1 files changed, 223 insertions, 0 deletions
diff --git a/tools/releasetools/images.py b/tools/releasetools/images.py
new file mode 100644
index 0000000000..a24148ae1b
--- /dev/null
+++ b/tools/releasetools/images.py
@@ -0,0 +1,223 @@
+# Copyright (C) 2019 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
+
+import os
+import threading
+from hashlib import sha1
+
+from rangelib import RangeSet
+
+__all__ = ["EmptyImage", "DataImage", "FileImage"]
+
+
+class Image(object):
+  def RangeSha1(self, ranges):
+    raise NotImplementedError
+
+  def ReadRangeSet(self, ranges):
+    raise NotImplementedError
+
+  def TotalSha1(self, include_clobbered_blocks=False):
+    raise NotImplementedError
+
+  def WriteRangeDataToFd(self, ranges, fd):
+    raise NotImplementedError
+
+
+class EmptyImage(Image):
+  """A zero-length image."""
+
+  def __init__(self):
+    self.blocksize = 4096
+    self.care_map = RangeSet()
+    self.clobbered_blocks = RangeSet()
+    self.extended = RangeSet()
+    self.total_blocks = 0
+    self.file_map = {}
+    self.hashtree_info = None
+
+  def RangeSha1(self, ranges):
+    return sha1().hexdigest()
+
+  def ReadRangeSet(self, ranges):
+    return ()
+
+  def TotalSha1(self, include_clobbered_blocks=False):
+    # EmptyImage always carries empty clobbered_blocks, so
+    # include_clobbered_blocks can be ignored.
+    assert self.clobbered_blocks.size() == 0
+    return sha1().hexdigest()
+
+  def WriteRangeDataToFd(self, ranges, fd):
+    raise ValueError("Can't write data from EmptyImage to file")
+
+
+class DataImage(Image):
+  """An image wrapped around a single string of data."""
+
+  def __init__(self, data, trim=False, pad=False):
+    self.data = data
+    self.blocksize = 4096
+
+    assert not (trim and pad)
+
+    partial = len(self.data) % self.blocksize
+    padded = False
+    if partial > 0:
+      if trim:
+        self.data = self.data[:-partial]
+      elif pad:
+        self.data += '\0' * (self.blocksize - partial)
+        padded = True
+      else:
+        raise ValueError(("data for DataImage must be multiple of %d bytes "
+                          "unless trim or pad is specified") %
+                         (self.blocksize,))
+
+    assert len(self.data) % self.blocksize == 0
+
+    self.total_blocks = len(self.data) // self.blocksize
+    self.care_map = RangeSet(data=(0, self.total_blocks))
+    # When the last block is padded, we always write the whole block even for
+    # incremental OTAs. Because otherwise the last block may get skipped if
+    # unchanged for an incremental, but would fail the post-install
+    # verification if it has non-zero contents in the padding bytes.
+    # Bug: 23828506
+    if padded:
+      clobbered_blocks = [self.total_blocks-1, self.total_blocks]
+    else:
+      clobbered_blocks = []
+    self.clobbered_blocks = clobbered_blocks
+    self.extended = RangeSet()
+
+    zero_blocks = []
+    nonzero_blocks = []
+    reference = '\0' * self.blocksize
+
+    for i in range(self.total_blocks-1 if padded else self.total_blocks):
+      d = self.data[i*self.blocksize : (i+1)*self.blocksize]
+      if d == reference:
+        zero_blocks.append(i)
+        zero_blocks.append(i+1)
+      else:
+        nonzero_blocks.append(i)
+        nonzero_blocks.append(i+1)
+
+    assert zero_blocks or nonzero_blocks or clobbered_blocks
+
+    self.file_map = dict()
+    if zero_blocks:
+      self.file_map["__ZERO"] = RangeSet(data=zero_blocks)
+    if nonzero_blocks:
+      self.file_map["__NONZERO"] = RangeSet(data=nonzero_blocks)
+    if clobbered_blocks:
+      self.file_map["__COPY"] = RangeSet(data=clobbered_blocks)
+
+  def _GetRangeData(self, ranges):
+    for s, e in ranges:
+      yield self.data[s*self.blocksize:e*self.blocksize]
+
+  def RangeSha1(self, ranges):
+    h = sha1()
+    for data in self._GetRangeData(ranges): # pylint: disable=not-an-iterable
+      h.update(data)
+    return h.hexdigest()
+
+  def ReadRangeSet(self, ranges):
+    return list(self._GetRangeData(ranges))
+
+  def TotalSha1(self, include_clobbered_blocks=False):
+    if not include_clobbered_blocks:
+      return self.RangeSha1(self.care_map.subtract(self.clobbered_blocks))
+    return sha1(self.data).hexdigest()
+
+  def WriteRangeDataToFd(self, ranges, fd):
+    for data in self._GetRangeData(ranges): # pylint: disable=not-an-iterable
+      fd.write(data)
+
+
+class FileImage(Image):
+  """An image wrapped around a raw image file."""
+
+  def __init__(self, path, hashtree_info_generator=None):
+    self.path = path
+    self.blocksize = 4096
+    self._file_size = os.path.getsize(self.path)
+    self._file = open(self.path, 'rb')
+
+    if self._file_size % self.blocksize != 0:
+      raise ValueError("Size of file %s must be multiple of %d bytes, but is %d"
+                       % self.path, self.blocksize, self._file_size)
+
+    self.total_blocks = self._file_size // self.blocksize
+    self.care_map = RangeSet(data=(0, self.total_blocks))
+    self.clobbered_blocks = RangeSet()
+    self.extended = RangeSet()
+
+    self.generator_lock = threading.Lock()
+
+    self.hashtree_info = None
+    if hashtree_info_generator:
+      self.hashtree_info = hashtree_info_generator.Generate(self)
+
+    zero_blocks = []
+    nonzero_blocks = []
+    reference = '\0' * self.blocksize
+
+    for i in range(self.total_blocks):
+      d = self._file.read(self.blocksize)
+      if d == reference:
+        zero_blocks.append(i)
+        zero_blocks.append(i+1)
+      else:
+        nonzero_blocks.append(i)
+        nonzero_blocks.append(i+1)
+
+    assert zero_blocks or nonzero_blocks
+
+    self.file_map = {}
+    if zero_blocks:
+      self.file_map["__ZERO"] = RangeSet(data=zero_blocks)
+    if nonzero_blocks:
+      self.file_map["__NONZERO"] = RangeSet(data=nonzero_blocks)
+    if self.hashtree_info:
+      self.file_map["__HASHTREE"] = self.hashtree_info.hashtree_range
+
+  def __del__(self):
+    self._file.close()
+
+  def _GetRangeData(self, ranges):
+    # Use a lock to protect the generator so that we will not run two
+    # instances of this generator on the same object simultaneously.
+    with self.generator_lock:
+      for s, e in ranges:
+        self._file.seek(s * self.blocksize)
+        for _ in range(s, e):
+          yield self._file.read(self.blocksize)
+
+  def RangeSha1(self, ranges):
+    h = sha1()
+    for data in self._GetRangeData(ranges): # pylint: disable=not-an-iterable
+      h.update(data)
+    return h.hexdigest()
+
+  def ReadRangeSet(self, ranges):
+    return list(self._GetRangeData(ranges))
+
+  def TotalSha1(self, include_clobbered_blocks=False):
+    assert not self.clobbered_blocks
+    return self.RangeSha1(self.care_map)
+
+  def WriteRangeDataToFd(self, ranges, fd):
+    for data in self._GetRangeData(ranges): # pylint: disable=not-an-iterable
+      fd.write(data)