https://github.com/python/cpython/commit/30ce3d462dc97c8f351964e872c418abacaaabfd
commit: 30ce3d462dc97c8f351964e872c418abacaaabfd
branch: main
author: Victor Stinner <[email protected]>
committer: vstinner <[email protected]>
date: 2026-10-05T04:47:04+02:00
summary:
gh-158585: Simplify PyBytesWriter_Finish() (#158822)
PyBytesWriter_Finish() doesn't need to check the size. It's known to
be valid.
PyBytesWriter_Create() now only calls byteswriter_resize() if the
size is larger than the small buffer.
Remove byteswriter_data() function: call static inline
_PyBytesWriter_GetData() function directly.
files:
M Modules/_struct.c
M Objects/bytesobject.c
M Objects/unicodeobject.c
M Python/assemble.c
diff --git a/Modules/_struct.c b/Modules/_struct.c
index fb2f40ab9766c5..1e5d52b758f7e2 100644
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -2498,7 +2498,8 @@ Struct_pack_impl(PyStructObject *self, PyObject * const
*values,
return NULL;
}
- return PyBytesWriter_FinishWithSize(writer, self->s_size);
+ assert(PyBytesWriter_GetSize(writer) == self->s_size);
+ return PyBytesWriter_Finish(writer);
}
/*[clinic input]
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index af5dce763e1f25..9bd9afc9b51ba4 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -3731,12 +3731,6 @@ _PyBytes_RepeatBuffer(char* dest, Py_ssize_t len_dest,
// one extra NUL byte which is a common error.
#define PyBytesWriter_CANARY_BYTE PYMEM_DEADBYTE
-static inline char*
-byteswriter_data(PyBytesWriter *writer)
-{
- return _PyBytesWriter_GetData(writer);
-}
-
static inline Py_ssize_t
byteswriter_allocated(PyBytesWriter *writer)
@@ -3758,7 +3752,7 @@ byteswriter_allocated(PyBytesWriter *writer)
static void
byteswriter_write_canary_byte(PyBytesWriter *writer)
{
- unsigned char *data = (unsigned char*)byteswriter_data(writer);
+ unsigned char *data = (unsigned char*)_PyBytesWriter_GetData(writer);
data[writer->size] = PyBytesWriter_CANARY_BYTE;
}
@@ -3770,7 +3764,7 @@ byteswriter_reset_trailing_byte(PyBytesWriter *writer)
// bytes/bytearray expects the last byte to be a null byte.
// Reset the last byte to null for bytes/bytearray.
Py_ssize_t allocated = byteswriter_allocated(writer);
- char *data = byteswriter_data(writer);
+ char *data = _PyBytesWriter_GetData(writer);
data[allocated] = '\0';
}
#endif
@@ -3801,7 +3795,7 @@ byteswriter_check_consistency(PyBytesWriter *writer)
}
#ifdef Py_DEBUG
- const unsigned char *data = (const unsigned char*)byteswriter_data(writer);
+ const unsigned char *data = (const unsigned
char*)_PyBytesWriter_GetData(writer);
unsigned char canary = data[writer->size];
if (canary != PyBytesWriter_CANARY_BYTE) {
_Py_FatalErrorFormat(__func__,
@@ -3895,7 +3889,7 @@ byteswriter_resize(PyBytesWriter *writer, Py_ssize_t
new_size, int resize)
if (resize) {
Py_ssize_t old_size = writer->size;
assert(allocated > old_size);
- memset(byteswriter_data(writer) + old_size, PyBytesWrite_NEW_BYTE,
+ memset(_PyBytesWriter_GetData(writer) + old_size,
PyBytesWrite_NEW_BYTE,
allocated - old_size);
}
#endif
@@ -3921,24 +3915,25 @@ byteswriter_create(Py_ssize_t size, int use_bytearray)
}
}
writer->obj = NULL;
- writer->size = 0;
+ writer->size = size;
writer->use_bytearray = use_bytearray;
writer->overallocate = !use_bytearray;
- if (size >= 1) {
+ Py_ssize_t allocated = sizeof(writer->small_buffer) - 1;
