Merged revisions 85450-85455,85460-85465 via svnmerge from
svn+ssh://svn.python.org/python/branches/py3k

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  r85450 | georg.brandl | 2010-10-14 08:35:53 +0200 (Do, 14 Okt 2010) | 1 line

  #7642: update to os.system() docs.
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  r85451 | georg.brandl | 2010-10-14 08:41:42 +0200 (Do, 14 Okt 2010) | 1 line

  #3865: add note about benchmarking with profilers, and move licensing stuff to bottom of document.
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  r85452 | georg.brandl | 2010-10-14 08:43:22 +0200 (Do, 14 Okt 2010) | 1 line

  #10046: small correction to atexit docs.
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  r85453 | georg.brandl | 2010-10-14 08:46:08 +0200 (Do, 14 Okt 2010) | 1 line

  #6825: small correction to split() docs.
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  r85454 | georg.brandl | 2010-10-14 08:48:47 +0200 (Do, 14 Okt 2010) | 1 line

  Mention 2to3.
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  r85455 | georg.brandl | 2010-10-14 08:59:45 +0200 (Do, 14 Okt 2010) | 1 line

  #1710703: write zipfile structures also in the case of closing a new, but empty, archive.
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  r85460 | georg.brandl | 2010-10-14 09:24:28 +0200 (Do, 14 Okt 2010) | 1 line

  #9964: fix running test_import under -O or -OO.
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  r85461 | georg.brandl | 2010-10-14 09:29:08 +0200 (Do, 14 Okt 2010) | 1 line

  #9964: fix lib2to3 fixer fix_operator when running under -OO.
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  r85462 | georg.brandl | 2010-10-14 09:32:52 +0200 (Do, 14 Okt 2010) | 1 line

  #9964: fix running test_xml_etree under -OO.
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  r85463 | georg.brandl | 2010-10-14 09:34:56 +0200 (Do, 14 Okt 2010) | 1 line

  Better check for "any optimize option given".
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  r85464 | georg.brandl | 2010-10-14 09:42:27 +0200 (Do, 14 Okt 2010) | 1 line

  #9964: fix running test_compileall under -O and -OO.
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  r85465 | georg.brandl | 2010-10-14 10:08:56 +0200 (Do, 14 Okt 2010) | 1 line

  #9964: fix running test_cmd_line_script under -O and -OO.
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diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index e32d2d0..26bc47b 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -902,6 +902,31 @@
         def test_read_return_size_deflated(self):
             self.check_read_return_size(zipfile.ZIP_DEFLATED)
 
+    def test_empty_zipfile(self):
+        # Check that creating a file in 'w' or 'a' mode and closing without
+        # adding any files to the archives creates a valid empty ZIP file
+        zipf = zipfile.ZipFile(TESTFN, mode="w")
+        zipf.close()
+        try:
+            zipf = zipfile.ZipFile(TESTFN, mode="r")
+        except zipfile.BadZipFile:
+            self.fail("Unable to create empty ZIP file in 'w' mode")
+
+        zipf = zipfile.ZipFile(TESTFN, mode="a")
+        zipf.close()
+        try:
+            zipf = zipfile.ZipFile(TESTFN, mode="r")
+        except:
+            self.fail("Unable to create empty ZIP file in 'a' mode")
+
+    def test_open_empty_file(self):
+        # Issue 1710703: Check that opening a file with less than 22 bytes
+        # raises a BadZipfile exception (rather than the previously unhelpful
+        # IOError)
+        f = open(TESTFN, 'w')
+        f.close()
+        self.assertRaises(zipfile.BadZipfile, zipfile.ZipFile, TESTFN, 'r')
+
     def tearDown(self):
         support.unlink(TESTFN)
         support.unlink(TESTFN2)
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index 3d2d57b..c376ee4 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -158,7 +158,13 @@
     """
     Read the ZIP64 end-of-archive records and use that to update endrec
     """
-    fpin.seek(offset - sizeEndCentDir64Locator, 2)
+    try:
+        fpin.seek(offset - sizeEndCentDir64Locator, 2)
+    except IOError:
+        # If the seek fails, the file is not large enough to contain a ZIP64
+        # end-of-archive record, so just return the end record we were given.
+        return endrec
+
     data = fpin.read(sizeEndCentDir64Locator)
     sig, diskno, reloff, disks = struct.unpack(structEndArchive64Locator, data)
     if sig != stringEndArchive64Locator:
@@ -723,14 +729,22 @@
         if key == 'r':
             self._GetContents()
         elif key == 'w':
-            pass
+            # set the modified flag so central directory gets written
+            # even if no files are added to the archive
+            self._didModify = True
         elif key == 'a':
-            try:                        # See if file is a zip file
+            try:
+                # See if file is a zip file
                 self._RealGetContents()
                 # seek to start of directory and overwrite
                 self.fp.seek(self.start_dir, 0)
-            except BadZipfile:          # file is not a zip file, just append
+            except BadZipfile:
+                # file is not a zip file, just append
                 self.fp.seek(0, 2)
+
+                # set the modified flag so central directory gets written
+                # even if no files are added to the archive
+                self._didModify = True
         else:
             if not self._filePassed:
                 self.fp.close()
@@ -751,7 +765,10 @@
     def _RealGetContents(self):
         """Read in the table of contents for the ZIP file."""
         fp = self.fp
-        endrec = _EndRecData(fp)
+        try:
+            endrec = _EndRecData(fp)
+        except IOError:
+            raise BadZipfile("File is not a zip file")
         if not endrec:
             raise BadZipfile("File is not a zip file")
         if self.debug > 1: