scripts: import blockdiff
This was added to dev/host/ for debug helping with paycheck.py,
so move it here so it's alongside that script.
BUG=None
TEST=None
Change-Id: I63ae858464cc13344335613093907673052a9859
Reviewed-on: https://chromium-review.googlesource.com/704200
Commit-Ready: Mike Frysinger <[email protected]>
Tested-by: Mike Frysinger <[email protected]>
Reviewed-by: Amin Hassani <[email protected]>
diff --git a/scripts/blockdiff.py b/scripts/blockdiff.py
new file mode 100755
index 0000000..feb5bd9
--- /dev/null
+++ b/scripts/blockdiff.py
@@ -0,0 +1,113 @@
+#!/usr/bin/python
+#
+# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Block diff utility."""
+
+import optparse
+import sys
+
+
+class BlockDiffError(Exception):
+ pass
+
+
+def BlockDiff(block_size, file1, file2, name1, name2, max_length=-1):
+ """Performs a binary diff of two files by blocks.
+
+ Args:
+ block_size: the size of a block to diff by
+ file1: first file object
+ file2: second file object
+ name1: name of first file (for error reporting)
+ name2: name of second file (for error reporting)
+ max_length: the maximum length to read/diff in bytes (optional)
+ Returns:
+ A list of (start, length) pairs representing block extents that differ
+ between the two files.
+ Raises:
+ BlockDiffError if there were errors while diffing.
+
+ """
+ if max_length < 0:
+ max_length = sys.maxint
+ diff_list = []
+ num_blocks = extent_start = extent_length = 0
+ while max_length or extent_length:
+ read_length = min(max_length, block_size)
+ data1 = file1.read(read_length)
+ data2 = file2.read(read_length)
+ if len(data1) != len(data2):
+ raise BlockDiffError('read %d bytes from %s but %d bytes from %s' %
+ (len(data1), name1, len(data2), name2))
+
+ if data1 != data2:
+ # Data is different, mark it down.
+ if extent_length:
+ # Stretch the current diff extent.
+ extent_length += 1
+ else:
+ # Start a new diff extent.
+ extent_start = num_blocks
+ extent_length = 1
+ elif extent_length:
+ # Record the previous extent.
+ diff_list.append((extent_start, extent_length))
+ extent_length = 0
+
+ # Are we done reading?
+ if not data1:
+ break
+
+ max_length -= len(data1)
+ num_blocks += 1
+
+ return diff_list
+
+
+def main(argv):
+ # Parse command-line arguments.
+ parser = optparse.OptionParser(
+ usage='Usage: %prog FILE1 FILE2',
+ description='Compare FILE1 and FILE2 by blocks.')
+
+ parser.add_option('-b', '--block-size', metavar='NUM', type=int, default=4096,
+ help='the block size to use (default: %default)')
+ parser.add_option('-m', '--max-length', metavar='NUM', type=int, default=-1,
+ help='maximum number of bytes to compared')
+
+ opts, args = parser.parse_args(argv[1:])
+
+ try:
+ name1, name2 = args
+ except ValueError:
+ parser.error('unexpected number of arguments')
+
+ # Perform the block diff.
+ try:
+ with open(name1) as file1:
+ with open(name2) as file2:
+ diff_list = BlockDiff(opts.block_size, file1, file2, name1, name2,
+ opts.max_length)
+ except BlockDiffError as e:
+ print >> sys.stderr, 'Error:', e
+ return 2
+
+ # Print the diff, if such was found.
+ if diff_list:
+ total_diff_blocks = 0
+ for extent_start, extent_length in diff_list:
+ total_diff_blocks += extent_length
+ print('%d->%d (%d)' %
+ (extent_start, extent_start + extent_length, extent_length))
+
+ print 'total diff: %d blocks' % total_diff_blocks
+ return 1
+
+ return 0
+
+
+if __name__ == '__main__':
+ sys.exit(main(sys.argv))
