#!/usr/bin/env python

# Test case to demonstrate pyexpat crash under NetBSD.
# This causes a segfault with 2.6.7 under both 5.99.47/amd64 and
# 5.1_STABLE/i386.

from __future__ import print_function

import platform
import sys
import xml.parsers.expat

def start_element(name, attrs):
    pass

def end_element(name):
    pass

def char_data(data):
    pass

ep = None

def instantiate_parser():
    """Create an Expat parser instance (intended for re-use across multiple
    calls to its Parse() method) and attach generic delegate methods."""

    global ep

    try:
        ep = xml.parsers.expat.ParserCreate()

        ep.StartElementHandler = start_element
        ep.EndElementHandler = end_element
        ep.CharacterDataHandler = char_data

    except xml.parsers.expat.ExpatError as error:
        print("An error occurred during Expat set-up.  " \
              + "Error ID: " + str(error.code) \
              + ".  Error message: " \
              + xml.parsers.expat.ErrorString(error.code), file=sys.stderr)

# We're not actually using this function since we'll crash before it
# gets called...
def destroy_parser():
    """Invoke a final call to the Expat parser's Parse() method to pass the
    IsFinal value of True so it will destroy itself."""

    global ep

    if ep != None:
        try:
            ep.Parse('', True)
        except xml.parsers.expat.ExpatError as error:
            print("An error occurred during XML parsing.  " \
                + "Error ID: " + str(error.code) \
                + ".  Error message: " \
                + xml.parsers.expat.ErrorString(error.code), file=sys.stderr)
        finally:
            ep = None

def parse_doc(input_string):
    """Accepts a string representing relevant data from an XML file and
    initiates the extraction of relevant data via proxy methods."""

    global ep

    if ep == None:
        instantiate_parser()

    try:
        ep.Parse(input_string, False)
    except xml.parsers.expat.ExpatError as error:
        print("An error occurred during XML parsing.  " \
              + "Error ID: " + str(error.code) \
              + ".  Error message: " \
              + xml.parsers.expat.ErrorString(error.code), file=sys.stderr)
        print("Line number:", ep.ErrorLineNumber, file=sys.stderr)

small_test_file = \
"""<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<foobar>
  <foo>777</foo>
  <bar>443></bar>
</foobar>"""

# 3,970,856 bytes is the exact minimum file (buffer growth) size that triggers
# the segmentation fault in my NetBSD test environments.
if platform.system() == 'NetBSD':
    data_size = 248174
# XXX Expand as necessary for other OSes...  I haven't been able to get this to
# crash on Mac OS X with any input size...
else:
    data_size = 1

large_test_file = \
  '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' \
  + "\n<footwo>\n" \
  + "<foo>1234</foo>\n" * data_size \
  + '</footwo>'

if __name__ == "__main__":
    parse_doc(small_test_file)  # Initial, successful parse
    parse_doc(small_test_file)  # First triggering of a parser error
    parse_doc(large_test_file)  # Subsequent parser error, with more data
    destroy_parser()