/*
 * Transfer a user or group name starting at *input into the output buffer,
 * dequoting if needed.  Returns a pointer to just past the input name.
 * The name is taken to end at an unquoted '=' or end of string.
 */
static char *
copyAclUserName(PQExpBuffer output, char *input)
{
	resetPQExpBuffer(output);

	while (*input && *input != '=')
	{
		/*
		 * If user name isn't quoted, then just add it to the output buffer
		 */
		if (*input != '"')
			appendPQExpBufferChar(output, *input++);
		else
		{
			/* Otherwise, it's a quoted username */
			input++;
			/* Loop until we come across an unescaped quote */
			while (!(*input == '"' && *(input + 1) != '"'))
			{
				if (*input == '\0')
					return input;		/* really a syntax error... */

				/*
				 * Quoting convention is to escape " as "".  Keep this code in
				 * sync with putid() in backend's acl.c.
				 */
				if (*input == '"' && *(input + 1) == '"')
					input++;
				appendPQExpBufferChar(output, *input++);
			}
			input++;
		}
	}
	return input;
}

/*
 * pqGets[_append]:
 * get a null-terminated string from the connection,
 * and store it in an expansible PQExpBuffer.
 * If we run out of memory, all of the string is still read,
 * but the excess characters are silently discarded.
 */
static int
pqGets_internal(PQExpBuffer buf, PGconn *conn, bool resetbuffer)
{
	/* Copy conn data to locals for faster search loop */
	char	   *inBuffer = conn->inBuffer;
	int			inCursor = conn->inCursor;
	int			inEnd = conn->inEnd;
	int			slen;

	while (inCursor < inEnd && inBuffer[inCursor])
		inCursor++;

	if (inCursor >= inEnd)
		return EOF;

	slen = inCursor - conn->inCursor;

	if (resetbuffer)
	resetPQExpBuffer(buf);

	appendBinaryPQExpBuffer(buf, inBuffer + conn->inCursor, slen);

	conn->inCursor = ++inCursor;

	if (conn->Pfdebug)
		fprintf(conn->Pfdebug, "From backend> \"%s\"\n",
				buf->data);

	return 0;
}

/*
 *	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
}

/*
 * gets_fromFile
 *
 * Gets a line of noninteractive input from a file (which could be stdin).
 * The result is a malloc'd string, or NULL on EOF or input error.
 *
 * Caller *must* have set up sigint_interrupt_jmp before calling.
 *
 * Note: we re-use a static PQExpBuffer for each call.	This is to avoid
 * leaking memory if interrupted by SIGINT.
 */
char *
gets_fromFile(FILE *source)
{
	static PQExpBuffer buffer = NULL;

	char		line[1024];

	if (buffer == NULL)			/* first time through? */
		buffer = createPQExpBuffer();
	else
		resetPQExpBuffer(buffer);

	for (;;)
	{
		char	   *result;

		/* Enable SIGINT to longjmp to sigint_interrupt_jmp */
		sigint_interrupt_enabled = true;

		/* Get some data */
		result = fgets(line, sizeof(line), source);

		/* Disable SIGINT again */
		sigint_interrupt_enabled = false;

		/* EOF or error? */
		if (result == NULL)
		{
			if (ferror(source))
			{
				psql_error("could not read from input file: %s\n",
						   strerror(errno));
				return NULL;
			}
			break;
		}

		appendPQExpBufferStr(buffer, line);

		if (PQExpBufferBroken(buffer))
		{
			psql_error("out of memory\n");
			return NULL;
		}

		/* EOL? */
		if (buffer->data[buffer->len - 1] == '\n')
		{
			buffer->data[buffer->len - 1] = '\0';
			return pg_strdup(buffer->data);
		}
	}

	if (buffer->len > 0)		/* EOF after reading some bufferload(s) */
		return pg_strdup(buffer->data);

	/* EOF, so return null */
	return NULL;
}

/*
 * Issue a query on a catalog table, and produce calls to a preassign support
 * function from the result set.
 *
 * The output is a string, containing SQL calls like:
 *
 * SELECT binary_upgrade.preassign_*_oid(<oid>, <other args);
 *
 * 'funcname' is the "preassign_*_oid" function to use.
 * 'sql' is the query to issue. The columns of the result set are passed as
 * arguments to the preassign-support function.
 *
 */
static void
dump_rows(migratorContext *ctx, PQExpBuffer buf, FILE *file, PGconn *conn,
		  const char *sql, const char *funcname)
{
	int			ntups;
	int			ncols;
	int			row;
	int			col;
	PGresult   *res;

	if (file != NULL)
		buf = createPQExpBuffer();

