libpq-fe.h

跨平台C++基础库

/*-------------------------------------------------------------------------
 *
 * libpq-fe.h
 *	  This file contains definitions for structures and
 *	  externs for functions used by frontend postgres applications.
 *
 * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.134 2006/10/04 00:30:13 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */

#ifndef LIBPQ_FE_H
#define LIBPQ_FE_H

#ifdef __cplusplus
extern		"C"
{
#endif

#include <stdio.h>

/*
 * postgres_ext.h defines the backend's externally visible types,
 * such as Oid.
 */
#include "postgres_ext.h"

/* Application-visible enum types */

typedef enum
{
	/*
	 * Although it is okay to add to this list, values which become unused
	 * should never be removed, nor should constants be redefined - that would
	 * break compatibility with existing code.
	 */
	CONNECTION_OK,
	CONNECTION_BAD,
	/* Non-blocking mode only below here */

	/*
	 * The existence of these should never be relied upon - they should only
	 * be used for user feedback or similar purposes.
	 */
	CONNECTION_STARTED,			/* Waiting for connection to be made.  */
	CONNECTION_MADE,			/* Connection OK; waiting to send.	   */
	CONNECTION_AWAITING_RESPONSE,		/* Waiting for a response from the
										 * postmaster.		  */
	CONNECTION_AUTH_OK,			/* Received authentication; waiting for
								 * backend startup. */
	CONNECTION_SETENV,			/* Negotiating environment. */
	CONNECTION_SSL_STARTUP,		/* Negotiating SSL. */
	CONNECTION_NEEDED			/* Internal state: connect() needed */
} ConnStatusType;

typedef enum
{
	PGRES_POLLING_FAILED = 0,
	PGRES_POLLING_READING,		/* These two indicate that one may	  */
	PGRES_POLLING_WRITING,		/* use select before polling again.   */
	PGRES_POLLING_OK,
	PGRES_POLLING_ACTIVE		/* unused; keep for awhile for backwards
								 * compatibility */
} PostgresPollingStatusType;

typedef enum
{
	PGRES_EMPTY_QUERY = 0,		/* empty query string was executed */
	PGRES_COMMAND_OK,			/* a query command that doesn't return
								 * anything was executed properly by the
								 * backend */
	PGRES_TUPLES_OK,			/* a query command that returns tuples was
								 * executed properly by the backend, PGresult
								 * contains the result tuples */
	PGRES_COPY_OUT,				/* Copy Out data transfer in progress */
	PGRES_COPY_IN,				/* Copy In data transfer in progress */
	PGRES_BAD_RESPONSE,			/* an unexpected response was recv'd from the
								 * backend */
	PGRES_NONFATAL_ERROR,		/* notice or warning message */
	PGRES_FATAL_ERROR			/* query failed */
} ExecStatusType;

typedef enum
{
	PQTRANS_IDLE,				/* connection idle */
	PQTRANS_ACTIVE,				/* command in progress */
	PQTRANS_INTRANS,			/* idle, within transaction block */
	PQTRANS_INERROR,			/* idle, within failed transaction */
	PQTRANS_UNKNOWN				/* cannot determine status */
} PGTransactionStatusType;

typedef enum
{
	PQERRORS_TERSE,				/* single-line error messages */
	PQERRORS_DEFAULT,			/* recommended style */
	PQERRORS_VERBOSE			/* all the facts, ma'am */
} PGVerbosity;

/* PGconn encapsulates a connection to the backend.
 * The contents of this struct are not supposed to be known to applications.
 */
typedef struct pg_conn PGconn;

/* PGresult encapsulates the result of a query (or more precisely, of a single
 * SQL command --- a query string given to PQsendQuery can contain multiple
 * commands and thus return multiple PGresult objects).
 * The contents of this struct are not supposed to be known to applications.
 */
typedef struct pg_result PGresult;

/* PGcancel encapsulates the information needed to cancel a running
 * query on an existing connection.
 * The contents of this struct are not supposed to be known to applications.
 */
typedef struct pg_cancel PGcancel;

/* PGnotify represents the occurrence of a NOTIFY message.
 * Ideally this would be an opaque typedef, but it's so simple that it's
 * unlikely to change.
 * NOTE: in Postgres 6.4 and later, the be_pid is the notifying backend's,
 * whereas in earlier versions it was always your own backend's PID.
 */
typedef struct pgNotify
{
	char	   *relname;		/* notification condition name */
	int			be_pid;			/* process ID of notifying server process */
	char	   *extra;			/* notification parameter */
	/* Fields below here are private to libpq; apps should not use 'em */
	struct pgNotify *next;		/* list link */
} PGnotify;

