[Python-checkins] Fix IndexError when parsing unexpectedly ending quoted-string. (GH-14813)

[Barry Warsaw]

https://github.com/python/cpython/commit/719a062bcb7b08a56e6576dcd75f4244e6053209
commit: 719a062bcb7b08a56e6576dcd75f4244e6053209
branch: master
author: Abhilash Raj <maxking at users.noreply.github.com>
committer: Barry Warsaw <barry at python.org>
date: 2019-07-17T09:48:52-07:00
summary:

Fix IndexError when parsing unexpectedly ending quoted-string. (GH-14813)

This exception was caused because the input ended unexpectedly with only one
single quote instead of a pair with some value inside it.

files:
A Misc/NEWS.d/next/Library/2019-07-17-06-54-43.bpo-37491.op0aMs.rst
M Lib/email/_header_value_parser.py
M Lib/test/test_email/test__header_value_parser.py

diff --git a/Lib/email/_header_value_parser.py b/Lib/email/_header_value_parser.py
index 66b042ee0ef0..daff57b9cfa2 100644
--- a/Lib/email/_header_value_parser.py
+++ b/Lib/email/_header_value_parser.py
@@ -1191,7 +1191,7 @@ def get_bare_quoted_string(value):
             "expected '\"' but found '{}'".format(value))
     bare_quoted_string = BareQuotedString()
     value = value[1:]
-    if value[0] == '"':
+    if value and value[0] == '"':
         token, value = get_qcontent(value)
         bare_quoted_string.append(token)
     while value and value[0] != '"':
diff --git a/Lib/test/test_email/test__header_value_parser.py b/Lib/test/test_email/test__header_value_parser.py
index a83915d6d059..4fa56b16c478 100644
--- a/Lib/test/test_email/test__header_value_parser.py
+++ b/Lib/test/test_email/test__header_value_parser.py
@@ -522,6 +522,10 @@ def test_get_bare_quoted_string_only_quotes(self):
         self._test_get_x(parser.get_bare_quoted_string,
                          '""', '""', '', [], '')
 
+    def test_get_bare_quoted_string_missing_endquotes(self):
+        self._test_get_x(parser.get_bare_quoted_string,
+                         '"', '""', '', [errors.InvalidHeaderDefect], '')
+
     def test_get_bare_quoted_string_following_wsp_preserved(self):
         self._test_get_x(parser.get_bare_quoted_string,
              '"foo"\t bar', '"foo"', 'foo', [], '\t bar')
diff --git a/Misc/NEWS.d/next/Library/2019-07-17-06-54-43.bpo-37491.op0aMs.rst b/Misc/NEWS.d/next/Library/2019-07-17-06-54-43.bpo-37491.op0aMs.rst
new file mode 100644
index 000000000000..af4287ba478b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-07-17-06-54-43.bpo-37491.op0aMs.rst
@@ -0,0 +1,2 @@
+Fix ``IndexError`` when parsing email headers with unexpectedly ending
+bare-quoted string value. Patch by Abhilash Raj.