diff --git a/core/Makefile b/core/Makefile
index 5e5c735..2052294 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -754,6 +754,7 @@
 	  $(HOST_OUT_EXECUTABLES)/zipalign \
 	  $(HOST_OUT_EXECUTABLES)/aapt \
 	  $(HOST_OUT_EXECUTABLES)/bsdiff \
+	  $(HOST_OUT_EXECUTABLES)/imgdiff \
 	  $(HOST_OUT_JAVA_LIBRARIES)/dumpkey.jar \
 	  $(HOST_OUT_JAVA_LIBRARIES)/signapk.jar
 
diff --git a/tools/releasetools/amend_generator.py b/tools/releasetools/amend_generator.py
new file mode 100644
index 0000000..8341599
--- /dev/null
+++ b/tools/releasetools/amend_generator.py
@@ -0,0 +1,205 @@
+# Copyright (C) 2009 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+
+import common
+
+class AmendGenerator(object):
+  """Class to generate scripts in the 'amend' recovery script language
+  used up through cupcake."""
+
+  def __init__(self):
+    self.script = ['assert compatible_with("0.2") == "true"']
+    self.included_files = set()
+
+  def MakeTemporary(self):
+    """Make a temporary script object whose commands can latter be
+    appended to the parent script with AppendScript().  Used when the
+    caller wants to generate script commands out-of-order."""
+    x = AmendGenerator()
+    x.script = []
+    x.included_files = self.included_files
+    return x
+
+  @staticmethod
+  def _FileRoot(fn):
+    """Convert a file path to the 'root' notation used by amend."""
+    if fn.startswith("/system/"):
+      return "SYSTEM:" + fn[8:]
+    elif fn == "/system":
+      return "SYSTEM:"
+    elif fn.startswith("/tmp/"):
+      return "CACHE:.." + fn
+    else:
+      raise ValueError("don't know root for \"%s\"" % (fn,))
+
+  @staticmethod
+  def _PartitionRoot(partition):
+    """Convert a partition name to the 'root' notation used by amend."""
+    if partition == "userdata":
+      return "DATA:"
+    else:
+      return partition.upper() + ":"
+
+  def AppendScript(self, other):
+    """Append the contents of another script (which should be created
+    with temporary=True) to this one."""
+    self.script.extend(other.script)
+    self.included_files.update(other.included_files)
+
+  def AssertSomeFingerprint(self, *fp):
+    """Assert that the current fingerprint is one of *fp."""
+    x = [('file_contains("SYSTEM:build.prop", '
+          '"ro.build.fingerprint=%s") == "true"') % i for i in fp]
+    self.script.append("assert %s" % (" || ".join(x),))
+
+  def AssertOlderBuild(self, timestamp):
+    """Assert that the build on the device is older (or the same as)
+    the given timestamp."""
+    self.script.append("run_program PACKAGE:check_prereq %s" % (timestamp,))
+    self.included_files.add("check_prereq")
+
+  def AssertDevice(self, device):
+    """Assert that the device identifier is the given string."""
+    self.script.append('assert getprop("ro.product.device") == "%s" || '
+                       'getprop("ro.build.product") == "%s"' % (device, device))
+
+  def AssertSomeBootloader(self, *bootloaders):
+    """Asert that the bootloader version is one of *bootloaders."""
+    self.script.append("assert " +
+                  " || ".join(['getprop("ro.bootloader") == "%s"' % (b,)
+                               for b in bootloaders]))
+
+  def ShowProgress(self, frac, dur):
+    """Update the progress bar, advancing it over 'frac' over the next
+    'dur' seconds."""
+    self.script.append("show_progress %f %d" % (frac, int(dur)))
+
+  def PatchCheck(self, filename, *sha1):
+    """Check that the given file (or MTD reference) has one of the
+    given *sha1 hashes."""
+    out = ["run_program PACKAGE:applypatch -c %s" % (filename,)]
+    for i in sha1:
+      out.append(" " + i)
+    self.script.append("".join(out))
+    self.included_files.add("applypatch")
+
+  def CacheFreeSpaceCheck(self, amount):
+    """Check that there's at least 'amount' space that can be made
+    available on /cache."""
+    self.script.append("run_program PACKAGE:applypatch -s %d" % (amount,))
+    self.included_files.add("applypatch")
+
+  def Mount(self, kind, what, path):
+    # no-op; amend uses it's 'roots' system to automatically mount
+    # things when they're referred to
+    pass
+
+  def UnpackPackageDir(self, src, dst):
+    """Unpack a given directory from the OTA package into the given