+ if (size > allocated) {
if (byteswriter_resize(writer, size, 0) < 0) {
#ifdef Py_DEBUG
// Write the canary byte so byteswriter_check_consistency()
// doesn't fail in PyBytesWriter_Discard()
+ writer->size = 0;
byteswriter_write_canary_byte(writer);
#endif
PyBytesWriter_Discard(writer);
return NULL;
}
- writer->size = size;
}
#ifdef Py_DEBUG
- memset(byteswriter_data(writer), PyBytesWrite_NEW_BYTE,
+ memset(_PyBytesWriter_GetData(writer), PyBytesWrite_NEW_BYTE,
byteswriter_allocated(writer));
byteswriter_write_canary_byte(writer);
#endif
@@ -3967,34 +3962,23 @@ PyBytesWriter_Discard(PyBytesWriter *writer)
}
assert(byteswriter_check_consistency(writer));
-#ifdef Py_DEBUG
if (writer->obj != NULL) {
+#ifdef Py_DEBUG
byteswriter_reset_trailing_byte(writer);
- }
#endif
-
- Py_XDECREF(writer->obj);
+ Py_DECREF(writer->obj);
+ }
_Py_FREELIST_FREE(bytes_writers, writer, PyMem_Free);
}
-PyObject*
-PyBytesWriter_FinishWithSize(PyBytesWriter *writer, Py_ssize_t size)
+static inline PyObject*
+byteswriter_finish_with_size(PyBytesWriter *writer, Py_ssize_t final_size)
{
assert(byteswriter_check_consistency(writer));
- if (size < 0) {
- PyErr_Format(PyExc_ValueError, "size must be positive");
- goto error;
- }
-
- if (size > writer->size) {
- PyErr_SetString(PyExc_ValueError, "size larger than allocated size");
- goto error;
- }
-
PyObject *result;
- if (size == 0 && !writer->use_bytearray) {
+ if (final_size == 0 && !writer->use_bytearray) {
result = bytes_get_empty();
if (writer->obj != NULL) {
#ifdef Py_DEBUG
@@ -4011,19 +3995,19 @@ PyBytesWriter_FinishWithSize(PyBytesWriter *writer,
Py_ssize_t size)
#endif
if (writer->use_bytearray) {
- if (size != PyByteArray_GET_SIZE(writer->obj)) {
- if (PyByteArray_Resize(writer->obj, size)) {
+ if (final_size != PyByteArray_GET_SIZE(writer->obj)) {
+ if (PyByteArray_Resize(writer->obj, final_size)) {
goto error;
}
}
}
else {
- if (size == 1) {
+ if (final_size == 1) {
unsigned char ch = PyBytes_AS_STRING(writer->obj)[0];
Py_SETREF(writer->obj, bytes_get_char(ch));
}
- else if (size != PyBytes_GET_SIZE(writer->obj)) {
- if (bytes_resize_inplace(&writer->obj, size)) {
+ else if (final_size != PyBytes_GET_SIZE(writer->obj)) {
+ if (bytes_resize_inplace(&writer->obj, final_size)) {
goto error;
}
}
@@ -4036,18 +4020,18 @@ PyBytesWriter_FinishWithSize(PyBytesWriter *writer,
Py_ssize_t size)
// Create an object from the small buffer
const char *buffer = (const char *)writer->small_buffer;
if (writer->use_bytearray) {
- result = PyByteArray_FromStringAndSize(buffer, size);
+ result = PyByteArray_FromStringAndSize(buffer, final_size);
}
else {
- if (size == 1) {
+ if (final_size == 1) {
result = bytes_get_char((uint8_t)buffer[0]);
}
else {
- result = bytes_alloc(size);
+ result = bytes_alloc(final_size);
if (result == NULL) {
goto error;
}
- memcpy(PyBytes_AS_STRING(result), buffer, size);
+ memcpy(PyBytes_AS_STRING(result), buffer, final_size);
}
}
}
@@ -4061,17 +4045,36 @@ PyBytesWriter_FinishWithSize(PyBytesWriter *writer,
Py_ssize_t size)
return NULL;
}
+PyObject*
+PyBytesWriter_FinishWithSize(PyBytesWriter *writer, Py_ssize_t size)
+{
+ if (size < 0) {
+ PyErr_Format(PyExc_ValueError, "size must be positive");
+ goto error;
+ }
+ if (size > writer->size) {
+ PyErr_SetString(PyExc_ValueError, "size larger than allocated size");
+ goto error;
+ }
