Adding upstream version 15.5.upstream/15.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2388 insertions, 0 deletions

diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
new file mode 100644
index 0000000..f5909f9
--- /dev/null
+++ b/src/bin/psql/common.c
@@ -0,0 +1,2388 @@
+/*
+ * psql - the PostgreSQL interactive terminal
+ *
+ * Copyright (c) 2000-2022, PostgreSQL Global Development Group
+ *
+ * src/bin/psql/common.c
+ */
+#include "postgres_fe.h"
+
+#include <ctype.h>
+#include <limits.h>
+#include <math.h>
+#include <pwd.h>
+#include <signal.h>
+#ifndef WIN32
+#include <unistd.h>				/* for write() */
+#else
+#include <io.h>					/* for _write() */
+#include <win32.h>
+#endif
+
+#include "command.h"
+#include "common.h"
+#include "common/logging.h"
+#include "copy.h"
+#include "crosstabview.h"
+#include "fe_utils/cancel.h"
+#include "fe_utils/mbprint.h"
+#include "fe_utils/string_utils.h"
+#include "portability/instr_time.h"
+#include "settings.h"
+
+static bool DescribeQuery(const char *query, double *elapsed_msec);
+static bool ExecQueryUsingCursor(const char *query, double *elapsed_msec);
+static int	ExecQueryAndProcessResults(const char *query,
+									   double *elapsed_msec,
+									   bool *svpt_gone_p,
+									   bool is_watch,
+									   const printQueryOpt *opt,
+									   FILE *printQueryFout);
+static bool command_no_begin(const char *query);
+static bool is_select_command(const char *query);
+
+
+/*
+ * openQueryOutputFile --- attempt to open a query output file
+ *
+ * fname == NULL selects stdout, else an initial '|' selects a pipe,
+ * else plain file.
+ *
+ * Returns output file pointer into *fout, and is-a-pipe flag into *is_pipe.
+ * Caller is responsible for adjusting SIGPIPE state if it's a pipe.
+ *
+ * On error, reports suitable error message and returns false.
+ */
+bool
+openQueryOutputFile(const char *fname, FILE **fout, bool *is_pipe)
+{
+	if (!fname || fname[0] == '\0')
+	{
+		*fout = stdout;
+		*is_pipe = false;
+	}
+	else if (*fname == '|')
+	{
+		*fout = popen(fname + 1, "w");
+		*is_pipe = true;
+	}
+	else
+	{
+		*fout = fopen(fname, "w");
+		*is_pipe = false;
+	}
+
+	if (*fout == NULL)
+	{
+		pg_log_error("%s: %m", fname);
+		return false;
+	}
+
+	return true;
+}
+
+/*
+ * setQFout
+ * -- handler for -o command line option and \o command
+ *
+ * On success, updates pset with the new output file and returns true.
+ * On failure, returns false without changing pset state.
+ */
+bool
+setQFout(const char *fname)
+{
+	FILE	   *fout;
+	bool		is_pipe;
+
+	/* First make sure we can open the new output file/pipe */
+	if (!openQueryOutputFile(fname, &fout, &is_pipe))
+		return false;
+
+	/* Close old file/pipe */
+	if (pset.queryFout && pset.queryFout != stdout && pset.queryFout != stderr)
+	{
+		if (pset.queryFoutPipe)
+			pclose(pset.queryFout);
+		else
+			fclose(pset.queryFout);
+	}
+
+	pset.queryFout = fout;
+	pset.queryFoutPipe = is_pipe;
+
+	/* Adjust SIGPIPE handling appropriately: ignore signal if is_pipe */
+	set_sigpipe_trap_state(is_pipe);
+	restore_sigpipe_trap();
+
+	return true;
+}
+
+
+/*
+ * Variable-fetching callback for flex lexer
+ *
+ * If the specified variable exists, return its value as a string (malloc'd
+ * and expected to be freed by the caller); else return NULL.
+ *
+ * If "quote" isn't PQUOTE_PLAIN, then return the value suitably quoted and
+ * escaped for the specified quoting requirement.  (Failure in escaping
+ * should lead to printing an error and returning NULL.)
+ *
+ * "passthrough" is the pointer previously given to psql_scan_set_passthrough.
+ * In psql, passthrough points to a ConditionalStack, which we check to
+ * determine whether variable expansion is allowed.
