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gh-129813, PEP 782: Use PyBytesWriter in binascii #138825

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Sep 13, 2025
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gh-129813, PEP 782: Use PyBytesWriter in binascii #138825

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97 changes: 50 additions & 47 deletions Modules/binascii.c
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Original file line number Diff line number Diff line change
Expand Up @@ -205,11 +205,9 @@ binascii_a2b_uu_impl(PyObject *module, Py_buffer *data)
/*[clinic end generated code: output=e027f8e0b0598742 input=7cafeaf73df63d1c]*/
{
const unsigned char *ascii_data;
unsigned char *bin_data;
int leftbits = 0;
unsigned char this_ch;
unsigned int leftchar = 0;
PyObject *rv;
Py_ssize_t ascii_len, bin_len;
binascii_state *state;

Expand All @@ -223,9 +221,11 @@ binascii_a2b_uu_impl(PyObject *module, Py_buffer *data)
ascii_len--;

/* Allocate the buffer */
if ( (rv=PyBytes_FromStringAndSize(NULL, bin_len)) == NULL )
PyBytesWriter *writer = PyBytesWriter_Create(bin_len);
if (writer == NULL) {
return NULL;
bin_data = (unsigned char *)PyBytes_AS_STRING(rv);
}
unsigned char *bin_data = PyBytesWriter_GetData(writer);

for( ; bin_len > 0 ; ascii_len--, ascii_data++ ) {
/* XXX is it really best to add NULs if there's no more data */
Expand All @@ -245,11 +245,10 @@ binascii_a2b_uu_impl(PyObject *module, Py_buffer *data)
if ( this_ch < ' ' || this_ch > (' ' + 64)) {
state = get_binascii_state(module);
if (state == NULL) {
return NULL;
goto error;
}
PyErr_SetString(state->Error, "Illegal char");
Py_DECREF(rv);
return NULL;
goto error;
}
this_ch = (this_ch - ' ') & 077;
}
Expand Down Expand Up @@ -277,14 +276,17 @@ binascii_a2b_uu_impl(PyObject *module, Py_buffer *data)
this_ch != '\n' && this_ch != '\r' ) {
state = get_binascii_state(module);
if (state == NULL) {
return NULL;
goto error;
}
PyErr_SetString(state->Error, "Trailing garbage");
Py_DECREF(rv);
return NULL;
goto error;
}
}
return rv;
return PyBytesWriter_Finish(writer);

error:
PyBytesWriter_Discard(writer);
return NULL;
}

/*[clinic input]
Expand All @@ -302,16 +304,13 @@ static PyObject *
binascii_b2a_uu_impl(PyObject *module, Py_buffer *data, int backtick)
/*[clinic end generated code: output=b1b99de62d9bbeb8 input=beb27822241095cd]*/
{
unsigned char *ascii_data;
const unsigned char *bin_data;
int leftbits = 0;
unsigned char this_ch;
unsigned int leftchar = 0;
binascii_state *state;
Py_ssize_t bin_len, out_len;
_PyBytesWriter writer;
Py_ssize_t bin_len;

_PyBytesWriter_Init(&writer);
bin_data = data->buf;
bin_len = data->len;
if ( bin_len > 45 ) {
Expand All @@ -325,10 +324,12 @@ binascii_b2a_uu_impl(PyObject *module, Py_buffer *data, int backtick)
}

/* We're lazy and allocate to much (fixed up later) */
out_len = 2 + (bin_len + 2) / 3 * 4;
ascii_data = _PyBytesWriter_Alloc(&writer, out_len);
if (ascii_data == NULL)
Py_ssize_t out_len = 2 + (bin_len + 2) / 3 * 4;
PyBytesWriter *writer = PyBytesWriter_Create(out_len);
if (writer == NULL) {
return NULL;
}
unsigned char *ascii_data = PyBytesWriter_GetData(writer);

/* Store the length */
if (backtick && !bin_len)
Expand Down Expand Up @@ -356,7 +357,7 @@ binascii_b2a_uu_impl(PyObject *module, Py_buffer *data, int backtick)
}
*ascii_data++ = '\n'; /* Append a courtesy newline */

return _PyBytesWriter_Finish(&writer, ascii_data);
return PyBytesWriter_FinishWithPointer(writer, ascii_data);
}

/*[clinic input]
Expand Down Expand Up @@ -388,12 +389,11 @@ binascii_a2b_base64_impl(PyObject *module, Py_buffer *data, int strict_mode)