	/*
	 * Add a WHERE or AND clause to filter out built-in objects.
	 *
	 * If the query contains "UNION ALL", then it's the caller's
	 * responsibility to do the filtering. This special case is for the
	 * one more complicated query in get_old_oids() function; all the
	 * other queries are very simple ones.
	 */
	if (strstr(sql, "WHERE ") == NULL)
		res = executeQueryOrDie(ctx, conn, "%s WHERE oid >= %u", sql, FirstNormalObjectId);
	else if (strstr(sql, "UNION ALL") == NULL)
		res = executeQueryOrDie(ctx, conn, "%s AND oid >= %u", sql, FirstNormalObjectId);
	else
		res = executeQueryOrDie(ctx, conn, "%s", sql);

	ntups = PQntuples(res);
	ncols = PQnfields(res);

	for (row = 0; row < ntups; row++)
	{
		appendPQExpBuffer(buf, "SELECT binary_upgrade.%s('%s'",
						  funcname,
						  simple_escape_literal(ctx, conn, PQgetvalue(res, row, 0)));

		for (col = 1; col < ncols; col++)
			appendPQExpBuffer(buf, ", '%s'",
							  simple_escape_literal(ctx, conn, PQgetvalue(res, row, col)));
		appendPQExpBuffer(buf, ");\n");

		if (file)
		{
			fwrite(buf->data, buf->len, 1, file);
			resetPQExpBuffer(buf);
		}
	}
	PQclear(res);

	if (file != NULL)
		destroyPQExpBuffer(buf);
}

/*
 * GSSAPI errors contain two parts; put both into conn->errorMessage.
 */
static void
pg_GSS_error(const char *mprefix, PGconn *conn,
			 OM_uint32 maj_stat, OM_uint32 min_stat)
{
	resetPQExpBuffer(&conn->errorMessage);

	/* Fetch major error codes */
	pg_GSS_error_int(&conn->errorMessage, mprefix, maj_stat, GSS_C_GSS_CODE);

	/* Add the minor codes as well */
	pg_GSS_error_int(&conn->errorMessage, mprefix, min_stat, GSS_C_MECH_CODE);
}

/*
 * Reset a CdbDispatchResult object for possible reuse.
 */
void
cdbdisp_resetResult(CdbDispatchResult *dispatchResult)
{
	PQExpBuffer buf = dispatchResult->resultbuf;
	PGresult **begp = (PGresult **) buf->data;
	PGresult **endp = (PGresult **) (buf->data + buf->len);
	PGresult **p;

	/*
	 * Free the PGresult objects.
	 */
	for (p = begp; p < endp; ++p)
	{
		Assert(*p != NULL);
		PQclear(*p);
	}

	/*
	 * Reset summary indicators.
	 */
	dispatchResult->errcode = 0;
	dispatchResult->errindex = -1;
	dispatchResult->okindex = -1;

	/*
	 * Reset progress indicators.
	 */
	dispatchResult->hasDispatched = false;
	dispatchResult->stillRunning = false;
	dispatchResult->sentSignal = DISPATCH_WAIT_NONE;
	dispatchResult->wasCanceled = false;

	/*
	 * Empty (but don't free) the error message buffer and result buffer.
	 */
	resetPQExpBuffer(dispatchResult->resultbuf);
	resetPQExpBuffer(dispatchResult->error_message);
}

/*
 * gets_fromFile
 *
 * Gets a line of noninteractive input from a file (which could be stdin).
 * The result is a malloc'd string.
 *
 * Caller *must* have set up sigint_interrupt_jmp before calling.
 *
 * Note: we re-use a static PQExpBuffer for each call.	This is to avoid
 * leaking memory if interrupted by SIGINT.
 */
char *
gets_fromFile(FILE *source)
{
	static PQExpBuffer buffer = NULL;

	char		line[1024];

	if (buffer == NULL)			/* first time through? */
		buffer = createPQExpBuffer();
	else
		resetPQExpBuffer(buffer);

	for (;;)
	{
		char	   *result;

		/* Enable SIGINT to longjmp to sigint_interrupt_jmp */
		sigint_interrupt_enabled = true;