+ */
+char *
+psql_get_variable(const char *varname, PsqlScanQuoteType quote,
+				  void *passthrough)
+{
+	char	   *result = NULL;
+	const char *value;
+
+	/* In an inactive \if branch, suppress all variable substitutions */
+	if (passthrough && !conditional_active((ConditionalStack) passthrough))
+		return NULL;
+
+	value = GetVariable(pset.vars, varname);
+	if (!value)
+		return NULL;
+
+	switch (quote)
+	{
+		case PQUOTE_PLAIN:
+			result = pg_strdup(value);
+			break;
+		case PQUOTE_SQL_LITERAL:
+		case PQUOTE_SQL_IDENT:
+			{
+				/*
+				 * For these cases, we use libpq's quoting functions, which
+				 * assume the string is in the connection's client encoding.
+				 */
+				char	   *escaped_value;
+
+				if (!pset.db)
+				{
+					pg_log_error("cannot escape without active connection");
+					return NULL;
+				}
+
+				if (quote == PQUOTE_SQL_LITERAL)
+					escaped_value =
+						PQescapeLiteral(pset.db, value, strlen(value));
+				else
+					escaped_value =
+						PQescapeIdentifier(pset.db, value, strlen(value));
+
+				if (escaped_value == NULL)
+				{
+					const char *error = PQerrorMessage(pset.db);
+
+					pg_log_info("%s", error);
+					return NULL;
+				}
+
+				/*
+				 * Rather than complicate the lexer's API with a notion of
+				 * which free() routine to use, just pay the price of an extra
+				 * strdup().
+				 */
+				result = pg_strdup(escaped_value);
+				PQfreemem(escaped_value);
+				break;
+			}
+		case PQUOTE_SHELL_ARG:
+			{
+				/*
+				 * For this we use appendShellStringNoError, which is
+				 * encoding-agnostic, which is fine since the shell probably
+				 * is too.  In any case, the only special character is "'",
+				 * which is not known to appear in valid multibyte characters.
+				 */
+				PQExpBufferData buf;
+
+				initPQExpBuffer(&buf);
+				if (!appendShellStringNoError(&buf, value))
+				{
+					pg_log_error("shell command argument contains a newline or carriage return: \"%s\"",
+								 value);
+					free(buf.data);
+					return NULL;
+				}
+				result = buf.data;
+				break;
+			}
+
+			/* No default: we want a compiler warning for missing cases */
+	}
+
+	return result;
+}
+
+
+/*
+ * for backend Notice messages (INFO, WARNING, etc)
+ */
+void
+NoticeProcessor(void *arg, const char *message)
+{
+	(void) arg;					/* not used */
+	pg_log_info("%s", message);
+}
+
+
+
+/*
+ * Code to support query cancellation
+ *
+ * Before we start a query, we enable the SIGINT signal catcher to send a
+ * cancel request to the backend.
+ *
+ * SIGINT is supposed to abort all long-running psql operations, not only
+ * database queries.  In most places, this is accomplished by checking
+ * cancel_pressed during long-running loops.  However, that won't work when
+ * blocked on user input (in readline() or fgets()).  In those places, we
+ * set sigint_interrupt_enabled true while blocked, instructing the signal
+ * catcher to longjmp through sigint_interrupt_jmp.  We assume readline and
+ * fgets are coded to handle possible interruption.
+ *
+ * On Windows, currently this does not work, so control-C is less useful
+ * there.
+ */
+volatile bool sigint_interrupt_enabled = false;
+
+sigjmp_buf	sigint_interrupt_jmp;
+
+static void
+psql_cancel_callback(void)
+{
+#ifndef WIN32
+	/* if we are waiting for input, longjmp out of it */
+	if (sigint_interrupt_enabled)
+	{
+		sigint_interrupt_enabled = false;
+		siglongjmp(sigint_interrupt_jmp, 1);
+	}
+#endif
+
+	/* else, set cancel flag to stop any long-running loops */
+	cancel_pressed = true;
+}
+
+void
+psql_setup_cancel_handler(void)
+{
+	setup_cancel_handler(psql_cancel_callback);
+}
+
+
+/* ConnectionUp
+ *
+ * Returns whether our backend connection is still there.
