Solve SF bug #231249: cgi.py opens too many (temporary) files.
class FieldStorage: this patch changes read_lines() and co. to use a
StringIO() instead of a real file. The write() calls are redirected
to a private method that replaces it with a real, external file only
when it gets too big (> 1000 bytes).
This avoids problems in forms using the multipart/form-data encoding
with many fields. The original code created a temporary file for
*every* field (not just for file upload fields), thereby sometimes
exceeding the open file limit of some systems.
Note that the simpler solution "use a real file only for file uploads"
can't be used because the form field parser has no way to tell which
fields correspond to file uploads.
It's *possible* but extremely unlikely that this would break someone's
code; they would have to be stepping way outside the documented
interface for FieldStorage and use f.file.fileno(), or depend on
overriding make_file() to return a file-like object with additional
known properties.
diff --git a/Lib/cgi.py b/Lib/cgi.py
index 4fa696f..3534360 100755
--- a/Lib/cgi.py
+++ b/Lib/cgi.py
@@ -28,7 +28,7 @@
# responsible for its maintenance.
#
-__version__ = "2.5"
+__version__ = "2.6"
# Imports
@@ -633,12 +633,20 @@
def read_lines(self):
"""Internal: read lines until EOF or outerboundary."""
- self.file = self.make_file('')
+ self.file = self.__file = StringIO()
if self.outerboundary:
self.read_lines_to_outerboundary()
else:
self.read_lines_to_eof()
+ def __write(self, line):
+ if self.__file is not None:
+ if self.__file.tell() + len(line) > 1000:
+ self.file = self.make_file('')
+ self.file.write(self.__file.getvalue())
+ self.__file = None
+ self.file.write(line)
+
def read_lines_to_eof(self):
"""Internal: read lines until EOF."""
while 1:
@@ -646,7 +654,7 @@
if not line:
self.done = -1
break
- self.file.write(line)
+ self.__write(line)
def read_lines_to_outerboundary(self):
"""Internal: read lines until outerboundary."""
@@ -674,7 +682,7 @@
line = line[:-1]
else:
delim = ""
- self.file.write(odelim + line)
+ self.__write(odelim + line)
def skip_lines(self):
"""Internal: skip lines until outer boundary if defined."""