		/* Get some data */
		result = fgets(line, sizeof(line), source);

		/* Disable SIGINT again */
		sigint_interrupt_enabled = false;

		/* EOF? */
		if (result == NULL)
			break;

		appendPQExpBufferStr(buffer, line);

		/* EOL? */
		if (buffer->data[buffer->len - 1] == '\n')
		{
			buffer->data[buffer->len - 1] = '\0';
			return pg_strdup(buffer->data);
		}
	}

	if (buffer->len > 0)		/* EOF after reading some bufferload(s) */
		return pg_strdup(buffer->data);

	/* EOF, so return null */
	return NULL;
}

/*
 * printfPQExpBuffer
 * Format text data under the control of fmt (an sprintf-like format string)
 * and insert it into str.	More space is allocated to str if necessary.
 * This is a convenience routine that does the same thing as
 * resetPQExpBuffer() followed by appendPQExpBuffer().
 */
void
printfPQExpBuffer(PQExpBuffer str, const char *fmt,...)
{
	va_list		args;
	size_t		avail;
	int			nprinted;

	resetPQExpBuffer(str);

	if (PQExpBufferBroken(str))
		return;					/* already failed */

	for (;;)
	{
		/*
		 * Try to format the given string into the available space; but if
		 * there's hardly any space, don't bother trying, just fall through to
		 * enlarge the buffer first.
		 */
		if (str->maxlen > str->len + 16)
		{
			avail = str->maxlen - str->len - 1;
			va_start(args, fmt);
			nprinted = vsnprintf(str->data + str->len, avail,
								 fmt, args);
			va_end(args);

			/*
			 * Note: some versions of vsnprintf return the number of chars
			 * actually stored, but at least one returns -1 on failure. Be
			 * conservative about believing whether the print worked.
			 */
			if (nprinted >= 0 && nprinted < (int) avail - 1)
			{
				/* Success.  Note nprinted does not include trailing null. */
				str->len += nprinted;
				break;
			}
		}
		/* Double the buffer size and try again. */
		if (!enlargePQExpBuffer(str, str->maxlen))
			return;				/* oops, out of memory */
	}
}

/*
 * printfPQExpBuffer
 * Format text data under the control of fmt (an sprintf-like format string)
 * and insert it into str.  More space is allocated to str if necessary.
 * This is a convenience routine that does the same thing as
 * resetPQExpBuffer() followed by appendPQExpBuffer().
 */
void
printfPQExpBuffer(PQExpBuffer str, const char *fmt,...)
{
	va_list		args;
	bool		done;

	resetPQExpBuffer(str);

	if (PQExpBufferBroken(str))
		return;					/* already failed */

	/* Loop in case we have to retry after enlarging the buffer. */
	do
	{
		va_start(args, fmt);
		done = appendPQExpBufferVA(str, fmt, args);
		va_end(args);
	} while (!done);
}

/*
 * cluster_conn_opts()
 *
 * Return standard command-line options for connecting to this cluster when
 * using psql, pg_dump, etc.  Ideally this would match what get_db_conn()
 * sets, but the utilities we need aren't very consistent about the treatment
 * of database name options, so we leave that out.
 *
 * Result is valid until the next call to this function.
 */
char *
cluster_conn_opts(ClusterInfo *cluster)
{
	static PQExpBuffer buf;

	if (buf == NULL)
		buf = createPQExpBuffer();
	else
		resetPQExpBuffer(buf);

	if (cluster->sockdir)
	{
		appendPQExpBufferStr(buf, "--host ");
		appendShellString(buf, cluster->sockdir);
		appendPQExpBufferChar(buf, ' ');
	}
	appendPQExpBuffer(buf, "--port %d --username ", cluster->port);
	appendShellString(buf, os_info.user);

	return buf->data;
}

static void
cluster_all_databases(bool verbose, const char *maintenance_db,
					  const char *host, const char *port,
					  const char *username, enum trivalue prompt_password,
					  const char *progname, bool echo, bool quiet)
{
	PGconn	   *conn;
	PGresult   *result;
	PQExpBufferData connstr;
	int			i;

	conn = connectMaintenanceDatabase(maintenance_db, host, port, username,
									  prompt_password, progname, echo);
	result = executeQuery(conn, "SELECT datname FROM pg_database WHERE datallowconn ORDER BY 1;", progname, echo);
	PQfinish(conn);

	initPQExpBuffer(&connstr);
	for (i = 0; i < PQntuples(result); i++)
	{
		char	   *dbname = PQgetvalue(result, i, 0);

		if (!quiet)
		{
			printf(_("%s: clustering database \"%s\"\n"), progname, dbname);
			fflush(stdout);
		}

		resetPQExpBuffer(&connstr);
		appendPQExpBuffer(&connstr, "dbname=");
		appendConnStrVal(&connstr, dbname);

		cluster_one_database(connstr.data, verbose, NULL,
							 host, port, username, prompt_password,
							 progname, echo);
	}
	termPQExpBuffer(&connstr);

