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gh-129813, PEP 782: Use PyBytesWriter in _PyBytes_FromList() #138837

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Merged
merged 1 commit into from
Sep 13, 2025
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gh-129813, PEP 782: Use PyBytesWriter in _PyBytes_FromList() #138837

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137 changes: 78 additions & 59 deletions Objects/bytesobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,9 @@ class bytes "PyBytesObject *" "&PyBytes_Type"
/* Forward declaration */
Py_LOCAL_INLINE(Py_ssize_t) _PyBytesWriter_GetSize(_PyBytesWriter *writer,
char *str);
static void* _PyBytesWriter_ResizeAndUpdatePointer(PyBytesWriter *writer,
Py_ssize_t size, void *data);
static Py_ssize_t _PyBytesWriter_GetAllocated(PyBytesWriter *writer);


#define CHARACTERS _Py_SINGLETON(bytes_characters)
Expand Down Expand Up @@ -2535,17 +2538,13 @@ bytes_fromhex_impl(PyTypeObject *type, PyObject *string)
PyObject*
_PyBytes_FromHex(PyObject *string, int use_bytearray)
{
char *buf;
Py_ssize_t hexlen, invalid_char;
unsigned int top, bot;
const Py_UCS1 *str, *start, *end;
_PyBytesWriter writer;
PyBytesWriter *writer = NULL;
Py_buffer view;
view.obj = NULL;

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

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

Expand Down Expand Up @@ -2581,10 +2580,16 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
}

/* This overestimates if there are spaces */
buf = _PyBytesWriter_Alloc(&writer, hexlen / 2);
if (buf == NULL) {
if (use_bytearray) {
writer = _PyBytesWriter_CreateByteArray(hexlen / 2);
}
else {
writer = PyBytesWriter_Create(hexlen / 2);
}
if (writer == NULL) {
goto release_buffer;
}
char *buf = PyBytesWriter_GetData(writer);

start = str;
end = str + hexlen;
Expand Down Expand Up @@ -2623,7 +2628,7 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
if (view.obj != NULL) {
PyBuffer_Release(&view);
}
return _PyBytesWriter_Finish(&writer, buf);
return PyBytesWriter_FinishWithPointer(writer, buf);

error:
if (invalid_char == -1) {
Expand All @@ -2634,7 +2639,7 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
"non-hexadecimal number found in "
"fromhex() arg at position %zd", invalid_char);
}
_PyBytesWriter_Dealloc(&writer);
PyBytesWriter_Discard(writer);

release_buffer:
if (view.obj != NULL) {
Expand Down Expand Up @@ -2861,47 +2866,44 @@ bytes_new_impl(PyTypeObject *type, PyObject *x, const char *encoding,
static PyObject*
_PyBytes_FromBuffer(PyObject *x)
{
PyObject *new;
Py_buffer view;

if (PyObject_GetBuffer(x, &view, PyBUF_FULL_RO) < 0)
return NULL;

new = PyBytes_FromStringAndSize(NULL, view.len);
if (!new)
PyBytesWriter *writer = PyBytesWriter_Create(view.len);
if (writer == NULL) {
goto fail;
if (PyBuffer_ToContiguous(((PyBytesObject *)new)->ob_sval,
&view, view.len, 'C') < 0)
}

if (PyBuffer_ToContiguous(PyBytesWriter_GetData(writer),
&view, view.len, 'C') < 0) {
goto fail;
}

PyBuffer_Release(&view);
return new;
return PyBytesWriter_Finish(writer);

fail:
Py_XDECREF(new);
PyBytesWriter_Discard(writer);
PyBuffer_Release(&view);
return NULL;
}

static PyObject*
_PyBytes_FromList(PyObject *x)
{
Py_ssize_t i, size = PyList_GET_SIZE(x);
Py_ssize_t value;
char *str;
PyObject *item;
_PyBytesWriter writer;

_PyBytesWriter_Init(&writer);
str = _PyBytesWriter_Alloc(&writer, size);
if (str == NULL)
Py_ssize_t size = PyList_GET_SIZE(x);
PyBytesWriter *writer = PyBytesWriter_Create(size);
if (writer == NULL) {
return NULL;
writer.overallocate = 1;
size = writer.allocated;
}
char *str = PyBytesWriter_GetData(writer);
size = _PyBytesWriter_GetAllocated(writer);

