8000 gh-129349: Accept bytes in bytes.fromhex()/bytearray.fromhex() by lordmauve · Pull Request #129844 · python/cpython · GitHub
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gh-129349: Accept bytes in bytes.fromhex()/bytearray.fromhex() #129844

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Merged
merged 10 commits into from
Mar 12, 2025
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gh-129349: Accept bytes in bytes.fromhex()/bytearray.fromhex() #129844

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81d7ea2
Accept bytes in bytes.fromhex()/bytearray.fromhex()
lordmauve Feb 8, 2025
ea02542
Update documentation
lordmauve Feb 8, 2025
76d28ce
Apply suggestions from @picnixz in #129844
lordmauve Feb 9, 2025
cff091c
Fix sphinx-lint
lordmauve Mar 7, 2025
be92188
Mention bytearray in docs and blurb
lordmauve Mar 7, 2025
b0e3eb5
Use buffer protocol to support all byte-like objects
lordmauve Mar 7, 2025
ef92b4e
Insert missing braces
lordmauve Mar 7, 2025
685f583
Update Doc/library/stdtypes.rst
vstinner Mar 8, 2025
f859c3c
Add test for invalid type in bytes.fromhex()
lordmauve Mar 9, 2025
31b9ab0
PEP-7
lordmauve Mar 10, 2025
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8 changes: 8 additions & 0 deletions Doc/library/stdtypes.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -2744,6 +2744,10 @@ data and are closely related to string objects in a variety of other ways.
:meth:`bytes.fromhex` now skips all ASCII whitespace in the string,
not just spaces.

.. versionchanged:: next
:meth:`bytes.fromhex` now accepts ASCII :class:`bytes` and
:term:`bytes-like objects <bytes-like object>` as input.

A reverse conversion function exists to transform a bytes object into its
hexadecimal representation.

Expand Down Expand Up @@ -2829,6 +2833,10 @@ objects.
:meth:`bytearray.fromhex` now skips all ASCII whitespace in the string,
not just spaces.

.. versionchanged:: next
:meth:`bytearray.fromhex` now accepts ASCII :class:`bytes` and
:term:`bytes-like objects <bytes-like object>` as input.

A reverse conversion function exists to transform a bytearray object into its
hexadecimal representation.

Expand Down
4 changes: 4 additions & 0 deletions Doc/whatsnew/3.14.rst
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Expand Up @@ -354,6 +354,10 @@ Other language changes
(with :func:`format` or :ref:`f-strings`).
(Contrubuted by Sergey B Kirpichev in :gh:`87790`.)

* The :func:`bytes.fromhex` and :func:`bytearray.fromhex` methods now accept
ASCII :class:`bytes` and :term:`bytes-like objects <bytes-like object>`.
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Question: are bytes also bytes-like objects? if so, you can just link the term. Or more generally, isn't it objects that support the buffer protocol?

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Yes, but it seems less accessible to users to just link bytes-like object because that dives into a description of the buffer protocol which is lower level than the audience I was writing for in builtins docs.

Maybe the fault is with :term:\bytes-like object`` because it could just list types that duck-type like bytes.

So I hedged and did both.

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@picnixz picnixz Mar 7, 2025 •
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You could sa "that support the buffer protocol such as memoryviews" and add a link to whatever example of a type that supports the buffer protocol you used

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I prefer to say "bytes and bytes-like", it's more explicit.

(Contributed by Daniel Pope in :gh:`129349`.)

* ``\B`` in :mod:`regular expression <re>` now matches empty input string.
Now it is always the opposite of ``\b``.
(Contributed by Serhiy Storchaka in :gh:`124130`.)
Expand Down
23 changes: 22 additions & 1 deletion Lib/test/test_bytes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -450,13 +450,34 @@ def test_fromhex(self):

# check that ASCII whitespace is ignored
self.assertEqual(self.type2test.fromhex(' 1A\n2B\t30\v'), b)
self.assertEqual(self.type2test.fromhex(b' 1A\n2B\t30\v'), b)
for c in "\x09\x0A\x0B\x0C\x0D\x20":
self.assertEqual(self.type2test.fromhex(c), self.type2test())
for c in "\x1C\x1D\x1E\x1F\x85\xa0\u2000\u2002\u2028":
self.assertRaises(ValueError, self.type2test.fromhex, c)

# Check that we can parse bytes and bytearray
tests = [
("bytes", bytes),
("bytearray", bytearray),
("memoryview", memoryview),
("array.array", lambda bs: array.array('B', bs)),
]
for name, factory in tests:
with self.subTest(name=name):
self.assertEqual(self.type2test.fromhex(factory(b' 1A 2B 30 ')), b)

# Invalid bytes are rejected
for u8 in b"\0\x1C\x1D\x1E\x1F\x85\xa0":
b = bytes([30, 31, u8])
self.assertRaises(ValueError, self.type2test.fromhex, b)

self.assertEqual(self.type2test.fromhex('0000'), b'\0\0')
self.assertRaises(TypeError, self.type2test.fromhex, b'1B')
with self.assertRaisesRegex(
TypeError,
r'fromhex\(\) argument must be str or bytes-like, not tuple',
):
self.type2test.fromhex(())
self.assertRaises(ValueError, self.type2test.fromhex, 'a')
self.assertRaises(ValueError, self.type2test.fromhex, 'rt')
self.assertRaises(ValueError, self.type2test.fromhex, '1a b cd')
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2025-02-08-09-55-33.gh-issue-129349.PkcG-l.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
:meth:`bytes.fromhex` and :meth:`bytearray.fromhex` now accepts ASCII
:class:`bytes` and :term:`bytes-like objects <bytes-like object>`.
6 changes: 3 additions & 3 deletions Objects/bytearrayobject.c
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Expand Up @@ -2533,7 +2533,7 @@ bytearray_splitlines_impl(PyByteArrayObject *self, int keepends)
@classmethod
bytearray.fromhex