	PQclear(result);
}

/*
 * Emit accumulated history entry to readline's history mechanism,
 * then reset the buffer to empty.
 *
 * Note: we write nothing if history_buf is empty, so extra calls to this
 * function don't hurt.  There must have been at least one line added by
 * pg_append_history before we'll do anything.
 */
void
pg_send_history(PQExpBuffer history_buf)
{
#ifdef USE_READLINE
	static char *prev_hist = NULL;

	char	   *s = history_buf->data;
	int			i;

	/* Trim any trailing \n's (OK to scribble on history_buf) */
	for (i = strlen(s) - 1; i >= 0 && s[i] == '\n'; i--)
		;
	s[i + 1] = '\0';

	if (useHistory && s[0])
	{
		if (((pset.histcontrol & hctl_ignorespace) &&
			 s[0] == ' ') ||
			((pset.histcontrol & hctl_ignoredups) &&
			 prev_hist && strcmp(s, prev_hist) == 0))
		{
			/* Ignore this line as far as history is concerned */
		}
		else
		{
			/* Save each previous line for ignoredups processing */
			if (prev_hist)
				free(prev_hist);
			prev_hist = pg_strdup(s);
			/* And send it to readline */
			add_history(s);
			/* Count lines added to history for use later */
			history_lines_added++;
		}
	}

	resetPQExpBuffer(history_buf);
#endif
}

//.........这里部分代码省略.........
		char		ch = *cp;

		if (ch == '"')
		{
			if (inquotes && cp[1] == '"')
			{
				/* emit one quote, stay in inquotes mode */
				appendPQExpBufferChar(&namebuf, '"');
				cp++;
			}
			else
				inquotes = !inquotes;
			cp++;
		}
		else if (!inquotes && isupper((unsigned char) ch))
		{
			appendPQExpBufferChar(&namebuf,
								  pg_tolower((unsigned char) ch));
			cp++;
		}
		else if (!inquotes && ch == '*')
		{
			appendPQExpBufferStr(&namebuf, ".*");
			cp++;
		}
		else if (!inquotes && ch == '?')
		{
			appendPQExpBufferChar(&namebuf, '.');
			cp++;
		}
		else if (!inquotes && ch == '.')
		{
			/* Found schema/name separator, move current pattern to schema */
			resetPQExpBuffer(&schemabuf);
			appendPQExpBufferStr(&schemabuf, namebuf.data);
			resetPQExpBuffer(&namebuf);
			appendPQExpBufferStr(&namebuf, "^(");
			cp++;
		}
		else if (ch == '$')
		{
			/*
			 * Dollar is always quoted, whether inside quotes or not. The
			 * reason is that it's allowed in SQL identifiers, so there's a
			 * significant use-case for treating it literally, while because
			 * we anchor the pattern automatically there is no use-case for
			 * having it possess its regexp meaning.
			 */
			appendPQExpBufferStr(&namebuf, "\\$");
			cp++;
		}
		else
		{
			/*
			 * Ordinary data character, transfer to pattern
			 *
			 * Inside double quotes, or at all times if force_escape is true,
			 * quote regexp special characters with a backslash to avoid
			 * regexp errors.  Outside quotes, however, let them pass through
			 * as-is; this lets knowledgeable users build regexp expressions
			 * that are more powerful than shell-style patterns.
			 */
			if ((inquotes || force_escape) &&
				strchr("|*+?()[]{}.^$\\", ch))
				appendPQExpBufferChar(&namebuf, '\\');
			i = PQmblen(cp, encoding);

