https://github.com/python/cpython/commit/af386fd36151b4ff94d04002dc8fa7462d83633e
commit: af386fd36151b4ff94d04002dc8fa7462d83633e
branch: main
author: Victor Stinner <[email protected]>
committer: vstinner <[email protected]>
date: 2025-09-13T18:57:46+02:00
summary:
gh-129813, PEP 782: Use PyBytesWriter in posix extension (#138829)
Replace PyBytes_FromStringAndSize(NULL, size) and _PyBytes_Resize()
with the new public PyBytesWriter API.
files:
M Modules/posixmodule.c
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index f229c4e8dd9322..5e735e86bdee9e 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -11507,9 +11507,6 @@ static PyObject *
os_read_impl(PyObject *module, int fd, Py_ssize_t length)
/*[clinic end generated code: output=dafbe9a5cddb987b input=1df2eaa27c0bf1d3]*/
{
- Py_ssize_t n;
- PyObject *buffer;
-
if (length < 0) {
errno = EINVAL;
return posix_error();
@@ -11517,20 +11514,18 @@ os_read_impl(PyObject *module, int fd, Py_ssize_t
length)
length = Py_MIN(length, _PY_READ_MAX);
- buffer = PyBytes_FromStringAndSize((char *)NULL, length);
- if (buffer == NULL)
+ PyBytesWriter *writer = PyBytesWriter_Create(length);
+ if (writer == NULL) {
return NULL;
+ }
- n = _Py_read(fd, PyBytes_AS_STRING(buffer), length);
+ Py_ssize_t n = _Py_read(fd, PyBytesWriter_GetData(writer), length);
if (n == -1) {
- Py_DECREF(buffer);
+ PyBytesWriter_Discard(writer);
return NULL;
}
- if (n != length)
- _PyBytes_Resize(&buffer, n);
-
- return buffer;
+ return PyBytesWriter_FinishWithSize(writer, n);
}
/*[clinic input]
@@ -11708,20 +11703,20 @@ os_pread_impl(PyObject *module, int fd, Py_ssize_t
length, Py_off_t offset)
{
Py_ssize_t n;
int async_err = 0;
- PyObject *buffer;
if (length < 0) {
errno = EINVAL;
return posix_error();
}
- buffer = PyBytes_FromStringAndSize((char *)NULL, length);
- if (buffer == NULL)
+ PyBytesWriter *writer = PyBytesWriter_Create(length);
+ if (writer == NULL) {
return NULL;
+ }
do {
Py_BEGIN_ALLOW_THREADS
_Py_BEGIN_SUPPRESS_IPH
- n = pread(fd, PyBytes_AS_STRING(buffer), length, offset);
+ n = pread(fd, PyBytesWriter_GetData(writer), length, offset);
_Py_END_SUPPRESS_IPH
Py_END_ALLOW_THREADS
} while (n < 0 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
@@ -11730,12 +11725,10 @@ os_pread_impl(PyObject *module, int fd, Py_ssize_t
length, Py_off_t offset)
if (!async_err) {
posix_error();
}
- Py_DECREF(buffer);
+ PyBytesWriter_Discard(writer);
return NULL;
}
- if (n != length)
- _PyBytes_Resize(&buffer, n);
- return buffer;
+ return PyBytesWriter_FinishWithSize(writer, n);
}
#endif /* HAVE_PREAD */
@@ -14945,9 +14938,6 @@ os_getxattr_impl(PyObject *module, path_t *path, path_t
*attribute,
int follow_symlinks)
/*[clinic end generated code: output=5f2f44200a43cff2 input=025789491708f7eb]*/
{
- Py_ssize_t i;
- PyObject *buffer = NULL;
-
if (fd_and_follow_symlinks_invalid("getxattr", path->fd, follow_symlinks))
return NULL;
@@ -14955,8 +14945,7 @@ os_getxattr_impl(PyObject *module, path_t *path, path_t
*attribute,
return NULL;
}
