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
  16
  17 __all__ = ["cmp","dircmp","cmpfiles"]
  18
  19 _cache = {}
  20 BUFSIZE=8*1024
  21
  22 def cmp(f1, f2, shallow=1, use_statcache=None):
  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     use_statcache -- obsolete argument.
  35
  36     Return value:
  37
  38     True if the files are the same, False otherwise.
  39
  40     This function uses a cache for past comparisons and the results,
  41     with a cache invalidation mechanism relying on stale signatures.
  42
  43     """
  44     if use_statcache is not None:
  45         warnings.warn("use_statcache argument is deprecated",
  46                       DeprecationWarning)
  47
  48     s1 = _sig(os.stat(f1))
  49     s2 = _sig(os.stat(f2))
  50     if s1[0] != stat.S_IFREG or s2[0] != stat.S_IFREG:
  51         return False
  52     if shallow and s1 == s2:
  53         return True
  54     if s1[1] != s2[1]:
  55         return False
  56
  57     result = _cache.get((f1, f2))
  58     if result and (s1, s2) == result[:2]:
  59         return result[2]
  60     outcome = _do_cmp(f1, f2)
  61     _cache[f1, f2] = s1, s2, outcome
  62     return outcome
  63
  64 def _sig(st):
  65     return (stat.S_IFMT(st.st_mode),
  66             st.st_size,
  67             st.st_mtime)
  68
  69 def _do_cmp(f1, f2):
  70     bufsize = BUFSIZE
  71     fp1 = open(f1, 'rb')
  72     fp2 = open(f2, 'rb')
  73     while True:
  74         b1 = fp1.read(bufsize)
  75         b2 = fp2.read(bufsize)
  76         if b1 != b2:
  77             return False
  78         if not b1:
  79             return True
  80
  81 # Directory comparison class.
  82 #
  83 class dircmp:
  84     """A class that manages the comparison of 2 directories.
  85
  86     dircmp(a,b,ignore=None,hide=None)
  87       A and B are directories.
  88       IGNORE is a list of names to ignore,
  89         defaults to ['RCS', 'CVS', 'tags'].
  90       HIDE is a list of names to hide,
  91         defaults to [os.curdir, os.pardir].
  92
  93     High level usage:
  94       x = dircmp(dir1, dir2)
  95       x.report() -> prints a report on the differences between dir1 and dir2
  96        or
  97       x.report_partial_closure() -> prints report on differences between dir1
  98             and dir2, and reports on common immediate subdirectories.
  99       x.report_full_closure() -> like report_partial_closure,
 100             but fully recursive.
 101
 102     Attributes:
 103      left_list, right_list: The files in dir1 and dir2,
 104         filtered by hide and ignore.
 105      common: a list of names in both dir1 and dir2.
 106      left_only, right_only: names only in dir1, dir2.
 107      common_dirs: subdirectories in both dir1 and dir2.
 108      common_files: files in both dir1 and dir2.
 109      common_funny: names in both dir1 and dir2 where the type differs between
 110         dir1 and dir2, or the name is not stat-able.
 111      same_files: list of identical files.
 112      diff_files: list of filenames which differ.
 113      funny_files: list of files which could not be compared.
 114      subdirs: a dictionary of dircmp objects, keyed by names in common_dirs.
 115      """
 116
 117     def __init__(self, a, b, ignore=None, hide=None): # Initialize
 118         self.left = a
 119         self.right = b
 120         if hide is None:
 121             self.hide = [os.curdir, os.pardir] # Names never to be shown
 122         else:
 123             self.hide = hide
 124         if ignore is None:
 125             self.ignore = ['RCS', 'CVS', 'tags'] # Names ignored in comparison
 126         else:
 127             self.ignore = ignore
 128
 129     def phase0(self): # Compare everything except common subdirectories
 130         self.left_list = _filter(os.listdir(self.left),
 131                                  self.hide+self.ignore)
 132         self.right_list = _filter(os.listdir(self.right),
 133                                   self.hide+self.ignore)
 134         self.left_list.sort()
 135         self.right_list.sort()
 136
 137     def phase1(self): # Compute common names
 138         b = dict.fromkeys(self.right_list)
 139         common = dict.fromkeys(ifilter(b.has_key, self.left_list))
 140         self.left_only = list(ifilterfalse(common.has_key, self.left_list))
 141         self.right_only = list(ifilterfalse(common.has_key, self.right_list))
 142         self.common = common.keys()
 143
 144     def phase2(self): # Distinguish files, directories, funnies
 145         self.common_dirs = []
 146         self.common_files = []
 147         self.common_funny = []
 148
 149         for x in self.common:
 150             a_path = os.path.join(self.left, x)
 151             b_path = os.path.join(self.right, x)
 152
 153             ok = 1
 154             try:
 155                 a_stat = os.stat(a_path)
 156             except os.error, why:
 157                 # print 'Can\'t stat', a_path, ':', why[1]
 158                 ok = 0
 159             try:
 160                 b_stat = os.stat(b_path)
 161             except os.error, why:
 162                 # print 'Can\'t stat', b_path, ':', why[1]
 163                 ok = 0
 164
 165             if ok:
 166                 a_type = stat.S_IFMT(a_stat.st_mode)
 167                 b_type = stat.S_IFMT(b_stat.st_mode)
 168                 if a_type != b_type:
 169                     self.common_funny.append(x)
 170                 elif stat.S_ISDIR(a_type):
 171                     self.common_dirs.append(x)
 172                 elif stat.S_ISREG(a_type):
 173                     self.common_files.append(x)
 174                 else:
 175                     self.common_funny.append(x)
 176             else:
 177                 self.common_funny.append(x)
 178
 179     def phase3(self): # Find out differences between common files
 180         xx = cmpfiles(self.left, self.right, self.common_files)
 181         self.same_files, self.diff_files, self.funny_files = xx
 182
 183     def phase4(self): # Find out differences between common subdirectories
 184         # A new dircmp object is created for each common subdirectory,
 185         # these are stored in a dictionary indexed by filename.
