Changeset 5048

Timestamp:

Feb 19, 2008, 10:30:48 AM (16 years ago)

Author:

ole

Message:

Refactored 64 bit fix into new function: safe_crc

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

@@ -170 +170 @@
         if verbose is True:
             print 'Version info stored to %s' %filename
-            
+
+def safe_crc(string):
+    """64 bit safe crc computation.
+
+       See Guido's 64 bit fix at http://bugs.python.org/issue1202            
+    """
+
+    from zlib import crc32
+    import os
+
+    x = crc32(string)
+        
+    if os.name == 'posix' and os.uname()[4] == 'x86_64':
+        crcval = x - ((x & 0x80000000) << 1)
+    else:
+        crcval = x
+        
+    return crcval
+
 
 def compute_checksum(filename, max_length=2**20):
@@ -180 +198 @@
     """
 
-    from zlib import crc32
-    
     fid = open(filename, 'rb') # Use binary for portability
-    x = crc32(fid.read(max_length))
-
+    crcval = safe_crc(fid.read(max_length))
     fid.close()
 
-    if os.name == 'posix' and os.uname()[4] == 'x86_64':
-        #Guido's 64 bit fix (http://bugs.python.org/issue1202)        
-        crcval = x - ((x & 0x80000000) << 1)
-    else:
-        crcval = x
     return crcval

anuga_core/source/anuga/utilities/test_system_tools.py

@@ -39 +39 @@
         # Generate a text file
         tmp_fd , tmp_name = mkstemp(suffix='.tmp', dir='.')
-        fid = os.fdopen(tmp_fd, 'w')
+        fid = os.fdopen(tmp_fd, 'w+b')
         string = 'My temp file with textual content. AAAABBBBCCCC1234'
         fid.write(string)
         fid.close()
 
-        ref_crc = zlib.crc32(string)
+        # Have to apply the 64 bit fix here since we aren't comparing two
+        # files, but rather a string and a file.
+        ref_crc = safe_crc(string)
+
         checksum = compute_checksum(tmp_name)
         assert checksum == ref_crc
@@ -60 +63 @@
         fid.close()
 
-
-        ref_crc = zlib.crc32(string)
+        ref_crc = safe_crc(string)
         checksum = compute_checksum(tmp_name)