cpython/Lib/filecmp.py
2002-06-02 18:55:56 +00:00

332 lines
10 KiB
Python

"""Utilities for comparing files and directories.
Classes:
dircmp
Functions:
cmp(f1, f2, shallow=1, use_statcache=0) -> int
cmpfiles(a, b, common) -> ([], [], [])
"""
import os
import stat
import statcache
__all__ = ["cmp","dircmp","cmpfiles"]
_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:
True if the files are the same, False 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.
"""
if use_statcache:
stat_function = statcache.stat
else:
stat_function = os.stat
s1 = _sig(stat_function(f1))
s2 = _sig(stat_function(f2))
if s1[0] != stat.S_IFREG or s2[0] != stat.S_IFREG:
return False
if shallow and s1 == s2:
return True
if s1[1] != s2[1]:
return False
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.st_mode),
st.st_size,
st.st_mtime)
def _do_cmp(f1, f2):
bufsize = BUFSIZE
fp1 = open(f1, 'rb')
fp2 = open(f2, 'rb')
while 1:
b1 = fp1.read(bufsize)
b2 = fp2.read(bufsize)
if b1 != b2:
return 0
if not b1:
return 1
# Directory comparison class.
#
class dircmp:
"""A class that manages the comparison of 2 directories.
dircmp(a,b,ignore=None,hide=None)
A and B are directories.
IGNORE is a list of names to ignore,
defaults to ['RCS', 'CVS', 'tags'].
HIDE is a list of names to hide,
defaults to [os.curdir, os.pardir].
High level usage:
x = dircmp(dir1, dir2)
x.report() -> prints a report on the differences between dir1 and dir2
or
x.report_partial_closure() -> prints report on differences between dir1
and dir2, and reports on common immediate subdirectories.
x.report_full_closure() -> like report_partial_closure,
but fully recursive.
Attributes:
left_list, right_list: The files in dir1 and dir2,
filtered by hide and ignore.
common: a list of names in both dir1 and dir2.
left_only, right_only: names only in dir1, dir2.
common_dirs: subdirectories in both dir1 and dir2.
common_files: files in both dir1 and dir2.
common_funny: names in both dir1 and dir2 where the type differs between
dir1 and dir2, or the name is not stat-able.
same_files: list of identical files.
diff_files: list of filenames which differ.
funny_files: list of files which could not be compared.
subdirs: a dictionary of dircmp objects, keyed by names in common_dirs.
"""
def __init__(self, a, b, ignore=None, hide=None): # Initialize
self.left = a
self.right = b
if hide is None:
self.hide = [os.curdir, os.pardir] # Names never to be shown
else:
self.hide = hide
if ignore is None:
self.ignore = ['RCS', 'CVS', 'tags'] # Names ignored in comparison
else:
self.ignore = ignore
def phase0(self): # Compare everything except common subdirectories
self.left_list = _filter(os.listdir(self.left),
self.hide+self.ignore)
self.right_list = _filter(os.listdir(self.right),
self.hide+self.ignore)
self.left_list.sort()
self.right_list.sort()
__p4_attrs = ('subdirs',)
__p3_attrs = ('same_files', 'diff_files', 'funny_files')
__p2_attrs = ('common_dirs', 'common_files', 'common_funny')
__p1_attrs = ('common', 'left_only', 'right_only')
__p0_attrs = ('left_list', 'right_list')
def __getattr__(self, attr):
if attr in self.__p4_attrs:
self.phase4()
elif attr in self.__p3_attrs:
self.phase3()
elif attr in self.__p2_attrs:
self.phase2()
elif attr in self.__p1_attrs:
self.phase1()
elif attr in self.__p0_attrs:
self.phase0()
else:
raise AttributeError, attr
return getattr(self, attr)
def phase1(self): # Compute common names
a_only, b_only = [], []
common = {}
b = {}
for fnm in self.right_list:
b[fnm] = 1
for x in self.left_list:
if b.get(x, 0):
common[x] = 1
else:
a_only.append(x)
for x in self.right_list:
if common.get(x, 0):
pass
else:
b_only.append(x)
self.common = common.keys()
self.left_only = a_only
self.right_only = b_only
def phase2(self): # Distinguish files, directories, funnies
