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bpo-36311: Fixes decoding multibyte characters around chunk boundaries and improves decoding performance (GH-15083)

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Steve Dower 2019-08-21 16:22:33 -07:00 committed by GitHub
parent df0c21ff46
commit 7ebdda0dbe
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 29 additions and 9 deletions
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20
Lib/test/test_codecs.py
View file

@ -3075,13 +3075,13 @@ def test_mbcs_alias(self):
self.assertEqual(codec.name, 'mbcs')
@support.bigmemtest(size=2**31, memuse=7, dry_run=False)
def test_large_input(self):
def test_large_input(self, size):
# Test input longer than INT_MAX.
# Input should contain undecodable bytes before and after
# the INT_MAX limit.
encoded = (b'01234567' * (2**28-1) +
encoded = (b'01234567' * ((size//8)-1) +
b'\x85\x86\xea\xeb\xec\xef\xfc\xfd\xfe\xff')
self.assertEqual(len(encoded), 2**31+2)
self.assertEqual(len(encoded), size+2)
decoded = codecs.code_page_decode(932, encoded, 'surrogateescape', True)
self.assertEqual(decoded[1], len(encoded))
del encoded
@ -3092,6 +3092,20 @@ def test_large_input(self):
'\udc85\udc86\udcea\udceb\udcec'
'\udcef\udcfc\udcfd\udcfe\udcff')
@support.bigmemtest(size=2**31, memuse=6, dry_run=False)
def test_large_utf8_input(self, size):
# Test input longer than INT_MAX.
# Input should contain a decodable multi-byte character
# surrounding INT_MAX
encoded = (b'0123456\xed\x84\x80' * (size//8))
self.assertEqual(len(encoded), size // 8 * 10)
decoded = codecs.code_page_decode(65001, encoded, 'ignore', True)
self.assertEqual(decoded[1], len(encoded))
del encoded
self.assertEqual(len(decoded[0]), size)
self.assertEqual(decoded[0][:10], '0123456\ud10001')
self.assertEqual(decoded[0][-11:], '56\ud1000123456\ud100')
class ASCIITest(unittest.TestCase):
def test_encode(self):

2
Misc/NEWS.d/next/Core and Builtins/2019-08-02-15-01-33.bpo-36311.uY5vt-.rst Normal file
View file

@ -0,0 +1,2 @@
Decoding bytes objects larger than 2GiB is faster and no longer fails when a
multibyte characters spans a chunk boundary.

16
Objects/unicodeobject.c
View file

@ -7186,6 +7186,12 @@ PyUnicode_AsASCIIString(PyObject *unicode)
#define NEED_RETRY
#endif
/* INT_MAX is the theoretical largest chunk (or INT_MAX / 2 when
transcoding from UTF-16), but INT_MAX / 4 perfoms better in
both cases also and avoids partial characters overrunning the
length limit in MultiByteToWideChar on Windows */
#define DECODING_CHUNK_SIZE (INT_MAX/4)
#ifndef WC_ERR_INVALID_CHARS
# define WC_ERR_INVALID_CHARS 0x0080
#endif
@ -7422,8 +7428,8 @@ decode_code_page_stateful(int code_page,
do
{
#ifdef NEED_RETRY
if (size > INT_MAX) {
chunk_size = INT_MAX;
if (size > DECODING_CHUNK_SIZE) {
chunk_size = DECODING_CHUNK_SIZE;
final = 0;
done = 0;
}
@ -7827,10 +7833,8 @@ encode_code_page(int code_page,
do
{
#ifdef NEED_RETRY
/* UTF-16 encoding may double the size, so use only INT_MAX/2
chunks. */
if (len > INT_MAX/2) {
chunk_len = INT_MAX/2;
if (len > DECODING_CHUNK_SIZE) {
chunk_len = DECODING_CHUNK_SIZE;
done = 0;
}
else