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memoryobject.c
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3455 lines (2924 loc) · 99.5 KB
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/*
* Memoryview object implementation
* --------------------------------
*
* This implementation is a complete rewrite contributed by Stefan Krah in
* Python 3.3. Substantial credit goes to Antoine Pitrou (who had already
* fortified and rewritten the previous implementation) and Nick Coghlan
* (who came up with the idea of the ManagedBuffer) for analyzing the complex
* ownership rules.
*
*/
#include "Python.h"
#include "pycore_abstract.h" // _PyIndex_Check()
#include "pycore_memoryobject.h" // _PyManagedBuffer_Type
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
#include "pycore_strhex.h" // _Py_strhex_with_sep()
#include <stddef.h> // offsetof()
/*[clinic input]
class memoryview "PyMemoryViewObject *" "&PyMemoryView_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=e2e49d2192835219]*/
#include "clinic/memoryobject.c.h"
/****************************************************************************/
/* ManagedBuffer Object */
/****************************************************************************/
/*
ManagedBuffer Object:
---------------------
The purpose of this object is to facilitate the handling of chained
memoryviews that have the same underlying exporting object. PEP-3118
allows the underlying object to change while a view is exported. This
could lead to unexpected results when constructing a new memoryview
from an existing memoryview.
Rather than repeatedly redirecting buffer requests to the original base
object, all chained memoryviews use a single buffer snapshot. This
snapshot is generated by the constructor _PyManagedBuffer_FromObject().
Ownership rules:
----------------
The master buffer inside a managed buffer is filled in by the original
base object. shape, strides, suboffsets and format are read-only for
all consumers.
A memoryview's buffer is a private copy of the exporter's buffer. shape,
strides and suboffsets belong to the memoryview and are thus writable.
If a memoryview itself exports several buffers via memory_getbuf(), all
buffer copies share shape, strides and suboffsets. In this case, the
arrays are NOT writable.
Reference count assumptions:
----------------------------
The 'obj' member of a Py_buffer must either be NULL or refer to the
exporting base object. In the Python codebase, all getbufferprocs
return a new reference to view.obj (example: bytes_buffer_getbuffer()).
PyBuffer_Release() decrements view.obj (if non-NULL), so the
releasebufferprocs must NOT decrement view.obj.
*/
static inline _PyManagedBufferObject *
mbuf_alloc(void)
{
_PyManagedBufferObject *mbuf;
mbuf = (_PyManagedBufferObject *)
PyObject_GC_New(_PyManagedBufferObject, &_PyManagedBuffer_Type);
if (mbuf == NULL)
return NULL;
mbuf->flags = 0;
mbuf->exports = 0;
mbuf->master.obj = NULL;
_PyObject_GC_TRACK(mbuf);
return mbuf;
}
static PyObject *
_PyManagedBuffer_FromObject(PyObject *base, int flags)
{
_PyManagedBufferObject *mbuf;
mbuf = mbuf_alloc();
if (mbuf == NULL)
return NULL;
if (PyObject_GetBuffer(base, &mbuf->master, flags) < 0) {
mbuf->master.obj = NULL;
Py_DECREF(mbuf);
return NULL;
}
return (PyObject *)mbuf;
}
static void
mbuf_release(_PyManagedBufferObject *self)
{
if (self->flags&_Py_MANAGED_BUFFER_RELEASED)
return;
self->flags |= _Py_MANAGED_BUFFER_RELEASED;
/* PyBuffer_Release() decrements master->obj and sets it to NULL. */
_PyObject_GC_UNTRACK(self);
PyBuffer_Release(&self->master);
}
static void
mbuf_dealloc(PyObject *_self)
{
_PyManagedBufferObject *self = (_PyManagedBufferObject *)_self;
assert(self->exports == 0);
mbuf_release(self);
if (self->flags&_Py_MANAGED_BUFFER_FREE_FORMAT)
PyMem_Free(self->master.format);
PyObject_GC_Del(self);
}
static int
mbuf_traverse(PyObject *_self, visitproc visit, void *arg)
{
