fe-connect.c

关系型数据库 Postgresql 6.5.2

 * PQrequestCancel: attempt to request cancellation of the current operation.
 *
 * The return value is TRUE if the cancel request was successfully
 * dispatched, FALSE if not (in which case errorMessage is set).
 * Note: successful dispatch is no guarantee that there will be any effect at
 * the backend.  The application must read the operation result as usual.
 *
 * CAUTION: we want this routine to be safely callable from a signal handler
 * (for example, an application might want to call it in a SIGINT handler).
 * This means we cannot use any C library routine that might be non-reentrant.
 * malloc/free are often non-reentrant, and anything that might call them is
 * just as dangerous.  We avoid sprintf here for that reason.  Building up
 * error messages with strcpy/strcat is tedious but should be quite safe.
 */

int
PQrequestCancel(PGconn *conn)
{
	int			tmpsock = -1;
	struct
	{
		uint32		packetlen;
		CancelRequestPacket cp;
	}			crp;

	/* Check we have an open connection */
	if (!conn)
		return FALSE;

	if (conn->sock < 0)
	{
		strcpy(conn->errorMessage,
			   "PQrequestCancel() -- connection is not open\n");
		return FALSE;
	}

	/*
	 * We need to open a temporary connection to the postmaster. Use the
	 * information saved by connectDB to do this with only kernel calls.
	 */
	if ((tmpsock = socket(conn->raddr.sa.sa_family, SOCK_STREAM, 0)) < 0)
	{
		strcpy(conn->errorMessage, "PQrequestCancel() -- socket() failed: ");
		goto cancel_errReturn;
	}
	if (connect(tmpsock, &conn->raddr.sa, conn->raddr_len) < 0)
	{
		strcpy(conn->errorMessage, "PQrequestCancel() -- connect() failed: ");
		goto cancel_errReturn;
	}

	/*
	 * We needn't set nonblocking I/O or NODELAY options here.
	 */

	/* Create and send the cancel request packet. */

	crp.packetlen = htonl((uint32) sizeof(crp));
	crp.cp.cancelRequestCode = (MsgType) htonl(CANCEL_REQUEST_CODE);
	crp.cp.backendPID = htonl(conn->be_pid);
	crp.cp.cancelAuthCode = htonl(conn->be_key);

	if (send(tmpsock, (char *) &crp, sizeof(crp), 0) != (int) sizeof(crp))
	{
		strcpy(conn->errorMessage, "PQrequestCancel() -- send() failed: ");
		goto cancel_errReturn;
	}

	/* Sent it, done */
#ifdef WIN32
	closesocket(tmpsock);
#else
	close(tmpsock);
#endif

	return TRUE;

cancel_errReturn:
	strcat(conn->errorMessage, strerror(errno));
	strcat(conn->errorMessage, "\n");
	if (tmpsock >= 0)
	{
#ifdef WIN32
		closesocket(tmpsock);
#else
		close(tmpsock);
#endif
	}
	return FALSE;
}


/*
 * pqPacketSend() -- send a single-packet message.
 * this is like PacketSend(), defined in backend/libpq/pqpacket.c
 *
 * RETURNS: STATUS_ERROR if the write fails, STATUS_OK otherwise.
 * SIDE_EFFECTS: may block.
*/
int
pqPacketSend(PGconn *conn, const char *buf, size_t len)
{
	/* Send the total packet size. */

	if (pqPutInt(4 + len, 4, conn))
		return STATUS_ERROR;

	/* Send the packet itself. */

	if (pqPutnchar(buf, len, conn))
		return STATUS_ERROR;

	if (pqFlush(conn))
		return STATUS_ERROR;

	return STATUS_OK;
}


/* ----------------
 * Conninfo parser routine
 * ----------------
 */
static int
conninfo_parse(const char *conninfo, char *errorMessage)
{
	char	   *pname;
	char	   *pval;
	char	   *buf;
	char	   *tmp;
	char	   *cp;
	char	   *cp2;
	PQconninfoOption *option;
	char		errortmp[ERROR_MSG_LENGTH];

	conninfo_free();

	if ((buf = strdup(conninfo)) == NULL)
	{
		strcpy(errorMessage,
		  "FATAL: cannot allocate memory for copy of conninfo string\n");
		return -1;
	}
	cp = buf;

	while (*cp)
	{
		/* Skip blanks before the parameter name */
		if (isspace(*cp))
		{
			cp++;
			continue;
		}

		/* Get the parameter name */
		pname = cp;
		while (*cp)
		{
			if (*cp == '=')
				break;
			if (isspace(*cp))
			{
				*cp++ = '\0';
				while (*cp)
				{
					if (!isspace(*cp))
						break;
					cp++;
				}
				break;
			}
			cp++;
		}

		/* Check that there is a following '=' */
		if (*cp != '=')
		{
			sprintf(errorMessage,
			"ERROR: PQconnectdb() - Missing '=' after '%s' in conninfo\n",
					pname);
			free(buf);
			return -1;
		}
		*cp++ = '\0';