+    destination directory."""
+    dst = self._FileRoot(dst)
+    self.script.append("copy_dir PACKAGE:%s %s" % (src, dst))
+
+  def Comment(self, comment):
+    """Write a comment into the update script."""
+    self.script.append("")
+    for i in comment.split("\n"):
+      self.script.append("# " + i)
+    self.script.append("")
+
+  def Print(self, message):
+    """Log a message to the screen (if the logs are visible)."""
+    # no way to do this from amend; substitute a script comment instead
+    self.Comment(message)
+
+  def FormatPartition(self, partition):
+    """Format the given MTD partition."""
+    self.script.append("format %s" % (self._PartitionRoot(partition),))
+
+  def DeleteFiles(self, file_list):
+    """Delete all files in file_list."""
+    line = []
+    t = 0
+    for i in file_list:
+      i = self._FileRoot(i)
+      line.append(i)
+      t += len(i) + 1
+      if t > 80:
+        self.script.append("delete " + " ".join(line))
+        line = []
+        t = 0
+    if line:
+      self.script.append("delete " + " ".join(line))
+
+  def ApplyPatch(self, srcfile, tgtfile, tgtsize, tgtsha1, *patchpairs):
+    """Apply binary patches (in *patchpairs) to the given srcfile to
+    produce tgtfile (which may be "-" to indicate overwriting the
+    source file."""
+    if len(patchpairs) % 2 != 0:
+      raise ValueError("bad patches given to ApplyPatch")
+    self.script.append(
+        ("run_program PACKAGE:applypatch %s %s %s %d " %
+         (srcfile, tgtfile, tgtsha1, tgtsize)) +
+        " ".join(["%s:%s" % patchpairs[i:i+2]
+                  for i in range(0, len(patchpairs), 2)]))
+    self.included_files.add("applypatch")
+
+  def WriteFirmwareImage(self, kind, fn):
+    """Arrange to update the given firmware image (kind must be
+    "hboot" or "radio") when recovery finishes."""
+    self.script.append("write_%s_image PACKAGE:%s" % (kind, fn))
+
+  def WriteRawImage(self, partition, fn):
+    """Write the given file into the given MTD partition."""
+    self.script.append("write_raw_image PACKAGE:%s %s" %
+                       (fn, self._PartitionRoot(partition)))
+
+  def SetPermissions(self, fn, uid, gid, mode):
+    """Set file ownership and permissions."""
+    fn = self._FileRoot(fn)
+    self.script.append("set_perm %d %d 0%o %s" % (uid, gid, mode, fn))
+
+  def SetPermissionsRecursive(self, fn, uid, gid, dmode, fmode):
+    """Recursively set path ownership and permissions."""
+    fn = self._FileRoot(fn)
+    self.script.append("set_perm_recursive %d %d 0%o 0%o %s" %
+                       (uid, gid, dmode, fmode, fn))
+
+  def MakeSymlinks(self, symlink_list):
+    """Create symlinks, given a list of (dest, link) pairs."""
+    self.script.extend(["symlink %s %s" % (i[0], self._FileRoot(i[1]))
+                        for i in sorted(symlink_list)])
+
+  def AppendExtra(self, extra):
+    """Append text verbatim to the output script."""
+    self.script.append(extra)
+
+  def AddToZip(self, input_zip, output_zip, input_path=None):
+    """Write the accumulated script to the output_zip file.  input_zip
+    is used as the source for any ancillary binaries needed by the
+    script.  If input_path is not None, it will be used as a local
+    path for binaries instead of input_zip."""
+    common.ZipWriteStr(output_zip, "META-INF/com/google/android/update-script",
+                       "\n".join(self.script) + "\n")
+    for i in self.included_files:
+      try:
+        if input_path is None:
+          data = input_zip.read(os.path.join("OTA/bin", i))
+        else:
+          data = open(os.path.join(input_path, i)).read()
+        common.ZipWriteStr(output_zip, i, data, perms=0755)
+      except (IOError, KeyError), e:
+        raise ExternalError("unable to include binary %s: %s" % (i, e))
diff --git a/tools/releasetools/edify_generator.py b/tools/releasetools/edify_generator.py
new file mode 100644
index 0000000..e7a15cd
--- /dev/null
+++ b/tools/releasetools/edify_generator.py
@@ -0,0 +1,226 @@
+# Copyright (C) 2009 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import re
+
+import common
+
+class EdifyGenerator(object):
+  """Class to generate scripts in the 'edify' recovery script language
