mirror of https://github.com/python/cpython
554 lines
11 KiB
C
554 lines
11 KiB
C
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/* Buffer object implementation */
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#include "Python.h"
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typedef struct {
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PyObject_HEAD
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PyObject *b_base;
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void *b_ptr;
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int b_size;
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int b_readonly;
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#ifdef CACHE_HASH
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long b_hash;
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#endif
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} PyBufferObject;
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static PyObject *
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_PyBuffer_FromMemory(PyObject *base, void *ptr, int size, int readonly)
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{
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PyBufferObject * b;
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if ( size < 0 ) {
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PyErr_SetString(PyExc_ValueError,
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"size must be zero or positive");
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return NULL;
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}
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b = PyObject_NEW(PyBufferObject, &PyBuffer_Type);
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if ( b == NULL )
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return NULL;
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Py_XINCREF(base);
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b->b_base = base;
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b->b_ptr = ptr;
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b->b_size = size;
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b->b_readonly = readonly;
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#ifdef CACHE_HASH
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b->b_hash = -1;
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#endif
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return (PyObject *) b;
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}
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static PyObject *
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_PyBuffer_FromObject(PyObject *base, int offset, int size,
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getreadbufferproc proc, int readonly)
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{
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PyBufferProcs *pb = base->ob_type->tp_as_buffer;
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void *p;
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int count;
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if ( offset < 0 ) {
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PyErr_SetString(PyExc_ValueError,
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"offset must be zero or positive");
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return NULL;
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}
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if ( (*pb->bf_getsegcount)(base, NULL) != 1 )
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{
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PyErr_SetString(PyExc_TypeError,
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"single-segment buffer object expected");
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return NULL;
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}
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if ( (count = (*proc)(base, 0, &p)) < 0 )
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return NULL;
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/* apply constraints to the start/end */
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if ( size == Py_END_OF_BUFFER || size < 0 )
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size = count;
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if ( offset > count )
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offset = count;
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if ( offset + size > count )
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size = count - offset;
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/* if the base object is another buffer, then "deref" it,
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* except if the base of the other buffer is NULL
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*/
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if ( PyBuffer_Check(base) && (((PyBufferObject *)base)->b_base) )
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base = ((PyBufferObject *)base)->b_base;
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return _PyBuffer_FromMemory(base, (char *)p + offset, size, readonly);
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}
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PyObject *
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PyBuffer_FromObject(PyObject *base, int offset, int size)
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{
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PyBufferProcs *pb = base->ob_type->tp_as_buffer;
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if ( pb == NULL ||
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pb->bf_getreadbuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_SetString(PyExc_TypeError, "buffer object expected");
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return NULL;
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}
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return _PyBuffer_FromObject(base, offset, size,
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pb->bf_getreadbuffer, 1);
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}
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PyObject *
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PyBuffer_FromReadWriteObject(PyObject *base, int offset, int size)
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{
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PyBufferProcs *pb = base->ob_type->tp_as_buffer;
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if ( pb == NULL ||
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pb->bf_getwritebuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_SetString(PyExc_TypeError, "buffer object expected");
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return NULL;
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}
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return _PyBuffer_FromObject(base, offset, size,
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(getreadbufferproc)pb->bf_getwritebuffer,
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0);
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}
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PyObject *
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PyBuffer_FromMemory(void *ptr, int size)
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{
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return _PyBuffer_FromMemory(NULL, ptr, size, 1);
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}
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PyObject *
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PyBuffer_FromReadWriteMemory(void *ptr, int size)
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{
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return _PyBuffer_FromMemory(NULL, ptr, size, 0);
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}
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PyObject *
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PyBuffer_New(int size)
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{
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PyObject *o;
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PyBufferObject * b;
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if (size < 0) {
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PyErr_SetString(PyExc_ValueError,
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"size must be zero or positive");
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return NULL;
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}
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/* PyObject_New is inlined */
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o = PyObject_MALLOC(sizeof(*b) + size);
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if ( o == NULL )
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return PyErr_NoMemory();
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b = (PyBufferObject *) PyObject_INIT(o, &PyBuffer_Type);
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b->b_base = NULL;
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b->b_ptr = (void *)(b + 1);
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b->b_size = size;
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b->b_readonly = 0;
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#ifdef CACHE_HASH
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b->b_hash = -1;
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#endif
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return o;
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}
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/* Methods */
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static void
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buffer_dealloc(PyBufferObject *self)
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{
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Py_XDECREF(self->b_base);
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PyObject_DEL(self);
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}
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static int
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buffer_compare(PyBufferObject *self, PyBufferObject *other)
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{
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int len_self = self->b_size;
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int len_other = other->b_size;
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int min_len = (len_self < len_other) ? len_self : len_other;
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int cmp;
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if (min_len > 0) {
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cmp = memcmp(self->b_ptr, other->b_ptr, min_len);
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if (cmp != 0)
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return cmp;
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}
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return (len_self < len_other) ? -1 : (len_self > len_other) ? 1 : 0;
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}
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static PyObject *
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buffer_repr(PyBufferObject *self)
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{
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char *status = self->b_readonly ? "read-only" : "read-write";
