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Make buffer objects based on mutable objects (like array) safe.

This commit is contained in:
Neil Schemenauer 2004-03-11 02:42:45 +00:00
parent 0eadcd9cbb
commit 4252a7a5d1
2 changed files with 154 additions and 82 deletions
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5
Misc/NEWS
View File

@ -172,6 +172,11 @@ Core and builtins
to clear the error when attempts to get the __getstate__ attribute to clear the error when attempts to get the __getstate__ attribute
fail caused intermittent errors and odd behavior. fail caused intermittent errors and odd behavior.
- buffer objects based on other objects no longer cache a pointer to
the data and the data length. Instead, the appropriate tp_as_buffer
method is called as necessary.
Extension modules Extension modules
----------------- -----------------

229
Objects/bufferobject.c
View File

@ -9,17 +9,59 @@ typedef struct {
PyObject *b_base; PyObject *b_base;
void *b_ptr; void *b_ptr;
int b_size; int b_size;
int b_offset;
int b_readonly; int b_readonly;
long b_hash; long b_hash;
} PyBufferObject; } PyBufferObject;
static int
get_buf(PyBufferObject *self, void **ptr, int *size)
{
if (self->b_base == NULL) {
assert (ptr != NULL);
*ptr = self->b_ptr;
*size = self->b_size;
}
else {
int count, offset;
getreadbufferproc proc;
PyBufferProcs *bp = self->b_base->ob_type->tp_as_buffer;
if ((*bp->bf_getsegcount)(self->b_base, NULL) != 1) {
PyErr_SetString(PyExc_TypeError,
"single-segment buffer object expected");
return 0;
}
if (self->b_readonly)
proc = bp->bf_getreadbuffer;
else
proc = (getreadbufferproc)bp->bf_getwritebuffer;
if ((count = (*proc)(self->b_base, 0, ptr)) < 0)
return 0;
/* apply constraints to the start/end */
if (self->b_offset > count)
offset = count;
else
offset = self->b_offset;
(char *)*ptr = (char *)*ptr + offset;
if (self->b_size == Py_END_OF_BUFFER)
*size = count;
else
*size = self->b_size;
if (offset + *size > count)
*size = count - offset;
}
return 1;
}
static PyObject * static PyObject *
buffer_from_memory(PyObject *base, void *ptr, int size, int readonly) buffer_from_memory(PyObject *base, int size, int offset, void *ptr,
int readonly)
{ {
PyBufferObject * b; PyBufferObject * b;
if ( size < 0 ) { if (size < 0 && size != Py_END_OF_BUFFER) {
PyErr_SetString(PyExc_ValueError, PyErr_SetString(PyExc_ValueError,
"size must be zero or positive"); "size must be zero or positive");
return NULL; return NULL;
@ -33,6 +75,7 @@ buffer_from_memory(PyObject *base, void *ptr, int size, int readonly)
b->b_base = base; b->b_base = base;
b->b_ptr = ptr; b->b_ptr = ptr;
b->b_size = size; b->b_size = size;
b->b_offset = offset;
b->b_readonly = readonly; b->b_readonly = readonly;
b->b_hash = -1; b->b_hash = -1;
@ -40,43 +83,23 @@ buffer_from_memory(PyObject *base, void *ptr, int size, int readonly)
} }
static PyObject * static PyObject *
buffer_from_object(PyObject *base, int offset, int size, buffer_from_object(PyObject *base, int size, int offset, int readonly)
getreadbufferproc proc, int readonly)
{ {
PyBufferProcs *pb = base->ob_type->tp_as_buffer;
void *p;
int count;
if ( offset < 0 ) { if ( offset < 0 ) {
PyErr_SetString(PyExc_ValueError, PyErr_SetString(PyExc_ValueError,
"offset must be zero or positive"); "offset must be zero or positive");
return NULL; return NULL;
} }
if ( (*pb->bf_getsegcount)(base, NULL) != 1 ) /* if the base object is another buffer, then try to refer to the
{ * base object.