+  used from donut onwards."""
+
+  def __init__(self, version):
+    self.script = []
+    self.mounts = set()
+    self.version = version
+
+  def MakeTemporary(self):
+    """Make a temporary script object whose commands can latter be
+    appended to the parent script with AppendScript().  Used when the
+    caller wants to generate script commands out-of-order."""
+    x = EdifyGenerator(self.version)
+    x.mounts = self.mounts
+    return x
+
+  @staticmethod
+  def _WordWrap(cmd, linelen=80):
+    """'cmd' should be a function call with null characters after each
+    parameter (eg, "somefun(foo,\0bar,\0baz)").  This function wraps cmd
+    to a given line length, replacing nulls with spaces and/or newlines
+    to format it nicely."""
+    indent = cmd.index("(")+1
+    out = []
+    first = True
+    x = re.compile("^(.{,%d})\0" % (linelen-indent,))
+    while True:
+      if not first:
+        out.append(" " * indent)
+      first = False
+      m = x.search(cmd)
+      if not m:
+        parts = cmd.split("\0", 1)
+        out.append(parts[0]+"\n")
+        if len(parts) == 1:
+          break
+        else:
+          cmd = parts[1]
+          continue
+      out.append(m.group(1)+"\n")
+      cmd = cmd[m.end():]
+
+    return "".join(out).replace("\0", " ").rstrip("\n")
+
+  def AppendScript(self, other):
+    """Append the contents of another script (which should be created
+    with temporary=True) to this one."""
+    self.script.extend(other.script)
+
+  def AssertSomeFingerprint(self, *fp):
+    """Assert that the current system build fingerprint is one of *fp."""
+    if not fp:
+      raise ValueError("must specify some fingerprints")
+    cmd = ('assert(' +
+           ' ||\0'.join([('file_getprop("/system/build.prop", '
+                         '"ro.build.fingerprint") == "%s"')
+                        % i for i in fp]) +
+           ');')
+    self.script.append(self._WordWrap(cmd))
+
+  def AssertOlderBuild(self, timestamp):
+    """Assert that the build on the device is older (or the same as)
+    the given timestamp."""
+    self.script.append(('assert(!less_than_int(%s, '
+                        'getprop("ro.build.date.utc")));') % (timestamp,))
+
+  def AssertDevice(self, device):
+    """Assert that the device identifier is the given string."""
+    cmd = ('assert(getprop("ro.product.device") == "%s" ||\0'
+           'getprop("ro.build.product") == "%s");' % (device, device))
+    self.script.append(self._WordWrap(cmd))
+
+  def AssertSomeBootloader(self, *bootloaders):
+    """Asert that the bootloader version is one of *bootloaders."""
+    cmd = ("assert(" +
+           " ||\0".join(['getprop("ro.bootloader") == "%s"' % (b,)
+                         for b in bootloaders]) +
+           ");")
+    self.script.append(self._WordWrap(cmd))
+
+  def ShowProgress(self, frac, dur):
+    """Update the progress bar, advancing it over 'frac' over the next
+    'dur' seconds."""
+    self.script.append("show_progress(%f, %d);" % (frac, int(dur)))
+
+  def PatchCheck(self, filename, *sha1):
+    """Check that the given file (or MTD reference) has one of the
+    given *sha1 hashes."""
+    self.script.append('assert(apply_patch_check("%s"' % (filename,) +
+                       "".join([', "%s"' % (i,) for i in sha1]) +
+                       '));')
+
+  def CacheFreeSpaceCheck(self, amount):
+    """Check that there's at least 'amount' space that can be made
+    available on /cache."""
+    self.script.append("assert(apply_patch_space(%d));" % (amount,))
+
+  def Mount(self, kind, what, path):
+    """Mount the given 'what' at the given path.  'what' should be a
+    partition name if kind is "MTD", or a block device if kind is
+    "vfat".  No other values of 'kind' are supported."""
+    self.script.append('mount("%s", "%s", "%s");' % (kind, what, path))
+    self.mounts.add(path)
+
+  def UnpackPackageDir(self, src, dst):
+    """Unpack a given directory from the OTA package into the given
+    destination directory."""
+    self.script.append('package_extract_dir("%s", "%s");' % (src, dst))
+
+  def Comment(self, comment):
+    """Write a comment into the update script."""
+    self.script.append("")
