Fix for SF bug #1175396: readline() will now read one more character, if

the last character read is "\r" (and size is None, i.e. we're allowed to
call read() multiple times), so that we can return the correct line ending
(this additional character might be a "\n").

If the stream is temporarily exhausted, we might return the wrong line ending
(if the last character read is "\r" and the next one (after the byte stream
provides more data) is "\n", but at least the atcr member ensure that we
get the correct number of lines (i.e. this "\n" will not be treated as
another line ending.)

Lib/codecs.py

@@ -310,6 +310,15 @@ class StreamReader(Codec):
                 data = data[1:]
             if data:
                 self.atcr = data.endswith(u"\r")
+                # If we're at a "\r" (and are allowed to read more), read one
+                # extra character (which might be a "\n") to get a proper
+                # line ending (If the stream is temporarily exhausted we return
+                # the wrong line ending, but at least we won't generate a bogus
+                # second line.
+                if self.atcr and size is None:
+                    data += self.read(size=1, chars=1)
+                    self.atcr = data.endswith(u"\r")
+
             line += data
             lines = line.splitlines(True)
             if lines:

Lib/test/test_codecs.py

@@ -73,16 +73,89 @@ class ReadTest(unittest.TestCase):
         # reader has to look ahead whether this is a lone \r or a \r\n
         for size in xrange(80):
             for lineend in u"\n \r\n \r \u2028".split():
-                s = size*u"a" + lineend + u"xxx\n"
+                s = 10*(size*u"a" + lineend + u"xxx\n")
+                reader = getreader(s)
+                for i in xrange(10):
                     self.assertEqual(
-                    getreader(s).readline(keepends=True),
+                        reader.readline(keepends=True),
                         size*u"a" + lineend,
                     )
+                reader = getreader(s)
+                for i in xrange(10):
                     self.assertEqual(
-                    getreader(s).readline(keepends=False),
+                        reader.readline(keepends=False),
                         size*u"a",
                     )
 
+    def test_bug1175396(self):
+        s = [
+            '<%!--===================================================\r\n',
+            '    BLOG index page: show recent articles,\r\n',
+            '    today\'s articles, or articles of a specific date.\r\n',
+            '========================================================--%>\r\n',
+            '<%@inputencoding="ISO-8859-1"%>\r\n',
+            '<%@pagetemplate=TEMPLATE.y%>\r\n',
+            '<%@import=import frog.util, frog%>\r\n',
+            '<%@import=import frog.objects%>\r\n',
+            '<%@import=from frog.storageerrors import StorageError%>\r\n',
+            '<%\r\n',
+            '\r\n',
+            'import logging\r\n',
+            'log=logging.getLogger("Snakelets.logger")\r\n',
+            '\r\n',
+            '\r\n',
+            'user=self.SessionCtx.user\r\n',
+            'storageEngine=self.SessionCtx.storageEngine\r\n',
+            '\r\n',
+            '\r\n',
+            'def readArticlesFromDate(date, count=None):\r\n',
+            '    entryids=storageEngine.listBlogEntries(date)\r\n',
+            '    entryids.reverse() # descending\r\n',
+            '    if count:\r\n',
+            '        entryids=entryids[:count]\r\n',
+            '    try:\r\n',
+            '        return [ frog.objects.BlogEntry.load(storageEngine, date, Id) for Id in entryids ]\r\n',
+            '    except StorageError,x:\r\n',
+            '        log.error("Error loading articles: "+str(x))\r\n',
+            '        self.abort("cannot load articles")\r\n',
+            '\r\n',
+            'showdate=None\r\n',
+            '\r\n',
+            'arg=self.Request.getArg()\r\n',
+            'if arg=="today":\r\n',
+            '    #-------------------- TODAY\'S ARTICLES\r\n',
+            '    self.write("<h2>Today\'s articles</h2>")\r\n',
+            '    showdate = frog.util.isodatestr() \r\n',
+            '    entries = readArticlesFromDate(showdate)\r\n',
+            'elif arg=="active":\r\n',
+            '    #-------------------- ACTIVE ARTICLES redirect\r\n',
+            '    self.Yredirect("active.y")\r\n',
+            'elif arg=="login":\r\n',
+            '    #-------------------- LOGIN PAGE redirect\r\n',
+            '    self.Yredirect("login.y")\r\n',
+            'elif arg=="date":\r\n',
+            '    #-------------------- ARTICLES OF A SPECIFIC DATE\r\n',
+            '    showdate = self.Request.getParameter("date")\r\n',
+            '    self.write("<h2>Articles written on %s</h2>"% frog.util.mediumdatestr(showdate))\r\n',
+            '    entries = readArticlesFromDate(showdate)\r\n',
+            'else:\r\n',
+            '    #-------------------- RECENT ARTICLES\r\n',
+            '    self.write("<h2>Recent articles</h2>")\r\n',
+            '    dates=storageEngine.listBlogEntryDates()\r\n',
+            '    if dates:\r\n',
+            '        entries=[]\r\n',
+            '        SHOWAMOUNT=10\r\n',
+            '        for showdate in dates:\r\n',
+            '            entries.extend( readArticlesFromDate(showdate, SHOWAMOUNT-len(entries)) )\r\n',
+            '            if len(entries)>=SHOWAMOUNT:\r\n',
+            '                break\r\n',
+            '                \r\n',
+        ]
+        stream = StringIO.StringIO("".join(s).encode(self.encoding))
+        reader = codecs.getreader(self.encoding)(stream)
+        for (i, line) in enumerate(reader):
+            self.assertEqual(line, s[i])
+
     def test_readlinequeue(self):
         q = Queue()
         writer = codecs.getwriter(self.encoding)(q)