PyErr_SetString(PyExc_TypeError,
"single-segment buffer object expected");
return NULL;
}
if ( (count = (*proc)(base, 0, &p)) < 0 )
return NULL;
/* apply constraints to the start/end */
if ( size == Py_END_OF_BUFFER || size < 0 )
size = count;
if ( offset > count )
offset = count;
if ( offset + size > count )
size = count - offset;
/* if the base object is another buffer, then "deref" it,
* except if the base of the other buffer is NULL
*/ */
if ( PyBuffer_Check(base) && (((PyBufferObject *)base)->b_base) ) if ( PyBuffer_Check(base) && (((PyBufferObject *)base)->b_base) ) {
base = ((PyBufferObject *)base)->b_base; base = ((PyBufferObject *)base)->b_base;
offset = ((PyBufferObject *)base)->b_offset + offset;
}
return buffer_from_memory(base, (char *)p + offset, size, readonly); return buffer_from_memory(base, size, offset, NULL, readonly);
} }
@ -93,7 +116,7 @@ PyBuffer_FromObject(PyObject *base, int offset, int size)
return NULL; return NULL;
} }
return buffer_from_object(base, offset, size, pb->bf_getreadbuffer, 1); return buffer_from_object(base, size, offset, 1);
} }
PyObject * PyObject *
@ -109,21 +132,19 @@ PyBuffer_FromReadWriteObject(PyObject *base, int offset, int size)
return NULL; return NULL;
} }
return buffer_from_object(base, offset, size, return buffer_from_object(base, size, offset, 0);
(getreadbufferproc)pb->bf_getwritebuffer,
0);
} }
PyObject * PyObject *
PyBuffer_FromMemory(void *ptr, int size) PyBuffer_FromMemory(void *ptr, int size)
{ {
return buffer_from_memory(NULL, ptr, size, 1); return buffer_from_memory(NULL, size, 0, ptr, 1);
} }
PyObject * PyObject *
PyBuffer_FromReadWriteMemory(void *ptr, int size) PyBuffer_FromReadWriteMemory(void *ptr, int size)
{ {
return buffer_from_memory(NULL, ptr, size, 0); return buffer_from_memory(NULL, size, 0, ptr, 0);
} }
PyObject * PyObject *
@ -146,6 +167,7 @@ PyBuffer_New(int size)
b->b_base = NULL; b->b_base = NULL;
b->b_ptr = (void *)(b + 1); b->b_ptr = (void *)(b + 1);
b->b_size = size; b->b_size = size;
b->b_offset = 0;
b->b_readonly = 0; b->b_readonly = 0;
b->b_hash = -1; b->b_hash = -1;
@ -185,12 +207,16 @@ buffer_dealloc(PyBufferObject *self)
static int static int
buffer_compare(PyBufferObject *self, PyBufferObject *other) buffer_compare(PyBufferObject *self, PyBufferObject *other)
{ {
int len_self = self->b_size; void *p1, *p2;
int len_other = other->b_size; int len_self, len_other, min_len, cmp;
int min_len = (len_self < len_other) ? len_self : len_other;
int cmp; if (!get_buf(self, &p1, &len_self))
return -1;
if (!get_buf(other, &p2, &len_other))
return -1;
min_len = (len_self < len_other) ? len_self : len_other;
if (min_len > 0) { if (min_len > 0) {
cmp = memcmp(self->b_ptr, other->b_ptr, min_len); cmp = memcmp(p1, p2, min_len);
if (cmp != 0) if (cmp != 0)
return cmp; return cmp;
} }
@ -210,17 +236,19 @@ buffer_repr(PyBufferObject *self)
self); self);
else else
return PyString_FromFormat( return PyString_FromFormat(
"<%s buffer for %p, ptr %p, size %d at %p>", "<%s buffer for %p, size %d, offset %d at %p>",
status, status,
self->b_base, self->b_base,
self->b_ptr,
self->b_size, self->b_size,
self->b_offset,
self); self);
} }
static long static long
buffer_hash(PyBufferObject *self) buffer_hash(PyBufferObject *self)
{ {
void *ptr;
int size;
register int len; register int len;
register unsigned char *p; register unsigned char *p;
register long x; register long x;
@ -242,12 +270,14 @@ buffer_hash(PyBufferObject *self)
return -1; return -1;
} }
len = self->b_size; if (!get_buf(self, &ptr, &size))
p = (unsigned char *) self->b_ptr; return -1;
p = (unsigned char *) ptr;
len = size;
x = *p << 7; x = *p << 7;
while (--len >= 0) while (--len >= 0)
x = (1000003*x) ^ *p++; x = (1000003*x) ^ *p++;
x ^= self->b_size; x ^= size;
if (x == -1) if (x == -1)
x = -2; x = -2;
self->b_hash = x; self->b_hash = x;
@ -257,7 +287,11 @@ buffer_hash(PyBufferObject *self)
static PyObject * static PyObject *
