Changeset 6625 for anuga_core

Timestamp:

Mar 26, 2009, 11:15:20 AM (16 years ago)

Author:

rwilson

Message:

Added file digest functions and test code.

Location:

anuga_core/source/anuga/utilities

Files:

• system_tools.py (modified) (2 diffs)
• test_system_tools.py (modified) (2 diffs)

anuga_core/source/anuga/utilities/system_tools.py

@@ -10 +10 @@
 import getpass
 import tarfile
+import md5
 
 
@@ -387 +388 @@
         o.extract(member, target_dir)
     o.close()
+
+
+##
+# @brief Return a hex digest (MD5) of a given file.
+# @param filename Path to the file of interest.
+# @return A hex digest string (16 bytes).
+# @note Uses MD5 digest.
+def get_file_hexdigest(filename):
+    '''Get a hex digest of a file.'''
+    
+    BLOCKSIZE = 1024*1024*10
+
+    m = md5.new()
+    fd = open(filename, 'r')
+    
+    while True:
+        data = fd.read(BLOCKSIZE)
+        if len(data) == 0:
+            break
+        m.update(data)
+        
+    fd.close()
+    return m.hexdigest()
+
+
+##
+# @brief Create a file containing a hexdigest string of a data file.
+# @param data_file Path to the file to get the hexdigest from.
+# @param digest_file Path to hexdigest file to create.
+# @note Uses MD5 digest.
+def make_digest_file(data_file, digest_file):
+    '''Create a file containing the hex digest string of a data file.'''
+    
+    hexdigest = get_file_hexdigest(data_file)
+    fd = open(digest_file, 'w')
+    fd.write(hexdigest)
+    fd.close()
+
+

anuga_core/source/anuga/utilities/test_system_tools.py

@@ -164 +164 @@
         test_it(source, expected)
 
+
     def test_tar_untar_files(self):
         '''Test that tarring & untarring files is OK.'''
@@ -209 +210 @@
         os.remove(tar_filename)
 
+
+    def test_file_digest(self):
+        '''Test that file digest functions give 'correct' answer.
+        
+        Not a good test as we get 'expected_digest' from a digest file,
+        but *does* alert us if the digest algorithm gives us a different string.
+        '''
+
+        # we expect this digest string from the data file
+        expected_digest = '831a1dde6edd365ec4163a47871fa21b'
+
+        # prepare test directory and filenames
+        tmp_dir = tempfile.mkdtemp()
+        data_file = os.path.join(tmp_dir, 'test.data')
+        digest_file = os.path.join(tmp_dir, 'test.digest')
+
+        # create the data file
+        data_line = 'The quick brown fox jumps over the lazy dog. 0123456789\n'
+        fd = open(data_file, 'w')
+        for line in range(100):
+            fd.write(data_line)
+        fd.close()
+
+        # create the digest file
+        make_digest_file(data_file, digest_file)
+
+        # get digest string for the data file
+        digest = get_file_hexdigest(data_file)
+
+        # check that digest is as expected, string
+        msg = ("Digest string wrong, got '%s', expected '%s'"
+               % (digest, expected_digest))
+        self.failUnless(expected_digest == digest, msg)
+
+        # check that digest is as expected, file
+        msg = ("Digest file wrong, got '%s', expected '%s'"
+               % (digest, expected_digest))
+        fd = open(digest_file, 'r')
+        digest = fd.readline()
+        fd.close()
+        self.failUnless(expected_digest == digest, msg)
+
+
 #-------------------------------------------------------------
 if __name__ == "__main__":