FCL/sf/adapt/qemu: comparison symbian-qemu-0.9.1-12/python-2.6.1/Lib/gzip.py

equal deleted inserted replaced

-:ffa851df0825
+:2fb8b9db1c86
+"""Functions that read and write gzipped files.
+The user of the file doesn't have to worry about the compression,
+but random access is not allowed."""
+# based on Andrew Kuchling's minigzip.py distributed with the zlib module
+import struct, sys, time
+import zlib
+import __builtin__
+__all__ = ["GzipFile","open"]
+FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 16
+READ, WRITE = 1, 2
+def write32u(output, value):
+# The L format writes the bit pattern correctly whether signed
+# or unsigned.
+output.write(struct.pack("<L", value))
+def read32(input):
+return struct.unpack("<I", input.read(4))[0]
+def open(filename, mode="rb", compresslevel=9):
+"""Shorthand for GzipFile(filename, mode, compresslevel).
+The filename argument is required; mode defaults to 'rb'
+and compresslevel defaults to 9.
+"""
+return GzipFile(filename, mode, compresslevel)
+class GzipFile:
+"""The GzipFile class simulates most of the methods of a file object with
+the exception of the readinto() and truncate() methods.
+"""
+myfileobj = None
+max_read_chunk = 10 * 1024 * 1024   # 10Mb
+def __init__(self, filename=None, mode=None,
+compresslevel=9, fileobj=None):
+"""Constructor for the GzipFile class.
+At least one of fileobj and filename must be given a
+non-trivial value.
+The new class instance is based on fileobj, which can be a regular
+file, a StringIO object, or any other object which simulates a file.
+It defaults to None, in which case filename is opened to provide
+a file object.
+When fileobj is not None, the filename argument is only used to be
+included in the gzip file header, which may includes the original
+filename of the uncompressed file.  It defaults to the filename of
+fileobj, if discernible; otherwise, it defaults to the empty string,
+and in this case the original filename is not included in the header.
+The mode argument can be any of 'r', 'rb', 'a', 'ab', 'w', or 'wb',
+depending on whether the file will be read or written.  The default
+is the mode of fileobj if discernible; otherwise, the default is 'rb'.
+Be aware that only the 'rb', 'ab', and 'wb' values should be used
+for cross-platform portability.
+The compresslevel argument is an integer from 1 to 9 controlling the
+level of compression; 1 is fastest and produces the least compression,
+and 9 is slowest and produces the most compression.  The default is 9.
+"""
+# guarantee the file is opened in binary mode on platforms
+# that care about that sort of thing
+if mode and 'b' not in mode:
+mode += 'b'
+if fileobj is None:
+fileobj = self.myfileobj = __builtin__.open(filename, mode or 'rb')
+if filename is None:
+if hasattr(fileobj, 'name'): filename = fileobj.name
+else: filename = ''
+if mode is None:
+if hasattr(fileobj, 'mode'): mode = fileobj.mode
+else: mode = 'rb'
+if mode[0:1] == 'r':
+self.mode = READ
+# Set flag indicating start of a new member
+self._new_member = True
+self.extrabuf = ""
+self.extrasize = 0
+self.name = filename
+# Starts small, scales exponentially
+self.min_readsize = 100
+elif mode[0:1] == 'w' or mode[0:1] == 'a':
+self.mode = WRITE
+self._init_write(filename)
+self.compress = zlib.compressobj(compresslevel,
+zlib.DEFLATED,
+-zlib.MAX_WBITS,
+zlib.DEF_MEM_LEVEL,
+0)
+else:
+raise IOError, "Mode " + mode + " not supported"
+self.fileobj = fileobj
+self.offset = 0
+if self.mode == WRITE:
+self._write_gzip_header()
+@property
+def filename(self):
+import warnings
+warnings.warn("use the name attribute", DeprecationWarning)
+if self.mode == WRITE and self.name[-3:] != ".gz":
+return self.name + ".gz"
+return self.name
+def __repr__(self):
+s = repr(self.fileobj)
+return '<gzip ' + s[1:-1] + ' ' + hex(id(self)) + '>'
+def _init_write(self, filename):
+self.name = filename
+self.crc = zlib.crc32("") & 0xffffffffL
+self.size = 0
+self.writebuf = []
+self.bufsize = 0
+def _write_gzip_header(self):
+self.fileobj.write('\037\213')             # magic header
+self.fileobj.write('\010')                 # compression method
+fname = self.name
+if fname.endswith(".gz"):
+fname = fname[:-3]
+flags = 0
+if fname:
+flags = FNAME
+self.fileobj.write(chr(flags))
+write32u(self.fileobj, long(time.time()))
+self.fileobj.write('\002')
+self.fileobj.write('\377')
+if fname:
+self.fileobj.write(fname + '\000')