buffer_str(PyBufferObject *self) buffer_str(PyBufferObject *self)
{ {
return PyString_FromStringAndSize(self->b_ptr, self->b_size); void *ptr;
int size;
if (!get_buf(self, &ptr, &size))
return NULL;
return PyString_FromStringAndSize(ptr, size);
} }
/* Sequence methods */ /* Sequence methods */
@ -265,17 +299,21 @@ buffer_str(PyBufferObject *self)
static int static int
buffer_length(PyBufferObject *self) buffer_length(PyBufferObject *self)
{ {
return self->b_size; void *ptr;
int size;
if (!get_buf(self, &ptr, &size))
return -1;
return size;
} }
static PyObject * static PyObject *
buffer_concat(PyBufferObject *self, PyObject *other) buffer_concat(PyBufferObject *self, PyObject *other)
{ {
PyBufferProcs *pb = other->ob_type->tp_as_buffer; PyBufferProcs *pb = other->ob_type->tp_as_buffer;
char *p1; void *ptr1, *ptr2;
void *p2; char *p;
PyObject *ob; PyObject *ob;
int count; int size, count;
if ( pb == NULL || if ( pb == NULL ||
pb->bf_getreadbuffer == NULL || pb->bf_getreadbuffer == NULL ||
@ -292,23 +330,26 @@ buffer_concat(PyBufferObject *self, PyObject *other)
return NULL; return NULL;
} }
if (!get_buf(self, &ptr1, &size))
return NULL;
/* optimize special case */ /* optimize special case */
if ( self->b_size == 0 ) if ( size == 0 )
{ {
Py_INCREF(other); Py_INCREF(other);
return other; return other;
} }
if ( (count = (*pb->bf_getreadbuffer)(other, 0, &p2)) < 0 ) if ( (count = (*pb->bf_getreadbuffer)(other, 0, &ptr2)) < 0 )
return NULL; return NULL;
ob = PyString_FromStringAndSize(NULL, self->b_size + count); ob = PyString_FromStringAndSize(NULL, size + count);
p1 = PyString_AS_STRING(ob); p = PyString_AS_STRING(ob);
memcpy(p1, self->b_ptr, self->b_size); memcpy(p, ptr1, size);
memcpy(p1 + self->b_size, p2, count); memcpy(p + size, ptr2, count);
/* there is an extra byte in the string object, so this is safe */ /* there is an extra byte in the string object, so this is safe */
p1[self->b_size + count] = '\0'; p[size + count] = '\0';
return ob; return ob;
} }
@ -318,11 +359,13 @@ buffer_repeat(PyBufferObject *self, int count)
{ {
PyObject *ob; PyObject *ob;
register char *p; register char *p;
void *ptr = self->b_ptr; void *ptr;
int size = self->b_size; int size;
if ( count < 0 ) if ( count < 0 )
count = 0; count = 0;
if (!get_buf(self, &ptr, &size))
return NULL;
ob = PyString_FromStringAndSize(NULL, size * count); ob = PyString_FromStringAndSize(NULL, size * count);
if ( ob == NULL ) if ( ob == NULL )
return NULL; return NULL;
@ -343,26 +386,33 @@ buffer_repeat(PyBufferObject *self, int count)
static PyObject * static PyObject *
buffer_item(PyBufferObject *self, int idx) buffer_item(PyBufferObject *self, int idx)
{ {
if ( idx < 0 || idx >= self->b_size ) void *ptr;
{ int size;
if (!get_buf(self, &ptr, &size))
return NULL;
if ( idx < 0 || idx >= size ) {
PyErr_SetString(PyExc_IndexError, "buffer index out of range"); PyErr_SetString(PyExc_IndexError, "buffer index out of range");
return NULL; return NULL;
} }
return PyString_FromStringAndSize((char *)self->b_ptr + idx, 1); return PyString_FromStringAndSize((char *)ptr + idx, 1);
} }
static PyObject * static PyObject *
buffer_slice(PyBufferObject *self, int left, int right) buffer_slice(PyBufferObject *self, int left, int right)
{ {
void *ptr;
int size;
if (!get_buf(self, &ptr, &size))
return NULL;
if ( left < 0 ) if ( left < 0 )
left = 0; left = 0;
if ( right < 0 ) if ( right < 0 )
right = 0; right = 0;
if ( right > self->b_size ) if ( right > size )
right = self->b_size; right = size;
if ( right < left ) if ( right < left )
right = left; right = left;
return PyString_FromStringAndSize((char *)self->b_ptr + left, return PyString_FromStringAndSize((char *)ptr + left,
right - left); right - left);
} }
@ -370,7 +420,8 @@ static int
buffer_ass_item(PyBufferObject *self, int idx, PyObject *other) buffer_ass_item(PyBufferObject *self, int idx, PyObject *other)
{ {
PyBufferProcs *pb; PyBufferProcs *pb;
