1 files changed, 76 insertions, 0 deletions
diff --git a/copy-diff.py b/copy-diff.py
new file mode 100755
index 0000000..076f2da
--- /dev/null
+++ b/copy-diff.py
@@ -0,0 +1,76 @@
+#!/usr/bin/env python
+
+import os
+import shutil
+import sys
+
+BUFFER_SIZE = 1024
+
+def is_file_different(a, b):
+    if os.path.getsize(a) != os.path.getsize(b):
+        # If the file size is different, the content must be different.
+        return True
+
+    # Read the content of the files, and compare them.
+    result = False
+
+    fa = open(a, 'rb')
+    fb = open(b, 'rb')
+
+    while True:
+        buff_a = fa.read(BUFFER_SIZE)
+        buff_b = fb.read(BUFFER_SIZE)
+
+        if buff_a != buff_b:
+            # File is different in this block.
+            result = True
+            break
+
+        if len(buff_a) < BUFFER_SIZE:
+            # Finished
+            break
+
+    fa.close()
+    fb.close()
+
+    # File is the same.
+    return result
+
+def copyfile(src, dest):
+    if not os.path.exists(src):
+        raise ValueError('Source file not found')
+
+    # Make parent directory (if necessary)
+    destdir = os.path.dirname(dest)
+    if not os.path.exists(destdir):
+        try:
+            os.makedirs(destdir)
+        except os.error, e:
+            raise ValueError('Unable to create directory ' + destdir)
+    elif not os.path.isdir(destdir):
+        raise ValueError(destdir + ' is not a directory')
+
+    if not os.path.exists(dest) or is_file_different(src, dest):
+        # If the destination file does not exist or the source file is
+        # different from the destination file, then we copy the file.
+        shutil.copyfile(src, dest)
+
+def main():
+    if len(sys.argv) < 3:
+        print >> sys.stderr, 'USAGE:', sys.argv[0], '<srcfile> <destfile>'
+        sys.exit(1)
+
+    srcfile = os.path.abspath(sys.argv[1])
+    destfile = os.path.abspath(sys.argv[2])
+
+    if srcfile == destfile:
+        print >> sys.stderr, 'WARNING: <srcfile> is equal to <destfile>'
+    else:
+        try:
+            copyfile(srcfile, destfile)
+        except ValueError, e:
+            print >> sys.stderr, 'ERROR: ', e
+            sys.exit(1)
+
+if __name__ == '__main__':
+    main()