+def _init_read(self):
+self.crc = zlib.crc32("") & 0xffffffffL
+self.size = 0
+def _read_gzip_header(self):
+magic = self.fileobj.read(2)
+if magic != '\037\213':
+raise IOError, 'Not a gzipped file'
+method = ord( self.fileobj.read(1) )
+if method != 8:
+raise IOError, 'Unknown compression method'
+flag = ord( self.fileobj.read(1) )
+# modtime = self.fileobj.read(4)
+# extraflag = self.fileobj.read(1)
+# os = self.fileobj.read(1)
+self.fileobj.read(6)
+if flag & FEXTRA:
+# Read & discard the extra field, if present
+xlen = ord(self.fileobj.read(1))
+xlen = xlen + 256*ord(self.fileobj.read(1))
+self.fileobj.read(xlen)
+if flag & FNAME:
+# Read and discard a null-terminated string containing the filename
+while True:
+s = self.fileobj.read(1)
+if not s or s=='\000':
+break
+if flag & FCOMMENT:
+# Read and discard a null-terminated string containing a comment
+while True:
+s = self.fileobj.read(1)
+if not s or s=='\000':
+break
+if flag & FHCRC:
+self.fileobj.read(2)     # Read & discard the 16-bit header CRC
+def write(self,data):
+if self.mode != WRITE:
+import errno
+raise IOError(errno.EBADF, "write() on read-only GzipFile object")
+if self.fileobj is None:
+raise ValueError, "write() on closed GzipFile object"
+if len(data) > 0:
+self.size = self.size + len(data)
+self.crc = zlib.crc32(data, self.crc) & 0xffffffffL
+self.fileobj.write( self.compress.compress(data) )
+self.offset += len(data)
+def read(self, size=-1):
+if self.mode != READ:
+import errno
+raise IOError(errno.EBADF, "read() on write-only GzipFile object")
+if self.extrasize <= 0 and self.fileobj is None:
+return ''
+readsize = 1024
+if size < 0:        # get the whole thing
+try:
+while True:
+self._read(readsize)
+readsize = min(self.max_read_chunk, readsize * 2)
+except EOFError:
+size = self.extrasize
+else:               # just get some more of it
+try:
+while size > self.extrasize:
+self._read(readsize)
+readsize = min(self.max_read_chunk, readsize * 2)
+except EOFError:
+if size > self.extrasize:
+size = self.extrasize
+chunk = self.extrabuf[:size]
+self.extrabuf = self.extrabuf[size:]
+self.extrasize = self.extrasize - size
+self.offset += size
+return chunk
+def _unread(self, buf):
+self.extrabuf = buf + self.extrabuf
+self.extrasize = len(buf) + self.extrasize
+self.offset -= len(buf)
+def _read(self, size=1024):
+if self.fileobj is None:
+raise EOFError, "Reached EOF"
+if self._new_member:
+# If the _new_member flag is set, we have to
+# jump to the next member, if there is one.
+#
+# First, check if we're at the end of the file;
+# if so, it's time to stop; no more members to read.
+pos = self.fileobj.tell()   # Save current position
+self.fileobj.seek(0, 2)     # Seek to end of file
+if pos == self.fileobj.tell():
+raise EOFError, "Reached EOF"
+else:
+self.fileobj.seek( pos ) # Return to original position
+self._init_read()
+self._read_gzip_header()
+self.decompress = zlib.decompressobj(-zlib.MAX_WBITS)
+self._new_member = False
+# Read a chunk of data from the file
+buf = self.fileobj.read(size)
+# If the EOF has been reached, flush the decompression object
+# and mark this object as finished.
+if buf == "":
+uncompress = self.decompress.flush()
+self._read_eof()
+self._add_read_data( uncompress )
+raise EOFError, 'Reached EOF'
+uncompress = self.decompress.decompress(buf)
+self._add_read_data( uncompress )
+if self.decompress.unused_data != "":
+# Ending case: we've come to the end of a member in the file,
+# so seek back to the start of the unused data, finish up
+# this member, and read a new gzip header.
+# (The number of bytes to seek back is the length of the unused
+# data, minus 8 because _read_eof() will rewind a further 8 bytes)
+self.fileobj.seek( -len(self.decompress.unused_data)+8, 1)
+# Check the CRC and file size, and set the flag so we read
+# a new member on the next call
+self._read_eof()
+self._new_member = True
+def _add_read_data(self, data):
+self.crc = zlib.crc32(data, self.crc) & 0xffffffffL
+self.extrabuf = self.extrabuf + data
+self.extrasize = self.extrasize + len(data)
+self.size = self.size + len(data)
+def _read_eof(self):
+# We've read to the end of the file, so we have to rewind in order
+# to reread the 8 bytes containing the CRC and the file size.
+# We check the that the computed CRC and size of the
+# uncompressed data matches the stored values.  Note that the size
+# stored is the true file size mod 2**32.