/*
 * This will parse an aclitem string, having the general form
 *		username=privilegecodes/grantor
 * or
 *		group groupname=privilegecodes/grantor
 * (the /grantor part will not be present if pre-7.4 database).
 *
 * The returned grantee string will be the dequoted username or groupname
 * (preceded with "group " in the latter case).  The returned grantor is
 * the dequoted grantor name or empty.	Privilege characters are decoded
 * and split between privileges with grant option (privswgo) and without
 * (privs).
 *
 * Note: for cross-version compatibility, it's important to use ALL when
 * appropriate.
 */
static bool
parseAclItem(const char *item, const char *type,
			 const char *name, const char *subname, int remoteVersion,
			 PQExpBuffer grantee, PQExpBuffer grantor,
			 PQExpBuffer privs, PQExpBuffer privswgo)
{
	char	   *buf;
	bool		all_with_go = true;
	bool		all_without_go = true;
	char	   *eqpos;
	char	   *slpos;
	char	   *pos;

	buf = strdup(item);
	if (!buf)
		return false;

	/* user or group name is string up to = */
	eqpos = copyAclUserName(grantee, buf);
	if (*eqpos != '=')
		return false;

	/* grantor may be listed after / */
	slpos = strchr(eqpos + 1, '/');
	if (slpos)
	{
		*slpos++ = '\0';
		slpos = copyAclUserName(grantor, slpos);
		if (*slpos != '\0')
			return false;
	}
	else
		resetPQExpBuffer(grantor);

	/* privilege codes */
#define CONVERT_PRIV(code, keywd) \
do { \
	if ((pos = strchr(eqpos + 1, code))) \
	{ \
		if (*(pos + 1) == '*') \
		{ \
			AddAcl(privswgo, keywd, subname); \
			all_without_go = false; \
		} \
		else \
		{ \
			AddAcl(privs, keywd, subname); \
			all_with_go = false; \
		} \
	} \
	else \
		all_with_go = all_without_go = false; \
} while (0)

	resetPQExpBuffer(privs);
	resetPQExpBuffer(privswgo);

	if (strcmp(type, "TABLE") == 0 || strcmp(type, "SEQUENCE") == 0 ||
		strcmp(type, "TABLES") == 0 || strcmp(type, "SEQUENCES") == 0)
	{
		CONVERT_PRIV('r', "SELECT");

		if (strcmp(type, "SEQUENCE") == 0 ||
			strcmp(type, "SEQUENCES") == 0)
			/* sequence only */
			CONVERT_PRIV('U', "USAGE");
		else
		{
			/* table only */
			CONVERT_PRIV('a', "INSERT");
			if (remoteVersion >= 70200)
				CONVERT_PRIV('x', "REFERENCES");
			/* rest are not applicable to columns */
			if (subname == NULL)
			{
				if (remoteVersion >= 70200)
				{
					CONVERT_PRIV('d', "DELETE");
					CONVERT_PRIV('t', "TRIGGER");
				}
				if (remoteVersion >= 80400)
					CONVERT_PRIV('D', "TRUNCATE");
			}
		}
//.........这里部分代码省略.........

/*
 *	Quotes input string if it's not a legitimate SQL identifier as-is.
 *
 *	Note that the returned string must be used before calling fmtId again,
 *	since we re-use the same return buffer each time.  Non-reentrant but
 *	reduces memory leakage. (On Windows the memory leakage will be one buffer
 *	per thread, which is at least better than one per call).
 */
const char *
fmtId(const char *rawid)
{
	/*
	 * The Tls code goes awry if we use a static var, so we provide for both
	 * static and auto, and omit any use of the static var when using Tls.
	 */
	static PQExpBuffer s_id_return = NULL;
	PQExpBuffer id_return;

	const char *cp;
	bool		need_quotes = false;

#ifdef WIN32
	if (parallel_init_done)
		id_return = (PQExpBuffer) TlsGetValue(tls_index);		/* 0 when not set */
	else
		id_return = s_id_return;
#else
	id_return = s_id_return;
#endif

	if (id_return)				/* first time through? */
	{
		/* same buffer, just wipe contents */
		resetPQExpBuffer(id_return);
	}
	else
	{
		/* new buffer */
		id_return = createPQExpBuffer();
#ifdef WIN32
		if (parallel_init_done)
			TlsSetValue(tls_index, id_return);
		else
			s_id_return = id_return;
#else
		s_id_return = id_return;
#endif

