New module by Moshe Zadka (submitted on Sept. 25). This unifies the

functionality of cmp.py and cmpcache.py, which are hereby declared
obsolescent.

diff --git a/Lib/filecmp.py b/Lib/filecmp.py
new file mode 100644 (file)
index 0000000..e1a30bc
--- /dev/null
+++ b/Lib/filecmp.py
@@ -0,0 +1,57 @@
+"""Compare files."""
+
+import os, stat, statcache
+
+_cache = {}
+BUFSIZE=8*1024
+
+def cmp(f1, f2, shallow=1,use_statcache=0): 
+       """Compare two files.
+
+       Arguments:
+
+       f1 -- First file name
+
+       f2 -- Second file name
+
+       shallow -- Just check stat signature (do not read the files).
+                  defaults to 1.
+
+       use_statcache -- Do not stat() each file directly: go through
+                        the statcache module for more efficiency.
+
+       Return value:
+
+       integer -- 1 if the files are the same, 0 otherwise.
+
+       This function uses a cache for past comparisons and the results,
+       with a cache invalidation mechanism relying on stale signatures.
+       Of course, if 'use_statcache' is true, this mechanism is defeated,
+       and the cache will never grow stale.
+
+       """
+       stat_function = (os.stat, statcache.stat)[use_statcache]
+       s1, s2 = _sig(stat_function(f1)), _sig(stat_function(f2))
+       if s1[0]!=stat.S_IFREG or s2[0]!=stat.S_IFREG: return 0
+       if shallow and s1 == s2: return 1
+       if s1[1]!=s2[1]:         return 0
+
+       result = _cache.get((f1, f2))
+       if result and (s1, s2)==result[:2]:
+               return result[2]
+       outcome = _do_cmp(f1, f2)
+       _cache[f1, f2] = s1, s2, outcome
+       return outcome
+
+def _sig(st):
+       return (stat.S_IFMT(st[stat.ST_MODE]), 
+               st[stat.ST_SIZE], 
+               st[stat.ST_MTIME])
+
+def _do_cmp(f1, f2):
+       bufsize = BUFSIZE
+       fp1 , fp2 = open(f1, 'rb'), open(f2, 'rb')
+       while 1:
+               b1, b2 = fp1.read(bufsize), fp2.read(bufsize)
+               if b1!=b2: return 0
+               if not b1: return 1