prism-auto: Use line ending agnostic file compare

The previously used filecmp.cmp opens the files to be compared in 'rb'
mode, i.e., it will tell us that two files that differ only in the
line-ending encoding (CRLF vs LF) are not equivalent.  However, we'd
like to get the export tests to succeed on Windows, regardless of the
line endings. So, we provide our own file comparison method that opens
the file in 'rU' mode (universal newline mode), which converts all the
newline encodings to '\n' transparently.


git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@11880 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/etc/scripts/prism-auto

@@ -11,7 +11,7 @@
 
 # Run "prism-auto -h" for details of further options.
 
-import os,sys,re,subprocess,signal,tempfile,functools,filecmp,logging,time,platform
+import os,sys,re,subprocess,signal,tempfile,functools,logging,time,platform
 from pipes import quote
 from optparse import OptionParser
 
@@ -24,6 +24,22 @@ def isWindows():
     s = platform.system()
     return s == 'Windows' or re.match('CYGWIN', s) != None
 
+# compare two files (with filenames f1,f2) for equality
+def compareFiles(f1,f2):
+    # We open the files in 'rU' mode (universal newline mode),
+    # which automatically converts all the different newline
+    # encodings to '\n'.
+    # This allow the two files to differ in their
+    # line ending encodings without affecting equality
+    with open(f1, 'rU') as fp1, open(f2, 'rU') as fp2:
+        while True:
+            s1 = fp1.readline()
+            s2 = fp2.readline()
+            if s1 != s2:  # mismatch
+                return False
+            if s1 == '':  # EOF (in both files)
+                return True
+
 # returns a sorted list of files / directories in dir
 def sortedListDir(dir):
     list = os.listdir(dir);
@@ -429,7 +445,7 @@ def verifyAndCleanupExports(outFiles, exportPrefix):
             if options.noExportTests:
                 msg = msg + "SKIPPED"
                 os.remove(expFile)
-            elif filecmp.cmp(outFile, expFile):
+            elif compareFiles(outFile, expFile):
                 # If successful, notify and delete exported file
                 msg = msg + "PASS"
                 os.remove(expFile)