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