_PyManagedBufferObject *self = (_PyManagedBufferObject *)_self;
Py_VISIT(self->master.obj);
return 0;
}
static int
mbuf_clear(PyObject *_self)
{
_PyManagedBufferObject *self = (_PyManagedBufferObject *)_self;
assert(self->exports >= 0);
mbuf_release(self);
return 0;
}
PyTypeObject _PyManagedBuffer_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"managedbuffer",
sizeof(_PyManagedBufferObject),
0,
mbuf_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
0, /* tp_doc */
mbuf_traverse, /* tp_traverse */
mbuf_clear /* tp_clear */
};
/****************************************************************************/
/* MemoryView Object */
/****************************************************************************/
/* In the process of breaking reference cycles mbuf_release() can be
called before memory_release(). */
#define BASE_INACCESSIBLE(mv) \
(((PyMemoryViewObject *)mv)->flags&_Py_MEMORYVIEW_RELEASED || \
((PyMemoryViewObject *)mv)->mbuf->flags&_Py_MANAGED_BUFFER_RELEASED)
#define CHECK_RELEASED(mv) \
if (BASE_INACCESSIBLE(mv)) { \
PyErr_SetString(PyExc_ValueError, \
"operation forbidden on released memoryview object"); \
return NULL; \
}
#define CHECK_RELEASED_INT(mv) \
if (BASE_INACCESSIBLE(mv)) { \
PyErr_SetString(PyExc_ValueError, \
"operation forbidden on released memoryview object"); \
return -1; \
}
#define CHECK_RESTRICTED(mv) \
if (((PyMemoryViewObject *)(mv))->flags & _Py_MEMORYVIEW_RESTRICTED) { \
PyErr_SetString(PyExc_ValueError, \
"cannot create new view on restricted memoryview"); \
return NULL; \
}
#define CHECK_RESTRICTED_INT(mv) \
if (((PyMemoryViewObject *)(mv))->flags & _Py_MEMORYVIEW_RESTRICTED) { \
PyErr_SetString(PyExc_ValueError, \
"cannot create new view on restricted memoryview"); \
return -1; \
}
/* See gh-92888. These macros signal that we need to check the memoryview
again due to possible read after frees. */
#define CHECK_RELEASED_AGAIN(mv) CHECK_RELEASED(mv)
#define CHECK_RELEASED_INT_AGAIN(mv) CHECK_RELEASED_INT(mv)
#define CHECK_LIST_OR_TUPLE(v) \
if (!PyList_Check(v) && !PyTuple_Check(v)) { \
PyErr_SetString(PyExc_TypeError, \
#v " must be a list or a tuple"); \
return NULL; \
}
#define VIEW_ADDR(mv) (&((PyMemoryViewObject *)mv)->view)
/* Check for the presence of suboffsets in the first dimension. */
#define HAVE_PTR(suboffsets, dim) (suboffsets && suboffsets[dim] >= 0)
/* Adjust ptr if suboffsets are present. */
#define ADJUST_PTR(ptr, suboffsets, dim) \
(HAVE_PTR(suboffsets, dim) ? *((char**)ptr) + suboffsets[dim] : ptr)
/* Memoryview buffer properties */
#define MV_C_CONTIGUOUS(flags) (flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C))
#define MV_F_CONTIGUOUS(flags) \
(flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_FORTRAN))
#define MV_ANY_CONTIGUOUS(flags) \
(flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN))
/* Fast contiguity test. Caller must ensure suboffsets==NULL and ndim==1. */
#define MV_CONTIGUOUS_NDIM1(view) \
((view)->shape[0] == 1 || (view)->strides[0] == (view)->itemsize)
/* getbuffer() requests */
#define REQ_INDIRECT(flags) ((flags&PyBUF_INDIRECT) == PyBUF_INDIRECT)
#define REQ_C_CONTIGUOUS(flags) ((flags&PyBUF_C_CONTIGUOUS) == PyBUF_C_CONTIGUOUS)
#define REQ_F_CONTIGUOUS(flags) ((flags&PyBUF_F_CONTIGUOUS) == PyBUF_F_CONTIGUOUS)
#define REQ_ANY_CONTIGUOUS(flags) ((flags&PyBUF_ANY_CONTIGUOUS) == PyBUF_ANY_CONTIGUOUS)
#define REQ_STRIDES(flags) ((flags&PyBUF_STRIDES) == PyBUF_STRIDES)
#define REQ_SHAPE(flags) ((flags&PyBUF_ND) == PyBUF_ND)
#define REQ_WRITABLE(flags) (flags&PyBUF_WRITABLE)
#define REQ_FORMAT(flags) (flags&PyBUF_FORMAT)
/**************************************************************************/
/* Copy memoryview buffers */
/**************************************************************************/
/* The functions in this section take a source and a destination buffer
with the same logical structure: format, itemsize, ndim and shape
are identical, with ndim > 0.
