Assert the stash size when generating OTAs.

With block-based OTA v2 and v3, it requires stash space on the /cache
partition to back up blocks during an update. We need to ensure that
it doesn't exceed the partition size. Since there might be other files
on /cache as well, we use cache_size * threshold as the maximum allowed
size. The threshold defaults to 0.8, which can be overridden by command
line option '--stash_threshold'.

Change-Id: Ieee5d373c9bfb2ea401d85ca8a3adb491579de76
(cherry picked from commit 23ac4042128e47f6fe1ef176e7cb96f907d8e149)

2 files changed, 39 insertions, 5 deletions

diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py
index 6ed9ca2..a007f81 100644
--- a/tools/releasetools/blockimgdiff.py
+++ b/tools/releasetools/blockimgdiff.py
@@ -16,6 +16,7 @@ from __future__ import print_function
 
 from collections import deque, OrderedDict
 from hashlib import sha1
+import common
 import heapq
 import itertools
 import multiprocessing
@@ -460,9 +461,20 @@ class BlockImageDiff(object):
       if free_string:
         out.append("".join(free_string))
 
-      # sanity check: abort if we're going to need more than 512 MB if
-      # stash space
-      assert max_stashed_blocks * self.tgt.blocksize < (512 << 20)
+      if self.version >= 2:
+        # Sanity check: abort if we're going to need more stash space than
+        # the allowed size (cache_size * threshold). There are two purposes
+        # of having a threshold here. a) Part of the cache may have been
+        # occupied by some recovery logs. b) It will buy us some time to deal
+        # with the oversize issue.
+        cache_size = common.OPTIONS.cache_size
+        stash_threshold = common.OPTIONS.stash_threshold
+        max_allowed = cache_size * stash_threshold
+        assert max_stashed_blocks * self.tgt.blocksize < max_allowed, \
+               'Stash size %d (%d * %d) exceeds the limit %d (%d * %.2f)' % (
+                   max_stashed_blocks * self.tgt.blocksize, max_stashed_blocks,
+                   self.tgt.blocksize, max_allowed, cache_size,
+                   stash_threshold)
 
     # Zero out extended blocks as a workaround for bug 20881595.
     if self.tgt.extended:
@@ -489,8 +501,11 @@ class BlockImageDiff(object):
         f.write(i)
 
     if self.version >= 2:
-      print("max stashed blocks: %d  (%d bytes)\n" % (
-          max_stashed_blocks, max_stashed_blocks * self.tgt.blocksize))
+      max_stashed_size = max_stashed_blocks * self.tgt.blocksize
+      max_allowed = common.OPTIONS.cache_size * common.OPTIONS.stash_threshold
+      print("max stashed blocks: %d  (%d bytes), limit: %d bytes (%.2f%%)\n" % (
+          max_stashed_blocks, max_stashed_size, max_allowed,
+          max_stashed_size * 100.0 / max_allowed))
 
   def ComputePatches(self, prefix):
     print("Reticulating splines...")
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index 531a728..3a69675 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -84,6 +84,9 @@ Usage:  ota_from_target_files [flags] input_target_files output_ota_package
       Specifies the number of worker-threads that will be used when
       generating patches for incremental updates (defaults to 3).
 
+  --stash_threshold <float>
+      Specifies the threshold that will be used to compute the maximum
+      allowed stash size (defaults to 0.8).
 """
 
 import sys
@@ -122,6 +125,10 @@ OPTIONS.updater_binary = None
 OPTIONS.oem_source = None
 OPTIONS.fallback_to_full = True
 OPTIONS.full_radio = False
+# Stash size cannot exceed cache_size * threshold.
+OPTIONS.cache_size = None
+OPTIONS.stash_threshold = 0.8
+
 
 def MostPopularKey(d, default):
   """Given a dict, return the key corresponding to the largest
@@ -1505,6 +1512,12 @@ def main(argv):
       OPTIONS.updater_binary = a
     elif o in ("--no_fallback_to_full",):
       OPTIONS.fallback_to_full = False
+    elif o == "--stash_threshold":
+      try:
+        OPTIONS.stash_threshold = float(a)
+      except ValueError:
+        raise ValueError("Cannot parse value %r for option %r - expecting "
+                         "a float" % (a, o))
     else:
       return False
     return True
@@ -1528,6 +1541,7 @@ def main(argv):
                                  "oem_settings=",
                                  "verify",
                                  "no_fallback_to_full",
+                                 "stash_threshold=",
                              ], extra_option_handler=option_handler)
 
   if len(args) != 2:
@@ -1585,6 +1599,11 @@ def main(argv):
       output_zip = zipfile.ZipFile(temp_zip_file, "w",
                                    compression=zipfile.ZIP_DEFLATED)
 
+    cache_size = OPTIONS.info_dict.get("cache_size", None)
+    if cache_size is None:
+      raise RuntimeError("can't determine the cache partition size")
+    OPTIONS.cache_size = cache_size
+
     if OPTIONS.incremental_source is None:
       WriteFullOTAPackage(input_zip, output_zip)
       if OPTIONS.package_key is None: