Lib/filecmp.py

   1 """Utilities for comparing files and directories.
   2
   3 Classes:
   4     dircmp
   5
   6 Functions:
   7     cmp(f1, f2, shallow=1) -> int
   8     cmpfiles(a, b, common) -> ([], [], [])
   9
  10 """
  11
  12 import os
  13 import stat
  14 import contextlib
  15 from itertools import ifilter, ifilterfalse, imap, izip
  16
  17 __all__ = ["cmp","dircmp","cmpfiles"]
  18
  19 _cache = {}
  20 BUFSIZE=8*1024
  21
  22 def cmp(f1, f2, shallow=1):
  23     """Compare two files.
  24
  25     Arguments:
  26
  27     f1 -- First file name
  28
  29     f2 -- Second file name
  30
  31     shallow -- Just check stat signature (do not read the files).
  32                defaults to 1.
  33
  34     Return value:
  35
  36     True if the files are the same, False otherwise.
  37
  38     This function uses a cache for past comparisons and the results,
  39     with a cache invalidation mechanism relying on stale signatures.
  40
  41     """
  42
  43     s1 = _sig(os.stat(f1))
  44     s2 = _sig(os.stat(f2))
  45     if s1[0] != stat.S_IFREG or s2[0] != stat.S_IFREG:
  46         return False
  47     if shallow and s1 == s2:
  48         return True
  49     if s1[1] != s2[1]:
  50         return False
  51
  52     result = _cache.get((f1, f2))
  53     if result and (s1, s2) == result[:2]:
  54         return result[2]
  55     outcome = _do_cmp(f1, f2)
  56     _cache[f1, f2] = s1, s2, outcome
  57     return outcome
  58
  59 def _sig(st):
  60     return (stat.S_IFMT(st.st_mode),
  61             st.st_size,
  62             st.st_mtime)
  63
  64 def _do_cmp(f1, f2):
  65     bufsize = BUFSIZE
  66     with contextlib.nested(open(f1, 'rb'), open(f2, 'rb')) as (fp1, fp2):
  67         while True:
  68             b1 = fp1.read(bufsize)
  69             b2 = fp2.read(bufsize)
  70             if b1 != b2:
  71                 return False
  72             if not b1:
  73                 return True
  74
  75 # Directory comparison class.
  76 #
  77 class dircmp:
  78     """A class that manages the comparison of 2 directories.
  79
  80     dircmp(a,b,ignore=None,hide=None)
  81       A and B are directories.
  82       IGNORE is a list of names to ignore,
  83         defaults to ['RCS', 'CVS', 'tags'].
  84       HIDE is a list of names to hide,
  85         defaults to [os.curdir, os.pardir].
  86
  87     High level usage:
  88       x = dircmp(dir1, dir2)
  89       x.report() -> prints a report on the differences between dir1 and dir2
  90        or
  91       x.report_partial_closure() -> prints report on differences between dir1
  92             and dir2, and reports on common immediate subdirectories.
  93       x.report_full_closure() -> like report_partial_closure,
  94             but fully recursive.
  95
  96     Attributes:
  97      left_list, right_list: The files in dir1 and dir2,
  98         filtered by hide and ignore.
  99      common: a list of names in both dir1 and dir2.
 100      left_only, right_only: names only in dir1, dir2.
 101      common_dirs: subdirectories in both dir1 and dir2.
 102      common_files: files in both dir1 and dir2.
 103      common_funny: names in both dir1 and dir2 where the type differs between
 104         dir1 and dir2, or the name is not stat-able.
 105      same_files: list of identical files.
 106      diff_files: list of filenames which differ.
 107      funny_files: list of files which could not be compared.
 108      subdirs: a dictionary of dircmp objects, keyed by names in common_dirs.
 109      """
 110
 111     def __init__(self, a, b, ignore=None, hide=None): # Initialize
 112         self.left = a
 113         self.right = b
 114         if hide is None:
 115             self.hide = [os.curdir, os.pardir] # Names never to be shown
 116         else:
 117             self.hide = hide
 118         if ignore is None:
 119             self.ignore = ['RCS', 'CVS', 'tags'] # Names ignored in comparison
 120         else:
 121             self.ignore = ignore
 122
 123     def phase0(self): # Compare everything except common subdirectories
 124         self.left_list = _filter(os.listdir(self.left),
 125                                  self.hide+self.ignore)
 126         self.right_list = _filter(os.listdir(self.right),
 127                                   self.hide+self.ignore)
 128         self.left_list.sort()
 129         self.right_list.sort()
 130
 131     def phase1(self): # Compute common names
 132         a = dict(izip(imap(os.path.normcase, self.left_list), self.left_list))
 133         b = dict(izip(imap(os.path.normcase, self.right_list), self.right_list))
 134         self.common = map(a.__getitem__, ifilter(b.__contains__, a))
 135         self.left_only = map(a.__getitem__, ifilterfalse(b.__contains__, a))
 136         self.right_only = map(b.__getitem__, ifilterfalse(a.__contains__, b))
 137
 138     def phase2(self): # Distinguish files, directories, funnies
 139         self.common_dirs = []
 140         self.common_files = []
 141         self.common_funny = []
 142
 143         for x in self.common:
 144             a_path = os.path.join(self.left, x)
 145             b_path = os.path.join(self.right, x)
 146
 147             ok = 1
 148             try:
 149                 a_stat = os.stat(a_path)
 150             except os.error, why:
 151                 # print 'Can\'t stat', a_path, ':', why[1]
 152                 ok = 0
 153             try:
 154                 b_stat = os.stat(b_path)
 155             except os.error, why:
 156                 # print 'Can\'t stat', b_path, ':', why[1]
 157                 ok = 0
 158
 159             if ok:
 160                 a_type = stat.S_IFMT(a_stat.st_mode)
 161                 b_type = stat.S_IFMT(b_stat.st_mode)
 162                 if a_type != b_type:
 163                     self.common_funny.append(x)
 164                 elif stat.S_ISDIR(a_type):
 165                     self.common_dirs.append(x)
 166                 elif stat.S_ISREG(a_type):
 167                     self.common_files.append(x)
 168                 else:
 169                     self.common_funny.append(x)
 170             else:
 171                 self.common_funny.append(x)
 172
 173     def phase3(self): # Find out differences between common files
 174         xx = cmpfiles(self.left, self.right, self.common_files)
 175         self.same_files, self.diff_files, self.funny_files = xx
 176
 177     def phase4(self): # Find out differences between common subdirectories
 178         # A new dircmp object is created for each common subdirectory,
 179         # these are stored in a dictionary indexed by filename.