NOTE: All buffers are assumed to have PyBUF_FULL information, which
is the case for memoryviews! */
/* Assumptions: ndim >= 1. The macro tests for a corner case that should
perhaps be explicitly forbidden in the PEP. */
#define HAVE_SUBOFFSETS_IN_LAST_DIM(view) \
(view->suboffsets && view->suboffsets[view->ndim-1] >= 0)
static inline int
last_dim_is_contiguous(const Py_buffer *dest, const Py_buffer *src)
{
assert(dest->ndim > 0 && src->ndim > 0);
return (!HAVE_SUBOFFSETS_IN_LAST_DIM(dest) &&
!HAVE_SUBOFFSETS_IN_LAST_DIM(src) &&
dest->strides[dest->ndim-1] == dest->itemsize &&
src->strides[src->ndim-1] == src->itemsize);
}
/* This is not a general function for determining format equivalence.
It is used in copy_single() and copy_buffer() to weed out non-matching
formats. Skipping the '@' character is specifically used in slice
assignments, where the lvalue is already known to have a single character
format. This is a performance hack that could be rewritten (if properly
benchmarked). */
static inline int
equiv_format(const Py_buffer *dest, const Py_buffer *src)
{
const char *dfmt, *sfmt;
assert(dest->format && src->format);
dfmt = dest->format[0] == '@' ? dest->format+1 : dest->format;
sfmt = src->format[0] == '@' ? src->format+1 : src->format;
if (strcmp(dfmt, sfmt) != 0 ||
dest->itemsize != src->itemsize) {
return 0;
}
return 1;
}
/* Two shapes are equivalent if they are either equal or identical up
to a zero element at the same position. For example, in NumPy arrays
the shapes [1, 0, 5] and [1, 0, 7] are equivalent. */
static inline int
equiv_shape(const Py_buffer *dest, const Py_buffer *src)
{
int i;
if (dest->ndim != src->ndim)
return 0;
for (i = 0; i < dest->ndim; i++) {
if (dest->shape[i] != src->shape[i])
return 0;
if (dest->shape[i] == 0)
break;
}
return 1;
}
/* Check that the logical structure of the destination and source buffers
is identical. */
static int
equiv_structure(const Py_buffer *dest, const Py_buffer *src)
{
if (!equiv_format(dest, src) ||
!equiv_shape(dest, src)) {
PyErr_SetString(PyExc_ValueError,
"memoryview assignment: lvalue and rvalue have different "
"structures");
return 0;
}
return 1;
}
/* Base case for recursive multi-dimensional copying. Contiguous arrays are
copied with very little overhead. Assumptions: ndim == 1, mem == NULL or
sizeof(mem) == shape[0] * itemsize. */
static void
copy_base(const Py_ssize_t *shape, Py_ssize_t itemsize,
char *dptr, const Py_ssize_t *dstrides, const Py_ssize_t *dsuboffsets,
char *sptr, const Py_ssize_t *sstrides, const Py_ssize_t *ssuboffsets,
char *mem)
{
if (mem == NULL) { /* contiguous */
Py_ssize_t size = shape[0] * itemsize;
if (dptr + size < sptr || sptr + size < dptr)
memcpy(dptr, sptr, size); /* no overlapping */
else
memmove(dptr, sptr, size);
}
else {
char *p;
Py_ssize_t i;