+    for i in comment.split("\n"):
+      self.script.append("# " + i)
+    self.script.append("")
+
+  def Print(self, message):
+    """Log a message to the screen (if the logs are visible)."""
+    self.script.append('ui_print("%s");' % (message,))
+
+  def FormatPartition(self, partition):
+    """Format the given MTD partition."""
+    self.script.append('format("MTD", "%s");' % (partition,))
+
+  def DeleteFiles(self, file_list):
+    """Delete all files in file_list."""
+    if not file_list: return
+    cmd = "delete(" + ",\0".join(['"%s"' % (i,) for i in file_list]) + ");"
+    self.script.append(self._WordWrap(cmd))
+
+  def ApplyPatch(self, srcfile, tgtfile, tgtsize, tgtsha1, *patchpairs):
+    """Apply binary patches (in *patchpairs) to the given srcfile to
+    produce tgtfile (which may be "-" to indicate overwriting the
+    source file."""
+    if len(patchpairs) % 2 != 0 or len(patchpairs) == 0:
+      raise ValueError("bad patches given to ApplyPatch")
+    cmd = ['apply_patch("%s",\0"%s",\0%s,\0%d'
+           % (srcfile, tgtfile, tgtsha1, tgtsize)]
+    for i in range(0, len(patchpairs), 2):
+      cmd.append(',\0"%s:%s"' % patchpairs[i:i+2])
+    cmd.append(');')
+    cmd = "".join(cmd)
+    self.script.append(self._WordWrap(cmd))
+
+  def WriteFirmwareImage(self, kind, fn):
+    """Arrange to update the given firmware image (kind must be
+    "hboot" or "radio") when recovery finishes."""
+    if self.version == 1:
+      self.script.append(
+          ('assert(package_extract_file("%(fn)s", "/tmp/%(kind)s.img"),\n'
+           '       write_firmware_image("/tmp/%(kind)s.img", "%(kind)s"));')
+          % {'kind': kind, 'fn': fn})
+    else:
+      self.script.append(
+          'write_firmware_image("PACKAGE:%s", "%s");' % (fn, kind))
+
+  def WriteRawImage(self, partition, fn):
+    """Write the given package file into the given MTD partition."""
+    self.script.append(
+        ('assert(package_extract_file("%(fn)s", "/tmp/%(partition)s.img"),\n'
+         '       write_raw_image("/tmp/%(partition)s.img", "%(partition)s"),\n'
+         '       delete("/tmp/%(partition)s.img"));')
+        % {'partition': partition, 'fn': fn})
+
+  def SetPermissions(self, fn, uid, gid, mode):
+    """Set file ownership and permissions."""
+    self.script.append('set_perm(%d, %d, 0%o, "%s");' % (uid, gid, mode, fn))
+
+  def SetPermissionsRecursive(self, fn, uid, gid, dmode, fmode):
+    """Recursively set path ownership and permissions."""
+    self.script.append('set_perm_recursive(%d, %d, 0%o, 0%o, "%s");'
+                       % (uid, gid, dmode, fmode, fn))
+
+  def MakeSymlinks(self, symlink_list):
+    """Create symlinks, given a list of (dest, link) pairs."""
+    by_dest = {}
+    for d, l in symlink_list:
+      by_dest.setdefault(d, []).append(l)
+
+    for dest, links in sorted(by_dest.iteritems()):
+      cmd = ('symlink("%s", ' % (dest,) +
+             ",\0".join(['"' + i + '"' for i in sorted(links)]) + ");")
+      self.script.append(self._WordWrap(cmd))
+
+  def AppendExtra(self, extra):
+    """Append text verbatim to the output script."""
+    self.script.append(extra)
+
+  def AddToZip(self, input_zip, output_zip, input_path=None):
+    """Write the accumulated script to the output_zip file.  input_zip
+    is used as the source for the 'updater' binary needed to run
+    script.  If input_path is not None, it will be used as a local
+    path for the binary instead of input_zip."""
+
+    for p in sorted(self.mounts):
+      self.script.append('unmount("%s");' % (p,))
+
+    common.ZipWriteStr(output_zip, "META-INF/com/google/android/updater-script",
+                       "\n".join(self.script) + "\n")
+
+    if input_path is None:
+      data = input_zip.read("OTA/bin/updater")
+    else:
+      data = open(os.path.join(input_path, "updater")).read()
+    common.ZipWriteStr(output_zip, "META-INF/com/google/android/update-binary",
+                       data, perms=0755)
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
index 1ac035a..1a6ebbf 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files
@@ -45,6 +45,10 @@
   -e  (--extra_script)  <file>
       Insert the contents of file at the end of the update script.
 