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if ( self->b_base == NULL )
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return PyString_FromFormat("<%s buffer ptr %p, size %d at %p>",
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status,
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self->b_ptr,
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self->b_size,
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self);
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else
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return PyString_FromFormat(
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"<%s buffer for %p, ptr %p, size %d at %p>",
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status,
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self->b_base,
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self->b_ptr,
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self->b_size,
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self);
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}
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static long
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buffer_hash(PyBufferObject *self)
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{
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register int len;
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register unsigned char *p;
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register long x;
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#ifdef CACHE_HASH
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if ( self->b_hash != -1 )
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return self->b_hash;
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#endif
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if ( !self->b_readonly )
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{
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/* ### use different wording, since this is conditional? */
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PyErr_SetString(PyExc_TypeError, "unhashable type");
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return -1;
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}
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len = self->b_size;
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p = (unsigned char *) self->b_ptr;
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x = *p << 7;
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while (--len >= 0)
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x = (1000003*x) ^ *p++;
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x ^= self->b_size;
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if (x == -1)
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x = -2;
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#ifdef CACHE_HASH
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self->b_hash = x;
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#endif
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return x;
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}
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static PyObject *
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buffer_str(PyBufferObject *self)
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{
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return PyString_FromStringAndSize(self->b_ptr, self->b_size);
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}
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/* Sequence methods */
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static int
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buffer_length(PyBufferObject *self)
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{
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return self->b_size;
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}
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static PyObject *
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buffer_concat(PyBufferObject *self, PyObject *other)
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{
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PyBufferProcs *pb = other->ob_type->tp_as_buffer;
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char *p1;
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void *p2;
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PyObject *ob;
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int count;
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if ( pb == NULL ||
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pb->bf_getreadbuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_BadArgument();
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return NULL;
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}
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if ( (*pb->bf_getsegcount)(other, NULL) != 1 )
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{
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/* ### use a different exception type/message? */
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PyErr_SetString(PyExc_TypeError,
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"single-segment buffer object expected");
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return NULL;
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}
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/* optimize special case */
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if ( self->b_size == 0 )
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{
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Py_INCREF(other);
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return other;
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}
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if ( (count = (*pb->bf_getreadbuffer)(other, 0, &p2)) < 0 )
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return NULL;
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/* optimize special case */
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if ( count == 0 )
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{
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Py_INCREF(self);
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return (PyObject *)self;
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}
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ob = PyString_FromStringAndSize(NULL, self->b_size + count);
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p1 = PyString_AS_STRING(ob);
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memcpy(p1, self->b_ptr, self->b_size);
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memcpy(p1 + self->b_size, p2, count);
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/* there is an extra byte in the string object, so this is safe */
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p1[self->b_size + count] = '\0';
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return ob;
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}
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static PyObject *
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buffer_repeat(PyBufferObject *self, int count)
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{
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PyObject *ob;
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register char *p;
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void *ptr = self->b_ptr;
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int size = self->b_size;
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if ( count < 0 )
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count = 0;
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ob = PyString_FromStringAndSize(NULL, size * count);
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if ( ob == NULL )
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return NULL;
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p = PyString_AS_STRING(ob);
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while ( count-- )
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{
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memcpy(p, ptr, size);
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p += size;
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}
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/* there is an extra byte in the string object, so this is safe */
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*p = '\0';
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return ob;
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}
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static PyObject *
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buffer_item(PyBufferObject *self, int idx)
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{
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if ( idx < 0 || idx >= self->b_size )
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{
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PyErr_SetString(PyExc_IndexError, "buffer index out of range");
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return NULL;
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}
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return PyString_FromStringAndSize((char *)self->b_ptr + idx, 1);
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}
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static PyObject *
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buffer_slice(PyBufferObject *self, int left, int right)
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{
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if ( left < 0 )
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left = 0;
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if ( right < 0 )
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right = 0;
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if ( right > self->b_size )
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right = self->b_size;
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if ( left == 0 && right == self->b_size )
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{
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/* same as self */
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Py_INCREF(self);
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return (PyObject *)self;
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}
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if ( right < left )
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right = left;
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return PyString_FromStringAndSize((char *)self->b_ptr + left,
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right - left);
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}
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static int
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buffer_ass_item(PyBufferObject *self, int idx, PyObject *other)
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{
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PyBufferProcs *pb;
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void *p;
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int count;
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if ( self->b_readonly ) {
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PyErr_SetString(PyExc_TypeError,
