Make FileForWriteOnceCompareSame respect umask.

python/lsst/daf/persistence/safeFileIo.py

@@ -75,6 +75,9 @@ def FileForWriteOnceCompareSame(name):
             # If the symlink was created then this is the process that created the first instance of the
             # file, and we know its contents match. Move the temp file over the symlink.
             os.rename(temp.name, name)
+            # At this point, we know the file has just been created. Set permissions according to the
+            # current umask.
+            setFileMode(name)
         except OSError as e:
             if e.errno != errno.EEXIST:
                 raise e

tests/safeFileIo.py

@@ -24,6 +24,7 @@
 
 import os
 import shutil
+import stat
 import unittest
 
 import lsst.daf.persistence as dp
@@ -75,6 +76,20 @@ def writeNonMatchingFile():
                 f.write('fop\n')
         self.assertRaises(RuntimeError, writeNonMatchingFile)
 
+    def testPermissions(self):
+        """Check that the file is created with the current umask."""
+        # The only way to get the umask is to set it.
+        umask = os.umask(0)
+        os.umask(umask)
+
+        fileName = os.path.join(ROOT, 'safeFileIo/test.txt')
+        with dp.safeFileIo.FileForWriteOnceCompareSame(fileName) as f:
+            f.write('bar\n')
+            f.write('baz\n')
+
+        filePerms = stat.S_IMODE(os.lstat(fileName).st_mode)
+        self.assertEqual(~umask & 0o666, filePerms)
+
 
 class MemoryTester(lsst.utils.tests.MemoryTestCase):
     pass