+self.fileobj.seek(-8, 1)
+crc32 = read32(self.fileobj)
+isize = read32(self.fileobj)  # may exceed 2GB
+if crc32 != self.crc:
+raise IOError("CRC check failed %s != %s" % (hex(crc32),
+hex(self.crc)))
+elif isize != (self.size & 0xffffffffL):
+raise IOError, "Incorrect length of data produced"
+def close(self):
+if self.fileobj is None:
+return
+if self.mode == WRITE:
+self.fileobj.write(self.compress.flush())
+write32u(self.fileobj, self.crc)
+# self.size may exceed 2GB, or even 4GB
+write32u(self.fileobj, self.size & 0xffffffffL)
+self.fileobj = None
+elif self.mode == READ:
+self.fileobj = None
+if self.myfileobj:
+self.myfileobj.close()
+self.myfileobj = None
+def __del__(self):
+try:
+if (self.myfileobj is None and
+self.fileobj is None):
+return
+except AttributeError:
+return
+self.close()
+def flush(self,zlib_mode=zlib.Z_SYNC_FLUSH):
+if self.mode == WRITE:
+# Ensure the compressor's buffer is flushed
+self.fileobj.write(self.compress.flush(zlib_mode))
+self.fileobj.flush()
+def fileno(self):
+"""Invoke the underlying file object's fileno() method.
+This will raise AttributeError if the underlying file object
+doesn't support fileno().
+"""
+return self.fileobj.fileno()
+def isatty(self):
+return False
+def tell(self):
+return self.offset
+def rewind(self):
+'''Return the uncompressed stream file position indicator to the
+beginning of the file'''
+if self.mode != READ:
+raise IOError("Can't rewind in write mode")
+self.fileobj.seek(0)
+self._new_member = True
+self.extrabuf = ""
+self.extrasize = 0
+self.offset = 0
+def seek(self, offset, whence=0):
+if whence:
+if whence == 1:
+offset = self.offset + offset
+else:
+raise ValueError('Seek from end not supported')
+if self.mode == WRITE:
+if offset < self.offset:
+raise IOError('Negative seek in write mode')
+count = offset - self.offset
+for i in range(count // 1024):
+self.write(1024 * '\0')
+self.write((count % 1024) * '\0')
+elif self.mode == READ:
+if offset < self.offset:
+# for negative seek, rewind and do positive seek
+self.rewind()
+count = offset - self.offset
+for i in range(count // 1024):
+self.read(1024)
+self.read(count % 1024)
+def readline(self, size=-1):
+if size < 0:
+size = sys.maxint
+readsize = self.min_readsize
+else:
+readsize = size
+bufs = []
+while size != 0:
+c = self.read(readsize)
+i = c.find('\n')
+# We set i=size to break out of the loop under two
+# conditions: 1) there's no newline, and the chunk is
+# larger than size, or 2) there is a newline, but the
+# resulting line would be longer than 'size'.
+if (size <= i) or (i == -1 and len(c) > size):
+i = size - 1
+if i >= 0 or c == '':
+bufs.append(c[:i + 1])    # Add portion of last chunk
+self._unread(c[i + 1:])   # Push back rest of chunk
+break
+# Append chunk to list, decrease 'size',
+bufs.append(c)
+size = size - len(c)
+readsize = min(size, readsize * 2)
+if readsize > self.min_readsize:
+self.min_readsize = min(readsize, self.min_readsize * 2, 512)
+return ''.join(bufs) # Return resulting line
+def readlines(self, sizehint=0):
+# Negative numbers result in reading all the lines
+if sizehint <= 0:
+sizehint = sys.maxint
+L = []
+while sizehint > 0:
+line = self.readline()
+if line == "":
+break
+L.append(line)
+sizehint = sizehint - len(line)
+return L
+def writelines(self, L):
+for line in L:
+self.write(line)
+def __iter__(self):
+return self
+def next(self):
+line = self.readline()
+if line:
+return line
+else:
+raise StopIteration
+def _test():
+# Act like gzip; with -d, act like gunzip.
+# The input file is not deleted, however, nor are any other gzip
+# options or features supported.
+args = sys.argv[1:]
+decompress = args and args[0] == "-d"
+if decompress:
+args = args[1:]
+if not args:
+args = ["-"]
+for arg in args:
+if decompress:
+if arg == "-":
+f = GzipFile(filename="", mode="rb", fileobj=sys.stdin)
+g = sys.stdout
+else:
+if arg[-3:] != ".gz":
+print "filename doesn't end in .gz:", repr(arg)
+continue
+f = open(arg, "rb")
+g = __builtin__.open(arg[:-3], "wb")
+else:
+if arg == "-":
+f = sys.stdin
+g = GzipFile(filename="", mode="wb", fileobj=sys.stdout)
+else:
+f = __builtin__.open(arg, "rb")
+g = open(arg + ".gz", "wb")
+while True:
+chunk = f.read(1024)
+if not chunk:
+break
+g.write(chunk)
+if g is not sys.stdout:
+g.close()
+if f is not sys.stdin:
+f.close()
+if __name__ == '__main__':
+_test()