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"buffer is read-only");
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return -1;
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}
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if (idx < 0 || idx >= self->b_size) {
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PyErr_SetString(PyExc_IndexError,
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"buffer assignment index out of range");
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return -1;
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}
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pb = other ? other->ob_type->tp_as_buffer : NULL;
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if ( pb == NULL ||
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pb->bf_getreadbuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_BadArgument();
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return -1;
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}
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if ( (*pb->bf_getsegcount)(other, NULL) != 1 )
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{
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/* ### use a different exception type/message? */
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PyErr_SetString(PyExc_TypeError,
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"single-segment buffer object expected");
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return -1;
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}
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if ( (count = (*pb->bf_getreadbuffer)(other, 0, &p)) < 0 )
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return -1;
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if ( count != 1 ) {
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PyErr_SetString(PyExc_TypeError,
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"right operand must be a single byte");
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return -1;
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}
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((char *)self->b_ptr)[idx] = *(char *)p;
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return 0;
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}
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static int
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buffer_ass_slice(PyBufferObject *self, int left, int right, PyObject *other)
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{
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PyBufferProcs *pb;
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void *p;
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int slice_len;
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int count;
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if ( self->b_readonly ) {
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PyErr_SetString(PyExc_TypeError,
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"buffer is read-only");
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return -1;
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}
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pb = other ? other->ob_type->tp_as_buffer : NULL;
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if ( pb == NULL ||
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pb->bf_getreadbuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_BadArgument();
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return -1;
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}
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if ( (*pb->bf_getsegcount)(other, NULL) != 1 )
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{
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/* ### use a different exception type/message? */
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PyErr_SetString(PyExc_TypeError,
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"single-segment buffer object expected");
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return -1;
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}
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if ( (count = (*pb->bf_getreadbuffer)(other, 0, &p)) < 0 )
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return -1;
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if ( left < 0 )
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left = 0;
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else if ( left > self->b_size )
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left = self->b_size;
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if ( right < left )
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right = left;
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else if ( right > self->b_size )
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right = self->b_size;
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slice_len = right - left;
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if ( count != slice_len ) {
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PyErr_SetString(
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PyExc_TypeError,
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"right operand length must match slice length");
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return -1;
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}
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if ( slice_len )
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memcpy((char *)self->b_ptr + left, p, slice_len);
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return 0;
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}
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/* Buffer methods */
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static int
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buffer_getreadbuf(PyBufferObject *self, int idx, void **pp)
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{
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if ( idx != 0 ) {
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PyErr_SetString(PyExc_SystemError,
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"accessing non-existent buffer segment");
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return -1;
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}
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*pp = self->b_ptr;
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return self->b_size;
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}
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static int
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buffer_getwritebuf(PyBufferObject *self, int idx, void **pp)
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{
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if ( self->b_readonly )
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{
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PyErr_SetString(PyExc_TypeError, "buffer is read-only");
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return -1;
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}
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return buffer_getreadbuf(self, idx, pp);
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}
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static int
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buffer_getsegcount(PyBufferObject *self, int *lenp)
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{
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if ( lenp )
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*lenp = self->b_size;
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return 1;
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}
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static int
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buffer_getcharbuf(PyBufferObject *self, int idx, const char **pp)
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{
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if ( idx != 0 ) {
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PyErr_SetString(PyExc_SystemError,
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"accessing non-existent buffer segment");
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return -1;
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}
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*pp = (const char *)self->b_ptr;
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return self->b_size;
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}
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static PySequenceMethods buffer_as_sequence = {
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(inquiry)buffer_length, /*sq_length*/
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(binaryfunc)buffer_concat, /*sq_concat*/
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(intargfunc)buffer_repeat, /*sq_repeat*/
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(intargfunc)buffer_item, /*sq_item*/
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(intintargfunc)buffer_slice, /*sq_slice*/
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(intobjargproc)buffer_ass_item, /*sq_ass_item*/
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(intintobjargproc)buffer_ass_slice, /*sq_ass_slice*/
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};
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static PyBufferProcs buffer_as_buffer = {
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(getreadbufferproc)buffer_getreadbuf,
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(getwritebufferproc)buffer_getwritebuf,
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(getsegcountproc)buffer_getsegcount,
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(getcharbufferproc)buffer_getcharbuf,
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};
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PyTypeObject PyBuffer_Type = {
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PyObject_HEAD_INIT(&PyType_Type)
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0,
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"buffer",
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sizeof(PyBufferObject),
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0,
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(destructor)buffer_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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(cmpfunc)buffer_compare, /* tp_compare */
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(reprfunc)buffer_repr, /* tp_repr */
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0, /* tp_as_number */
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&buffer_as_sequence, /* tp_as_sequence */
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0, /* tp_as_mapping */
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(hashfunc)buffer_hash, /* tp_hash */
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0, /* tp_call */
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(reprfunc)buffer_str, /* tp_str */
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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&buffer_as_buffer, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT, /* tp_flags */
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0, /* tp_doc */
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};
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