+  -m  (--script_mode)  <mode>
+      Specify 'amend' or 'edify' scripts, or 'auto' to pick
+      automatically (this is the default).
+
 """
 
 import sys
@@ -63,6 +67,8 @@
 import zipfile
 
 import common
+import amend_generator
+import edify_generator
 
 OPTIONS = common.OPTIONS
 OPTIONS.package_key = "build/target/product/security/testkey"
@@ -73,6 +79,7 @@
 OPTIONS.wipe_user_data = False
 OPTIONS.omit_prereq = False
 OPTIONS.extra_script = None
+OPTIONS.script_mode = 'auto'
 
 def MostPopularKey(d, default):
   """Given a dict, return the key corresponding to the largest
@@ -193,11 +200,10 @@
 
     return d
 
-  def SetPermissions(self, script, renamer=lambda x: x):
+  def SetPermissions(self, script):
     """Append set_perm/set_perm_recursive commands to 'script' to
     set all permissions, users, and groups for the tree of files
-    rooted at 'self'.  'renamer' turns the filenames stored in the
-    tree of Items into the strings used in the script."""
+    rooted at 'self'."""
 
     self.CountChildMetadata()
 
@@ -208,22 +214,19 @@
       # supposed to be something different.
       if item.dir:
         if current != item.best_subtree:
-          script.append("set_perm_recursive %d %d 0%o 0%o %s" %
-                        (item.best_subtree + (renamer(item.name),)))
+          script.SetPermissionsRecursive("/"+item.name, *item.best_subtree)
           current = item.best_subtree
 
         if item.uid != current[0] or item.gid != current[1] or \
            item.mode != current[2]:
-          script.append("set_perm %d %d 0%o %s" %
-                        (item.uid, item.gid, item.mode, renamer(item.name)))
+          script.SetPermissions("/"+item.name, item.uid, item.gid, item.mode)
 
         for i in item.children:
           recurse(i, current)
       else:
         if item.uid != current[0] or item.gid != current[1] or \
                item.mode != current[3]:
-          script.append("set_perm %d %d 0%o %s" %
-                        (item.uid, item.gid, item.mode, renamer(item.name)))
+          script.SetPermissions("/"+item.name, item.uid, item.gid, item.mode)
 
     recurse(self, (-1, -1, -1, -1))
 
@@ -245,7 +248,7 @@
       basefilename = info.filename[7:]
       if IsSymlink(info):
         symlinks.append((input_zip.read(info.filename),
-                         "SYSTEM:" + basefilename))
+                         "/system/" + basefilename))
       else:
         info2 = copy.copy(info)
         fn = info2.filename = "system/" + basefilename
@@ -266,11 +269,6 @@
   return symlinks
 
 
-def AddScript(script, output_zip):
-  common.ZipWriteStr(output_zip, "META-INF/com/google/android/update-script",
-                     "\n".join(script) + "\n")
-
-
 def SignOutput(temp_zip_name, output_zip_name):
   key_passwords = common.GetKeyPasswords([OPTIONS.package_key])
   pw = key_passwords[OPTIONS.package_key]
@@ -278,35 +276,15 @@
   common.SignFile(temp_zip_name, output_zip_name, OPTIONS.package_key, pw)
 
 
-def SubstituteRoot(s):
-  if s == "system": return "SYSTEM:"
-  assert s.startswith("system/")
-  return "SYSTEM:" + s[7:]
-
 def FixPermissions(script):
   Item.GetMetadata()
   root = Item.Get("system")
-  root.SetPermissions(script, renamer=SubstituteRoot)
+  root.SetPermissions(script)
 
-def DeleteFiles(script, to_delete):
-  line = []
-  t = 0
-  for i in to_delete:
-    line.append(i)
-    t += len(i) + 1
-    if t > 80:
-      script.append("delete " + " ".join(line))
-      line = []
-      t = 0
-  if line:
-    script.append("delete " + " ".join(line))
 
 def AppendAssertions(script, input_zip):
-  script.append('assert compatible_with("0.2") == "true"')
-
   device = GetBuildProp("ro.product.device", input_zip)
-  script.append('assert getprop("ro.product.device") == "%s" || '
-                'getprop("ro.build.product") == "%s"' % (device, device))
+  script.AssertDevice(device)
 
   info = input_zip.read("OTA/android-info.txt")
   m = re.search(r"require\s+version-bootloader\s*=\s*(\S+)", info)
@@ -314,47 +292,39 @@
     raise ExternalError("failed to find required bootloaders in "
                         "android-info.txt")
   bootloaders = m.group(1).split("|")
-  script.append("assert " +
-                " || ".join(['getprop("ro.bootloader") == "%s"' % (b,)
-                             for b in bootloaders]))
-
-
-def IncludeBinary(name, input_zip, output_zip, input_path=None):
-  try:
-    if input_path is not None:
-      data = open(input_path).read()
-    else:
-      data = input_zip.read(os.path.join("OTA/bin", name))
-    common.ZipWriteStr(output_zip, name, data, perms=0755)
-  except IOError:
-    raise ExternalError('unable to include device binary "%s"' % (name,))
+  script.AssertSomeBootloader(*bootloaders)
 
 
 def WriteFullOTAPackage(input_zip, output_zip):
-  script = []
+  if OPTIONS.script_mode in ("amend", "auto"):
+    script = amend_generator.AmendGenerator()
+  else:
+    # TODO: how to determine this?  We don't know what version it will
+    # be installed on top of.  For now, we expect the API just won't
+    # change very often.
+    script = edify_generator.EdifyGenerator(1)
 
   if not OPTIONS.omit_prereq:
     ts = GetBuildProp("ro.build.date.utc", input_zip)
-    script.append("run_program PACKAGE:check_prereq %s" % (ts,))
-    IncludeBinary("check_prereq", input_zip, output_zip)
+    script.AssertOlderBuild(ts)
 
