C++ printfPQExpBuffer函数代码示例

/*
 * This function takes a function description, e.g. "x" or "x(int)", and
 * issues a query on the given connection to retrieve the function's OID
 * using a cast to regproc or regprocedure (as appropriate). The result,
 * if there is one, is returned at *foid.  Note that we'll fail if the
 * function doesn't exist OR if there are multiple matching candidates
 * OR if there's something syntactically wrong with the function description;
 * unfortunately it can be hard to tell the difference.
 */
static bool
lookup_function_oid(PGconn *conn, const char *desc, Oid *foid)
{
	bool		result = true;
	PQExpBuffer query;
	PGresult   *res;

	query = createPQExpBuffer();
	printfPQExpBuffer(query, "SELECT ");
	appendStringLiteralConn(query, desc, conn);
	appendPQExpBuffer(query, "::pg_catalog.%s::pg_catalog.oid",
					  strchr(desc, '(') ? "regprocedure" : "regproc");

	res = PQexec(conn, query->data);
	if (PQresultStatus(res) == PGRES_TUPLES_OK && PQntuples(res) == 1)
		*foid = atooid(PQgetvalue(res, 0, 0));
	else
	{
		minimal_error_message(res);
		result = false;
	}

	PQclear(res);
	destroyPQExpBuffer(query);

	return result;
}

/*
 * Fetches the "CREATE OR REPLACE FUNCTION ..." command that describes the
 * function with the given OID.  If successful, the result is stored in buf.
 */
static bool
get_create_function_cmd(PGconn *conn, Oid oid, PQExpBuffer buf)
{
	bool		result = true;
	PQExpBuffer query;
	PGresult   *res;

	query = createPQExpBuffer();
	printfPQExpBuffer(query, "SELECT pg_catalog.pg_get_functiondef(%u)", oid);

	res = PQexec(conn, query->data);
	if (PQresultStatus(res) == PGRES_TUPLES_OK && PQntuples(res) == 1)
	{
		resetPQExpBuffer(buf);
		appendPQExpBufferStr(buf, PQgetvalue(res, 0, 0));
	}
	else
	{
		minimal_error_message(res);
		result = false;
	}

	PQclear(res);
	destroyPQExpBuffer(query);

	return result;
}

/*
 *	Attempt to negotiate secure session.
 */
PostgresPollingStatusType
pqsecure_open_client(PGconn *conn)
{
#ifdef USE_SSL
	/* First time through? */
	if (conn->ssl == NULL)
	{
		if (!(conn->ssl = SSL_new(SSL_context)) ||
			!SSL_set_app_data(conn->ssl, conn) ||
			!SSL_set_fd(conn->ssl, conn->sock))
		{
			char	   *err = SSLerrmessage();

			printfPQExpBuffer(&conn->errorMessage,
				   libpq_gettext("could not establish SSL connection: %s\n"),
							  err);
			SSLerrfree(err);
			close_SSL(conn);
			return PGRES_POLLING_FAILED;
		}

		/*
		 * Initialize errorMessage to empty.  This allows open_client_SSL() to
		 * detect whether client_cert_cb() has stored a message.
		 */
		resetPQExpBuffer(&conn->errorMessage);
	}
	/* Begin or continue the actual handshake */
	return open_client_SSL(conn);
#else
	/* shouldn't get here */
	return PGRES_POLLING_FAILED;
#endif
}

/*
 * Dump database-specific configuration
 */
static void
dumpDatabaseConfig(PGconn *conn, const char *dbname)
{
	PQExpBuffer buf = createPQExpBuffer();
	int			count = 1;

	for (;;)
	{
		PGresult   *res;

		printfPQExpBuffer(buf, "SELECT datconfig[%d] FROM pg_database WHERE datname = ", count);
		appendStringLiteralConn(buf, dbname, conn);
		appendPQExpBuffer(buf, ";");

		res = executeQuery(conn, buf->data);
		if (!PQgetisnull(res, 0, 0))
		{
			makeAlterConfigCommand(conn, PQgetvalue(res, 0, 0),
								   "DATABASE", dbname);
			PQclear(res);
			count++;
		}
		else
		{
			PQclear(res);
			break;
		}
	}

