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//proc/self/root/opt/alt/python33/lib64/python3.3/gzip.py
"""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, os import zlib import builtins import io __all__ = ["GzipFile", "open", "compress", "decompress"] FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 16 READ, WRITE = 1, 2 def open(filename, mode="rb", compresslevel=9, encoding=None, errors=None, newline=None): """Open a gzip-compressed file in binary or text mode. The filename argument can be an actual filename (a str or bytes object), or an existing file object to read from or write to. The mode argument can be "r", "rb", "w", "wb", "a" or "ab" for binary mode, or "rt", "wt" or "at" for text mode. The default mode is "rb", and the default compresslevel is 9. For binary mode, this function is equivalent to the GzipFile constructor: GzipFile(filename, mode, compresslevel). In this case, the encoding, errors and newline arguments must not be provided. For text mode, a GzipFile object is created, and wrapped in an io.TextIOWrapper instance with the specified encoding, error handling behavior, and line ending(s). """ if "t" in mode: if "b" in mode: raise ValueError("Invalid mode: %r" % (mode,)) else: if encoding is not None: raise ValueError("Argument 'encoding' not supported in binary mode") if errors is not None: raise ValueError("Argument 'errors' not supported in binary mode") if newline is not None: raise ValueError("Argument 'newline' not supported in binary mode") gz_mode = mode.replace("t", "") if isinstance(filename, (str, bytes)): binary_file = GzipFile(filename, gz_mode, compresslevel) elif hasattr(filename, "read") or hasattr(filename, "write"): binary_file = GzipFile(None, gz_mode, compresslevel, filename) else: raise TypeError("filename must be a str or bytes object, or a file") if "t" in mode: return io.TextIOWrapper(binary_file, encoding, errors, newline) else: return binary_file 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] class _PaddedFile: """Minimal read-only file object that prepends a string to the contents of an actual file. Shouldn't be used outside of gzip.py, as it lacks essential functionality.""" def __init__(self, f, prepend=b''): self._buffer = prepend self._length = len(prepend) self.file = f self._read = 0 def read(self, size): if self._read is None: return self.file.read(size) if self._read + size <= self._length: read = self._read self._read += size return self._buffer[read:self._read] else: read = self._read self._read = None return self._buffer[read:] + \ self.file.read(size-self._length+read) def prepend(self, prepend=b'', readprevious=False): if self._read is None: self._buffer = prepend elif readprevious and len(prepend) <= self._read: self._read -= len(prepend) return else: self._buffer = self._buffer[self._read:] + prepend self._length = len(self._buffer) self._read = 0 def unused(self): if self._read is None: return b'' return self._buffer[self._read:] def seek(self, offset, whence=0): # This is only ever called with offset=whence=0 if whence == 1 and self._read is not None: if 0 <= offset + self._read <= self._length: self._read += offset return else: offset += self._length - self._read self._read = None self._buffer = None return self.file.seek(offset, whence) def __getattr__(self, name): return getattr(self.file, name) class GzipFile(io.BufferedIOBase): """The GzipFile class simulates most of the methods of a file object with the exception of the readinto() and truncate() methods. This class only supports opening files in binary mode. If you need to open a compressed file in text mode, use the gzip.open() function. """ myfileobj = None max_read_chunk = 10 * 1024 * 1024 # 10Mb def __init__(self, filename=None, mode=None, compresslevel=9, fileobj=None, mtime=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, an io.BytesIO 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'. A mode of 'r' is equivalent to one of 'rb', and similarly for 'w' and 'wb', and 'a' and 'ab'. The compresslevel argument is an integer from 0 to 9 controlling the level of compression; 1 is fastest and produces the least compression, and 9 is slowest and produces the most compression. 