+ */
+static bool
+ConnectionUp(void)
+{
+	return PQstatus(pset.db) != CONNECTION_BAD;
+}
+
+
+
+/* CheckConnection
+ *
+ * Verify that we still have a good connection to the backend, and if not,
+ * see if it can be restored.
+ *
+ * Returns true if either the connection was still there, or it could be
+ * restored successfully; false otherwise.  If, however, there was no
+ * connection and the session is non-interactive, this will exit the program
+ * with a code of EXIT_BADCONN.
+ */
+static bool
+CheckConnection(void)
+{
+	bool		OK;
+
+	OK = ConnectionUp();
+	if (!OK)
+	{
+		if (!pset.cur_cmd_interactive)
+		{
+			pg_log_error("connection to server was lost");
+			exit(EXIT_BADCONN);
+		}
+
+		fprintf(stderr, _("The connection to the server was lost. Attempting reset: "));
+		PQreset(pset.db);
+		OK = ConnectionUp();
+		if (!OK)
+		{
+			fprintf(stderr, _("Failed.\n"));
+
+			/*
+			 * Transition to having no connection; but stash away the failed
+			 * connection so that we can still refer to its parameters in a
+			 * later \connect attempt.  Keep the state cleanup here in sync
+			 * with do_connect().
+			 */
+			if (pset.dead_conn)
+				PQfinish(pset.dead_conn);
+			pset.dead_conn = pset.db;
+			pset.db = NULL;
+			ResetCancelConn();
+			UnsyncVariables();
+		}
+		else
+		{
+			fprintf(stderr, _("Succeeded.\n"));
+
+			/*
+			 * Re-sync, just in case anything changed.  Keep this in sync with
+			 * do_connect().
+			 */
+			SyncVariables();
+			connection_warnings(false); /* Must be after SyncVariables */
+		}
+	}
+
+	return OK;
+}
+
+
+
+
+/*
+ * AcceptResult
+ *
+ * Checks whether a result is valid, giving an error message if necessary;
+ * and ensures that the connection to the backend is still up.
+ *
+ * Returns true for valid result, false for error state.
+ */
+static bool
+AcceptResult(const PGresult *result, bool show_error)
+{
+	bool		OK;
+
+	if (!result)
+		OK = false;
+	else
+		switch (PQresultStatus(result))
+		{
+			case PGRES_COMMAND_OK:
+			case PGRES_TUPLES_OK:
+			case PGRES_EMPTY_QUERY:
+			case PGRES_COPY_IN:
+			case PGRES_COPY_OUT:
+				/* Fine, do nothing */
+				OK = true;
+				break;
+
+			case PGRES_BAD_RESPONSE:
+			case PGRES_NONFATAL_ERROR:
+			case PGRES_FATAL_ERROR:
+				OK = false;
+				break;
+
+			default:
+				OK = false;
+				pg_log_error("unexpected PQresultStatus: %d",
+							 PQresultStatus(result));
+				break;
+		}
+
+	if (!OK && show_error)
+	{
+		const char *error = PQerrorMessage(pset.db);
+
+		if (strlen(error))
+			pg_log_info("%s", error);
+
+		CheckConnection();
+	}
+
+	return OK;
+}
+
+
+/*
+ * Set special variables from a query result
+ * - ERROR: true/false, whether an error occurred on this query
+ * - SQLSTATE: code of error, or "00000" if no error, or "" if unknown
+ * - ROW_COUNT: how many rows were returned or affected, or "0"
+ * - LAST_ERROR_SQLSTATE: same for last error
+ * - LAST_ERROR_MESSAGE: message of last error
+ *
+ * Note: current policy is to apply this only to the results of queries
+ * entered by the user, not queries generated by slash commands.
+ */
+static void
+SetResultVariables(PGresult *result, bool success)
+{
+	if (success)
+	{
+		const char *ntuples = PQcmdTuples(result);
+
+		SetVariable(pset.vars, "ERROR", "false");
+		SetVariable(pset.vars, "SQLSTATE", "00000");
+		SetVariable(pset.vars, "ROW_COUNT", *ntuples ? ntuples : "0");
+	}
+	else
+	{
+		const char *code = PQresultErrorField(result, PG_DIAG_SQLSTATE);
+		const char *mesg = PQresultErrorField(result, PG_DIAG_MESSAGE_PRIMARY);
+
+		SetVariable(pset.vars, "ERROR", "true");
+
+		/*
+		 * If there is no SQLSTATE code, use an empty string.  This can happen
+		 * for libpq-detected errors (e.g., lost connection, ENOMEM).