 180         # The hide and ignore properties are inherited from the parent
 181         self.subdirs = {}
 182         for x in self.common_dirs:
 183             a_x = os.path.join(self.left, x)
 184             b_x = os.path.join(self.right, x)
 185             self.subdirs[x]  = dircmp(a_x, b_x, self.ignore, self.hide)
 186
 187     def phase4_closure(self): # Recursively call phase4() on subdirectories
 188         self.phase4()
 189         for sd in self.subdirs.itervalues():
 190             sd.phase4_closure()
 191
 192     def report(self): # Print a report on the differences between a and b
 193         # Output format is purposely lousy
 194         print 'diff', self.left, self.right
 195         if self.left_only:
 196             self.left_only.sort()
 197             print 'Only in', self.left, ':', self.left_only
 198         if self.right_only:
 199             self.right_only.sort()
 200             print 'Only in', self.right, ':', self.right_only
 201         if self.same_files:
 202             self.same_files.sort()
 203             print 'Identical files :', self.same_files
 204         if self.diff_files:
 205             self.diff_files.sort()
 206             print 'Differing files :', self.diff_files
 207         if self.funny_files:
 208             self.funny_files.sort()
 209             print 'Trouble with common files :', self.funny_files
 210         if self.common_dirs:
 211             self.common_dirs.sort()
 212             print 'Common subdirectories :', self.common_dirs
 213         if self.common_funny:
 214             self.common_funny.sort()
 215             print 'Common funny cases :', self.common_funny
 216
 217     def report_partial_closure(self): # Print reports on self and on subdirs
 218         self.report()
 219         for sd in self.subdirs.itervalues():
 220             print
 221             sd.report()
 222
 223     def report_full_closure(self): # Report on self and subdirs recursively
 224         self.report()
 225         for sd in self.subdirs.itervalues():
 226             print
 227             sd.report_full_closure()
 228
 229     methodmap = dict(subdirs=phase4,
 230                      same_files=phase3, diff_files=phase3, funny_files=phase3,
 231                      common_dirs = phase2, common_files=phase2, common_funny=phase2,
 232                      common=phase1, left_only=phase1, right_only=phase1,
 233                      left_list=phase0, right_list=phase0)
 234
 235     def __getattr__(self, attr):
 236         if attr not in self.methodmap:
 237             raise AttributeError, attr
 238         self.methodmap[attr](self)
 239         return getattr(self, attr)
 240
 241 def cmpfiles(a, b, common, shallow=1):
 242     """Compare common files in two directories.
 243
 244     a, b -- directory names
 245     common -- list of file names found in both directories
 246     shallow -- if true, do comparison based solely on stat() information
 247
 248     Returns a tuple of three lists:
 249       files that compare equal
 250       files that are different
 251       filenames that aren't regular files.
 252
 253     """
 254     res = ([], [], [])
 255     for x in common:
 256         ax = os.path.join(a, x)
 257         bx = os.path.join(b, x)
 258         res[_cmp(ax, bx, shallow)].append(x)
 259     return res
 260
 261
 262 # Compare two files.
 263 # Return:
 264 #       0 for equal
 265 #       1 for different
 266 #       2 for funny cases (can't stat, etc.)
 267 #
 268 def _cmp(a, b, sh, abs=abs, cmp=cmp):
 269     try:
 270         return not abs(cmp(a, b, sh))
 271     except os.error:
 272         return 2
 273
 274
 275 # Return a copy with items that occur in skip removed.
 276 #
 277 def _filter(flist, skip):
 278     return list(ifilterfalse(skip.__contains__, flist))
 279
 280
 281 # Demonstration and testing.
 282 #
 283 def demo():
 284     import sys
 285     import getopt
 286     options, args = getopt.getopt(sys.argv[1:], 'r')
 287     if len(args) != 2:
 288         raise getopt.GetoptError('need exactly two args', None)
 289     dd = dircmp(args[0], args[1])
 290     if ('-r', '') in options:
 291         dd.report_full_closure()
 292     else:
 293         dd.report()
 294
 295 if __name__ == '__main__':
 296     demo()