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  • Committer: Robert Collins
  • Date: 2007-09-13 03:16:07 UTC
  • mto: (2839.1.1 ianc-integration2)
  • mto: This revision was merged to the branch mainline in revision 2841.
  • Revision ID: robertc@robertcollins.net-20070913031607-fit1cj291o8yu1z2
* New helper ``bzrlib.tuned_gzip.bytes_to_gzip`` which takes a byte string
  and returns a gzipped version of the same. This is used to avoid a bunch
  of api friction during adding of knit hunks. (Robert Collins)

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bzrlib/tuned_gzip.py
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# we want a \n preserved, break on \n only splitlines.
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import bzrlib
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__all__ = ["GzipFile"]
 
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__all__ = ["GzipFile", "bytes_to_gzip"]
 
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def bytes_to_gzip(bytes, factory=zlib.compressobj,
 
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    level=zlib.Z_DEFAULT_COMPRESSION, method=zlib.DEFLATED,
 
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    width=-zlib.MAX_WBITS, mem=zlib.DEF_MEM_LEVEL,
 
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    crc32=zlib.crc32):
 
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    """Create a gzip file containing bytes and return its content."""
 
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    result = [
 
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        '\037\213'  # self.fileobj.write('\037\213')  # magic header
 
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        '\010'      # self.fileobj.write('\010')      # compression method
 
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                    # fname = self.filename[:-3]
 
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                    # flags = 0
 
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                    # if fname:
 
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                    #     flags = FNAME
 
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        '\x00'      # self.fileobj.write(chr(flags))
 
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        '\0\0\0\0'  # write32u(self.fileobj, long(time.time()))
 
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        '\002'      # self.fileobj.write('\002')
 
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        '\377'      # self.fileobj.write('\377')
 
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                    # if fname:
 
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        ''          #     self.fileobj.write(fname + '\000')
 
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        ]
 
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    # using a compressobj avoids a small header and trailer that the compress()
 
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    # utility function adds.
 
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    compress = factory(level, method, width, mem, 0)
 
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    result.append(compress.compress(bytes))
 
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    result.append(compress.flush())
 
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    result.append(struct.pack("<L", LOWU32(crc32(bytes))))
 
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    # size may exceed 2GB, or even 4GB
 
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    result.append(struct.pack("<L", LOWU32(len(bytes))))
 
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    return ''.join(result)
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class GzipFile(gzip.GzipFile):