	}

	/*
	 * These checks need to match the identifier production in scan.l. Don't
	 * use islower() etc.
	 */
	if (quote_all_identifiers)
		need_quotes = true;
	/* slightly different rules for first character */
	else if (!((rawid[0] >= 'a' && rawid[0] <= 'z') || rawid[0] == '_'))
		need_quotes = true;
	else
	{
		/* otherwise check the entire string */
		for (cp = rawid; *cp; cp++)
		{
			if (!((*cp >= 'a' && *cp <= 'z')
				  || (*cp >= '0' && *cp <= '9')
				  || (*cp == '_')))
			{
				need_quotes = true;
				break;
			}
		}
	}

	if (!need_quotes)
	{
		/*
		 * Check for keyword.  We quote keywords except for unreserved ones.
		 * (In some cases we could avoid quoting a col_name or type_func_name
		 * keyword, but it seems much harder than it's worth to tell that.)
		 *
		 * Note: ScanKeywordLookup() does case-insensitive comparison, but
		 * that's fine, since we already know we have all-lower-case.
		 */
		const ScanKeyword *keyword = ScanKeywordLookup(rawid,
													   ScanKeywords,
													   NumScanKeywords);

		if (keyword != NULL && keyword->category != UNRESERVED_KEYWORD)
			need_quotes = true;
	}

	if (!need_quotes)
	{
		/* no quoting needed */
		appendPQExpBufferStr(id_return, rawid);
	}
	else
	{
		appendPQExpBufferChar(id_return, '\"');
//.........这里部分代码省略.........

/*
 * PQendcopy
 *
 * See fe-exec.c for documentation.
 */
int
pqEndcopy3(PGconn *conn)
{
	PGresult   *result;

	if (conn->asyncStatus != PGASYNC_COPY_IN &&
		conn->asyncStatus != PGASYNC_COPY_OUT)
	{
		printfPQExpBuffer(&conn->errorMessage,
						  libpq_gettext("no COPY in progress\n"));
		return 1;
	}

	/* Send the CopyDone message if needed */
	if (conn->asyncStatus == PGASYNC_COPY_IN)
	{
		if (pqPutMsgStart('c', false, conn) < 0 ||
			pqPutMsgEnd(conn) < 0)
			return 1;

		/*
		 * If we sent the COPY command in extended-query mode, we must issue a
		 * Sync as well.
		 */
		if (conn->queryclass != PGQUERY_SIMPLE)
		{
			if (pqPutMsgStart('S', false, conn) < 0 ||
				pqPutMsgEnd(conn) < 0)
				return 1;
		}
	}

	/*
	 * make sure no data is waiting to be sent, abort if we are non-blocking
	 * and the flush fails
	 */
	if (pqFlush(conn) && pqIsnonblocking(conn))
		return 1;

	/* Return to active duty */
	conn->asyncStatus = PGASYNC_BUSY;
	resetPQExpBuffer(&conn->errorMessage);

	/*
	 * Non blocking connections may have to abort at this point.  If everyone
	 * played the game there should be no problem, but in error scenarios the
	 * expected messages may not have arrived yet.	(We are assuming that the
	 * backend's packetizing will ensure that CommandComplete arrives along
	 * with the CopyDone; are there corner cases where that doesn't happen?)
	 */
	if (pqIsnonblocking(conn) && PQisBusy(conn))
		return 1;

	/* Wait for the completion response */
	result = PQgetResult(conn);

	/* Expecting a successful result */
	if (result && result->resultStatus == PGRES_COMMAND_OK)
	{
		PQclear(result);
		return 0;
	}

	/*
	 * Trouble. For backwards-compatibility reasons, we issue the error
	 * message as if it were a notice (would be nice to get rid of this
	 * silliness, but too many apps probably don't handle errors from
	 * PQendcopy reasonably).  Note that the app can still obtain the error
	 * status from the PGconn object.
	 */
	if (conn->errorMessage.len > 0)
	{
		/* We have to strip the trailing newline ... pain in neck... */
		char		svLast = conn->errorMessage.data[conn->errorMessage.len - 1];

		if (svLast == '\n')
			conn->errorMessage.data[conn->errorMessage.len - 1] = '\0';
		pqInternalNotice(&conn->noticeHooks, "%s", conn->errorMessage.data);
		conn->errorMessage.data[conn->errorMessage.len - 1] = svLast;
	}