for (i = 0; i < PyList_GET_SIZE(x); i++) {
item = PyList_GET_ITEM(x, i);
for (Py_ssize_t i = 0; i < PyList_GET_SIZE(x); i++) {
PyObject *item = PyList_GET_ITEM(x, i);
Py_INCREF(item);
value = PyNumber_AsSsize_t(item, NULL);
Py_ssize_t value = PyNumber_AsSsize_t(item, NULL);
Py_DECREF(item);
if (value == -1 && PyErr_Occurred())
goto error;
Expand All @@ -2913,33 +2915,33 @@ _PyBytes_FromList(PyObject *x)
}

if (i >= size) {
str = _PyBytesWriter_Resize(&writer, str, size+1);
if (str == NULL)
return NULL;
size = writer.allocated;
str = _PyBytesWriter_ResizeAndUpdatePointer(writer, size + 1, str);
if (str == NULL) {
goto error;
}
size = _PyBytesWriter_GetAllocated(writer);
}
*str++ = (char) value;
}
return _PyBytesWriter_Finish(&writer, str);
return PyBytesWriter_FinishWithPointer(writer, str);

error:
_PyBytesWriter_Dealloc(&writer);
error:
PyBytesWriter_Discard(writer);
return NULL;
}

static PyObject*
_PyBytes_FromTuple(PyObject *x)
{
PyObject *bytes;
Py_ssize_t i, size = PyTuple_GET_SIZE(x);
Py_ssize_t value;
char *str;
PyObject *item;

bytes = PyBytes_FromStringAndSize(NULL, size);
if (bytes == NULL)
PyBytesWriter *writer = PyBytesWriter_Create(size);
if (writer == NULL) {
return NULL;
str = ((PyBytesObject *)bytes)->ob_sval;
}
char *str = PyBytesWriter_GetData(writer);

for (i = 0; i < size; i++) {
item = PyTuple_GET_ITEM(x, i);
Expand All @@ -2954,31 +2956,29 @@ _PyBytes_FromTuple(PyObject *x)
}
*str++ = (char) value;
}
return bytes;
return PyBytesWriter_Finish(writer);

error:
Py_DECREF(bytes);
PyBytesWriter_Discard(writer);
return NULL;
}

static PyObject *
_PyBytes_FromIterator(PyObject *it, PyObject *x)
{
char *str;
Py_ssize_t i, size;
_PyBytesWriter writer;

/* For iterator version, create a bytes object and resize as needed */
size = PyObject_LengthHint(x, 64);
if (size == -1 && PyErr_Occurred())
return NULL;

_PyBytesWriter_Init(&writer);
str = _PyBytesWriter_Alloc(&writer, size);
if (str == NULL)
PyBytesWriter *writer = PyBytesWriter_Create(size);
if (writer == NULL) {
return NULL;
writer.overallocate = 1;
size = writer.allocated;
}
char *str = PyBytesWriter_GetData(writer);
size = _PyBytesWriter_GetAllocated(writer);

/* Run the iterator to exhaustion */
for (i = 0; ; i++) {
Expand Down Expand Up @@ -3008,18 +3008,18 @@ _PyBytes_FromIterator(PyObject *it, PyObject *x)

/* Append the byte */
if (i >= size) {
str = _PyBytesWriter_Resize(&writer, str, size+1);
if (str == NULL)
return NULL;
size = writer.allocated;
str = _PyBytesWriter_ResizeAndUpdatePointer(writer, size + 1, str);
if (str == NULL) {
goto error;
}
size = _PyBytesWriter_GetAllocated(writer);
}
*str++ = (char) value;
}

return _PyBytesWriter_Finish(&writer, str);
return PyBytesWriter_FinishWithPointer(writer, str);

error:
_PyBytesWriter_Dealloc(&writer);
PyBytesWriter_Discard(writer);
return NULL;
}

Expand Down Expand Up @@ -3987,6 +3987,13 @@ PyBytesWriter_GetSize(PyBytesWriter *writer)
}


static Py_ssize_t
_PyBytesWriter_GetAllocated(PyBytesWriter *writer)
{
return byteswriter_allocated(writer);
}


int
PyBytesWriter_Resize(PyBytesWriter *writer, Py_ssize_t size)
{
Expand All @@ -4002,6 +4009,18 @@ PyBytesWriter_Resize(PyBytesWriter *writer, Py_ssize_t size)
}


static void*
_PyBytesWriter_ResizeAndUpdatePointer(PyBytesWriter *writer, Py_ssize_t size,
void *data)
{
Py_ssize_t pos = (char*)data - byteswriter_data(writer);
if (PyBytesWriter_Resize(writer, size) < 0) {
return NULL;
}
return byteswriter_data(writer) + pos;
}


int
PyBytesWriter_Grow(PyBytesWriter *writer, Py_ssize_t size)
{
Expand Down
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