for (i=0, p=mem; i < shape[0]; p+=itemsize, sptr+=sstrides[0], i++) {
char *xsptr = ADJUST_PTR(sptr, ssuboffsets, 0);
memcpy(p, xsptr, itemsize);
}
for (i=0, p=mem; i < shape[0]; p+=itemsize, dptr+=dstrides[0], i++) {
char *xdptr = ADJUST_PTR(dptr, dsuboffsets, 0);
memcpy(xdptr, p, itemsize);
}
}
}
/* Recursively copy a source buffer to a destination buffer. The two buffers
have the same ndim, shape and itemsize. */
static void
copy_rec(const Py_ssize_t *shape, Py_ssize_t ndim, Py_ssize_t itemsize,
char *dptr, const Py_ssize_t *dstrides, const Py_ssize_t *dsuboffsets,
char *sptr, const Py_ssize_t *sstrides, const Py_ssize_t *ssuboffsets,
char *mem)
{
Py_ssize_t i;
assert(ndim >= 1);
if (ndim == 1) {
copy_base(shape, itemsize,
dptr, dstrides, dsuboffsets,
sptr, sstrides, ssuboffsets,
mem);
return;
}
for (i = 0; i < shape[0]; dptr+=dstrides[0], sptr+=sstrides[0], i++) {
char *xdptr = ADJUST_PTR(dptr, dsuboffsets, 0);
char *xsptr = ADJUST_PTR(sptr, ssuboffsets, 0);
copy_rec(shape+1, ndim-1, itemsize,
xdptr, dstrides+1, dsuboffsets ? dsuboffsets+1 : NULL,
xsptr, sstrides+1, ssuboffsets ? ssuboffsets+1 : NULL,
mem);
}
}
/* Faster copying of one-dimensional arrays. */
static int
copy_single(PyMemoryViewObject *self, const Py_buffer *dest, const Py_buffer *src)
{
CHECK_RELEASED_INT_AGAIN(self);
char *mem = NULL;
assert(dest->ndim == 1);
if (!equiv_structure(dest, src))
return -1;
if (!last_dim_is_contiguous(dest, src)) {
mem = PyMem_Malloc(dest->shape[0] * dest->itemsize);
if (mem == NULL) {
PyErr_NoMemory();
return -1;
}
}
copy_base(dest->shape, dest->itemsize,
dest->buf, dest->strides, dest->suboffsets,
src->buf, src->strides, src->suboffsets,
mem);
if (mem)
PyMem_Free(mem);
return 0;
}
/* Recursively copy src to dest. Both buffers must have the same basic
structure. Copying is atomic, the function never fails with a partial
copy. */
static int
copy_buffer(const Py_buffer *dest, const Py_buffer *src)
{
char *mem = NULL;
assert(dest->ndim > 0);
if (!equiv_structure(dest, src))
return -1;
if (!last_dim_is_contiguous(dest, src)) {
mem = PyMem_Malloc(dest->shape[dest->ndim-1] * dest->itemsize);
if (mem == NULL) {
PyErr_NoMemory();
return -1;
}
}
copy_rec(dest->shape, dest->ndim, dest->itemsize,
dest->buf, dest->strides, dest->suboffsets,
src->buf, src->strides, src->suboffsets,
mem);
if (mem)
PyMem_Free(mem);
return 0;
}
/* Initialize strides for a C-contiguous array. */
static inline void
init_strides_from_shape(Py_buffer *view)
{
Py_ssize_t i;
assert(view->ndim > 0);
view->strides[view->ndim-1] = view->itemsize;
for (i = view->ndim-2; i >= 0; i--)
view->strides[i] = view->strides[i+1] * view->shape[i+1];
}
/* Initialize strides for a Fortran-contiguous array. */
static inline void
init_fortran_strides_from_shape(Py_buffer *view)
{
Py_ssize_t i;
assert(view->ndim > 0);
view->strides[0] = view->itemsize;
