<[e-mail]>".

mercurial/archival.py

@@ -12,6 +12,7 b' import cmdutil'
 import scmutil, util, encoding
 import cStringIO, os, tarfile, time, zipfile
 import zlib, gzip
+import struct
 
 def tidyprefix(dest, kind, prefix):
     '''choose prefix to use for names in archive.  make sure prefix is
@@ -165,6 +166,7 b' class zipit(object):'
         if mtime < epoch:
             mtime = epoch
 
+        self.mtime = mtime
         self.date_time = time.gmtime(mtime)[:6]
 
     def addfile(self, name, mode, islink, data):
@@ -178,6 +180,14 b' class zipit(object):'
             mode = 0777
             ftype = 0xa000 # UNX_IFLNK in unzip source code
         i.external_attr = (mode | ftype) << 16L
+        # add "extended-timestamp" extra block, because zip archives
+        # without this will be extracted with unexpected timestamp,
+        # if TZ is not configured as GMT
+        i.extra += struct.pack('<hhBl',
+                               0x5455,     # block type: "extended-timestamp"
+                               1 + 4,      # size of this block
+                               1,          # "modification time is present"
+                               self.mtime) # time of last modification (UTC)
         self.z.writestr(i, data)
 
     def done(self):

tests/test-archive.t

@@ -270,3 +270,31 b' old file -- date clamped to 1980'
   \s*147\s+2 files (re)
 
   $ cd ..
+
+issue3600: check whether "hg archive" can create archive files which
+are extracted with expected timestamp, even though TZ is not
+configured as GMT.
+
+  $ mkdir issue3600
+  $ cd issue3600
+
+  $ hg init repo
+  $ echo a > repo/a
+  $ hg -R repo add repo/a
+  $ hg -R repo commit -m '#0' -d '456789012 21600'
+  $ cat > show_mtime.py <<EOF
+  > import sys, os
+  > print int(os.stat(sys.argv[1]).st_mtime)
+  > EOF
+
+  $ hg -R repo archive --prefix tar-extracted archive.tar
+  $ (TZ=UTC-3; export TZ; tar xf archive.tar)
+  $ python show_mtime.py tar-extracted/a
+  456789012
+
+  $ hg -R repo archive --prefix zip-extracted archive.zip
+  $ (TZ=UTC-3; export TZ; unzip -q archive.zip)
+  $ python show_mtime.py zip-extracted/a
+  456789012
+
+  $ cd ..