+		 */
+		if (code == NULL)
+			code = "";
+		SetVariable(pset.vars, "SQLSTATE", code);
+		SetVariable(pset.vars, "ROW_COUNT", "0");
+		SetVariable(pset.vars, "LAST_ERROR_SQLSTATE", code);
+		SetVariable(pset.vars, "LAST_ERROR_MESSAGE", mesg ? mesg : "");
+	}
+}
+
+
+/*
+ * ClearOrSaveResult
+ *
+ * If the result represents an error, remember it for possible display by
+ * \errverbose.  Otherwise, just PQclear() it.
+ *
+ * Note: current policy is to apply this to the results of all queries,
+ * including "back door" queries, for debugging's sake.  It's OK to use
+ * PQclear() directly on results known to not be error results, however.
+ */
+static void
+ClearOrSaveResult(PGresult *result)
+{
+	if (result)
+	{
+		switch (PQresultStatus(result))
+		{
+			case PGRES_NONFATAL_ERROR:
+			case PGRES_FATAL_ERROR:
+				if (pset.last_error_result)
+					PQclear(pset.last_error_result);
+				pset.last_error_result = result;
+				break;
+
+			default:
+				PQclear(result);
+				break;
+		}
+	}
+}
+
+
+/*
+ * Consume all results
+ */
+static void
+ClearOrSaveAllResults(void)
+{
+	PGresult   *result;
+
+	while ((result = PQgetResult(pset.db)) != NULL)
+		ClearOrSaveResult(result);
+}
+
+
+/*
+ * Print microtiming output.  Always print raw milliseconds; if the interval
+ * is >= 1 second, also break it down into days/hours/minutes/seconds.
+ */
+static void
+PrintTiming(double elapsed_msec)
+{
+	double		seconds;
+	double		minutes;
+	double		hours;
+	double		days;
+
+	if (elapsed_msec < 1000.0)
+	{
+		/* This is the traditional (pre-v10) output format */
+		printf(_("Time: %.3f ms\n"), elapsed_msec);
+		return;
+	}
+
+	/*
+	 * Note: we could print just seconds, in a format like %06.3f, when the
+	 * total is less than 1min.  But that's hard to interpret unless we tack
+	 * on "s" or otherwise annotate it.  Forcing the display to include
+	 * minutes seems like a better solution.
+	 */
+	seconds = elapsed_msec / 1000.0;
+	minutes = floor(seconds / 60.0);
+	seconds -= 60.0 * minutes;
+	if (minutes < 60.0)
+	{
+		printf(_("Time: %.3f ms (%02d:%06.3f)\n"),
+			   elapsed_msec, (int) minutes, seconds);
+		return;
+	}
+
+	hours = floor(minutes / 60.0);
+	minutes -= 60.0 * hours;
+	if (hours < 24.0)
+	{
+		printf(_("Time: %.3f ms (%02d:%02d:%06.3f)\n"),
+			   elapsed_msec, (int) hours, (int) minutes, seconds);
+		return;
+	}
+
+	days = floor(hours / 24.0);
+	hours -= 24.0 * days;
+	printf(_("Time: %.3f ms (%.0f d %02d:%02d:%06.3f)\n"),
+		   elapsed_msec, days, (int) hours, (int) minutes, seconds);
+}
+
+
+/*
+ * PSQLexec
+ *
+ * This is the way to send "backdoor" queries (those not directly entered
+ * by the user). It is subject to -E but not -e.
+ *
+ * Caller is responsible for handling the ensuing processing if a COPY
+ * command is sent.
+ *
+ * Note: we don't bother to check PQclientEncoding; it is assumed that no
+ * caller uses this path to issue "SET CLIENT_ENCODING".
