summaryrefslogtreecommitdiffstats
path: root/Objects/picklebufobject.c
blob: a135e5575e28c52f64831597bc67622e44155ee1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
/* PickleBuffer object implementation */

#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include <stddef.h>

typedef struct {
    PyObject_HEAD
    /* The view exported by the original object */
    Py_buffer view;
    PyObject *weakreflist;
} PyPickleBufferObject;

/* C API */

PyObject *
PyPickleBuffer_FromObject(PyObject *base)
{
    PyTypeObject *type = &PyPickleBuffer_Type;
    PyPickleBufferObject *self;

    self = (PyPickleBufferObject *) type->tp_alloc(type, 0);
    if (self == NULL) {
        return NULL;
    }
    self->view.obj = NULL;
    self->weakreflist = NULL;
    if (PyObject_GetBuffer(base, &self->view, PyBUF_FULL_RO) < 0) {
        Py_DECREF(self);
        return NULL;
    }
    return (PyObject *) self;
}

const Py_buffer *
PyPickleBuffer_GetBuffer(PyObject *obj)
{
    PyPickleBufferObject *self = (PyPickleBufferObject *) obj;

    if (!PyPickleBuffer_Check(obj)) {
        PyErr_Format(PyExc_TypeError,
                     "expected PickleBuffer, %.200s found",
                     Py_TYPE(obj)->tp_name);
        return NULL;
    }
    if (self->view.obj == NULL) {
        PyErr_SetString(PyExc_ValueError,
                        "operation forbidden on released PickleBuffer object");
        return NULL;
    }
    return &self->view;
}

int
PyPickleBuffer_Release(PyObject *obj)
{
    PyPickleBufferObject *self = (PyPickleBufferObject *) obj;

    if (!PyPickleBuffer_Check(obj)) {
        PyErr_Format(PyExc_TypeError,
                     "expected PickleBuffer, %.200s found",
                     Py_TYPE(obj)->tp_name);
        return -1;
    }
    PyBuffer_Release(&self->view);
    return 0;
}

static PyObject *
picklebuf_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    PyPickleBufferObject *self;
    PyObject *base;
    char *keywords[] = {"", NULL};

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O:PickleBuffer",
                                     keywords, &base)) {
        return NULL;
    }

    self = (PyPickleBufferObject *) type->tp_alloc(type, 0);
    if (self == NULL) {
        return NULL;
    }
    self->view.obj = NULL;
    self->weakreflist = NULL;
    if (PyObject_GetBuffer(base, &self->view, PyBUF_FULL_RO) < 0) {
        Py_DECREF(self);
        return NULL;
    }
    return (PyObject *) self;
}

static int
picklebuf_traverse(PyPickleBufferObject *self, visitproc visit, void *arg)
{
    Py_VISIT(self->view.obj);
    return 0;
}

static int
picklebuf_clear(PyPickleBufferObject *self)
{
    PyBuffer_Release(&self->view);
    return 0;
}

static void
picklebuf_dealloc(PyPickleBufferObject *self)
{
    PyObject_GC_UnTrack(self);
    if (self->weakreflist != NULL)
        PyObject_ClearWeakRefs((PyObject *) self);
    PyBuffer_Release(&self->view);
    Py_TYPE(self)->tp_free((PyObject *) self);
}

/* Buffer API */

static int
picklebuf_getbuf(PyPickleBufferObject *self, Py_buffer *view, int flags)
{
    if (self->view.obj == NULL) {
        PyErr_SetString(PyExc_ValueError,
                        "operation forbidden on released PickleBuffer object");
        return -1;
    }
    return PyObject_GetBuffer(self->view.obj, view, flags);
}

static void
picklebuf_releasebuf(PyPickleBufferObject *self, Py_buffer *view)
{
    /* Since our bf_getbuffer redirects to the original object, this
     * implementation is never called.  It only exists to signal that
     * buffers exported by PickleBuffer have non-trivial releasing
     * behaviour (see check in Python/getargs.c).
     */
}

static PyBufferProcs picklebuf_as_buffer = {
    .bf_getbuffer = (getbufferproc) picklebuf_getbuf,
    .bf_releasebuffer = (releasebufferproc) picklebuf_releasebuf,
};

/* Methods */

static PyObject *
picklebuf_raw(PyPickleBufferObject *self, PyObject *Py_UNUSED(ignored))
{
    if (self->view.obj == NULL) {
        PyErr_SetString(PyExc_ValueError,
                        "operation forbidden on released PickleBuffer object");
        return NULL;
    }
    if (self->view.suboffsets != NULL
        || !PyBuffer_IsContiguous(&self->view, 'A')) {
        PyErr_SetString(PyExc_BufferError,
                        "cannot extract raw buffer from non-contiguous buffer");
        return NULL;
    }
    PyObject *m = PyMemoryView_FromObject((PyObject *) self);
    if (m == NULL) {
        return NULL;
    }
    PyMemoryViewObject *mv = (PyMemoryViewObject *) m;
    assert(mv->view.suboffsets == NULL);
    /* Mutate memoryview instance to make it a "raw" memoryview */
    mv->view.format = "B";
    mv->view.ndim = 1;
    mv->view.itemsize = 1;
    /* shape = (length,) */
    mv->view.shape = &mv->view.len;
    /* strides = (1,) */
    mv->view.strides = &mv->view.itemsize;
    /* Fix memoryview state flags */
    /* XXX Expose memoryobject.c's init_flags() instead? */
    mv->flags = _Py_MEMORYVIEW_C | _Py_MEMORYVIEW_FORTRAN;
    return m;
}

PyDoc_STRVAR(picklebuf_raw_doc,
"raw($self, /)\n--\n\
\n\
Return a memoryview of the raw memory underlying this buffer.\n\
Will raise BufferError is the buffer isn't contiguous.");

static PyObject *
picklebuf_release(PyPickleBufferObject *self, PyObject *Py_UNUSED(ignored))
{
    PyBuffer_Release(&self->view);
    Py_RETURN_NONE;
}

PyDoc_STRVAR(picklebuf_release_doc,
"release($self, /)\n--\n\
\n\
Release the underlying buffer exposed by the PickleBuffer object.");

static PyMethodDef picklebuf_methods[] = {
    {"raw",     (PyCFunction) picklebuf_raw,     METH_NOARGS, picklebuf_raw_doc},
    {"release", (PyCFunction) picklebuf_release, METH_NOARGS, picklebuf_release_doc},
    {NULL,      NULL}
};

PyTypeObject PyPickleBuffer_Type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    .tp_name = "pickle.PickleBuffer",
    .tp_doc = "Wrapper for potentially out-of-band buffers",
    .tp_basicsize = sizeof(PyPickleBufferObject),
    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
    .tp_new = picklebuf_new,
    .tp_dealloc = (destructor) picklebuf_dealloc,
    .tp_traverse = (traverseproc) picklebuf_traverse,
    .tp_clear = (inquiry) picklebuf_clear,
    .tp_weaklistoffset = offsetof(PyPickleBufferObject, weakreflist),
    .tp_as_buffer = &picklebuf_as_buffer,
    .tp_methods = picklebuf_methods,
};