	destroyPQExpBuffer(buf);
}

/*
 * Dump user-specific configuration
 */
static void
dumpUserConfig(PGconn *conn, const char *username)
{
	PQExpBuffer buf = createPQExpBuffer();
	int			count = 1;

	for (;;)
	{
		PGresult   *res;

		printfPQExpBuffer(buf, "SELECT rolconfig[%d] FROM pg_authid WHERE rolname = ", count);

		appendStringLiteralConn(buf, username, conn);

		res = executeQuery(conn, buf->data);
		if (PQntuples(res) == 1 &&
			!PQgetisnull(res, 0, 0))
		{
			makeAlterConfigCommand(conn, PQgetvalue(res, 0, 0),
								   "ROLE", username);
			PQclear(res);
			count++;
		}
		else
		{
			PQclear(res);
			break;
		}
	}

	destroyPQExpBuffer(buf);
}

/*
 * Dump user-and-database-specific configuration
 */
static void
dumpDbRoleConfig(PGconn *conn)
{
	PQExpBuffer buf = createPQExpBuffer();
	PGresult   *res;
	int			i;

	printfPQExpBuffer(buf, "SELECT rolname, datname, unnest(setconfig) "
					  "FROM pg_db_role_setting, pg_authid, pg_database "
		  "WHERE setrole = pg_authid.oid AND setdatabase = pg_database.oid");
	res = executeQuery(conn, buf->data);

	if (PQntuples(res) > 0)
	{
		fprintf(OPF, "--\n-- Per-Database Role Settings \n--\n\n");

		for (i = 0; i < PQntuples(res); i++)
		{
			makeAlterConfigCommand(conn, PQgetvalue(res, i, 2),
								   "ROLE", PQgetvalue(res, i, 0),
								   "DATABASE", PQgetvalue(res, i, 1));
		}

		fprintf(OPF, "\n\n");
	}

	PQclear(res);
	destroyPQExpBuffer(buf);
}

/*
 * Dump group memberships from a pre-8.1 server.  It's annoying that we
 * can't share any useful amount of code with the post-8.1 case, but
 * the catalog representations are too different.
 *
 * Note: we expect dumpRoles already created all the roles, but there is
 * no membership yet.
 */
static void
dumpGroups(PGconn *conn)
{
	PQExpBuffer buf = createPQExpBuffer();
	PGresult   *res;
	int			i;

	res = executeQuery(conn,
					   "SELECT groname, grolist FROM pg_group ORDER BY 1");

	if (PQntuples(res) > 0)
		fprintf(OPF, "--\n-- Role memberships\n--\n\n");

	for (i = 0; i < PQntuples(res); i++)
	{
		char	   *groname = PQgetvalue(res, i, 0);
		char	   *grolist = PQgetvalue(res, i, 1);
		PGresult   *res2;
		int			j;

		/*
		 * Array representation is {1,2,3} ... convert to (1,2,3)
		 */
		if (strlen(grolist) < 3)
			continue;

		grolist = strdup(grolist);
		grolist[0] = '(';
		grolist[strlen(grolist) - 1] = ')';
		printfPQExpBuffer(buf,
						  "SELECT usename FROM pg_shadow "
						  "WHERE usesysid IN %s ORDER BY 1",
						  grolist);
		free(grolist);

		res2 = executeQuery(conn, buf->data);

		for (j = 0; j < PQntuples(res2); j++)
		{
			char	   *usename = PQgetvalue(res2, j, 0);

			/*
			 * Don't try to grant a role to itself; can happen if old
			 * installation has identically named user and group.
			 */
			if (strcmp(groname, usename) == 0)
				continue;

			fprintf(OPF, "GRANT %s", fmtId(groname));
			fprintf(OPF, " TO %s;\n", fmtId(usename));
		}

		PQclear(res2);
	}

	PQclear(res);
	destroyPQExpBuffer(buf);

	fprintf(OPF, "\n\n");
}

/*
 * Make sure conn's output buffer can hold bytes_needed bytes (caller must
 * include already-stored data into the value!)
 *
 * Returns 0 on success, EOF if failed to enlarge buffer
 */
int
pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn)
{
    int			newsize = conn->outBufSize;
    char	   *newbuf;

    /* Quick exit if we have enough space */
    if (bytes_needed <= (size_t) newsize)
        return 0;