	PQclear(result);

	return 1;
}

/*
 * Attempt to read an Error or Notice response message.
 * This is possible in several places, so we break it out as a subroutine.
 * Entry: 'E' or 'N' message type and length have already been consumed.
 * Exit: returns 0 if successfully consumed message.
 *		 returns EOF if not enough data.
 */
int
pqGetErrorNotice3(PGconn *conn, bool isError)
{
	PGresult   *res = NULL;
	PQExpBufferData workBuf;
	char		id;
	const char *val;
	const char *querytext = NULL;
	int			querypos = 0;

	/*
	 * Since the fields might be pretty long, we create a temporary
	 * PQExpBuffer rather than using conn->workBuffer.	workBuffer is intended
	 * for stuff that is expected to be short.	We shouldn't use
	 * conn->errorMessage either, since this might be only a notice.
	 */
	initPQExpBuffer(&workBuf);

	/*
	 * Make a PGresult to hold the accumulated fields.	We temporarily lie
	 * about the result status, so that PQmakeEmptyPGresult doesn't uselessly
	 * copy conn->errorMessage.
	 */
	res = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY);
	if (!res)
		goto fail;
	res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR;

	/*
	 * Read the fields and save into res.
	 */
	for (;;)
	{
		if (pqGetc(&id, conn))
			goto fail;
		if (id == '\0')
			break;				/* terminator found */
		if (pqGets(&workBuf, conn))
			goto fail;
		pqSaveMessageField(res, id, workBuf.data);
	}

	/*
	 * Now build the "overall" error message for PQresultErrorMessage.
	 */
	resetPQExpBuffer(&workBuf);
	val = PQresultErrorField(res, PG_DIAG_SEVERITY);
	if (val)
		appendPQExpBuffer(&workBuf, "%s:  ", val);
	if (conn->verbosity == PQERRORS_VERBOSE)
	{
		val = PQresultErrorField(res, PG_DIAG_SQLSTATE);
		if (val)
			appendPQExpBuffer(&workBuf, "%s: ", val);
	}
	val = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
	if (val)
		appendPQExpBufferStr(&workBuf, val);
	val = PQresultErrorField(res, PG_DIAG_STATEMENT_POSITION);
	if (val)
	{
		if (conn->verbosity != PQERRORS_TERSE && conn->last_query != NULL)
		{
			/* emit position as a syntax cursor display */
			querytext = conn->last_query;
			querypos = atoi(val);
		}
		else
		{
			/* emit position as text addition to primary message */
			/* translator: %s represents a digit string */
			appendPQExpBuffer(&workBuf, libpq_gettext(" at character %s"),
							  val);
		}
	}
	else
	{
		val = PQresultErrorField(res, PG_DIAG_INTERNAL_POSITION);
		if (val)
		{
			querytext = PQresultErrorField(res, PG_DIAG_INTERNAL_QUERY);
			if (conn->verbosity != PQERRORS_TERSE && querytext != NULL)
			{
				/* emit position as a syntax cursor display */
				querypos = atoi(val);
			}
			else
			{
				/* emit position as text addition to primary message */
				/* translator: %s represents a digit string */
				appendPQExpBuffer(&workBuf, libpq_gettext(" at character %s"),
								  val);
			}
//.........这里部分代码省略.........

/*
 * Main processing loop for reading lines of input
 *	and sending them to the backend.
 *
 * This loop is re-entrant. May be called by \i command
 *	which reads input from a file.
 */
int
MainLoop(FILE *source)
{
	PsqlScanState scan_state;	/* lexer working state */
	volatile PQExpBuffer query_buf;		/* buffer for query being accumulated */
	volatile PQExpBuffer previous_buf;	/* if there isn't anything in the new
										 * buffer yet, use this one for \e,
										 * etc. */
	PQExpBuffer history_buf;	/* earlier lines of a multi-line command, not
								 * yet saved to readline history */
	char	   *line;			/* current line of input */
	int			added_nl_pos;
	bool		success;
	bool		line_saved_in_history;
	volatile int successResult = EXIT_SUCCESS;
	volatile backslashResult slashCmdStatus = PSQL_CMD_UNKNOWN;
	volatile promptStatus_t prompt_status = PROMPT_READY;
	volatile int count_eof = 0;
	volatile bool die_on_error = false;

	/* Save the prior command source */
	FILE	   *prev_cmd_source;
	bool		prev_cmd_interactive;
	uint64		prev_lineno;

