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/Lib/filecmp.py

http://unladen-swallow.googlecode.com/
Python | 296 lines | 228 code | 14 blank | 54 comment | 14 complexity | a5596a43f9a20732be903dbb9c4eb5ec MD5 | raw file
  1"""Utilities for comparing files and directories.
  2
  3Classes:
  4    dircmp
  5
  6Functions:
  7    cmp(f1, f2, shallow=1) -> int
  8    cmpfiles(a, b, common) -> ([], [], [])
  9
 10"""
 11
 12import os
 13import stat
 14from itertools import ifilter, ifilterfalse, imap, izip
 15
 16__all__ = ["cmp","dircmp","cmpfiles"]
 17
 18_cache = {}
 19BUFSIZE=8*1024
 20
 21def 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
 58def _sig(st):
 59    return (stat.S_IFMT(st.st_mode),
 60            st.st_size,
 61            st.st_mtime)
 62
 63def _do_cmp(f1, f2):
 64    bufsize = BUFSIZE
 65    fp1 = open(f1, 'rb')
 66    fp2 = open(f2, 'rb')
 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#
 77class 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
241def 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#
268def _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#
277def _filter(flist, skip):
278    return list(ifilterfalse(skip.__contains__, flist))
279
280
281# Demonstration and testing.
282#
283def 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
295if __name__ == '__main__':
296    demo()