    /*
     * If we need to enlarge the buffer, we first try to double it in size; if
     * that doesn't work, enlarge in multiples of 8K.  This avoids thrashing
     * the malloc pool by repeated small enlargements.
     *
     * Note: tests for newsize > 0 are to catch integer overflow.
     */
    do
    {
        newsize *= 2;
    } while (newsize > 0 && bytes_needed > (size_t) newsize);

    if (newsize > 0 && bytes_needed <= (size_t) newsize)
    {
        newbuf = realloc(conn->outBuffer, newsize);
        if (newbuf)
        {
            /* realloc succeeded */
            conn->outBuffer = newbuf;
            conn->outBufSize = newsize;
            return 0;
        }
    }

    newsize = conn->outBufSize;
    do
    {
        newsize += 8192;
    } while (newsize > 0 && bytes_needed > (size_t) newsize);

    if (newsize > 0 && bytes_needed <= (size_t) newsize)
    {
        newbuf = realloc(conn->outBuffer, newsize);
        if (newbuf)
        {
            /* realloc succeeded */
            conn->outBuffer = newbuf;
            conn->outBufSize = newsize;
            return 0;
        }
    }

    /* realloc failed. Probably out of memory */
    printfPQExpBuffer(&conn->errorMessage,
                      "cannot allocate memory for output buffer\n");
    return EOF;
}

static int
pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
{
	int			ret;
	char	   *crypt_pwd = NULL;
	const char *pwd_to_send;

	/* Encrypt the password if needed. */

	switch (areq)
	{
		case AUTH_REQ_MD5:
			{
				char	   *crypt_pwd2;

				/* Allocate enough space for two MD5 hashes */
				crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1));
				if (!crypt_pwd)
				{
					printfPQExpBuffer(&conn->errorMessage,
									  libpq_gettext("out of memory\n"));
					return STATUS_ERROR;
				}

				crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1;
				if (!pg_md5_encrypt(password, conn->pguser,
									strlen(conn->pguser), crypt_pwd2))
				{
					free(crypt_pwd);
					return STATUS_ERROR;
				}
				if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), conn->md5Salt,
									sizeof(conn->md5Salt), crypt_pwd))
				{
					free(crypt_pwd);
					return STATUS_ERROR;
				}

				pwd_to_send = crypt_pwd;
				break;
			}
		case AUTH_REQ_PASSWORD:
			pwd_to_send = password;
			break;
		default:
			return STATUS_ERROR;
	}
	/* Packet has a message type as of protocol 3.0 */
	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
		ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
	else
		ret = pqPacketSend(conn, 0, pwd_to_send, strlen(pwd_to_send) + 1);
	if (crypt_pwd)
		free(crypt_pwd);
	return ret;
}

/*
 * Dump user-specific configuration
 */
static void
dumpUserConfig(PGconn *conn, const char *username)
{
	PQExpBuffer buf = createPQExpBuffer();
	int			count = 1;

	for (;;)
	{
		PGresult   *res;

		if (server_version >= 90000)
			printfPQExpBuffer(buf, "SELECT setconfig[%d] FROM pg_db_role_setting WHERE "
							  "setdatabase = 0 AND setrole = "
					   "(SELECT oid FROM pg_authid WHERE rolname = ", count);
		else if (server_version >= 80100)
			printfPQExpBuffer(buf, "SELECT rolconfig[%d] FROM pg_authid WHERE rolname = ", count);
		else
			printfPQExpBuffer(buf, "SELECT useconfig[%d] FROM pg_shadow WHERE usename = ", count);
		appendStringLiteralConn(buf, username, conn);
		if (server_version >= 90000)
			appendPQExpBuffer(buf, ")");

		res = executeQuery(conn, buf->data);
		if (PQntuples(res) == 1 &&
			!PQgetisnull(res, 0, 0))
		{
			makeAlterConfigCommand(conn, PQgetvalue(res, 0, 0),
								   "ROLE", username, NULL, NULL);
			PQclear(res);
			count++;
		}
		else
		{
			PQclear(res);
			break;
		}
	}

	destroyPQExpBuffer(buf);
}

/*
 * Checks a socket, using poll or select, for data to be read, written,
 * or both.  Returns >0 if one or more conditions are met, 0 if it timed
 * out, -1 if an error occurred.
 *
 * If SSL is in use, the SSL buffer is checked prior to checking the socket
 * for read data directly.
 */
static int
pqSocketCheck(PGconn *conn, int forRead, int forWrite, time_t end_time)
{
	int			result;

	if (!conn)
		return -1;
	if (conn->sock < 0)
	{
		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("socket not open\n"));
		return -1;
	}