self.common_dirs = []
self.common_files = []
self.common_funny = []
for x in self.common:
a_path = os.path.join(self.left, x)
b_path = os.path.join(self.right, x)
ok = 1
try:
a_stat = statcache.stat(a_path)
except os.error, why:
# print 'Can\'t stat', a_path, ':', why[1]
ok = 0
try:
b_stat = statcache.stat(b_path)
except os.error, why:
# print 'Can\'t stat', b_path, ':', why[1]
ok = 0
if ok:
a_type = stat.S_IFMT(a_stat.st_mode)
b_type = stat.S_IFMT(b_stat.st_mode)
if a_type != b_type:
self.common_funny.append(x)
elif stat.S_ISDIR(a_type):
self.common_dirs.append(x)
elif stat.S_ISREG(a_type):
self.common_files.append(x)
else:
self.common_funny.append(x)
else:
self.common_funny.append(x)
def phase3(self): # Find out differences between common files
xx = cmpfiles(self.left, self.right, self.common_files)
self.same_files, self.diff_files, self.funny_files = xx
def phase4(self): # Find out differences between common subdirectories
# A new dircmp object is created for each common subdirectory,
# these are stored in a dictionary indexed by filename.
# The hide and ignore properties are inherited from the parent
self.subdirs = {}
for x in self.common_dirs:
a_x = os.path.join(self.left, x)
b_x = os.path.join(self.right, x)
self.subdirs[x] = dircmp(a_x, b_x, self.ignore, self.hide)
def phase4_closure(self): # Recursively call phase4() on subdirectories
self.phase4()
for sd in self.subdirs.itervalues():
sd.phase4_closure()
def report(self): # Print a report on the differences between a and b
# Output format is purposely lousy
print 'diff', self.left, self.right
if self.left_only:
self.left_only.sort()
print 'Only in', self.left, ':', self.left_only
if self.right_only:
self.right_only.sort()
print 'Only in', self.right, ':', self.right_only
if self.same_files:
self.same_files.sort()
print 'Identical files :', self.same_files
if self.diff_files:
self.diff_files.sort()
print 'Differing files :', self.diff_files
if self.funny_files:
self.funny_files.sort()
print 'Trouble with common files :', self.funny_files
if self.common_dirs:
self.common_dirs.sort()
print 'Common subdirectories :', self.common_dirs
if self.common_funny:
self.common_funny.sort()
print 'Common funny cases :', self.common_funny
def report_partial_closure(self): # Print reports on self and on subdirs
self.report()
for sd in self.subdirs.itervalues():
print
sd.report()
def report_full_closure(self): # Report on self and subdirs recursively
self.report()
for sd in self.subdirs.itervalues():
print
sd.report_full_closure()
def cmpfiles(a, b, common, shallow=1, use_statcache=0):
"""Compare common files in two directories.
a, b -- directory names
common -- list of file names found in both directories
shallow -- if true, do comparison based solely on stat() information
use_statcache -- if true, use statcache.stat() instead of os.stat()
Returns a tuple of three lists:
files that compare equal
files that are different
filenames that aren't regular files.
"""
res = ([], [], [])
for x in common:
ax = os.path.join(a, x)
bx = os.path.join(b, x)
res[_cmp(ax, bx, shallow, use_statcache)].append(x)
return res
# Compare two files.
# Return:
# 0 for equal
# 1 for different
# 2 for funny cases (can't stat, etc.)
#
def _cmp(a, b, sh, st):
try:
return not abs(cmp(a, b, sh, st))
except os.error:
return 2
# Return a copy with items that occur in skip removed.
#
def _filter(list, skip):
result = []
for item in list:
if item not in skip: result.append(item)
return result
# Demonstration and testing.
#
def demo():
import sys
import getopt
options, args = getopt.getopt(sys.argv[1:], 'r')
if len(args) != 2:
raise getopt.error, 'need exactly two args'
dd = dircmp(args[0], args[1])
if ('-r', '') in options:
dd.report_full_closure()
else:
dd.report()
if __name__ == '__main__':
demo()