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extract-partitions.py: fix unaligned files

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Seeking on a file open for appending does not really work. Also fix
offset in debug message.
This commit is contained in:
Peter Wu 2015-12-26 22:03:29 +01:00
parent d9aa205b17
commit e0f269128f
1 changed files with 10 additions and 3 deletions
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13
scripts/extract-partitions.py
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@ -79,13 +79,20 @@ def dump_file(comm, remote_path, local_path, size):
# Read offsets must be a multiple of 512 bytes, enforce this
BLOCK_SIZE = 512
unaligned_bytes = offset % BLOCK_SIZE
offset = BLOCK_SIZE * (offset // BLOCK_SIZE)
with laf_open_ro(comm, remote_path) as fd_num:
_logger.debug("Opened fd %d for %s (size %dK, offset %dK)",
fd_num, remote_path, size / 1024, offset * BLOCK_SIZE / 1024)
_logger.debug("Opened fd %d for %s (final size %.2fK, offset %.2fK)",
fd_num, remote_path, size / 1024, offset / 1024)
with open(local_path, 'ab') as f:
f.seek(BLOCK_SIZE * offset)
# Offset should be aligned to block size. If not, read at most a
# whole block and drop the leading bytes.
if unaligned_bytes:
chunksize = min(size - offset, BLOCK_SIZE)
data = laf_read(comm, fd_num, offset // BLOCK_SIZE, chunksize)
f.write(data[unaligned_bytes:])
offset += BLOCK_SIZE
while offset < size:
chunksize = min(size - offset, BLOCK_SIZE * MAX_BLOCK_SIZE)
data = laf_read(comm, fd_num, offset // BLOCK_SIZE, chunksize)