+ return byteswriter_finish_with_size(writer, size);
+
+error:
+ PyBytesWriter_Discard(writer);
+ return NULL;
+}
+
PyObject*
PyBytesWriter_Finish(PyBytesWriter *writer)
{
- return PyBytesWriter_FinishWithSize(writer, writer->size);
+ return byteswriter_finish_with_size(writer, writer->size);
}
PyObject*
PyBytesWriter_FinishWithPointer(PyBytesWriter *writer, void *buf)
{
- Py_ssize_t size = (char*)buf - byteswriter_data(writer);
+ Py_ssize_t size = (char*)buf - _PyBytesWriter_GetData(writer);
+ // Call PyBytesWriter_FinishWithSize() to check size
return PyBytesWriter_FinishWithSize(writer, size);
}
@@ -4081,7 +4084,7 @@ PyBytesWriter_GetData(PyBytesWriter *writer)
{
assert(byteswriter_check_consistency(writer));
- return byteswriter_data(writer);
+ return _PyBytesWriter_GetData(writer);
}
@@ -4125,11 +4128,11 @@ static void*
_PyBytesWriter_ResizeAndUpdatePointer(PyBytesWriter *writer, Py_ssize_t size,
void *data)
{
- Py_ssize_t pos = (char*)data - byteswriter_data(writer);
+ Py_ssize_t pos = (char*)data - _PyBytesWriter_GetData(writer);
if (PyBytesWriter_Resize(writer, size) < 0) {
return NULL;
}
- return byteswriter_data(writer) + pos;
+ return _PyBytesWriter_GetData(writer) + pos;
}
@@ -4176,11 +4179,11 @@ void*
PyBytesWriter_GrowAndUpdatePointer(PyBytesWriter *writer, Py_ssize_t size,
void *buf)
{
- Py_ssize_t pos = (char*)buf - byteswriter_data(writer);
+ Py_ssize_t pos = (char*)buf - _PyBytesWriter_GetData(writer);
if (PyBytesWriter_Grow(writer, size) < 0) {
return NULL;
}
- return byteswriter_data(writer) + pos;
+ return _PyBytesWriter_GetData(writer) + pos;
}
@@ -4201,7 +4204,7 @@ PyBytesWriter_WriteBytes(PyBytesWriter *writer,
if (PyBytesWriter_Grow(writer, size) < 0) {
return -1;
}
- char *buf = byteswriter_data(writer);
+ char *buf = _PyBytesWriter_GetData(writer);
memcpy(buf + pos, bytes, size);
assert(byteswriter_check_consistency(writer));
@@ -4232,7 +4235,7 @@ PyBytesWriter_Format(PyBytesWriter *writer, const char
*format, ...)
return -1;
}
- Py_ssize_t size = buf - byteswriter_data(writer);
+ Py_ssize_t size = buf - _PyBytesWriter_GetData(writer);
return PyBytesWriter_Resize(writer, size);
}
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 157e005c3c0b60..ded13cc37f69f1 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -4880,7 +4880,7 @@ _PyUnicode_EncodeUTF7(PyObject *str,
else { /* not in a shift sequence */
if (ch == '+') {
*out++ = '+';
- *out++ = '-';
+ *out++ = '-';
}
else if (ENCODE_DIRECT(ch)) {
*out++ = (char) ch;
@@ -8644,10 +8644,7 @@ _PyUnicode_EncodeIconv(const char *encoding, PyObject
*unicode,
iconv(cd, NULL, NULL, NULL, NULL);
}
- if (PyBytesWriter_Resize(writer, out - (char
*)PyBytesWriter_GetData(writer)) < 0) {
- goto done;
- }
- result = PyBytesWriter_Finish(writer);
+ result = PyBytesWriter_FinishWithPointer(writer, out);
writer = NULL;
done:
diff --git a/Python/assemble.c b/Python/assemble.c
index 2c8abb116b2e33..8f68e233ab7b93 100644
--- a/Python/assemble.c
+++ b/Python/assemble.c
@@ -102,7 +102,7 @@ assemble_free(struct assembler *a)
static inline void
write_except_byte(struct assembler *a, int byte) {
- unsigned char *p = (unsigned char *)
PyBytesWriter_GetData(a->a_except_table_writer);
+ unsigned char *p = PyBytesWriter_GetData(a->a_except_table_writer);
p[a->a_except_table_off++] = byte;
}
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