pgmodule.c

关系型数据库 Postgresql 6.5.2

/*
 * PyGres, version 2.2 A Python interface for PostgreSQL database. Written by
 * D'Arcy J.M. Cain, ([e-mail]).  Based heavily on code written by
 * Pascal Andre, [e-mail]. Copyright (c) 1995, Pascal Andre
 * ([e-mail]).
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without a written
 * agreement is hereby granted, provided that the above copyright notice and
 * this paragraph and the following two paragraphs appear in all copies or in
 * any new file that contains a substantial portion of this file.
 *
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
 * SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS,
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE
 * AUTHOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE
 * AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
 * ENHANCEMENTS, OR MODIFICATIONS.
 *
 * Further modifications copyright 1997, 1998, 1999 by D'Arcy J.M. Cain
 * ([e-mail]) subject to the same terms and conditions as above.
 *
 */

#include <Python.h>
#include <libpq-fe.h>
#include <libpq/libpq-fs.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* really bad stuff here - I'm so naughty */
/* If you need to you can run mkdefines to get */
/* current defines but it should not have changed */
#define INT2OID		21
#define INT4OID		23
#define OIDOID		26
#define FLOAT4OID	700
#define FLOAT8OID	701
#define CASHOID		790

static PyObject *PGError;
static const char *PyPgVersion = "2.4";

/* taken from fileobject.c */
#define BUF(v) PyString_AS_STRING((PyStringObject *)(v))

/* default values */
#define MODULE_NAME			"pgsql"
#define ARRAYSIZE			1

/* flags for object validity checks */
#define CHECK_OPEN			1
#define CHECK_CLOSE			2
#define CHECK_CNX			4
#define CHECK_RESULT		8
#define CHECK_DQL			16

#define MAX_BUFFER_SIZE   8192	/* maximum transaction size */

#ifndef NO_DIRECT
#define DIRECT_ACCESS	  1		/* enables direct access functions */
#endif	 /* NO_DIRECT */

#ifndef NO_LARGE
#define LARGE_OBJECTS	  1		/* enables large objects support */
#endif	 /* NO_LARGE */

#ifndef NO_DEF_VAR
#define DEFAULT_VARS	  1		/* enables default variables use */
#endif	 /* NO_DEF_VAR */

/* --------------------------------------------------------------------- */

/* MODULE GLOBAL VARIABLES */

#ifdef DEFAULT_VARS

static PyObject *pg_default_host;		/* default database host */
static PyObject *pg_default_base;		/* default database name */
static PyObject *pg_default_opt;/* default connection options */
static PyObject *pg_default_tty;/* default debug tty */
static PyObject *pg_default_port;		/* default connection port */
static PyObject *pg_default_user;		/* default username */
static PyObject *pg_default_passwd;		/* default password */

#endif	 /* DEFAULT_VARS */

/* --------------------------------------------------------------------- */
/* OBJECTS DECLARATION */

/* pg connection object */

typedef struct
{
	PyObject_HEAD
	int			valid;			/* validity flag */
	PGconn	   *cnx;			/* PostGres connection handle */
}			pgobject;

staticforward PyTypeObject PgType;

#define is_pgobject(v) ((v)->ob_type == &PgType)

/* pg query object */

typedef struct
{
	PyObject_HEAD
	PGresult   *last_result;	/* last result content */
}			pgqueryobject;

staticforward PyTypeObject PgQueryType;

#define is_pgqueryobject(v) ((v)->ob_type == &PgQueryType)

#ifdef LARGE_OBJECTS
/* pg large object */

typedef struct
{
	PyObject_HEAD
	pgobject * pgcnx;			/* parent connection object */
	Oid			lo_oid;			/* large object oid */
	int			lo_fd;			/* large object fd */
}			pglargeobject;

staticforward PyTypeObject PglargeType;

#define is_pglargeobject(v) ((v)->ob_type == &PglargeType)
#endif	 /* LARGE_OBJECTS */

