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/* typecast_binary.c - binary typecasting functions to python types
*
* Copyright (C) 2001-2010 Federico Di Gregorio <fog@debian.org>
*
* This file is part of psycopg.
*
* psycopg2 is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* In addition, as a special exception, the copyright holders give
* permission to link this program with the OpenSSL library (or with
* modified versions of OpenSSL that use the same license as OpenSSL),
* and distribute linked combinations including the two.
*
* You must obey the GNU Lesser General Public License in all respects for
* all of the code used other than OpenSSL.
*
* psycopg2 is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*/
#include "typecast_binary.h"
#include <stdlib.h>
/* Python object holding a memory chunk. The memory is deallocated when
the object is destroyed. This type is used to let users directly access
memory chunks holding unescaped binary data through the buffer interface.
*/
static void
chunk_dealloc(chunkObject *self)
{
Dprintf("chunk_dealloc: deallocating memory at %p, size "
FORMAT_CODE_PY_SSIZE_T,
self->base, self->len
);
PyMem_Free(self->base);
Py_TYPE(self)->tp_free((PyObject *)self);
}
static PyObject *
chunk_repr(chunkObject *self)
{
return PyString_FromFormat(
"<memory chunk at %p size " FORMAT_CODE_PY_SSIZE_T ">",
self->base, self->len
);
}
#if PY_MAJOR_VERSION < 3
static Py_ssize_t
chunk_getreadbuffer(chunkObject *self, Py_ssize_t segment, void **ptr)
{
if (segment != 0)
{
PyErr_SetString(PyExc_SystemError,
"acessing non-existant buffer segment");
return -1;
}
*ptr = self->base;
return self->len;
}
static Py_ssize_t
chunk_getsegcount(chunkObject *self, Py_ssize_t *lenp)
{
if (lenp != NULL)
*lenp = self->len;
return 1;
}
static PyBufferProcs chunk_as_buffer =
{
(readbufferproc) chunk_getreadbuffer,
(writebufferproc) NULL,
(segcountproc) chunk_getsegcount,
(charbufferproc) NULL
};
#else
/* 3.0 buffer interface */
int chunk_getbuffer(PyObject *_self, Py_buffer *view, int flags)
{
int rv;
chunkObject *self = (chunkObject*)_self;
rv = PyBuffer_FillInfo(view, _self, self->base, self->len, 1, flags);
if (rv == 0) {
view->format = "c";
}
return rv;
}
static PyBufferProcs chunk_as_buffer =
{
chunk_getbuffer,
NULL,
};
#endif
#define chunk_doc "memory chunk"
PyTypeObject chunkType = {
PyVarObject_HEAD_INIT(NULL, 0)
"psycopg2._psycopg.chunk", /* tp_name */
sizeof(chunkObject), /* tp_basicsize */
0, /* tp_itemsize */
(destructor) chunk_dealloc, /* tp_dealloc*/
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_compare */
(reprfunc) chunk_repr, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
0, /* tp_getattro */
0, /* tp_setattro */
&chunk_as_buffer, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE, /* tp_flags */
chunk_doc /* tp_doc */
};
static char *psycopg_parse_hex(
const char *bufin, Py_ssize_t sizein, Py_ssize_t *sizeout);
static char *psycopg_parse_escape(
const char *bufin, Py_ssize_t sizein, Py_ssize_t *sizeout);
/* The function is not static and not hidden as we use ctypes to test it. */
PyObject *
typecast_BINARY_cast(const char *s, Py_ssize_t l, PyObject *curs)
{
chunkObject *chunk = NULL;
PyObject *res = NULL;
char *buffer = NULL;
Py_ssize_t len;
if (s == NULL) {Py_INCREF(Py_None); return Py_None;}
if (s[0] == '\\' && s[1] == 'x') {
/* This is a buffer escaped in hex format: libpq before 9.0 can't
* parse it and we can't detect reliably the libpq version at runtime.
* So the only robust option is to parse it ourselves - luckily it's
* an easy format.