void *p; void *ptr1, *ptr2;
int size;
int count; int count;
if ( self->b_readonly ) { if ( self->b_readonly ) {
@ -379,7 +430,10 @@ buffer_ass_item(PyBufferObject *self, int idx, PyObject *other)
return -1; return -1;
} }
if (idx < 0 || idx >= self->b_size) { if (!get_buf(self, &ptr1, &size))
return -1;
if (idx < 0 || idx >= size) {
PyErr_SetString(PyExc_IndexError, PyErr_SetString(PyExc_IndexError,
"buffer assignment index out of range"); "buffer assignment index out of range");
return -1; return -1;
@ -401,7 +455,7 @@ buffer_ass_item(PyBufferObject *self, int idx, PyObject *other)
return -1; return -1;
} }
if ( (count = (*pb->bf_getreadbuffer)(other, 0, &p)) < 0 ) if ( (count = (*pb->bf_getreadbuffer)(other, 0, &ptr2)) < 0 )
return -1; return -1;
if ( count != 1 ) { if ( count != 1 ) {
PyErr_SetString(PyExc_TypeError, PyErr_SetString(PyExc_TypeError,
@ -409,7 +463,7 @@ buffer_ass_item(PyBufferObject *self, int idx, PyObject *other)
return -1; return -1;
} }
((char *)self->b_ptr)[idx] = *(char *)p; ((char *)ptr1)[idx] = *(char *)ptr2;
return 0; return 0;
} }
@ -417,7 +471,8 @@ static int
buffer_ass_slice(PyBufferObject *self, int left, int right, PyObject *other) buffer_ass_slice(PyBufferObject *self, int left, int right, PyObject *other)
{ {
PyBufferProcs *pb; PyBufferProcs *pb;
void *p; void *ptr1, *ptr2;
int size;
int slice_len; int slice_len;
int count; int count;
@ -442,17 +497,19 @@ buffer_ass_slice(PyBufferObject *self, int left, int right, PyObject *other)
"single-segment buffer object expected"); "single-segment buffer object expected");
return -1; return -1;
} }
if ( (count = (*pb->bf_getreadbuffer)(other, 0, &p)) < 0 ) if (!get_buf(self, &ptr1, &size))
return -1;
if ( (count = (*pb->bf_getreadbuffer)(other, 0, &ptr2)) < 0 )
return -1; return -1;
if ( left < 0 ) if ( left < 0 )
left = 0; left = 0;
else if ( left > self->b_size ) else if ( left > size )
left = self->b_size; left = size;
if ( right < left ) if ( right < left )
right = left; right = left;
else if ( right > self->b_size ) else if ( right > size )
right = self->b_size; right = size;
slice_len = right - left; slice_len = right - left;
if ( count != slice_len ) { if ( count != slice_len ) {
@ -463,7 +520,7 @@ buffer_ass_slice(PyBufferObject *self, int left, int right, PyObject *other)
} }
if ( slice_len ) if ( slice_len )
memcpy((char *)self->b_ptr + left, p, slice_len); memcpy((char *)ptr1 + left, ptr2, slice_len);
return 0; return 0;
} }
@ -473,13 +530,15 @@ buffer_ass_slice(PyBufferObject *self, int left, int right, PyObject *other)
static int static int
buffer_getreadbuf(PyBufferObject *self, int idx, void **pp) buffer_getreadbuf(PyBufferObject *self, int idx, void **pp)
{ {
int size;
if ( idx != 0 ) { if ( idx != 0 ) {
PyErr_SetString(PyExc_SystemError, PyErr_SetString(PyExc_SystemError,
"accessing non-existent buffer segment"); "accessing non-existent buffer segment");
return -1; return -1;
} }
*pp = self->b_ptr; if (!get_buf(self, pp, &size))
return self->b_size; return -1;
return size;
} }
static int static int
@ -496,21 +555,29 @@ buffer_getwritebuf(PyBufferObject *self, int idx, void **pp)
static int static int
buffer_getsegcount(PyBufferObject *self, int *lenp) buffer_getsegcount(PyBufferObject *self, int *lenp)
{ {
void *ptr;
int size;
if (!get_buf(self, &ptr, &size))
return -1;
if (lenp) if (lenp)
*lenp = self->b_size; *lenp = size;
return 1; return 1;
} }
static int static int
buffer_getcharbuf(PyBufferObject *self, int idx, const char **pp) buffer_getcharbuf(PyBufferObject *self, int idx, const char **pp)
{ {
void *ptr;
int size;
if ( idx != 0 ) { if ( idx != 0 ) {
PyErr_SetString(PyExc_SystemError, PyErr_SetString(PyExc_SystemError,
"accessing non-existent buffer segment"); "accessing non-existent buffer segment");
return -1; return -1;
} }
*pp = (const char *)self->b_ptr; if (!get_buf(self, &ptr, &size))
return self->b_size; return -1;
*pp = (const char *)ptr;
return size;
} }