0 is no compression at all. The default is 9. The mtime argument is an optional numeric timestamp to be written to the stream when compressing. All gzip compressed streams are required to contain a timestamp. If omitted or None, the current time is used. This module ignores the timestamp when decompressing; however, some programs, such as gunzip, make use of it. The format of the timestamp is the same as that of the return value of time.time() and of the st_mtime member of the object returned by os.stat(). """ if mode and ('t' in mode or 'U' in mode): raise ValueError("Invalid mode: {!r}".format(mode)) if mode and 'b' not in mode: mode += 'b' if fileobj is None: fileobj = self.myfileobj = builtins.open(filename, mode or 'rb') if filename is None: filename = getattr(fileobj, 'name', '') if not isinstance(filename, (str, bytes)): filename = '' if mode is None: mode = getattr(fileobj, 'mode', 'rb') if mode.startswith('r'): self.mode = READ # Set flag indicating start of a new member self._new_member = True # Buffer data read from gzip file. extrastart is offset in # stream where buffer starts. extrasize is number of # bytes remaining in buffer from current stream position. self.extrabuf = b"" self.extrasize = 0 self.extrastart = 0 self.name = filename # Starts small, scales exponentially self.min_readsize = 100 fileobj = _PaddedFile(fileobj) elif mode.startswith(('w', '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 ValueError("Invalid mode: {!r}".format(mode)) self.fileobj = fileobj self.offset = 0 self.mtime = mtime if self.mode == WRITE: self._write_gzip_header() @property def filename(self): import warnings warnings.warn("use the name attribute", DeprecationWarning, 2) if self.mode == WRITE and self.name[-3:] != ".gz": return self.name + ".gz" return self.name def __repr__(self): fileobj = self.fileobj if isinstance(fileobj, _PaddedFile): fileobj = fileobj.file s = repr(fileobj) return '<gzip ' + s[1:-1] + ' ' + hex(id(self)) + '>' def _check_closed(self): """Raises a ValueError if the underlying file object has been closed. """ if self.closed: raise ValueError('I/O operation on closed file.') def _init_write(self, filename): self.name = filename self.crc = zlib.crc32(b"") & 0xffffffff self.size = 0 self.writebuf = [] self.bufsize = 0 def _write_gzip_header(self): self.fileobj.write(b'\037\213') # magic header self.fileobj.write(b'\010') # compression method try: # RFC 1952 requires the FNAME field to be Latin-1. Do not # include filenames that cannot be represented that way. fname = os.path.basename(self.name) if not isinstance(fname, bytes): fname = fname.encode('latin-1') if fname.endswith(b'.gz'): fname = fname[:-3] except UnicodeEncodeError: fname = b'' flags = 0 if fname: flags = FNAME self.fileobj.write(chr(flags).encode('latin-1')) mtime = self.mtime if mtime is None: mtime = time.time() write32u(self.fileobj, int(mtime)) self.fileobj.write(b'\002') self.fileobj.write(b'\377') if fname: self.fileobj.write(fname + b'\000') def _init_read(self): self.crc = zlib.crc32(b"") & 0xffffffff self.size = 0 def _read_gzip_header(self): magic = self.fileobj.read(2) if magic == b'': raise EOFError("Reached EOF") if magic != b'\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) ) self.mtime = read32(self.fileobj) # extraflag = self.fileobj.read(1) # os = self.fileobj.read(1) self.fileobj.read(2) 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==b'\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==b'\000': break if flag & FHCRC: self.fileobj.read(2) # Read & discard the 16-bit header CRC unused = self.fileobj.unused() if unused: uncompress = self.decompress.decompress(unused) self._add_read_data(uncompress) def write(self,data): self._check_closed() 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") # Convert data type if called by io.BufferedWriter. if isinstance(data, memoryview): data = data.tobytes() if len(data) > 0: self.size = self.size + len(data) self.crc = zlib.crc32(data, self.crc) & 0xffffffff self.fileobj.write( self.compress.compress(data) ) self.offset += len(data) return len(data) def read(self, size=-1): self._check_closed() 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 b'' 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 offset = self.offset - self.extrastart chunk = self.extrabuf[offset: offset + size] self.extrasize = self.extrasize - size self.offset += size return chunk def read1(self, size=-1): self._check_closed() if self.mode != READ: import errno raise IOError(errno.EBADF, "read1() on write-only GzipFile object") if self.extrasize <= 0 and self.fileobj is None: return b'' try: # For certain input data, a single call to _read() may not return # any data. In this case, retry until we get some data or reach EOF. while self.extrasize <= 0: self._read() except EOFError: pass if size < 0 or size > self.extrasize: size = self.extrasize