"""Utilities for comparing files and directories.

Classes:

dircmp

Functions:

cmp(f1, f2, shallow=True) -> int

cmpfiles(a, b, common) -> ([], [], [])

clear_cache()

"""

import os

import stat

from itertools import filterfalse

from types import GenericAlias

__all__ = ['clear_cache', 'cmp', 'dircmp', 'cmpfiles', 'DEFAULT_IGNORES']

_cache = {}

BUFSIZE = 8*1024

DEFAULT_IGNORES = [

'RCS', 'CVS', 'tags', '.git', '.hg', '.bzr', '_darcs', '__pycache__']

def clear_cache():

"""Clear the filecmp cache."""

_cache.clear()

def cmp(f1, f2, shallow=True):

"""Compare two files.

Arguments:

f1 -- First file name

f2 -- Second file name

shallow -- treat files as identical if their stat signatures (type, size,

mtime) are identical. Otherwise, files are considered different

if their sizes or contents differ. [default: True]

Return value:

True if the files are the same, False otherwise.

This function uses a cache for past comparisons and the results,

with cache entries invalidated if their stat information

changes. The cache may be cleared by calling clear_cache().

"""

s1 = _sig(os.stat(f1))

s2 = _sig(os.stat(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

outcome = _cache.get((f1, f2, s1, s2))

if outcome is None:

outcome = _do_cmp(f1, f2)

if len(_cache) > 100: # limit the maximum size of the cache

clear_cache()

_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

with open(f1, 'rb') as fp1, open(f2, 'rb') as fp2:

while True:

b1 = fp1.read(bufsize)

b2 = fp2.read(bufsize)

if b1 != b2:

return False

if not b1:

return True

# Directory comparison class.

#

class dircmp:

"""A class that manages the comparison of 2 directories.

dircmp(a, b, ignore=None, hide=None, *, shallow=True)

A and B are directories.

IGNORE is a list of names to ignore,

defaults to DEFAULT_IGNORES.

HIDE is a list of names to hide,

defaults to [os.curdir, os.pardir].

SHALLOW specifies whether to just check the stat signature (do not read

the files).

defaults to True.

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 instances (or MyDirCmp instances if this

object is of type MyDirCmp, a subclass of dircmp), keyed by names

in common_dirs.

"""

def __init__(self, a, b, ignore=None, hide=None, *, shallow=True): # 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 = DEFAULT_IGNORES

else:

self.ignore = ignore

self.shallow = shallow

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()

def phase1(self): # Compute common names

a = dict(zip(map(os.path.normcase, self.left_list), self.left_list))

b = dict(zip(map(os.path.normcase, self.right_list), self.right_list))

self.common = list(map(a.__getitem__, filter(b.__contains__, a)))

self.left_only = list(map(a.__getitem__, filterfalse(b.__contains__, a)))

self.right_only = list(map(b.__getitem__, filterfalse(a.__contains__, b)))

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 = True

try:

a_stat = os.stat(a_path)

except (OSError, ValueError):

# See https://github.com/python/cpython/issues/122400

# for the rationale for protecting against ValueError.

# print('Can\'t stat', a_path, ':', why.args[1])

ok = False

try:

b_stat = os.stat(b_path)

except (OSError, ValueError):

# print('Can\'t stat', b_path, ':', why.args[1])

ok = False

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.shallow)

self.same_files, self.diff_files, self.funny_files = xx

def phase4(self): # Find out differences between common subdirectories

# A new dircmp (or MyDirCmp if dircmp was subclassed) 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] = self.__class__(a_x, b_x, self.ignore, self.hide,

shallow=self.shallow)

def phase4_closure(self): # Recursively call phase4() on subdirectories

self.phase4()

for sd in self.subdirs.values():

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.values():

print()

sd.report()

def report_full_closure(self): # Report on self and subdirs recursively

self.report()

for sd in self.subdirs.values():

print()

sd.report_full_closure()

methodmap = dict(subdirs=phase4,

same_files=phase3, diff_files=phase3, funny_files=phase3,

common_dirs=phase2, common_files=phase2, common_funny=phase2,

common=phase1, left_only=phase1, right_only=phase1,

left_list=phase0, right_list=phase0)

def __getattr__(self, attr):

if attr not in self.methodmap:

raise AttributeError(attr)

self.methodmap[attr](self)

return getattr(self, attr)

__class_getitem__ = classmethod(GenericAlias)

def cmpfiles(a, b, common, shallow=True):

"""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

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)].append(x)

return res

# Compare two files.

# Return:

# 0 for equal

# 1 for different

# 2 for funny cases (can't stat, NUL bytes, etc.)

#

def _cmp(a, b, sh, abs=abs, cmp=cmp):

try:

return not abs(cmp(a, b, sh))

except (OSError, ValueError):

return 2

# Return a copy with items that occur in skip removed.

#

def _filter(flist, skip):

return list(filterfalse(skip.__contains__, flist))

# Demonstration and testing.

#

def demo():

import sys

import getopt

options, args = getopt.getopt(sys.argv[1:], 'r')

if len(args) != 2:

raise getopt.GetoptError('need exactly two args', None)

dd = dircmp(args[0], args[1])

if ('-r', '') in options:

dd.report_full_closure()

else:

dd.report()

if __name__ == '__main__':

demo()