- for (i = 0; ; i++) {
- void *ptr;
+ for (Py_ssize_t i = 0; ; i++) {
ssize_t result;
static const Py_ssize_t buffer_sizes[] = {128, XATTR_SIZE_MAX, 0};
Py_ssize_t buffer_size = buffer_sizes[i];
@@ -14964,10 +14953,11 @@ os_getxattr_impl(PyObject *module, path_t *path,
path_t *attribute,
path_error(path);
return NULL;
}
- buffer = PyBytes_FromStringAndSize(NULL, buffer_size);
- if (!buffer)
+ PyBytesWriter *writer = PyBytesWriter_Create(buffer_size);
+ if (writer == NULL) {
return NULL;
- ptr = PyBytes_AS_STRING(buffer);
+ }
+ void *ptr = PyBytesWriter_GetData(writer);
Py_BEGIN_ALLOW_THREADS;
if (path->fd >= 0)
@@ -14979,23 +14969,16 @@ os_getxattr_impl(PyObject *module, path_t *path,
path_t *attribute,
Py_END_ALLOW_THREADS;
if (result < 0) {
+ PyBytesWriter_Discard(writer);
if (errno == ERANGE) {
- Py_DECREF(buffer);
continue;
}
path_error(path);
- Py_DECREF(buffer);
return NULL;
}
- if (result != buffer_size) {
- /* Can only shrink. */
- _PyBytes_Resize(&buffer, result);
- }
- break;
+ return PyBytesWriter_FinishWithSize(writer, result);
}
-
- return buffer;
}
@@ -15222,19 +15205,22 @@ static PyObject *
os_urandom_impl(PyObject *module, Py_ssize_t size)
/*[clinic end generated code: output=42c5cca9d18068e9 input=58a0def87dbc2c22]*/
{
- PyObject *bytes;
- int result;
+ if (size < 0) {
+ return PyErr_Format(PyExc_ValueError,
+ "negative argument not allowed");
+ }
- bytes = PyBytes_FromStringAndSize(NULL, size);
- if (bytes == NULL)
+ PyBytesWriter *writer = PyBytesWriter_Create(size);
+ if (writer == NULL) {
return NULL;
+ }
- result = _PyOS_URandom(PyBytes_AS_STRING(bytes), PyBytes_GET_SIZE(bytes));
+ int result = _PyOS_URandom(PyBytesWriter_GetData(writer), size);
if (result == -1) {
- Py_DECREF(bytes);
+ PyBytesWriter_Discard(writer);
return NULL;
}
- return bytes;
+ return PyBytesWriter_Finish(writer);
}
#ifdef HAVE_MEMFD_CREATE
@@ -16704,25 +16690,20 @@ static PyObject *
os_getrandom_impl(PyObject *module, Py_ssize_t size, int flags)
/*[clinic end generated code: output=b3a618196a61409c input=59bafac39c594947]*/
{
- PyObject *bytes;
- Py_ssize_t n;
-
if (size < 0) {
errno = EINVAL;
return posix_error();
}
- bytes = PyBytes_FromStringAndSize(NULL, size);
- if (bytes == NULL) {
- PyErr_NoMemory();
+ PyBytesWriter *writer = PyBytesWriter_Create(size);
+ if (writer == NULL) {
return NULL;
}
+ void *data = PyBytesWriter_GetData(writer);
+ Py_ssize_t n;
while (1) {
- n = syscall(SYS_getrandom,
- PyBytes_AS_STRING(bytes),
- PyBytes_GET_SIZE(bytes),
- flags);
+ n = syscall(SYS_getrandom, data, size, flags);
if (n < 0 && errno == EINTR) {
if (PyErr_CheckSignals() < 0) {
goto error;
@@ -16739,14 +16720,10 @@ os_getrandom_impl(PyObject *module, Py_ssize_t size,
int flags)
goto error;
}
- if (n != size) {
- _PyBytes_Resize(&bytes, n);
- }
-
- return bytes;
+ return PyBytesWriter_FinishWithSize(writer, n);
error:
- Py_DECREF(bytes);
+ PyBytesWriter_Discard(writer);
return NULL;
}
#endif /* HAVE_GETRANDOM_SYSCALL */
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