   AppendAssertions(script, input_zip)
 
-  script.append("format BOOT:")
-  script.append("show_progress 0.1 0")
+  script.ShowProgress(0.1, 0)
 
   common.ZipWriteStr(output_zip, "radio.img", input_zip.read("RADIO/image"))
-  script.append("write_radio_image PACKAGE:radio.img")
-  script.append("show_progress 0.5 0")
+  script.WriteFirmwareImage("radio", "radio.img")
+  script.ShowProgress(0.5, 0)
 
   if OPTIONS.wipe_user_data:
-    script.append("format DATA:")
+    script.FormatPartition("userdata")
 
-  script.append("format SYSTEM:")
-  script.append("copy_dir PACKAGE:system SYSTEM:")
+  script.FormatPartition("system")
+  script.Mount("MTD", "system", "/system")
+  script.UnpackPackageDir("system", "/system")
 
   symlinks = CopySystemFiles(input_zip, output_zip)
-  script.extend(["symlink %s %s" % s for s in symlinks])
+  script.MakeSymlinks(symlinks)
 
   common.BuildAndAddBootableImage(os.path.join(OPTIONS.input_tmp, "RECOVERY"),
                                   "system/recovery.img", output_zip)
@@ -363,14 +333,15 @@
   FixPermissions(script)
 
   common.AddBoot(output_zip)
-  script.append("show_progress 0.2 0")
-  script.append("write_raw_image PACKAGE:boot.img BOOT:")
-  script.append("show_progress 0.2 10")
+  script.ShowProgress(0.2, 0)
+
+  script.WriteRawImage("boot", "boot.img")
+  script.ShowProgress(0.2, 10)
 
   if OPTIONS.extra_script is not None:
-    script.append(OPTIONS.extra_script)
+    script.AppendExtra(OPTIONS.extra_script)
 
-  AddScript(script, output_zip)
+  script.AddToZip(input_zip, output_zip)
 
 
 class File(object):
@@ -448,8 +419,38 @@
   return m.group(1).strip()
 
 
+def GetRecoveryAPIVersion(zip):
+  """Returns the version of the recovery API.  Version 0 is the older
+  amend code (no separate binary)."""
+  try:
+    version = zip.read("META/recovery-api-version.txt")
+    return int(version)
+  except KeyError:
+    try:
+      # version one didn't have the recovery-api-version.txt file, but
+      # it did include an updater binary.
+      zip.getinfo("OTA/bin/updater")
+      return 1
+    except KeyError:
+      return 0
+
 def WriteIncrementalOTAPackage(target_zip, source_zip, output_zip):
-  script = []
+  source_version = GetRecoveryAPIVersion(source_zip)
+
+  if OPTIONS.script_mode == 'amend':
+    script = amend_generator.AmendGenerator()
+  elif OPTIONS.script_mode == 'edify':
+    if source_version == 0:
+      print ("WARNING: generating edify script for a source that "
+             "can't install it.")
+    script = edify_generator.EdifyGenerator(source_version)
+  elif OPTIONS.script_mode == 'auto':
+    if source_version > 0:
+      script = edify_generator.EdifyGenerator(source_version)
+    else:
+      script = amend_generator.AmendGenerator()
+  else:
+    raise ValueError('unknown script mode "%s"' % (OPTIONS.script_mode,))
 
   print "Loading target..."
   target_data = LoadSystemFiles(target_zip)
@@ -496,11 +497,8 @@
   source_fp = GetBuildProp("ro.build.fingerprint", source_zip)
   target_fp = GetBuildProp("ro.build.fingerprint", target_zip)
 
-  script.append(('assert file_contains("SYSTEM:build.prop", '
-                 '"ro.build.fingerprint=%s") == "true" || '
-                 'file_contains("SYSTEM:build.prop", '
-                 '"ro.build.fingerprint=%s") == "true"') %
-                (source_fp, target_fp))
+  script.Mount("MTD", "system", "/system")
+  script.AssertSomeFingerprint(source_fp, target_fp)
 
   source_boot = File("/tmp/boot.img",
                      common.BuildBootableImage(
@@ -532,6 +530,8 @@
 
   AppendAssertions(script, target_zip)
 
