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

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

1 files changed, 57 insertions, 0 deletions

diff --git a/Lib/filecmp.py b/Lib/filecmp.py
new file mode 100644
index 0000000000..e1a30bc5f0
--- /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