/* --------------------------------------------------------------------- */
/* INTERNAL FUNCTIONS */

/* checks connection validity */
static int
check_cnx_obj(pgobject * self)
{
	if (!self->valid)
	{
		PyErr_SetString(PGError, "connection has been closed");
		return 0;
	}
	return 1;
}

#ifdef LARGE_OBJECTS
/* checks large object validity */
static int
check_lo_obj(pglargeobject * self, int level)
{
	if (!check_cnx_obj(self->pgcnx))
		return 0;

	if (!self->lo_oid)
	{
		PyErr_SetString(PGError, "object is not valid (null oid).");
		return 0;
	}

	if (level & CHECK_OPEN)
	{
		if (self->lo_fd < 0)
		{
			PyErr_SetString(PyExc_IOError, "object is not opened.");
			return 0;
		}
	}

	if (level & CHECK_CLOSE)
	{
		if (self->lo_fd >= 0)
		{
			PyErr_SetString(PyExc_IOError, "object is already opened.");
			return 0;
		}
	}

	return 1;
}

#endif	 /* LARGE_OBJECTS */

/* --------------------------------------------------------------------- */
/* PG CONNECTION OBJECT IMPLEMENTATION */

#ifdef LARGE_OBJECTS

/* constructor (internal use only) */
static pglargeobject *
pglarge_new(pgobject * pgcnx, Oid oid)
{
	pglargeobject *npglo;

	if ((npglo = PyObject_NEW(pglargeobject, &PglargeType)) == NULL)
		return NULL;

	Py_XINCREF(pgcnx);
	npglo->pgcnx = pgcnx;
	npglo->lo_fd = -1;
	npglo->lo_oid = oid;

	return npglo;
}

/* destructor */
static void
pglarge_dealloc(pglargeobject * self)
{
	if (self->lo_fd >= 0 && check_cnx_obj(self->pgcnx))
		lo_close(self->pgcnx->cnx, self->lo_fd);

	Py_XDECREF(self->pgcnx);
	PyMem_DEL(self);
}

/* opens large object */
static char pglarge_open__doc__[] =
"open(mode) -- open access to large object with specified mode "
"(INV_READ, INV_WRITE constants defined by module).";

static PyObject *
pglarge_open(pglargeobject * self, PyObject * args)
{
	int			mode,
				fd;

	/* check validity */
	if (!check_lo_obj(self, CHECK_CLOSE))
		return NULL;

	/* gets arguments */
	if (!PyArg_ParseTuple(args, "i", &mode))
	{
		PyErr_SetString(PyExc_TypeError, "open(mode), with mode(integer).");
		return NULL;
	}

	/* opens large object */
	if ((fd = lo_open(self->pgcnx->cnx, self->lo_oid, mode)) < 0)
	{
		PyErr_SetString(PyExc_IOError, "can't open large object.");
		return NULL;
	}
	self->lo_fd = fd;

	/* no error : returns Py_None */
	Py_INCREF(Py_None);
	return Py_None;
}

/* close large object */
static char pglarge_close__doc__[] =
"close() -- close access to large object data.";

static PyObject *
pglarge_close(pglargeobject * self, PyObject * args)
{
	/* checks args */
	if (!PyArg_ParseTuple(args, ""))
	{
		PyErr_SetString(PyExc_SyntaxError,
						"method close() takes no parameters.");
		return NULL;
	}

	/* checks validity */
	if (!check_lo_obj(self, CHECK_OPEN))
		return NULL;

	/* closes large object */
	if (lo_close(self->pgcnx->cnx, self->lo_fd))
	{
		PyErr_SetString(PyExc_IOError, "error while closing large object fd.");
		return NULL;
	}
	self->lo_fd = -1;

	/* no error : returns Py_None */
	Py_INCREF(Py_None);
	return Py_None;
}

/* reads from large object */
static char pglarge_read__doc__[] =
"read(integer) -- read from large object to sized string. "
"Object must be opened in read mode before calling this method.";

static PyObject *
pglarge_read(pglargeobject * self, PyObject * args)
{
	int			size;
	PyObject   *buffer;