+  script.Print("Verifying current system...")
+
   pb_verify = progress_bar_total * 0.3 * \
               (total_patched_size /
                float(total_patched_size+total_verbatim_size+1))
@@ -539,10 +539,9 @@
   for i, (fn, tf, sf, size) in enumerate(patch_list):
     if i % 5 == 0:
       next_sizes = sum([i[3] for i in patch_list[i:i+5]])
-      script.append("show_progress %f 1" %
-                    (next_sizes * pb_verify / (total_patched_size+1),))
-    script.append("run_program PACKAGE:applypatch -c /%s %s %s" %
-                  (fn, tf.sha1, sf.sha1))
+      script.ShowProgress(next_sizes * pb_verify / (total_patched_size+1), 1)
+
+    script.PatchCheck("/"+fn, tf.sha1, sf.sha1)
 
   if updating_recovery:
     d = Difference(target_recovery, source_recovery, "imgdiff")
@@ -551,10 +550,9 @@
 
     common.ZipWriteStr(output_zip, "patch/recovery.img.p", d)
 
-    script.append(("run_program PACKAGE:applypatch -c "
-                   "MTD:recovery:%d:%s:%d:%s") %
-                  (source_recovery.size, source_recovery.sha1,
-                   target_recovery.size, target_recovery.sha1))
+    script.PatchCheck("MTD:recovery:%d:%s:%d:%s" %
+                      (source_recovery.size, source_recovery.sha1,
+                       target_recovery.size, target_recovery.sha1))
 
   if updating_boot:
     d = Difference(target_boot, source_boot, "imgdiff")
@@ -563,36 +561,35 @@
 
     common.ZipWriteStr(output_zip, "patch/boot.img.p", d)
 
-    script.append(("run_program PACKAGE:applypatch -c "
-                   "MTD:boot:%d:%s:%d:%s") %
-                  (source_boot.size, source_boot.sha1,
-                   target_boot.size, target_boot.sha1))
+    script.PatchCheck("MTD:boot:%d:%s:%d:%s" %
+                      (source_boot.size, source_boot.sha1,
+                       target_boot.size, target_boot.sha1))
 
   if patch_list or updating_recovery or updating_boot:
-    script.append("run_program PACKAGE:applypatch -s %d" %
-                  (largest_source_size,))
-    script.append("copy_dir PACKAGE:patch CACHE:../tmp/patchtmp")
-    IncludeBinary("applypatch", target_zip, output_zip)
+    script.CacheFreeSpaceCheck(largest_source_size)
+    script.Print("Unpacking patches...")
+    script.UnpackPackageDir("patch", "/tmp/patchtmp")
 
-  script.append("\n# ---- start making changes here\n")
+  script.Comment("---- start making changes here ----")
 
   if OPTIONS.wipe_user_data:
-    script.append("format DATA:")
+    script.Print("Erasing user data...")
+    script.FormatPartition("userdata")
 
-  DeleteFiles(script, [SubstituteRoot(i[0]) for i in verbatim_targets])
+  script.Print("Removing unneeded files...")
+  script.DeleteFiles(["/"+i[0] for i in verbatim_targets])
 
   if updating_boot:
     # Produce the boot image by applying a patch to the current
     # contents of the boot partition, and write it back to the
     # partition.
-    script.append(("run_program PACKAGE:applypatch "
-                   "MTD:boot:%d:%s:%d:%s - "
-                   "%s %d %s:/tmp/patchtmp/boot.img.p")
-                  % (source_boot.size, source_boot.sha1,
-                     target_boot.size, target_boot.sha1,
-                     target_boot.sha1,
-                     target_boot.size,
-                     source_boot.sha1))
+    script.Print("Patching boot image...")
+    script.ApplyPatch("MTD:boot:%d:%s:%d:%s"
+                      % (source_boot.size, source_boot.sha1,
+                         target_boot.size, target_boot.sha1),
+                      "-",
+                      target_boot.size, target_boot.sha1,
+                      source_boot.sha1, "/tmp/patchtmp/boot.img.p")
     print "boot image changed; including."
   else:
     print "boot image unchanged; skipping."
@@ -600,41 +597,41 @@
   if updating_recovery:
     # Produce /system/recovery.img by applying a patch to the current
     # contents of the recovery partition.
-    script.append(("run_program PACKAGE:applypatch MTD:recovery:%d:%s:%d:%s "
-                   "/system/recovery.img %s %d %s:/tmp/patchtmp/recovery.img.p")
-                  % (source_recovery.size, source_recovery.sha1,
-                     target_recovery.size, target_recovery.sha1,
-                     target_recovery.sha1,
-                     target_recovery.size,
-                     source_recovery.sha1))
+    script.Print("Patching recovery image...")
+    script.ApplyPatch("MTD:recovery:%d:%s:%d:%s"
+                      % (source_recovery.size, source_recovery.sha1,
+                         target_recovery.size, target_recovery.sha1),
+                      "/system/recovery.img",
+                      target_recovery.size, target_recovery.sha1,
+                      source_recovery.sha1, "/tmp/patchtmp/recovery.img.p")
     print "recovery image changed; including."
   else:
     print "recovery image unchanged; skipping."
 
   if updating_radio:
-    script.append("show_progress 0.3 10")
-    script.append("write_radio_image PACKAGE:radio.img")
+    script.ShowProgress(0.3, 10)
+    script.Print("Writing radio image...")
+    script.WriteFirmwareImage("radio", "radio.img")
     common.ZipWriteStr(output_zip, "radio.img", target_radio)
     print "radio image changed; including."
   else:
     print "radio image unchanged; skipping."
 
