mirror of https://github.com/python/cpython.git
58 lines
1.4 KiB
Python
58 lines
1.4 KiB
Python
"""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
|