+ */
+PGresult *
+PSQLexec(const char *query)
+{
+	PGresult   *res;
+
+	if (!pset.db)
+	{
+		pg_log_error("You are currently not connected to a database.");
+		return NULL;
+	}
+
+	if (pset.echo_hidden != PSQL_ECHO_HIDDEN_OFF)
+	{
+		printf(_("********* QUERY **********\n"
+				 "%s\n"
+				 "**************************\n\n"), query);
+		fflush(stdout);
+		if (pset.logfile)
+		{
+			fprintf(pset.logfile,
+					_("********* QUERY **********\n"
+					  "%s\n"
+					  "**************************\n\n"), query);
+			fflush(pset.logfile);
+		}
+
+		if (pset.echo_hidden == PSQL_ECHO_HIDDEN_NOEXEC)
+			return NULL;
+	}
+
+	SetCancelConn(pset.db);
+
+	res = PQexec(pset.db, query);
+
+	ResetCancelConn();
+
+	if (!AcceptResult(res, true))
+	{
+		ClearOrSaveResult(res);
+		res = NULL;
+	}
+
+	return res;
+}
+
+
+/*
+ * PSQLexecWatch
+ *
+ * This function is used for \watch command to send the query to
+ * the server and print out the result.
+ *
+ * Returns 1 if the query executed successfully, 0 if it cannot be repeated,
+ * e.g., because of the interrupt, -1 on error.
+ */
+int
+PSQLexecWatch(const char *query, const printQueryOpt *opt, FILE *printQueryFout)
+{
+	bool		timing = pset.timing;
+	double		elapsed_msec = 0;
+	int			res;
+
+	if (!pset.db)
+	{
+		pg_log_error("You are currently not connected to a database.");
+		return 0;
+	}
+
+	SetCancelConn(pset.db);
+
+	res = ExecQueryAndProcessResults(query, &elapsed_msec, NULL, true, opt, printQueryFout);
+
+	ResetCancelConn();
+
+	/* Possible microtiming output */
+	if (timing)
+		PrintTiming(elapsed_msec);
+
+	return res;
+}
+
+
+/*
+ * PrintNotifications: check for asynchronous notifications, and print them out
+ */
+static void
+PrintNotifications(void)
+{
+	PGnotify   *notify;
+
+	PQconsumeInput(pset.db);
+	while ((notify = PQnotifies(pset.db)) != NULL)
+	{
+		/* for backward compatibility, only show payload if nonempty */
+		if (notify->extra[0])
+			fprintf(pset.queryFout, _("Asynchronous notification \"%s\" with payload \"%s\" received from server process with PID %d.\n"),
+					notify->relname, notify->extra, notify->be_pid);
+		else
+			fprintf(pset.queryFout, _("Asynchronous notification \"%s\" received from server process with PID %d.\n"),
+					notify->relname, notify->be_pid);
+		fflush(pset.queryFout);
+		PQfreemem(notify);
+		PQconsumeInput(pset.db);
+	}
+}
+
+
+/*
+ * PrintQueryTuples: assuming query result is OK, print its tuples
+ *
+ * We use the options given by opt unless that's NULL, in which case
+ * we use pset.popt.
+ *
+ * Output is to printQueryFout unless that's NULL, in which case
+ * we use pset.queryFout.
+ *
+ * Returns true if successful, false otherwise.
+ */
+static bool
+PrintQueryTuples(const PGresult *result, const printQueryOpt *opt,
+				 FILE *printQueryFout)
+{
+	bool		ok = true;
+	FILE	   *fout = printQueryFout ? printQueryFout : pset.queryFout;
+
+	printQuery(result, opt ? opt : &pset.popt, fout, false, pset.logfile);
+	fflush(fout);
+	if (ferror(fout))
+	{
+		pg_log_error("could not print result table: %m");
+		ok = false;
+	}
+
+	return ok;
+}
+
+
+/*
+ * StoreQueryTuple: assuming query result is OK, save data into variables
+ *
+ * Returns true if successful, false otherwise.