	/* checks validity */
	if (!check_lo_obj(self, CHECK_OPEN))
		return NULL;

	/* gets arguments */
	if (!PyArg_ParseTuple(args, "i", &size))
	{
		PyErr_SetString(PyExc_TypeError, "read(size), wih size (integer).");
		return NULL;
	}

	if (size <= 0)
	{
		PyErr_SetString(PyExc_ValueError, "size must be positive.");
		return NULL;
	}

	/* allocate buffer and runs read */
	buffer = PyString_FromStringAndSize((char *) NULL, size);

	if ((size = lo_read(self->pgcnx->cnx, self->lo_fd, BUF(buffer), size)) < 0)
	{
		PyErr_SetString(PyExc_IOError, "error while reading.");
		Py_XDECREF(buffer);
		return NULL;
	}

	/* resize buffer and returns it */
	_PyString_Resize(&buffer, size);
	return buffer;
}

/* write to large object */
static char pglarge_write__doc__[] =
"write(string) -- write sized string to large object. "
"Object must be opened in read mode before calling this method.";

static PyObject *
pglarge_write(pglargeobject * self, PyObject * args)
{
	char	   *buffer;
	int			size;

	/* checks validity */
	if (!check_lo_obj(self, CHECK_OPEN))
		return NULL;

	/* gets arguments */
	if (!PyArg_ParseTuple(args, "s", &buffer))
	{
		PyErr_SetString(PyExc_TypeError,
						"write(buffer), with buffer (sized string).");
		return NULL;
	}

	/* sends query */
	if ((size = lo_write(self->pgcnx->cnx, self->lo_fd, buffer,
						 strlen(buffer))) < strlen(buffer))
	{
		PyErr_SetString(PyExc_IOError, "buffer truncated during write.");
		return NULL;
	}

	/* no error : returns Py_None */
	Py_INCREF(Py_None);
	return Py_None;
}

/* go to position in large object */
static char pglarge_seek__doc__[] =
"seek(off, whence) -- move to specified position. Object must be opened "
"before calling this method. whence can be SEEK_SET, SEEK_CUR or SEEK_END, "
"constants defined by module.";

static PyObject *
pglarge_lseek(pglargeobject * self, PyObject * args)
{
	/* offset and whence are initialized to keep compiler happy */
	int			ret,
				offset = 0,
				whence = 0;

	/* checks validity */
	if (!check_lo_obj(self, CHECK_OPEN))
		return NULL;

	/* gets arguments */
	if (!PyArg_ParseTuple(args, "ii", &offset, &whence))
	{
		PyErr_SetString(PyExc_TypeError,
			"lseek(offset, whence), with offset and whence (integers).");
		return NULL;
	}

	/* sends query */
	if ((ret = lo_lseek(self->pgcnx->cnx, self->lo_fd, offset, whence)) == -1)
	{
		PyErr_SetString(PyExc_IOError, "error while moving cursor.");
		return NULL;
	}

	/* returns position */
	return PyInt_FromLong(ret);
}

/* gets large object size */
static char pglarge_size__doc__[] =
"size() -- return large object size. "
"Object must be opened before calling this method.";

static PyObject *
pglarge_size(pglargeobject * self, PyObject * args)
{
	int			start,
				end;

	/* checks args */
	if (!PyArg_ParseTuple(args, ""))
	{
		PyErr_SetString(PyExc_SyntaxError,
						"method size() takes no parameters.");
		return NULL;
	}

	/* checks validity */
	if (!check_lo_obj(self, CHECK_OPEN))
		return NULL;

	/* gets current position */
	if ((start = lo_tell(self->pgcnx->cnx, self->lo_fd)) == -1)
	{
		PyErr_SetString(PyExc_IOError, "error while getting current position.");
		return NULL;
	}

	/* gets end position */
	if ((end = lo_lseek(self->pgcnx->cnx, self->lo_fd, 0, SEEK_END)) == -1)
	{
		PyErr_SetString(PyExc_IOError, "error while getting end position.");
		return NULL;
	}