+  script.Print("Patching system files...")
   pb_apply = progress_bar_total * 0.7 * \
              (total_patched_size /
               float(total_patched_size+total_verbatim_size+1))
   for i, (fn, tf, sf, size) in enumerate(patch_list):
     if i % 5 == 0:
       next_sizes = sum([i[3] for i in patch_list[i:i+5]])
-      script.append("show_progress %f 1" %
-                    (next_sizes * pb_apply / (total_patched_size+1),))
-    script.append(("run_program PACKAGE:applypatch "
-                   "/%s - %s %d %s:/tmp/patchtmp/%s.p") %
-                  (fn, tf.sha1, tf.size, sf.sha1, fn))
+      script.ShowProgress(next_sizes * pb_apply / (total_patched_size+1), 1)
+    script.ApplyPatch("/"+fn, "-", tf.size, tf.sha1,
+                      sf.sha1, "/tmp/patchtmp/"+fn+".p")
 
   target_symlinks = CopySystemFiles(target_zip, None)
 
   target_symlinks_d = dict([(i[1], i[0]) for i in target_symlinks])
-  temp_script = []
+  temp_script = script.MakeTemporary()
   FixPermissions(temp_script)
 
   # Note that this call will mess up the tree of Items, so make sure
@@ -649,14 +646,17 @@
   for dest, link in source_symlinks:
     if link not in target_symlinks_d:
       to_delete.append(link)
-  DeleteFiles(script, to_delete)
+  script.DeleteFiles(to_delete)
 
   if verbatim_targets:
     pb_verbatim = progress_bar_total * \
                   (total_verbatim_size /
                    float(total_patched_size+total_verbatim_size+1))
-    script.append("show_progress %f 5" % (pb_verbatim,))
-    script.append("copy_dir PACKAGE:system SYSTEM:")
+    script.ShowProgress(pb_verbatim, 5)
+    script.Print("Unpacking new files...")
+    script.UnpackPackageDir("system", "/system")
+
+  script.Print("Finishing up...")
 
   # Create all the symlinks that don't already exist, or point to
   # somewhere different than what we want.  Delete each symlink before
@@ -668,17 +668,17 @@
         to_create.append((dest, link))
     else:
       to_create.append((dest, link))
-  DeleteFiles(script, [i[1] for i in to_create])
-  script.extend(["symlink %s %s" % s for s in to_create])
+  script.DeleteFiles([i[1] for i in to_create])
+  script.MakeSymlinks(to_create)
 
   # Now that the symlinks are created, we can set all the
   # permissions.
-  script.extend(temp_script)
+  script.AppendScript(temp_script)
 
   if OPTIONS.extra_script is not None:
-    script.append(OPTIONS.extra_script)
+    scirpt.AppendExtra(OPTIONS.extra_script)
 
-  AddScript(script, output_zip)
+  script.AddToZip(target_zip, output_zip)
 
 
 def main(argv):
@@ -696,18 +696,21 @@
       OPTIONS.omit_prereq = True
     elif o in ("-e", "--extra_script"):
       OPTIONS.extra_script = a
+    elif o in ("-m", "--script_mode"):
+      OPTIONS.script_mode = a
     else:
       return False
     return True
 
   args = common.ParseOptions(argv, __doc__,
-                             extra_opts="b:k:i:d:wne:",
+                             extra_opts="b:k:i:d:wne:m:",
                              extra_long_opts=["board_config=",
                                               "package_key=",
                                               "incremental_from=",
                                               "wipe_user_data",
                                               "no_prereq",
-                                              "extra_script="],
+                                              "extra_script=",
+                                              "script_mode="],
                              extra_option_handler=option_handler)
 
   if len(args) != 2:
@@ -721,6 +724,9 @@
     print "  images don't exceed partition sizes."
     print
 
+  if OPTIONS.script_mode not in ("amend", "edify", "auto"):
+    raise ValueError('unknown script mode "%s"' % (OPTIONS.script_mode,))
+
   if OPTIONS.extra_script is not None:
     OPTIONS.extra_script = open(OPTIONS.extra_script).read()