+ */
+static bool
+StoreQueryTuple(const PGresult *result)
+{
+	bool		success = true;
+
+	if (PQntuples(result) < 1)
+	{
+		pg_log_error("no rows returned for \\gset");
+		success = false;
+	}
+	else if (PQntuples(result) > 1)
+	{
+		pg_log_error("more than one row returned for \\gset");
+		success = false;
+	}
+	else
+	{
+		int			i;
+
+		for (i = 0; i < PQnfields(result); i++)
+		{
+			char	   *colname = PQfname(result, i);
+			char	   *varname;
+			char	   *value;
+
+			/* concatenate prefix and column name */
+			varname = psprintf("%s%s", pset.gset_prefix, colname);
+
+			if (VariableHasHook(pset.vars, varname))
+			{
+				pg_log_warning("attempt to \\gset into specially treated variable \"%s\" ignored",
+							   varname);
+				continue;
+			}
+
+			if (!PQgetisnull(result, 0, i))
+				value = PQgetvalue(result, 0, i);
+			else
+			{
+				/* for NULL value, unset rather than set the variable */
+				value = NULL;
+			}
+
+			if (!SetVariable(pset.vars, varname, value))
+			{
+				free(varname);
+				success = false;
+				break;
+			}
+
+			free(varname);
+		}
+	}
+
+	return success;
+}
+
+
+/*
+ * ExecQueryTuples: assuming query result is OK, execute each query
+ * result field as a SQL statement
+ *
+ * Returns true if successful, false otherwise.
+ */
+static bool
+ExecQueryTuples(const PGresult *result)
+{
+	bool		success = true;
+	int			nrows = PQntuples(result);
+	int			ncolumns = PQnfields(result);
+	int			r,
+				c;
+
+	/*
+	 * We must turn off gexec_flag to avoid infinite recursion.  Note that
+	 * this allows ExecQueryUsingCursor to be applied to the individual query
+	 * results.  SendQuery prevents it from being applied when fetching the
+	 * queries-to-execute, because it can't handle recursion either.
+	 */
+	pset.gexec_flag = false;
+
+	for (r = 0; r < nrows; r++)
+	{
+		for (c = 0; c < ncolumns; c++)
+		{
+			if (!PQgetisnull(result, r, c))
+			{
+				const char *query = PQgetvalue(result, r, c);
+
+				/* Abandon execution if cancel_pressed */
+				if (cancel_pressed)
+					goto loop_exit;
+
+				/*
+				 * ECHO_ALL mode should echo these queries, but SendQuery
+				 * assumes that MainLoop did that, so we have to do it here.
+				 */
+				if (pset.echo == PSQL_ECHO_ALL && !pset.singlestep)
+				{
+					puts(query);
+					fflush(stdout);
+				}
+
+				if (!SendQuery(query))
+				{
+					/* Error - abandon execution if ON_ERROR_STOP */
+					success = false;
+					if (pset.on_error_stop)
+						goto loop_exit;
+				}
+			}
+		}
+	}
+
+loop_exit:
+
+	/*
+	 * Restore state.  We know gexec_flag was on, else we'd not be here. (We
+	 * also know it'll get turned off at end of command, but that's not ours
+	 * to do here.)
+	 */
+	pset.gexec_flag = true;
+
+	/* Return true if all queries were successful */
+	return success;
+}
+
+
+/*
+ * Marshal the COPY data.  Either path will get the
+ * connection out of its COPY state, then call PQresultStatus()
+ * once and report any error.  Return whether all was ok.
+ *
+ * For COPY OUT, direct the output to copystream, or discard if that's NULL.
+ * For COPY IN, use pset.copyStream as data source if it's set,
+ * otherwise cur_cmd_source.
+ *
+ * Update *resultp if further processing is necessary; set to NULL otherwise.
+ * Return a result when queryFout can safely output a result status: on COPY
+ * IN, or on COPY OUT if written to something other than pset.queryFout.
+ * Returning NULL prevents the command status from being printed, which we
+ * want if the status line doesn't get taken as part of the COPY data.
+ */
+static bool
+HandleCopyResult(PGresult **resultp, FILE *copystream)
+{
+	bool		success;
+	PGresult   *copy_result;
+	ExecStatusType result_status = PQresultStatus(*resultp);
+
+	Assert(result_status == PGRES_COPY_OUT ||
+		   result_status == PGRES_COPY_IN);
+
+	SetCancelConn(pset.db);
+
+	if (result_status == PGRES_COPY_OUT)
+	{
+		success = handleCopyOut(pset.db,
+								copystream,
+								&copy_result)
+			&& (copystream != NULL);
+
+		/*
+		 * Suppress status printing if the report would go to the same place
+		 * as the COPY data just went.  Note this doesn't prevent error
+		 * reporting, since handleCopyOut did that.