for (i = 1; i < view->ndim; i++)
view->strides[i] = view->strides[i-1] * view->shape[i-1];
}
/* Copy src to a contiguous representation. order is one of 'C', 'F' (Fortran)
or 'A' (Any). Assumptions: src has PyBUF_FULL information, src->ndim >= 1,
len(mem) == src->len. */
static int
buffer_to_contiguous(char *mem, const Py_buffer *src, char order)
{
Py_buffer dest;
Py_ssize_t *strides;
int ret;
assert(src->ndim >= 1);
assert(src->shape != NULL);
assert(src->strides != NULL);
strides = PyMem_Malloc(src->ndim * (sizeof *src->strides));
if (strides == NULL) {
PyErr_NoMemory();
return -1;
}
/* initialize dest */
dest = *src;
dest.buf = mem;
/* shape is constant and shared: the logical representation of the
array is unaltered. */
/* The physical representation determined by strides (and possibly
suboffsets) may change. */
dest.strides = strides;
if (order == 'C' || order == 'A') {
init_strides_from_shape(&dest);
}
else {
init_fortran_strides_from_shape(&dest);
}
dest.suboffsets = NULL;
ret = copy_buffer(&dest, src);
PyMem_Free(strides);
return ret;
}
/****************************************************************************/
/* Constructors */
/****************************************************************************/
/* Initialize values that are shared with the managed buffer. */
static inline void
init_shared_values(Py_buffer *dest, const Py_buffer *src)
{
dest->obj = src->obj;
dest->buf = src->buf;
dest->len = src->len;
dest->itemsize = src->itemsize;
dest->readonly = src->readonly;
dest->format = src->format ? src->format : "B";
dest->internal = src->internal;
}
/* Copy shape and strides. Reconstruct missing values. */
static void
init_shape_strides(Py_buffer *dest, const Py_buffer *src)
{
Py_ssize_t i;
if (src->ndim == 0) {
dest->shape = NULL;
dest->strides = NULL;
return;
}
if (src->ndim == 1) {
dest->shape[0] = src->shape ? src->shape[0] : src->len / src->itemsize;
dest->strides[0] = src->strides ? src->strides[0] : src->itemsize;
return;
}
for (i = 0; i < src->ndim; i++)
dest->shape[i] = src->shape[i];
if (src->strides) {
for (i = 0; i < src->ndim; i++)
dest->strides[i] = src->strides[i];
}
else {
init_strides_from_shape(dest);
}
}
static inline void
init_suboffsets(Py_buffer *dest, const Py_buffer *src)
{
Py_ssize_t i;
if (src->suboffsets == NULL) {
dest->suboffsets = NULL;
return;
}
for (i = 0; i < src->ndim; i++)
dest->suboffsets[i] = src->suboffsets[i];
}
/* len = product(shape) * itemsize */
static inline void
init_len(Py_buffer *view)
{
Py_ssize_t i, len;
len = 1;
for (i = 0; i < view->ndim; i++)
len *= view->shape[i];
len *= view->itemsize;
view->len = len;
}
/* Initialize memoryview buffer properties. */
static void
init_flags(PyMemoryViewObject *mv)
{
const Py_buffer *view = &mv->view;
int flags = 0;
switch (view->ndim) {
case 0:
flags |= (_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C|
_Py_MEMORYVIEW_FORTRAN);
break;
case 1:
if (MV_CONTIGUOUS_NDIM1(view))
flags |= (_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN);
break;
default:
if (PyBuffer_IsContiguous(view, 'C'))
flags |= _Py_MEMORYVIEW_C;
if (PyBuffer_IsContiguous(view, 'F'))
flags |= _Py_MEMORYVIEW_FORTRAN;
break;
}
if (view->suboffsets) {
flags |= _Py_MEMORYVIEW_PIL;
flags &= ~(_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN);
}
mv->flags = flags;
}
/* Allocate a new memoryview and perform basic initialization. New memoryviews
are exclusively created through the mbuf_add functions. */
static inline PyMemoryViewObject *
memory_alloc(int ndim)
{
PyMemoryViewObject *mv;
mv = (PyMemoryViewObject *)
PyObject_GC_NewVar(PyMemoryViewObject, &PyMemoryView_Type, 3*ndim);
if (mv == NULL)
return NULL;
mv->mbuf = NULL;
mv->hash = -1;
mv->flags = 0;
mv->exports = 0;
mv->view.ndim = ndim;
mv->view.shape = mv->ob_array;
mv->view.strides = mv->ob_array + ndim;
mv->view.suboffsets = mv->ob_array + 2 * ndim;
mv->weakreflist = NULL;
_PyObject_GC_TRACK(mv);
return mv;
}
/*
Return a new memoryview that is registered with mbuf. If src is NULL,
use mbuf->master as the underlying buffer. Otherwise, use src.
The new memoryview has full buffer information: shape and strides
are always present, suboffsets as needed. Arrays are copied to
the memoryview's ob_array field.
*/
static PyObject *
mbuf_add_view(_PyManagedBufferObject *mbuf, const Py_buffer *src)
{
PyMemoryViewObject *mv;
Py_buffer *dest;
if (src == NULL)
src = &mbuf->master;
if (src->ndim > PyBUF_MAX_NDIM) {
PyErr_SetString(PyExc_ValueError,
"memoryview: number of dimensions must not exceed "
Py_STRINGIFY(PyBUF_MAX_NDIM));
return NULL;
}
mv = memory_alloc(src->ndim);
if (mv == NULL)
return NULL;
dest = &mv->view;
init_shared_values(dest, src);
init_shape_strides(dest, src);
init_suboffsets(dest, src);
init_flags(mv);
mv->mbuf = (_PyManagedBufferObject*)Py_NewRef(mbuf);
mbuf->exports++;
return (PyObject *)mv;
}
/* Register an incomplete view: shape, strides, suboffsets and flags still
need to be initialized. Use 'ndim' instead of src->ndim to determine the
size of the memoryview's ob_array.
Assumption: ndim <= PyBUF_MAX_NDIM. */
static PyObject *
mbuf_add_incomplete_view(_PyManagedBufferObject *mbuf, const Py_buffer *src,
int ndim)
{
PyMemoryViewObject *mv;
Py_buffer *dest;
if (src == NULL)
src = &mbuf->master;
assert(ndim <= PyBUF_MAX_NDIM);
mv = memory_alloc(ndim);
if (mv == NULL)
return NULL;
dest = &mv->view;
init_shared_values(dest, src);
mv->mbuf = (_PyManagedBufferObject*)Py_NewRef(mbuf);
mbuf->exports++;
return (PyObject *)mv;
}
/* Expose a raw memory area as a view of contiguous bytes. flags can be
PyBUF_READ or PyBUF_WRITE. view->format is set to "B" (unsigned bytes).
