symbian-qemu-0.9.1-12/python-2.6.1/Demo/zlib/minigzip.py
changeset 1 2fb8b9db1c86
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/symbian-qemu-0.9.1-12/python-2.6.1/Demo/zlib/minigzip.py	Fri Jul 31 15:01:17 2009 +0100
@@ -0,0 +1,133 @@
+#!/usr/bin/env python
+# Demo program for zlib; it compresses or decompresses files, but *doesn't*
+# delete the original.  This doesn't support all of gzip's options.
+#
+# The 'gzip' module in the standard library provides a more complete
+# implementation of gzip-format files.
+
+import zlib, sys, os
+
+FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 16
+
+def write32(output, value):
+    output.write(chr(value & 255)) ; value=value // 256
+    output.write(chr(value & 255)) ; value=value // 256
+    output.write(chr(value & 255)) ; value=value // 256
+    output.write(chr(value & 255))
+
+def read32(input):
+    v = ord(input.read(1))
+    v += (ord(input.read(1)) << 8 )
+    v += (ord(input.read(1)) << 16)
+    v += (ord(input.read(1)) << 24)
+    return v
+
+def compress (filename, input, output):
+    output.write('\037\213\010')        # Write the header, ...
+    output.write(chr(FNAME))            # ... flag byte ...
+
+    statval = os.stat(filename)           # ... modification time ...
+    mtime = statval[8]
+    write32(output, mtime)
+    output.write('\002')                # ... slowest compression alg. ...
+    output.write('\377')                # ... OS (=unknown) ...
+    output.write(filename+'\000')       # ... original filename ...
+
+    crcval = zlib.crc32("")
+    compobj = zlib.compressobj(9, zlib.DEFLATED, -zlib.MAX_WBITS,
+                             zlib.DEF_MEM_LEVEL, 0)
+    while True:
+        data = input.read(1024)
+        if data == "":
+            break
+        crcval = zlib.crc32(data, crcval)
+        output.write(compobj.compress(data))
+    output.write(compobj.flush())
+    write32(output, crcval)             # ... the CRC ...
+    write32(output, statval[6])         # and the file size.
+
+def decompress (input, output):
+    magic = input.read(2)
+    if magic != '\037\213':
+        print 'Not a gzipped file'
+        sys.exit(0)
+    if ord(input.read(1)) != 8:
+        print 'Unknown compression method'
+        sys.exit(0)
+    flag = ord(input.read(1))
+    input.read(4+1+1)                   # Discard modification time,
+                                        # extra flags, and OS byte.
+    if flag & FEXTRA:
+        # Read & discard the extra field, if present
+        xlen = ord(input.read(1))
+        xlen += 256*ord(input.read(1))
+        input.read(xlen)
+    if flag & FNAME:
+        # Read and discard a null-terminated string containing the filename
+        while True:
+            s = input.read(1)
+            if s == '\0': break
+    if flag & FCOMMENT:
+        # Read and discard a null-terminated string containing a comment
+        while True:
+            s=input.read(1)
+            if s=='\0': break
+    if flag & FHCRC:
+        input.read(2)                   # Read & discard the 16-bit header CRC
+
+    decompobj = zlib.decompressobj(-zlib.MAX_WBITS)
+    crcval = zlib.crc32("")
+    length = 0
+    while True:
+        data=input.read(1024)
+        if data == "":
+            break
+        decompdata = decompobj.decompress(data)
+        output.write(decompdata)
+        length += len(decompdata)
+        crcval = zlib.crc32(decompdata, crcval)
+
+    decompdata = decompobj.flush()
+    output.write(decompdata)
+    length += len(decompdata)
+    crcval = zlib.crc32(decompdata, crcval)
+
+    # 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.  The
+    # decompressor is smart and knows when to stop, so feeding it
+    # extra data is harmless.
+    input.seek(-8, 2)
+    crc32 = read32(input)
+    isize = read32(input)
+    if crc32 != crcval:
+        print 'CRC check failed.'
+    if isize != length:
+        print 'Incorrect length of data produced'
+
+def main():
+    if len(sys.argv)!=2:
+        print 'Usage: minigzip.py <filename>'
+        print '  The file will be compressed or decompressed.'
+        sys.exit(0)
+
+    filename = sys.argv[1]
+    if filename.endswith('.gz'):
+        compressing = False
+        outputname = filename[:-3]
+    else:
+        compressing = True
+        outputname = filename + '.gz'
+
+    input = open(filename, 'rb')
+    output = open(outputname, 'wb')
+
+    if compressing:
+        compress(filename, input, output)
+    else:
+        decompress(input, output)
+
+    input.close()
+    output.close()
+
+if __name__ == '__main__':
+    main()