extdiff: use archiver to take snapshots of committed revisions

This is the last step before supporting extdiff -S.  It maintains the existing
behavior of diffing the largefile standins instead of the largefiles themselves.
Note however that the standins are not updated immediately upon modification, so
uncommitted largefile changes are ignored, as they previously were, even with
the diff command.

hgext/extdiff.py

@@ -63,6 +63,7 b' pretty fast (at least faster than having'
 from mercurial.i18n import _
 from mercurial.node import short, nullid
 from mercurial import cmdutil, scmutil, util, commands, encoding, filemerge
+from mercurial import archival
 import os, shlex, shutil, tempfile, re
 
 cmdtable = {}
@@ -84,33 +85,34 b' def snapshot(ui, repo, files, node, tmpr'
         dirname = '%s.%s' % (dirname, short(node))
     base = os.path.join(tmproot, dirname)
     os.mkdir(base)
+    fns_and_mtime = []
+
     if node is not None:
         ui.note(_('making snapshot of %d files from rev %s\n') %
                 (len(files), short(node)))
     else:
         ui.note(_('making snapshot of %d files from working directory\n') %
             (len(files)))
-    wopener = scmutil.opener(base)
-    fns_and_mtime = []
-    ctx = repo[node]
-    for fn in sorted(files):
-        wfn = util.pconvert(fn)
-        if wfn not in ctx:
-            # File doesn't exist; could be a bogus modify
-            continue
-        ui.note('  %s\n' % wfn)
-        dest = os.path.join(base, wfn)
-        fctx = ctx[wfn]
-        data = repo.wwritedata(wfn, fctx.data())
-        if 'l' in fctx.flags():
-            wopener.symlink(data, wfn)
-        else:
-            wopener.write(wfn, data)
-            if 'x' in fctx.flags():
-                util.setflags(dest, False, True)
-        if node is None:
-            fns_and_mtime.append((dest, repo.wjoin(fn),
-                                  os.lstat(dest).st_mtime))
+
+    if files:
+        repo.ui.setconfig("ui", "archivemeta", False)
+
+        archival.archive(repo, base, node, 'files',
+                         matchfn=scmutil.matchfiles(repo, files))
+
+        ctx = repo[node]
+        for fn in sorted(files):
+            wfn = util.pconvert(fn)
+            if wfn not in ctx:
+                # File doesn't exist; could be a bogus modify
+                continue
+            ui.note('  %s\n' % wfn)
+
+            if node is None:
+                dest = os.path.join(base, wfn)
+
+                fns_and_mtime.append((dest, repo.wjoin(fn),
+                                      os.lstat(dest).st_mtime))
     return dirname, fns_and_mtime
 
 def dodiff(ui, repo, cmdline, pats, opts):

tests/test-largefiles-update.t

@@ -20,6 +20,20 b' directory (and ".hg/largefiles/dirstate"'
   $ echo 'large1 in #1' > large1
   $ echo 'normal1 in #1' > normal1
   $ hg commit -m '#1'
+  $ hg extdiff -r '.^' --config extensions.extdiff=
+  diff -Npru repo.0d9d9b8dc9a3/.hglf/large1 repo/.hglf/large1
+  --- repo.0d9d9b8dc9a3/.hglf/large1	* (glob)
+  +++ repo/.hglf/large1	* (glob)
+  @@ -1 +1 @@
+  -4669e532d5b2c093a78eca010077e708a071bb64
+  +58e24f733a964da346e2407a2bee99d9001184f5
+  diff -Npru repo.0d9d9b8dc9a3/normal1 repo/normal1
+  --- repo.0d9d9b8dc9a3/normal1	* (glob)
+  +++ repo/normal1	* (glob)
+  @@ -1 +1 @@
+  -normal1
+  +normal1 in #1
+  [1]
   $ hg update -q -C 0
   $ echo 'large2 in #2' > large2
   $ hg commit -m '#2'