	/* move back to start position */
	if ((start = lo_lseek(self->pgcnx->cnx, self->lo_fd, start, SEEK_SET)) == -1)
	{
		PyErr_SetString(PyExc_IOError,
						"error while moving back to first position.");
		return NULL;
	}

	/* returns size */
	return PyInt_FromLong(end);
}

/* gets large object cursor position */
static char pglarge_tell__doc__[] =
"tell() -- give current position in large object. "
"Object must be opened before calling this method.";

static PyObject *
pglarge_tell(pglargeobject * self, PyObject * args)
{
	int			start;

	/* checks args */
	if (!PyArg_ParseTuple(args, ""))
	{
		PyErr_SetString(PyExc_SyntaxError,
						"method tell() takes no parameters.");
		return NULL;
	}

	/* checks validity */
	if (!check_lo_obj(self, CHECK_OPEN))
		return NULL;

	/* gets current position */
	if ((start = lo_tell(self->pgcnx->cnx, self->lo_fd)) == -1)
	{
		PyErr_SetString(PyExc_IOError, "error while getting position.");
		return NULL;
	}

	/* returns size */
	return PyInt_FromLong(start);
}

/* exports large object as unix file */
static char pglarge_export__doc__[] =
"export(string) -- export large object data to specified file. "
"Object must be closed when calling this method.";

static PyObject *
pglarge_export(pglargeobject * self, PyObject * args)
{
	char	   *name;

	/* checks validity */
	if (!check_lo_obj(self, CHECK_CLOSE))
		return NULL;

	/* gets arguments */
	if (!PyArg_ParseTuple(args, "s", &name))
	{
		PyErr_SetString(PyExc_TypeError,
						"export(filename), with filename (string).");
		return NULL;
	}

	/* runs command */
	if (!lo_export(self->pgcnx->cnx, self->lo_oid, name))
	{
		PyErr_SetString(PyExc_IOError, "error while exporting large object.");
		return NULL;
	}

	Py_INCREF(Py_None);
	return Py_None;
}

/* deletes a large object */
static char pglarge_unlink__doc__[] =
"unlink() -- destroy large object. "
"Object must be closed when calling this method.";

static PyObject *
pglarge_unlink(pglargeobject * self, PyObject * args)
{
	/* checks args */
	if (!PyArg_ParseTuple(args, ""))
	{
		PyErr_SetString(PyExc_SyntaxError,
						"method unlink() takes no parameters.");
		return NULL;
	}

	/* checks validity */
	if (!check_lo_obj(self, CHECK_CLOSE))
		return NULL;

	/* deletes the object, invalidate it on success */
	if (!lo_unlink(self->pgcnx->cnx, self->lo_oid))
	{
		PyErr_SetString(PyExc_IOError, "error while unlinking large object");
		return NULL;
	}
	self->lo_oid = 0;

	Py_INCREF(Py_None);
	return Py_None;
}

/* large object methods */
static struct PyMethodDef pglarge_methods[] = {
	{"open", (PyCFunction) pglarge_open, 1, pglarge_open__doc__},
	{"close", (PyCFunction) pglarge_close, 1, pglarge_close__doc__},
	{"read", (PyCFunction) pglarge_read, 1, pglarge_read__doc__},
	{"write", (PyCFunction) pglarge_write, 1, pglarge_write__doc__},
	{"seek", (PyCFunction) pglarge_lseek, 1, pglarge_seek__doc__},
	{"size", (PyCFunction) pglarge_size, 1, pglarge_size__doc__},
	{"tell", (PyCFunction) pglarge_tell, 1, pglarge_tell__doc__},
	{"export", (PyCFunction) pglarge_export, 1, pglarge_export__doc__},
	{"unlink", (PyCFunction) pglarge_unlink, 1, pglarge_unlink__doc__},
	{NULL, NULL}
};

/* get attribute */
static PyObject *
pglarge_getattr(pglargeobject * self, char *name)
{
	/* list postgreSQL large object fields */

	/* associated pg connection object */
	if (!strcmp(name, "pgcnx"))
	{
		if (check_lo_obj(self, 0))