Mirror
/
cpython
mirror of https://github.com/python/cpython
4
1
Fork 0
Code Issues Releases Wiki Activity

Use functions; modernize code

This commit is contained in:
Andrew M. Kuchling 2006-06-03 23:39:07 +00:00
parent 3550613502
commit 0b4e554be5
1 changed files with 87 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

147
Demo/zlib/minigzip.py
View File

@ -1,106 +1,133 @@
#!/usr/bin/env python #!/usr/bin/env python
# Demo program for zlib; it compresses or decompresses files, but *doesn't* # Demo program for zlib; it compresses or decompresses files, but *doesn't*
# delete the original. This doesn't support all of gzip's options. # 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 FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 16
def write32(output, value): 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)) ; value=value // 256
output.write(chr(value & 255)) ; value=value / 256 output.write(chr(value & 255)) ; value=value // 256
output.write(chr(value & 255)) output.write(chr(value & 255))
def read32(input): def read32(input):
v=ord(input.read(1)) v = ord(input.read(1))
v=v+ (ord(input.read(1))<<8 ) v += (ord(input.read(1)) << 8 )
v=v+ (ord(input.read(1))<<16) v += (ord(input.read(1)) << 16)
v=v+ (ord(input.read(1))<<24) v += (ord(input.read(1)) << 24)
return v return v
import zlib, sys def compress (filename, input, output):
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]
compressing=1 ; outputname=filename+'.gz'
if filename[-3:]=='.gz':
compressing=0 ; outputname=filename[:-3]
input=open(filename) ; output=open(outputname, 'w')
if compressing:
output.write('\037\213\010') # Write the header, ... output.write('\037\213\010') # Write the header, ...
output.write(chr(FNAME)) # ... flag byte ... output.write(chr(FNAME)) # ... flag byte ...
import os # ... modification time ... statval = os.stat(filename) # ... modification time ...
statval=os.stat(filename) mtime = statval[8]
mtime=statval[8]
write32(output, mtime) write32(output, mtime)
output.write('\002') # ... slowest compression alg. ... output.write('\002') # ... slowest compression alg. ...
output.write('\377') # ... OS (=unknown) ... output.write('\377') # ... OS (=unknown) ...
output.write(filename+'\000') # ... original filename ... output.write(filename+'\000') # ... original filename ...
crcval=zlib.crc32("") crcval = zlib.crc32("")
compobj=zlib.compressobj(9, zlib.DEFLATED, -zlib.MAX_WBITS, compobj = zlib.compressobj(9, zlib.DEFLATED, -zlib.MAX_WBITS,
zlib.DEF_MEM_LEVEL, 0) zlib.DEF_MEM_LEVEL, 0)
while (1): while True:
data=input.read(1024) data = input.read(1024)
if data=="": break if data == "":
crcval=zlib.crc32(data, crcval) break
crcval = zlib.crc32(data, crcval)
output.write(compobj.compress(data)) output.write(compobj.compress(data))
output.write(compobj.flush()) output.write(compobj.flush())
write32(output, crcval) # ... the CRC ... write32(output, crcval) # ... the CRC ...
write32(output, statval[6]) # and the file size. write32(output, statval[6]) # and the file size.
else: def decompress (input, output):
magic=input.read(2) magic = input.read(2)
if magic!='\037\213': if magic != '\037\213':
print 'Not a gzipped file' ; sys.exit(0) print 'Not a gzipped file'
if ord(input.read(1))!=8: sys.exit(0)
print 'Unknown compression method' ; sys.exit(0) if ord(input.read(1)) != 8:
flag=ord(input.read(1)) print 'Unknown compression method'
sys.exit(0)
flag = ord(input.read(1))
input.read(4+1+1) # Discard modification time, input.read(4+1+1) # Discard modification time,
# extra flags, and OS byte. # extra flags, and OS byte.
if flag & FEXTRA: if flag & FEXTRA:
# Read & discard the extra field, if present # Read & discard the extra field, if present
xlen=ord(input.read(1)) xlen = ord(input.read(1))
xlen=xlen+256*ord(input.read(1)) xlen += 256*ord(input.read(1))
input.read(xlen) input.read(xlen)
if flag & FNAME: if flag & FNAME:
# Read and discard a null-terminated string containing the filename # Read and discard a null-terminated string containing the filename
while (1): while True:
s=input.read(1) s = input.read(1)
if s=='\000': break if s == '\0': break
if flag & FCOMMENT: if flag & FCOMMENT:
# Read and discard a null-terminated string containing a comment # Read and discard a null-terminated string containing a comment
while (1): while True:
s=input.read(1) s=input.read(1)
if s=='\000': break if s=='\0': break
if flag & FHCRC: if flag & FHCRC:
input.read(2) # Read & discard the 16-bit header CRC input.read(2) # Read & discard the 16-bit header CRC
decompobj=zlib.decompressobj(-zlib.MAX_WBITS)
crcval=zlib.crc32("") decompobj = zlib.decompressobj(-zlib.MAX_WBITS)
length=0 crcval = zlib.crc32("")
while (1): length = 0
while True:
data=input.read(1024) data=input.read(1024)
if data=="": break if data == "":
decompdata=decompobj.decompress(data) break
print len(decompdata) decompdata = decompobj.decompress(data)
output.write(decompdata) ; length=length+len(decompdata) output.write(decompdata)
crcval=zlib.crc32(decompdata, crcval) length += len(decompdata)
decompdata=decompobj.flush() crcval = zlib.crc32(decompdata, crcval)
output.write(decompdata) ; length=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 # 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 # to reread the 8 bytes containing the CRC and the file size. The
# decompressor is smart and knows when to stop, so feeding it # decompressor is smart and knows when to stop, so feeding it
# extra data is harmless. # extra data is harmless.
input.seek(-8, 2) input.seek(-8, 2)
crc32=read32(input) crc32 = read32(input)
isize=read32(input) isize = read32(input)
if crc32!=crcval: print 'CRC check failed.' if crc32 != crcval:
if isize!=length: print 'Incorrect length of data produced' print 'CRC check failed.'
if isize != length:
print 'Incorrect length of data produced'
input.close() ; output.close() 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()