The memoryview has complete buffer information. */
PyObject *
PyMemoryView_FromMemory(char *mem, Py_ssize_t size, int flags)
{
_PyManagedBufferObject *mbuf;
PyObject *mv;
int readonly;
assert(mem != NULL);
assert(flags == PyBUF_READ || flags == PyBUF_WRITE);
mbuf = mbuf_alloc();
if (mbuf == NULL)
return NULL;
readonly = (flags == PyBUF_WRITE) ? 0 : 1;
(void)PyBuffer_FillInfo(&mbuf->master, NULL, mem, size, readonly,
PyBUF_FULL_RO);
mv = mbuf_add_view(mbuf, NULL);
Py_DECREF(mbuf);
return mv;
}
/* Create a memoryview from a given Py_buffer. For simple byte views,
PyMemoryView_FromMemory() should be used instead.
This function is the only entry point that can create a master buffer
without full information. Because of this fact init_shape_strides()
must be able to reconstruct missing values. */
PyObject *
PyMemoryView_FromBuffer(const Py_buffer *info)
{
_PyManagedBufferObject *mbuf;
PyObject *mv;
if (info->buf == NULL) {
PyErr_SetString(PyExc_ValueError,
"PyMemoryView_FromBuffer(): info->buf must not be NULL");
return NULL;
}
mbuf = mbuf_alloc();
if (mbuf == NULL)
return NULL;
/* info->obj is either NULL or a borrowed reference. This reference
should not be decremented in PyBuffer_Release(). */
mbuf->master = *info;
mbuf->master.obj = NULL;
mv = mbuf_add_view(mbuf, NULL);
Py_DECREF(mbuf);
return mv;
}
/* Create a memoryview from an object that implements the buffer protocol,
using the given flags.
If the object is a memoryview, the new memoryview must be registered
with the same managed buffer. Otherwise, a new managed buffer is created. */
static PyObject *
PyMemoryView_FromObjectAndFlags(PyObject *v, int flags)
{
_PyManagedBufferObject *mbuf;
if (PyMemoryView_Check(v)) {
PyMemoryViewObject *mv = (PyMemoryViewObject *)v;
CHECK_RELEASED(mv);
CHECK_RESTRICTED(mv);
return mbuf_add_view(mv->mbuf, &mv->view);
}
else if (PyObject_CheckBuffer(v)) {
PyObject *ret;
mbuf = (_PyManagedBufferObject *)_PyManagedBuffer_FromObject(v, flags);
if (mbuf == NULL)
return NULL;
ret = mbuf_add_view(mbuf, NULL);
Py_DECREF(mbuf);
return ret;
}
PyErr_Format(PyExc_TypeError,
"memoryview: a bytes-like object is required, not '%.200s'",
Py_TYPE(v)->tp_name);
return NULL;
}
/* Create a memoryview from an object that implements the buffer protocol,
using the given flags.
If the object is a memoryview, the new memoryview must be registered
with the same managed buffer. Otherwise, a new managed buffer is created. */
PyObject *
_PyMemoryView_FromBufferProc(PyObject *v, int flags, getbufferproc bufferproc)
{
_PyManagedBufferObject *mbuf = mbuf_alloc();
if (mbuf == NULL)
return NULL;
int res = bufferproc(v, &mbuf->master, flags);
if (res < 0) {
mbuf->master.obj = NULL;
Py_DECREF(mbuf);
return NULL;
}
PyObject *ret = mbuf_add_view(mbuf, NULL);
Py_DECREF(mbuf);
return ret;
}
/* Create a memoryview from an object that implements the buffer protocol.
If the object is a memoryview, the new memoryview must be registered
with the same managed buffer. Otherwise, a new managed buffer is created. */
PyObject *
PyMemoryView_FromObject(PyObject *v)
{
return PyMemoryView_FromObjectAndFlags(v, PyBUF_FULL_RO);
}
/* Copy the format string from a base object that might vanish. */
static int
mbuf_copy_format(_PyManagedBufferObject *mbuf, const char *fmt)
{
if (fmt != NULL) {
char *cp = PyMem_Malloc(strlen(fmt)+1);
if (cp == NULL) {
PyErr_NoMemory();
return -1;
}
mbuf->master.format = strcpy(cp, fmt);
mbuf->flags |= _Py_MANAGED_BUFFER_FREE_FORMAT;
}
return 0;
}
/*
Return a memoryview that is based on a contiguous copy of src.