	/* Save old settings */
	prev_cmd_source = pset.cur_cmd_source;
	prev_cmd_interactive = pset.cur_cmd_interactive;
	prev_lineno = pset.lineno;

	/* Establish new source */
	pset.cur_cmd_source = source;
	pset.cur_cmd_interactive = ((source == stdin) && !pset.notty);
	pset.lineno = 0;

	/* Create working state */
	scan_state = psql_scan_create();

	query_buf = createPQExpBuffer();
	previous_buf = createPQExpBuffer();
	history_buf = createPQExpBuffer();
	if (PQExpBufferBroken(query_buf) ||
		PQExpBufferBroken(previous_buf) ||
		PQExpBufferBroken(history_buf))
	{
		psql_error("out of memory\n");
		exit(EXIT_FAILURE);
	}

	/* main loop to get queries and execute them */
	while (successResult == EXIT_SUCCESS)
	{
		/*
		 * Clean up after a previous Control-C
		 */
		if (cancel_pressed)
		{
			if (!pset.cur_cmd_interactive)
			{
				/*
				 * You get here if you stopped a script with Ctrl-C.
				 */
				successResult = EXIT_USER;
				break;
			}

			cancel_pressed = false;
		}

		/*
		 * Establish longjmp destination for exiting from wait-for-input. We
		 * must re-do this each time through the loop for safety, since the
		 * jmpbuf might get changed during command execution.
		 */
		if (sigsetjmp(sigint_interrupt_jmp, 1) != 0)
		{
			/* got here with longjmp */

			/* reset parsing state */
			psql_scan_finish(scan_state);
			psql_scan_reset(scan_state);
			resetPQExpBuffer(query_buf);
			resetPQExpBuffer(history_buf);
			count_eof = 0;
			slashCmdStatus = PSQL_CMD_UNKNOWN;
			prompt_status = PROMPT_READY;
			cancel_pressed = false;

			if (pset.cur_cmd_interactive)
				putc('\n', stdout);
			else
			{
				successResult = EXIT_USER;
//.........这里部分代码省略.........

/*
 * Vacuum/analyze all connectable databases.
 *
 * In analyze-in-stages mode, we process all databases in one stage before
 * moving on to the next stage.  That ensure minimal stats are available
 * quickly everywhere before generating more detailed ones.
 */
static void
vacuum_all_databases(vacuumingOptions *vacopts,
					 bool analyze_in_stages,
					 const char *maintenance_db, const char *host,
					 const char *port, const char *username,
					 enum trivalue prompt_password,
					 int concurrentCons,
					 const char *progname, bool echo, bool quiet)
{
	PGconn	   *conn;
	PGresult   *result;
	PQExpBufferData connstr;
	int			stage;
	int			i;

	conn = connectMaintenanceDatabase(maintenance_db, host, port, username,
									  prompt_password, progname, echo);
	result = executeQuery(conn,
						  "SELECT datname FROM pg_database WHERE datallowconn ORDER BY 1;",
						  progname, echo);
	PQfinish(conn);

	initPQExpBuffer(&connstr);
	if (analyze_in_stages)
	{
		/*
		 * When analyzing all databases in stages, we analyze them all in the
		 * fastest stage first, so that initial statistics become available
		 * for all of them as soon as possible.
		 *
		 * This means we establish several times as many connections, but
		 * that's a secondary consideration.
		 */
		for (stage = 0; stage < ANALYZE_NUM_STAGES; stage++)
		{
			for (i = 0; i < PQntuples(result); i++)
			{
				resetPQExpBuffer(&connstr);
				appendPQExpBuffer(&connstr, "dbname=");
				appendConnStrVal(&connstr, PQgetvalue(result, i, 0));

				vacuum_one_database(connstr.data, vacopts,
									stage,
									NULL,
									host, port, username, prompt_password,
									concurrentCons,
									progname, echo, quiet);
			}
		}
	}
	else
	{
		for (i = 0; i < PQntuples(result); i++)
		{
			resetPQExpBuffer(&connstr);
			appendPQExpBuffer(&connstr, "dbname=");
			appendConnStrVal(&connstr, PQgetvalue(result, i, 0));

			vacuum_one_database(connstr.data, vacopts,
								ANALYZE_NO_STAGE,
								NULL,
								host, port, username, prompt_password,
								concurrentCons,
								progname, echo, quiet);
		}
	}
	termPQExpBuffer(&connstr);

	PQclear(result);
}