offset = self.offset - self.extrastart chunk = self.extrabuf[offset: offset + size] self.extrasize -= size self.offset += size return chunk def peek(self, n): if self.mode != READ: import errno raise IOError(errno.EBADF, "peek() on write-only GzipFile object") # Do not return ridiculously small buffers, for one common idiom # is to call peek(1) and expect more bytes in return. if n < 100: n = 100 if self.extrasize == 0: if self.fileobj is None: return b'' try: # Ensure that we don't return b"" if we haven't reached EOF. while self.extrasize == 0: # 1024 is the same buffering heuristic used in read() self._read(max(n, 1024)) except EOFError: pass offset = self.offset - self.extrastart remaining = self.extrasize assert remaining == len(self.extrabuf) - offset return self.extrabuf[offset:offset + n] def _unread(self, buf): 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. 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 == b"": uncompress = self.decompress.flush() # Prepend the already read bytes to the fileobj to they can be # seen by _read_eof() self.fileobj.prepend(self.decompress.unused_data, True) 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 != b"": # 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. # Prepend the already read bytes to the fileobj to they can be # seen by _read_eof() and _read_gzip_header() self.fileobj.prepend(self.decompress.unused_data, True) # 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) & 0xffffffff offset = self.offset - self.extrastart self.extrabuf = self.extrabuf[offset:] + data self.extrasize = self.extrasize + len(data) self.extrastart = self.offset self.size = self.size + len(data) def _read_eof(self): # We've read to the end of the file # 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. 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 & 0xffffffff): raise IOError("Incorrect length of data produced") # Gzip files can be padded with zeroes and still have archives. # Consume all zero bytes and set the file position to the first # non-zero byte. See http://www.gzip.org/#faq8 c = b"\x00" while c == b"\x00": c = self.fileobj.read(1) if c: self.fileobj.prepend(c, True) @property def closed(self): return self.fileobj is None 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 & 0xffffffff) self.fileobj = None elif self.mode == READ: self.fileobj = None if self.myfileobj: self.myfileobj.close() self.myfileobj = None def flush(self,zlib_mode=zlib.Z_SYNC_FLUSH): self._check_closed() 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 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 = b"" self.extrasize = 0 self.extrastart = 0 self.offset = 0 def readable(self): return self.mode == READ def writable(self): return self.mode == WRITE def seekable(self): return True 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 chunk = bytes(1024) for i in range(count // 1024): self.write(chunk) self.write(bytes(count % 1024)) 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) return self.offset def readline(self, size=-1): if size < 0: # Shortcut common case - newline found in buffer. offset = self.offset - self.extrastart i = self.extrabuf.find(b'\n', offset) + 1 if i > 0: self.extrasize -= i - offset self.offset += i - offset return self.extrabuf[offset: i] size = sys.maxsize readsize = self.min_readsize else: readsize = size bufs = [] while size != 0: c = self.read(readsize) i = c.find(b'\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 == b'': 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 b''.join(bufs) # Return resulting line def compress(data, compresslevel=9): """Compress data in one shot and return the compressed string. Optional argument is the compression level, in range of 0-9. """ buf = io.BytesIO() with GzipFile(fileobj=buf, mode='wb', compresslevel=compresslevel) as f: f.write(data) return buf.getvalue() def decompress(data): """Decompress a gzip compressed string in one shot. Return the decompressed string. """ with GzipFile(fileobj=io.BytesIO(data)) as f: return f.read() 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.buffer) g = sys.stdout.buffer else: if arg[-3:] != ".gz": print("filename doesn't end in .gz:", repr(arg)) continue f = open(arg, "rb") g = builtins.open(arg[:-3], "wb") else: if arg == "-": f = sys.stdin.buffer g = GzipFile(filename="", mode="wb", fileobj=sys.stdout.buffer) else: f = builtins.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.buffer: g.close() if f is not sys.stdin.buffer: f.close() if __name__ == '__main__': _test()