+		 */
+		if (copystream == pset.queryFout)
+		{
+			PQclear(copy_result);
+			copy_result = NULL;
+		}
+	}
+	else
+	{
+		/* COPY IN */
+		/* Ignore the copystream argument passed to the function */
+		copystream = pset.copyStream ? pset.copyStream : pset.cur_cmd_source;
+		success = handleCopyIn(pset.db,
+							   copystream,
+							   PQbinaryTuples(*resultp),
+							   &copy_result);
+	}
+	ResetCancelConn();
+
+	/*
+	 * Replace the PGRES_COPY_OUT/IN result with COPY command's exit status,
+	 * or with NULL if we want to suppress printing anything.
+	 */
+	PQclear(*resultp);
+	*resultp = copy_result;
+
+	return success;
+}
+
+/*
+ * PrintQueryStatus: report command status as required
+ *
+ * Note: Utility function for use by PrintQueryResult() only.
+ */
+static void
+PrintQueryStatus(PGresult *result, FILE *printQueryFout)
+{
+	char		buf[16];
+	FILE	   *fout = printQueryFout ? printQueryFout : pset.queryFout;
+
+	if (!pset.quiet)
+	{
+		if (pset.popt.topt.format == PRINT_HTML)
+		{
+			fputs("<p>", fout);
+			html_escaped_print(PQcmdStatus(result), fout);
+			fputs("</p>\n", fout);
+		}
+		else
+			fprintf(fout, "%s\n", PQcmdStatus(result));
+		fflush(fout);
+	}
+
+	if (pset.logfile)
+		fprintf(pset.logfile, "%s\n", PQcmdStatus(result));
+
+	snprintf(buf, sizeof(buf), "%u", (unsigned int) PQoidValue(result));
+	SetVariable(pset.vars, "LASTOID", buf);
+}
+
+
+/*
+ * PrintQueryResult: print out (or store or execute) query result as required
+ *
+ * Note: Utility function for use by SendQuery() only.
+ *
+ * last is true if this is the last result of a command string.
+ * opt and printQueryFout are defined as for PrintQueryTuples.
+ * printStatusFout is where to send command status; NULL means pset.queryFout.
+ *
+ * Returns true if the query executed successfully, false otherwise.
+ */
+static bool
+PrintQueryResult(PGresult *result, bool last,
+				 const printQueryOpt *opt, FILE *printQueryFout,
+				 FILE *printStatusFout)
+{
+	bool		success;
+	const char *cmdstatus;
+
+	if (!result)
+		return false;
+
+	switch (PQresultStatus(result))
+	{
+		case PGRES_TUPLES_OK:
+			/* store or execute or print the data ... */
+			if (last && pset.gset_prefix)
+				success = StoreQueryTuple(result);
+			else if (last && pset.gexec_flag)
+				success = ExecQueryTuples(result);
+			else if (last && pset.crosstab_flag)
+				success = PrintResultInCrosstab(result);
+			else if (last || pset.show_all_results)
+				success = PrintQueryTuples(result, opt, printQueryFout);
+			else
+				success = true;
+
+			/* if it's INSERT/UPDATE/DELETE RETURNING, also print status */
+			if (last || pset.show_all_results)
+			{
+				cmdstatus = PQcmdStatus(result);
+				if (strncmp(cmdstatus, "INSERT", 6) == 0 ||
+					strncmp(cmdstatus, "UPDATE", 6) == 0 ||
+					strncmp(cmdstatus, "DELETE", 6) == 0)
+					PrintQueryStatus(result, printStatusFout);
+			}
+
+			break;
+
+		case PGRES_COMMAND_OK:
+			if (last || pset.show_all_results)
+				PrintQueryStatus(result, printStatusFout);
+			success = true;
+			break;
+
+		case PGRES_EMPTY_QUERY:
+			success = true;
+			break;
+
+		case PGRES_COPY_OUT:
+		case PGRES_COPY_IN:
+			/* nothing to do here: already processed */
+			success = true;
+			break;
+
+		case PGRES_BAD_RESPONSE:
+		case PGRES_NONFATAL_ERROR:
+		case PGRES_FATAL_ERROR:
+			success = false;
+			break;
+
+		default:
+			success = false;
+			pg_log_error("unexpected PQresultStatus: %d",
+						 PQresultStatus(result));
+			break;
+	}
+
+	return success;
+}
+
+/*
+ * SendQuery: send the query string to the backend
+ * (and print out result)
+ *
+ * Note: This is the "front door" way to send a query. That is, use it to
+ * send queries actually entered by the user. These queries will be subject to
+ * single step mode.