*/
if (NULL == (buffer = psycopg_parse_hex(s, l, &len))) {
goto exit;
}
}
else {
/* This is a buffer in the classic bytea format. So we can handle it
* to the PQunescapeBytea to have it parsed, rignt? ...Wrong. We
* could, but then we'd have to record whether buffer was allocated by
* Python or by the libpq to dispose it properly. Furthermore the
* PQunescapeBytea interface is not the most brilliant as it wants a
* null-terminated string even if we have known its length thus
* requiring a useless memcpy and strlen.
* So we'll just have our better integrated parser, let's finish this
* story.
*/
if (NULL == (buffer = psycopg_parse_escape(s, l, &len))) {
goto exit;
}
}
chunk = (chunkObject *) PyObject_New(chunkObject, &chunkType);
if (chunk == NULL) goto exit;
/* **Transfer** ownership of buffer's memory to the chunkObject: */
chunk->base = buffer;
buffer = NULL;
chunk->len = (Py_ssize_t)len;
#if PY_MAJOR_VERSION < 3
if ((res = PyBuffer_FromObject((PyObject *)chunk, 0, chunk->len)) == NULL)
goto exit;
#else
if ((res = PyMemoryView_FromObject((PyObject*)chunk)) == NULL)
goto exit;
#endif
exit:
Py_XDECREF((PyObject *)chunk);
PyMem_Free(buffer);
return res;
}
static const char hex_lut[128] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};
/* Parse a bytea output buffer encoded in 'hex' format.
*
* the format is described in
* http://www.postgresql.org/docs/current/static/datatype-binary.html
*
* Parse the buffer in 'bufin', whose length is 'sizein'.
* Return a new buffer allocated by PyMem_Malloc and set 'sizeout' to its size.
* In case of error set an exception and return NULL.
*/
static char *
psycopg_parse_hex(const char *bufin, Py_ssize_t sizein, Py_ssize_t *sizeout)
{
char *ret = NULL;
const char *bufend = bufin + sizein;
const char *pi = bufin + 2; /* past the \x */
char *bufout;
char *po;
po = bufout = PyMem_Malloc((sizein - 2) >> 1); /* output size upper bound */
if (NULL == bufout) {
PyErr_NoMemory();
goto exit;
}
/* Implementation note: we call this function upon database response, not
* user input (because we are parsing the output format of a buffer) so we
* don't expect errors. On bad input we reserve the right to return a bad
* output, not an error.
*/
while (pi < bufend) {
char c;
while (-1 == (c = hex_lut[*pi++ & '\x7f'])) {
if (pi >= bufend) { goto endloop; }
}
*po = c << 4;
while (-1 == (c = hex_lut[*pi++ & '\x7f'])) {
if (pi >= bufend) { goto endloop; }
}
*po++ |= c;
}
endloop:
ret = bufout;
*sizeout = po - bufout;
exit:
return ret;
}
/* Parse a bytea output buffer encoded in 'escape' format.
*
* the format is described in
* http://www.postgresql.org/docs/current/static/datatype-binary.html
*
* Parse the buffer in 'bufin', whose length is 'sizein'.
* Return a new buffer allocated by PyMem_Malloc and set 'sizeout' to its size.
* In case of error set an exception and return NULL.
*/
static char *
psycopg_parse_escape(const char *bufin, Py_ssize_t sizein, Py_ssize_t *sizeout)
{
char *ret = NULL;
const char *bufend = bufin + sizein;
const char *pi = bufin;
char *bufout;
char *po;
po = bufout = PyMem_Malloc(sizein); /* output size upper bound */
if (NULL == bufout) {
PyErr_NoMemory();
goto exit;
}
while (pi < bufend) {
if (*pi != '\\') {
/* Unescaped char */
*po++ = *pi++;
continue;
}
if ((pi[1] >= '0' && pi[1] <= '3') &&
(pi[2] >= '0' && pi[2] <= '7') &&
(pi[3] >= '0' && pi[3] <= '7'))
{
/* Escaped octal value */
*po++ = ((pi[1] - '0') << 6) |
((pi[2] - '0') << 3) |
((pi[3] - '0'));
pi += 4;
}
else {
/* Escaped char */
*po++ = pi[1];
pi += 2;
}
}
ret = bufout;
*sizeout = po - bufout;
exit:
return ret;
}
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