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"""Compare files."""
import os, stat, statcache
_cache = {}
BUFSIZE=8*1024
def cmp(f1, f2, shallow=1,use_statcache=0):
"""Compare two files.
Arguments:
f1 -- First file name
f2 -- Second file name
shallow -- Just check stat signature (do not read the files).
defaults to 1.
use_statcache -- Do not stat() each file directly: go through
the statcache module for more efficiency.
Return value:
integer -- 1 if the files are the same, 0 otherwise.
This function uses a cache for past comparisons and the results,
with a cache invalidation mechanism relying on stale signatures.
Of course, if 'use_statcache' is true, this mechanism is defeated,
and the cache will never grow stale.
"""
stat_function = (os.stat, statcache.stat)[use_statcache]
s1, s2 = _sig(stat_function(f1)), _sig(stat_function(f2))
if s1[0]!=stat.S_IFREG or s2[0]!=stat.S_IFREG: return 0
if shallow and s1 == s2: return 1
if s1[1]!=s2[1]: return 0
result = _cache.get((f1, f2))
if result and (s1, s2)==result[:2]:
return result[2]
outcome = _do_cmp(f1, f2)
_cache[f1, f2] = s1, s2, outcome
return outcome
def _sig(st):
return (stat.S_IFMT(st[stat.ST_MODE]),
st[stat.ST_SIZE],
st[stat.ST_MTIME])
def _do_cmp(f1, f2):
bufsize = BUFSIZE
fp1 , fp2 = open(f1, 'rb'), open(f2, 'rb')
while 1:
b1, b2 = fp1.read(bufsize), fp2.read(bufsize)
if b1!=b2: return 0
if not b1: return 1
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