 186         # The hide and ignore properties are inherited from the parent
 187         self.subdirs = {}
 188         for x in self.common_dirs:
 189             a_x = os.path.join(self.left, x)
 190             b_x = os.path.join(self.right, x)
 191             self.subdirs[x]  = dircmp(a_x, b_x, self.ignore, self.hide)
 192
 193     def phase4_closure(self): # Recursively call phase4() on subdirectories
 194         self.phase4()
 195         for sd in self.subdirs.itervalues():
 196             sd.phase4_closure()
 197
 198     def report(self): # Print a report on the differences between a and b
 199         # Output format is purposely lousy
 200         print 'diff', self.left, self.right
 201         if self.left_only:
 202             self.left_only.sort()
 203             print 'Only in', self.left, ':', self.left_only
 204         if self.right_only:
 205             self.right_only.sort()
 206             print 'Only in', self.right, ':', self.right_only
 207         if self.same_files:
 208             self.same_files.sort()
 209             print 'Identical files :', self.same_files
 210         if self.diff_files:
 211             self.diff_files.sort()
 212             print 'Differing files :', self.diff_files
 213         if self.funny_files:
 214             self.funny_files.sort()
 215             print 'Trouble with common files :', self.funny_files
 216         if self.common_dirs:
 217             self.common_dirs.sort()
 218             print 'Common subdirectories :', self.common_dirs
 219         if self.common_funny:
 220             self.common_funny.sort()
 221             print 'Common funny cases :', self.common_funny
 222
 223     def report_partial_closure(self): # Print reports on self and on subdirs
 224         self.report()
 225         for sd in self.subdirs.itervalues():
 226             print
 227             sd.report()
 228
 229     def report_full_closure(self): # Report on self and subdirs recursively
 230         self.report()
 231         for sd in self.subdirs.itervalues():
 232             print
 233             sd.report_full_closure()
 234
 235     methodmap = dict(subdirs=phase4,
 236                      same_files=phase3, diff_files=phase3, funny_files=phase3,
 237                      common_dirs = phase2, common_files=phase2, common_funny=phase2,
 238                      common=phase1, left_only=phase1, right_only=phase1,
 239                      left_list=phase0, right_list=phase0)
 240
 241     def __getattr__(self, attr):
 242         if attr not in self.methodmap:
 243             raise AttributeError, attr
 244         self.methodmap[attr](self)
 245         return getattr(self, attr)
 246
 247 def cmpfiles(a, b, common, shallow=1, use_statcache=None):
 248     """Compare common files in two directories.
 249
 250     a, b -- directory names
 251     common -- list of file names found in both directories
 252     shallow -- if true, do comparison based solely on stat() information
 253     use_statcache -- obsolete argument
 254
 255     Returns a tuple of three lists:
 256       files that compare equal
 257       files that are different
 258       filenames that aren't regular files.
 259
 260     """
 261     if use_statcache is not None:
 262         warnings.warn("use_statcache argument is deprecated",
 263                       DeprecationWarning)
 264     res = ([], [], [])
 265     for x in common:
 266         ax = os.path.join(a, x)
 267         bx = os.path.join(b, x)
 268         res[_cmp(ax, bx, shallow)].append(x)
 269     return res
 270
 271
 272 # Compare two files.
 273 # Return:
 274 #       0 for equal
 275 #       1 for different
 276 #       2 for funny cases (can't stat, etc.)
 277 #
 278 def _cmp(a, b, sh, abs=abs, cmp=cmp):
 279     try:
 280         return not abs(cmp(a, b, sh))
 281     except os.error:
 282         return 2
 283
 284
 285 # Return a copy with items that occur in skip removed.
 286 #
 287 def _filter(flist, skip):
 288     return list(ifilterfalse(skip.__contains__, flist))
 289
 290
 291 # Demonstration and testing.
 292 #
 293 def demo():
 294     import sys
 295     import getopt
 296     options, args = getopt.getopt(sys.argv[1:], 'r')
 297     if len(args) != 2:
 298         raise getopt.GetoptError('need exactly two args', None)
 299     dd = dircmp(args[0], args[1])
 300     if ('-r', '') in options:
 301         dd.report_full_closure()
 302     else:
 303         dd.report()
 304
 305 if __name__ == '__main__':
 306     demo()