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

[Miss Islington (bot)]

https://github.com/python/cpython/commit/635743355d9dbffdc9aa7a2cc8de1403fbdb8d9b
commit: 635743355d9dbffdc9aa7a2cc8de1403fbdb8d9b
branch: 3.8
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2019-07-17T10:29:18-07:00
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.
(cherry picked from commit 719a062bcb7b08a56e6576dcd75f4244e6053209)

Co-authored-by: Abhilash Raj <maxking at users.noreply.github.com>

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 2fc8abcbc5ad..7dfd9780a6e9 100644
--- a/Lib/email/_header_value_parser.py
+++ b/Lib/email/_header_value_parser.py
@@ -1170,7 +1170,7 @@ 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 629174999961..f4aad851c677 100644
--- a/Lib/test/test_email/test__header_value_parser.py
+++ b/Lib/test/test_email/test__header_value_parser.py
@@ -503,6 +503,10 @@ 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.