		/* Skip blanks after the '=' */
		while (*cp)
		{
			if (!isspace(*cp))
				break;
			cp++;
		}

		pval = cp;

		if (*cp != '\'')
		{
			cp2 = pval;
			while (*cp)
			{
				if (isspace(*cp))
				{
					*cp++ = '\0';
					break;
				}
				if (*cp == '\\')
				{
					cp++;
					if (*cp != '\0')
						*cp2++ = *cp++;
				}
				else
					*cp2++ = *cp++;
			}
			*cp2 = '\0';
		}
		else
		{
			cp2 = pval;
			cp++;
			for (;;)
			{
				if (*cp == '\0')
				{
					sprintf(errorMessage,
							"ERROR: PQconnectdb() - unterminated quoted string in conninfo\n");
					free(buf);
					return -1;
				}
				if (*cp == '\\')
				{
					cp++;
					if (*cp != '\0')
						*cp2++ = *cp++;
					continue;
				}
				if (*cp == '\'')
				{
					*cp2 = '\0';
					cp++;
					break;
				}
				*cp2++ = *cp++;
			}
		}

		/* ----------
		 * Now we have the name and the value. Search
		 * for the param record.
		 * ----------
		 */
		for (option = PQconninfoOptions; option->keyword != NULL; option++)
		{
			if (!strcmp(option->keyword, pname))
				break;
		}
		if (option->keyword == NULL)
		{
			sprintf(errorMessage,
					"ERROR: PQconnectdb() - unknown option '%s'\n",
					pname);
			free(buf);
			return -1;
		}

		/* ----------
		 * Store the value
		 * ----------
		 */
		option->val = strdup(pval);
	}

	free(buf);

	/* ----------
	 * Get the fallback resources for parameters not specified
	 * in the conninfo string.
	 * ----------
	 */
	for (option = PQconninfoOptions; option->keyword != NULL; option++)
	{
		if (option->val != NULL)
			continue;			/* Value was in conninfo */

		/* ----------
		 * Try to get the environment variable fallback
		 * ----------
		 */
		if (option->envvar != NULL)
		{
			if ((tmp = getenv(option->envvar)) != NULL)
			{
				option->val = strdup(tmp);
				continue;
			}
		}

		/* ----------
		 * No environment variable specified or this one isn't set -
		 * try compiled in
		 * ----------
		 */
		if (option->compiled != NULL)
		{
			option->val = strdup(option->compiled);
			continue;
		}

		/* ----------
		 * Special handling for user
		 * ----------
		 */
		if (!strcmp(option->keyword, "user"))
		{
			option->val = fe_getauthname(errortmp);
			continue;
		}

		/* ----------
		 * Special handling for dbname
		 * ----------
		 */
		if (!strcmp(option->keyword, "dbname"))
		{
			tmp = conninfo_getval("user");
			if (tmp)
				option->val = strdup(tmp);
			continue;
		}
	}

	return 0;
}


static char *
conninfo_getval(char *keyword)
{
	PQconninfoOption *option;

	for (option = PQconninfoOptions; option->keyword != NULL; option++)
	{
		if (!strcmp(option->keyword, keyword))
			return option->val;
	}

	return NULL;
}


static void
conninfo_free()
{
	PQconninfoOption *option;

	for (option = PQconninfoOptions; option->keyword != NULL; option++)
	{
		if (option->val != NULL)
		{
			free(option->val);
			option->val = NULL;
		}
	}
}

/* =========== accessor functions for PGconn ========= */
char *
PQdb(PGconn *conn)
{
	if (!conn)
		return (char *) NULL;
	return conn->dbName;
}

char *
PQuser(PGconn *conn)
{
	if (!conn)
		return (char *) NULL;
	return conn->pguser;
}

char *
PQpass(PGconn *conn)
{
	if (!conn)
		return (char *) NULL;
	return conn->pgpass;
}

char *
PQhost(PGconn *conn)
{
	if (!conn)
		return (char *) NULL;
	return conn->pghost;
}

char *
PQport(PGconn *conn)
{
	if (!conn)
		return (char *) NULL;
	return conn->pgport;
}

char *
PQtty(PGconn *conn)
{
	if (!conn)
		return (char *) NULL;
	return conn->pgtty;
}

char *
PQoptions(PGconn *conn)
{
	if (!conn)
		return (char *) NULL;
	return conn->pgoptions;
}

ConnStatusType
PQstatus(PGconn *conn)
{
	if (!conn)
		return CONNECTION_BAD;
	return conn->status;
}

char *
PQerrorMessage(PGconn *conn)
{
	static char noConn[] = "PQerrorMessage: conn pointer is NULL\n";

	if (!conn)
		return noConn;
	return conn->errorMessage;
}

int
PQsocket(PGconn *conn)
{
	if (!conn)
		return -1;
	return conn->sock;
}

int
PQbackendPID(PGconn *conn)
{
	if (!conn || conn->status != CONNECTION_OK)
		return 0;
	return conn->be_pid;
}

void
PQtrace(PGconn *conn, FILE *debug_port)
{
	if (conn == NULL ||
		conn->status == CONNECTION_BAD)
		return;
	PQuntrace(conn);
	conn->Pfdebug = debug_port;
}

void
PQuntrace(PGconn *conn)
{
	/* note: better allow untrace even when connection bad */
	if (conn == NULL)
		return;
	if (conn->Pfdebug)
	{
		fflush(conn->Pfdebug);
		conn->Pfdebug = NULL;
	}
}

void
PQsetNoticeProcessor(PGconn *conn, PQnoticeProcessor proc, void *arg)
{
	if (conn == NULL)
		return;
	conn->noticeHook = proc;
	conn->noticeArg = arg;
}

/*
 * The default notice/error message processor just prints the
 * message on stderr.  Applications can override this if they
 * want the messages to go elsewhere (a window, for example).
 * Note that simply discarding notices is probably a bad idea.
 */

static void
defaultNoticeProcessor(void *arg, const char *message)
{
	/* Note: we expect the supplied string to end with a newline already. */
	fprintf(stderr, "%s", message);
}