Assumptions: src has PyBUF_FULL_RO information, src->ndim > 0.
Ownership rules:
1) As usual, the returned memoryview has a private copy
of src->shape, src->strides and src->suboffsets.
2) src->format is copied to the master buffer and released
in mbuf_dealloc(). The releasebufferproc of the bytes
object is NULL, so it does not matter that mbuf_release()
passes the altered format pointer to PyBuffer_Release().
*/
static PyObject *
memory_from_contiguous_copy(const Py_buffer *src, char order)
{
_PyManagedBufferObject *mbuf;
PyMemoryViewObject *mv;
PyObject *bytes;
Py_buffer *dest;
int i;
assert(src->ndim > 0);
assert(src->shape != NULL);
bytes = PyBytes_FromStringAndSize(NULL, src->len);
if (bytes == NULL)
return NULL;
mbuf = (_PyManagedBufferObject *)_PyManagedBuffer_FromObject(bytes, PyBUF_FULL_RO);
Py_DECREF(bytes);
if (mbuf == NULL)
return NULL;
if (mbuf_copy_format(mbuf, src->format) < 0) {
Py_DECREF(mbuf);
return NULL;
}
mv = (PyMemoryViewObject *)mbuf_add_incomplete_view(mbuf, NULL, src->ndim);
Py_DECREF(mbuf);
if (mv == NULL)
return NULL;
dest = &mv->view;
/* shared values are initialized correctly except for itemsize */
dest->itemsize = src->itemsize;
/* shape and strides */
for (i = 0; i < src->ndim; i++) {
dest->shape[i] = src->shape[i];
}
if (order == 'C' || order == 'A') {
init_strides_from_shape(dest);
}
else {
init_fortran_strides_from_shape(dest);
}
/* suboffsets */
dest->suboffsets = NULL;
/* flags */
init_flags(mv);
if (copy_buffer(dest, src) < 0) {
Py_DECREF(mv);
return NULL;
}
return (PyObject *)mv;
}
/*
Return a new memoryview object based on a contiguous exporter with
buffertype={PyBUF_READ, PyBUF_WRITE} and order={'C', 'F'ortran, or 'A'ny}.
The logical structure of the input and output buffers is the same
(i.e. tolist(input) == tolist(output)), but the physical layout in
memory can be explicitly chosen.
As usual, if buffertype=PyBUF_WRITE, the exporter's buffer must be writable,
otherwise it may be writable or read-only.
If the exporter is already contiguous with the desired target order,
the memoryview will be directly based on the exporter.
Otherwise, if the buffertype is PyBUF_READ, the memoryview will be
based on a new bytes object. If order={'C', 'A'ny}, use 'C' order,
'F'ortran order otherwise.
*/
PyObject *
PyMemoryView_GetContiguous(PyObject *obj, int buffertype, char order)
{
PyMemoryViewObject *mv;
PyObject *ret;
Py_buffer *view;
assert(buffertype == PyBUF_READ || buffertype == PyBUF_WRITE);
assert(order == 'C' || order == 'F' || order == 'A');
mv = (PyMemoryViewObject *)PyMemoryView_FromObject(obj);
if (mv == NULL)
return NULL;
view = &mv->view;
if (buffertype == PyBUF_WRITE && view->readonly) {
PyErr_SetString(PyExc_BufferError,
"underlying buffer is not writable");
Py_DECREF(mv);
return NULL;
}
if (PyBuffer_IsContiguous(view, order))
return (PyObject *)mv;
if (buffertype == PyBUF_WRITE) {
PyErr_SetString(PyExc_BufferError,
"writable contiguous buffer requested "
"for a non-contiguous object.");
Py_DECREF(mv);
return NULL;
}
ret = memory_from_contiguous_copy(view, order);
Py_DECREF(mv);
return ret;