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