Replace cgi module with email.message (#11098)

Author: fungi

news/11099.process.rst

@@ -0,0 +1 @@
+Remove reliance on the stdlib cgi module, which is deprecated in Python 3.11.

src/pip/_internal/index/collector.py

@@ -2,8 +2,8 @@
 The main purpose of this module is to expose LinkCollector.collect_sources().
 """
 
-import cgi
 import collections
+import email.message
 import functools
 import itertools
 import logging
@@ -155,9 +155,11 @@ def _get_html_response(url: str, session: PipSession) -> Response:
 def _get_encoding_from_headers(headers: ResponseHeaders) -> Optional[str]:
     """Determine if we have any encoding information in our headers."""
     if headers and "Content-Type" in headers:
-        content_type, params = cgi.parse_header(headers["Content-Type"])
-        if "charset" in params:
-            return params["charset"]
+        m = email.message.Message()
+        m["content-type"] = headers["Content-Type"]
+        charset = m.get_param("charset")
+        if charset:
+            return str(charset)
     return None
 
 

src/pip/_internal/network/download.py

@@ -1,6 +1,6 @@
 """Download files with progress indicators.
 """
-import cgi
+import email.message
 import logging
 import mimetypes
 import os
@@ -81,12 +81,13 @@ def parse_content_disposition(content_disposition: str, default_filename: str) -
     Parse the "filename" value from a Content-Disposition header, and
     return the default filename if the result is empty.
     """
-    _type, params = cgi.parse_header(content_disposition)
-    filename = params.get("filename")
+    m = email.message.Message()
+    m["content-type"] = content_disposition
+    filename = m.get_param("filename")
     if filename:
         # We need to sanitize the filename to prevent directory traversal
         # in case the filename contains ".." path parts.
-        filename = sanitize_content_filename(filename)
+        filename = sanitize_content_filename(str(filename))
     return filename or default_filename