/* Function types for notice-handling callbacks */
typedef void (*PQnoticeReceiver) (void *arg, const PGresult *res);
typedef void (*PQnoticeProcessor) (void *arg, const char *message);

/* Print options for PQprint() */
typedef char pqbool;

typedef struct _PQprintOpt
{
	pqbool		header;			/* print output field headings and row count */
	pqbool		align;			/* fill align the fields */
	pqbool		standard;		/* old brain dead format */
	pqbool		html3;			/* output html tables */
	pqbool		expanded;		/* expand tables */
	pqbool		pager;			/* use pager for output if needed */
	char	   *fieldSep;		/* field separator */
	char	   *tableOpt;		/* insert to HTML <table ...> */
	char	   *caption;		/* HTML <caption> */
	char	  **fieldName;		/* null terminated array of replacement field
								 * names */
} PQprintOpt;

/* ----------------
 * Structure for the conninfo parameter definitions returned by PQconndefaults
 *
 * All fields except "val" point at static strings which must not be altered.
 * "val" is either NULL or a malloc'd current-value string.  PQconninfoFree()
 * will release both the val strings and the PQconninfoOption array itself.
 * ----------------
 */
typedef struct _PQconninfoOption
{
	char	   *keyword;		/* The keyword of the option			*/
	char	   *envvar;			/* Fallback environment variable name	*/
	char	   *compiled;		/* Fallback compiled in default value	*/
	char	   *val;			/* Option's current value, or NULL		 */
	char	   *label;			/* Label for field in connect dialog	*/
	char	   *dispchar;		/* Character to display for this field in a
								 * connect dialog. Values are: "" Display
								 * entered value as is "*" Password field -
								 * hide value "D"  Debug option - don't show
								 * by default */
	int			dispsize;		/* Field size in characters for dialog	*/
} PQconninfoOption;

/* ----------------
 * PQArgBlock -- structure for PQfn() arguments
 * ----------------
 */
typedef struct
{
	int			len;
	int			isint;
	union
	{
		int		   *ptr;		/* can't use void (dec compiler barfs)	 */
		int			integer;
	}			u;
} PQArgBlock;

/* ----------------
 * Exported functions of libpq
 * ----------------
 */

/* ===	in fe-connect.c === */

/* make a new client connection to the backend */
/* Asynchronous (non-blocking) */
extern PGconn *PQconnectStart(const char *conninfo);
extern PostgresPollingStatusType PQconnectPoll(PGconn *conn);

/* Synchronous (blocking) */
extern PGconn *PQconnectdb(const char *conninfo);
extern PGconn *PQsetdbLogin(const char *pghost, const char *pgport,
			 const char *pgoptions, const char *pgtty,
			 const char *dbName,
			 const char *login, const char *pwd);

#define PQsetdb(M_PGHOST,M_PGPORT,M_PGOPT,M_PGTTY,M_DBNAME)  \
	PQsetdbLogin(M_PGHOST, M_PGPORT, M_PGOPT, M_PGTTY, M_DBNAME, NULL, NULL)

/* close the current connection and free the PGconn data structure */
extern void PQfinish(PGconn *conn);

/* get info about connection options known to PQconnectdb */
extern PQconninfoOption *PQconndefaults(void);

/* free the data structure returned by PQconndefaults() */
extern void PQconninfoFree(PQconninfoOption *connOptions);

/*
 * close the current connection and restablish a new one with the same
 * parameters
 */
/* Asynchronous (non-blocking) */
extern int	PQresetStart(PGconn *conn);
extern PostgresPollingStatusType PQresetPoll(PGconn *conn);

/* Synchronous (blocking) */
extern void PQreset(PGconn *conn);

/* request a cancel structure */
extern PGcancel *PQgetCancel(PGconn *conn);

/* free a cancel structure */
extern void PQfreeCancel(PGcancel *cancel);

/* issue a cancel request */
extern int	PQcancel(PGcancel *cancel, char *errbuf, int errbufsize);

/* backwards compatible version of PQcancel; not thread-safe */
extern int	PQrequestCancel(PGconn *conn);

/* Accessor functions for PGconn objects */
extern char *PQdb(const PGconn *conn);
extern char *PQuser(const PGconn *conn);
extern char *PQpass(const PGconn *conn);
extern char *PQhost(const PGconn *conn);
extern char *PQport(const PGconn *conn);
extern char *PQtty(const PGconn *conn);
extern char *PQoptions(const PGconn *conn);
extern ConnStatusType PQstatus(const PGconn *conn);
extern PGTransactionStatusType PQtransactionStatus(const PGconn *conn);