#ifdef USE_SSL
	/* Check for SSL library buffering read bytes */
	if (forRead && conn->ssl && SSL_pending(conn->ssl) > 0)
	{
		/* short-circuit the select */
		return 1;
	}
#endif

	/* We will retry as long as we get EINTR */
	do
		result = pqSocketPoll(conn->sock, forRead, forWrite, end_time);
	while (result < 0 && SOCK_ERRNO == EINTR);

	if (result < 0)
	{
		char		sebuf[256];

		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("select() failed: %s\n"),
						  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
	}

	return result;
}

/*
 * Report just the primary error; this is to avoid cluttering the output
 * with, for instance, a redisplay of the internally generated query
 */
static void
minimal_error_message(PGresult *res)
{
	PQExpBuffer msg;
	const char *fld;

	msg = createPQExpBuffer();

	fld = PQresultErrorField(res, PG_DIAG_SEVERITY);
	if (fld)
		printfPQExpBuffer(msg, "%s:  ", fld);
	else
		printfPQExpBuffer(msg, "ERROR:  ");
	fld = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
	if (fld)
		appendPQExpBufferStr(msg, fld);
	else
		appendPQExpBufferStr(msg, "(not available)");
	appendPQExpBufferStr(msg, "\n");

	psql_error("%s", msg->data);

	destroyPQExpBuffer(msg);
}

/*
 * pgWaitTimeout: wait, but not past finish_time.
 * wrapper for pqSocketCheck.
 *
 * finish_time = ((time_t) -1) disables the wait limit.
 */
int
pqWaitTimeout(int forRead, int forWrite, PGconn *conn, time_t finish_time)
{
	int			result;

	result = pqSocketCheck(conn, forRead, forWrite, finish_time);

	if (result == 0)
	{
		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("timeout expired\n"));
	}

	return result;
}

/*
 * handleSyncLoss: clean up after loss of message-boundary sync
 *
 * There isn't really a lot we can do here except abandon the connection.
 */
static void
handleSyncLoss(PGconn *conn, char id, int msgLength)
{
	printfPQExpBuffer(&conn->errorMessage,
					  libpq_gettext(
	"lost synchronization with server: got message type \"%c\", length %d\n"),
					  id, msgLength);
	/* build an error result holding the error message */
	pqSaveErrorResult(conn);
	conn->asyncStatus = PGASYNC_READY;	/* drop out of GetResult wait loop */

	pqsecure_close(conn);
	closesocket(conn->sock);
	conn->sock = -1;
	conn->status = CONNECTION_BAD;		/* No more connection to backend */
}

/*
 * PQgetline - gets a newline-terminated string from the backend.
 *
 * See fe-exec.c for documentation.
 */
int
pqGetline3(PGconn *conn, char *s, int maxlen)
{
	int			status;

	if (conn->sock < 0 ||
		conn->asyncStatus != PGASYNC_COPY_OUT ||
		conn->copy_is_binary)
	{
		printfPQExpBuffer(&conn->errorMessage,
					  libpq_gettext("PQgetline: not doing text COPY OUT\n"));
		*s = '\0';
		return EOF;
	}

	while ((status = PQgetlineAsync(conn, s, maxlen - 1)) == 0)
	{
		/* need to load more data */
		if (pqWait(TRUE, FALSE, conn) ||
			pqReadData(conn) < 0)
		{
			*s = '\0';
			return EOF;
		}
	}

	if (status < 0)
	{
		/* End of copy detected; gin up old-style terminator */
		strcpy(s, "\\.");
		return 0;
	}

	/* Add null terminator, and strip trailing \n if present */
	if (s[status - 1] == '\n')
	{
		s[status - 1] = '\0';
		return 0;
	}
	else
	{
		s[status] = '\0';
		return 1;
	}
}