string: unicode
string: object
/

Create a bytearray object from a string of hexadecimal numbers.
Expand All @@ -2543,8 +2543,8 @@ Example: bytearray.fromhex('B9 01EF') -> bytearray(b'\\xb9\\x01\\xef')
[clinic start generated code]*/

static PyObject *
bytearray_fromhex_impl(PyTypeObject *type, PyObject *string)
/*[clinic end generated code: output=8f0f0b6d30fb3ba0 input=f033a16d1fb21f48]*/
bytearray_fromhex(PyTypeObject *type, PyObject *string)
/*[clinic end generated code: output=da84dc708e9c4b36 input=7e314e5b2d7ab484]*/
{
PyObject *result = _PyBytes_FromHex(string, type == &PyByteArray_Type);
if (type != &PyByteArray_Type && result != NULL) {
Expand Down
72 changes: 49 additions & 23 deletions Objects/bytesobject.c
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F438
Original file line number Diff line number Diff line change
Expand Up @@ -2484,7 +2484,7 @@ bytes_splitlines_impl(PyBytesObject *self, int keepends)
@classmethod
bytes.fromhex

string: unicode
string: object
/

Create a bytes object from a string of hexadecimal numbers.
Expand All @@ -2494,8 +2494,8 @@ Example: bytes.fromhex('B9 01EF') -> b'\\xb9\\x01\\xef'.
[clinic start generated code]*/

static PyObject *
bytes_fromhex_impl(PyTypeObject *type, PyObject *string)
/*[clinic end generated code: output=0973acc63661bb2e input=bf4d1c361670acd3]*/
bytes_fromhex(PyTypeObject *type, PyObject *string)
/*[clinic end generated code: output=d458ec88195da6b3 input=f37d98ed51088a21]*/
{
PyObject *result = _PyBytes_FromHex(string, 0);
if (type != &PyBytes_Type && result != NULL) {
Expand All @@ -2510,37 +2510,55 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
char *buf;
Py_ssize_t hexlen, invalid_char;
unsigned int top, bot;
const Py_UCS1 *str, *end;
const Py_UCS1 *str, *start, *end;
_PyBytesWriter writer;
Py_buffer view;
view.obj = NULL;

_PyBytesWriter_Init(&writer);
writer.use_bytearray = use_bytearray;

assert(PyUnicode_Check(string));
hexlen = PyUnicode_GET_LENGTH(string);
if (PyUnicode_Check(string)) {
hexlen = PyUnicode_GET_LENGTH(string);

if (!PyUnicode_IS_ASCII(string)) {
const void *data = PyUnicode_DATA(string);
int kind = PyUnicode_KIND(string);
Py_ssize_t i;
if (!PyUnicode_IS_ASCII(string)) {
const void *data = PyUnicode_DATA(string);
int kind = PyUnicode_KIND(string);
Py_ssize_t i;

/* search for the first non-ASCII character */
for (i = 0; i < hexlen; i++) {
if (PyUnicode_READ(kind, data, i) >= 128)
break;
/* search for the first non-ASCII character */
for (i = 0; i < hexlen; i++) {
if (PyUnicode_READ(kind, data, i) >= 128)
break;
}
invalid_char = i;
goto error;
}
invalid_char = i;
goto error;
}

assert(PyUnicode_KIND(string) == PyUnicode_1BYTE_KIND);
str = PyUnicode_1BYTE_DATA(string);
assert(PyUnicode_KIND(string) == PyUnicode_1BYTE_KIND);
str = PyUnicode_1BYTE_DATA(string);
}
else if (PyObject_CheckBuffer(string)) {
if (PyObject_GetBuffer(string, &view, PyBUF_SIMPLE) != 0) {
return NULL;
}
hexlen = view.len;
str = view.buf;
}
else {
PyErr_Format(PyExc_TypeError,
"fromhex() argument must be str or bytes-like, not %T",
string);
return NULL;
}

/* This overestimates if there are spaces */
buf = _PyBytesWriter_Alloc(&writer, hexlen / 2);
if (buf == NULL)
return NULL;
if (buf == NULL) {
goto release_buffer;
}

start = str;
end = str + hexlen;
while (str < end) {
/* skip over spaces in the input */
Expand All @@ -2554,7 +2572,7 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)

top = _PyLong_DigitValue[*str];
if (top >= 16) {
invalid_char = str - PyUnicode_1BYTE_DATA(string);
invalid_char = str - start;
goto error;
}
str++;
Expand All @@ -2565,7 +2583,7 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
if (str >= end){
invalid_char = -1;
} else {
invalid_char = str - PyUnicode_1BYTE_DATA(string);
invalid_char = str - start;
}
goto error;
}
Expand All @@ -2574,6 +2592,9 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
*buf++ = (unsigned char)((top << 4) + bot);
}

if (view.obj != NULL) {
PyBuffer_Release(&view);
}
return _PyBytesWriter_Finish(&writer, buf);

error:
Expand All @@ -2586,6 +2607,11 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
"fromhex() arg at position %zd", invalid_char);
}
_PyBytesWriter_Dealloc(&writer);

release_buffer:
if (view.obj != NULL) {
PyBuffer_Release(&view);
}
return NULL;
}

Expand Down
22 changes: 1 addition & 21 deletions Objects/clinic/bytearrayobject.c.h
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22 changes: 1 addition & 21 deletions Objects/clinic/bytesobject.c.h
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