/* Allocate the buffer */
Py_ssize_t bin_len = ((ascii_len+3)/4)*3; /* Upper bound, corrected later */
_PyBytesWriter writer;
_PyBytesWriter_Init(&writer);
unsigned char *bin_data = _PyBytesWriter_Alloc(&writer, bin_len);
if (bin_data == NULL)
PyBytesWriter *writer = PyBytesWriter_Create(bin_len);
if (writer == NULL) {
return NULL;
unsigned char *bin_data_start = bin_data;
}
unsigned char *bin_data = PyBytesWriter_GetData(writer);

if (strict_mode && ascii_len > 0 && ascii_data[0] == '=') {
state = get_binascii_state(module);
Expand Down Expand Up @@ -489,12 +489,14 @@ binascii_a2b_base64_impl(PyObject *module, Py_buffer *data, int strict_mode)
state = get_binascii_state(module);
if (state == NULL) {
/* error already set, from get_binascii_state */
assert(PyErr_Occurred());
} else if (quad_pos == 1) {
/*
** There is exactly one extra valid, non-padding, base64 character.
** This is an invalid length, as there is no possible input that
** could encoded into such a base64 string.
*/
unsigned char *bin_data_start = PyBytesWriter_GetData(writer);
PyErr_Format(state->Error,
"Invalid base64-encoded string: "
"number of data characters (%zd) cannot be 1 more "
Expand All @@ -503,13 +505,15 @@ binascii_a2b_base64_impl(PyObject *module, Py_buffer *data, int strict_mode)
} else {
PyErr_SetString(state->Error, "Incorrect padding");
}
error_end:
_PyBytesWriter_Dealloc(&writer);
return NULL;
goto error_end;
}

done:
return _PyBytesWriter_Finish(&writer, bin_data);
return PyBytesWriter_FinishWithPointer(writer, bin_data);

error_end:
PyBytesWriter_Discard(writer);
return NULL;
}


Expand All @@ -528,18 +532,15 @@ static PyObject *
binascii_b2a_base64_impl(PyObject *module, Py_buffer *data, int newline)
/*[clinic end generated code: output=4ad62c8e8485d3b3 input=0e20ff59c5f2e3e1]*/
{
unsigned char *ascii_data;
const unsigned char *bin_data;
int leftbits = 0;
unsigned char this_ch;
unsigned int leftchar = 0;
Py_ssize_t bin_len, out_len;
_PyBytesWriter writer;
Py_ssize_t bin_len;
binascii_state *state;

bin_data = data->buf;
bin_len = data->len;
_PyBytesWriter_Init(&writer);

assert(bin_len >= 0);

Expand All @@ -555,12 +556,15 @@ binascii_b2a_base64_impl(PyObject *module, Py_buffer *data, int newline)
/* We're lazy and allocate too much (fixed up later).
"+2" leaves room for up to two pad characters.
Note that 'b' gets encoded as 'Yg==\n' (1 in, 5 out). */
out_len = bin_len*2 + 2;
if (newline)
Py_ssize_t out_len = bin_len*2 + 2;
if (newline) {
out_len++;
ascii_data = _PyBytesWriter_Alloc(&writer, out_len);
if (ascii_data == NULL)
}
PyBytesWriter *writer = PyBytesWriter_Create(out_len);
if (writer == NULL) {
return NULL;
}
unsigned char *ascii_data = PyBytesWriter_GetData(writer);

for( ; bin_len > 0 ; bin_len--, bin_data++ ) {
/* Shift the data into our buffer */
Expand All @@ -585,7 +589,7 @@ binascii_b2a_base64_impl(PyObject *module, Py_buffer *data, int newline)
if (newline)
*ascii_data++ = '\n'; /* Append a courtesy newline */

return _PyBytesWriter_Finish(&writer, ascii_data);
return PyBytesWriter_FinishWithPointer(writer, ascii_data);
}


Expand Down Expand Up @@ -887,8 +891,6 @@ binascii_a2b_hex_impl(PyObject *module, Py_buffer *hexstr)
{
const char* argbuf;
Py_ssize_t arglen;
PyObject *retval;
char* retbuf;
Py_ssize_t i, j;
binascii_state *state;

Expand All @@ -910,29 +912,30 @@ binascii_a2b_hex_impl(PyObject *module, Py_buffer *hexstr)
return NULL;
}

retval = PyBytes_FromStringAndSize(NULL, (arglen/2));
if (!retval)
PyBytesWriter *writer = PyBytesWriter_Create(arglen/2);
if (writer == NULL) {
return NULL;
retbuf = PyBytes_AS_STRING(retval);
}
char *retbuf = PyBytesWriter_GetData(writer);

for (i=j=0; i < arglen; i += 2) {
unsigned int top = _PyLong_DigitValue[Py_CHARMASK(argbuf[i])];
unsigned int bot = _PyLong_DigitValue[Py_CHARMASK(argbuf[i+1])];
if (top >= 16 || bot >= 16) {
state = get_binascii_state(module);
if (state == NULL) {
return NULL;
goto error;
}
PyErr_SetString(state->Error,
"Non-hexadecimal digit found");
goto finally;
goto error;
}
retbuf[j++] = (top << 4) + bot;
}
return retval;
return PyBytesWriter_Finish(writer);

finally:
Py_DECREF(retval);
error:
PyBytesWriter_Discard(writer);
return NULL;
}

Expand Down
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