+ * To send "back door" queries (generated by slash commands, etc.) in a
+ * controlled way, use PSQLexec().
+ *
+ * Returns true if the query executed successfully, false otherwise.
+ */
+bool
+SendQuery(const char *query)
+{
+	bool		timing = pset.timing;
+	PGTransactionStatusType transaction_status;
+	double		elapsed_msec = 0;
+	bool		OK = false;
+	int			i;
+	bool		on_error_rollback_savepoint = false;
+	bool		svpt_gone = false;
+
+	if (!pset.db)
+	{
+		pg_log_error("You are currently not connected to a database.");
+		goto sendquery_cleanup;
+	}
+
+	if (pset.singlestep)
+	{
+		char		buf[3];
+
+		fflush(stderr);
+		printf(_("***(Single step mode: verify command)*******************************************\n"
+				 "%s\n"
+				 "***(press return to proceed or enter x and return to cancel)********************\n"),
+			   query);
+		fflush(stdout);
+		if (fgets(buf, sizeof(buf), stdin) != NULL)
+			if (buf[0] == 'x')
+				goto sendquery_cleanup;
+		if (cancel_pressed)
+			goto sendquery_cleanup;
+	}
+	else if (pset.echo == PSQL_ECHO_QUERIES)
+	{
+		puts(query);
+		fflush(stdout);
+	}
+
+	if (pset.logfile)
+	{
+		fprintf(pset.logfile,
+				_("********* QUERY **********\n"
+				  "%s\n"
+				  "**************************\n\n"), query);
+		fflush(pset.logfile);
+	}
+
+	SetCancelConn(pset.db);
+
+	transaction_status = PQtransactionStatus(pset.db);
+
+	if (transaction_status == PQTRANS_IDLE &&
+		!pset.autocommit &&
+		!command_no_begin(query))
+	{
+		PGresult   *result;
+
+		result = PQexec(pset.db, "BEGIN");
+		if (PQresultStatus(result) != PGRES_COMMAND_OK)
+		{
+			pg_log_info("%s", PQerrorMessage(pset.db));
+			ClearOrSaveResult(result);
+			goto sendquery_cleanup;
+		}
+		ClearOrSaveResult(result);
+		transaction_status = PQtransactionStatus(pset.db);
+	}
+
+	if (transaction_status == PQTRANS_INTRANS &&
+		pset.on_error_rollback != PSQL_ERROR_ROLLBACK_OFF &&
+		(pset.cur_cmd_interactive ||
+		 pset.on_error_rollback == PSQL_ERROR_ROLLBACK_ON))
+	{
+		PGresult   *result;
+
+		result = PQexec(pset.db, "SAVEPOINT pg_psql_temporary_savepoint");
+		if (PQresultStatus(result) != PGRES_COMMAND_OK)
+		{
+			pg_log_info("%s", PQerrorMessage(pset.db));
+			ClearOrSaveResult(result);
+			goto sendquery_cleanup;
+		}
+		ClearOrSaveResult(result);
+		on_error_rollback_savepoint = true;
+	}
+
+	if (pset.gdesc_flag)
+	{
+		/* Describe query's result columns, without executing it */
+		OK = DescribeQuery(query, &elapsed_msec);
+	}
+	else if (pset.fetch_count <= 0 || pset.gexec_flag ||
+			 pset.crosstab_flag || !is_select_command(query))
+	{
+		/* Default fetch-it-all-and-print mode */
+		OK = (ExecQueryAndProcessResults(query, &elapsed_msec, &svpt_gone, false, NULL, NULL) > 0);
+	}
+	else
+	{
+		/* Fetch-in-segments mode */
+		OK = ExecQueryUsingCursor(query, &elapsed_msec);
+	}
+
+	if (!OK && pset.echo == PSQL_ECHO_ERRORS)
+		pg_log_info("STATEMENT:  %s", query);
+
+	/* If we made a temporary savepoint, possibly release/rollback */
+	if (on_error_rollback_savepoint)
+	{
+		const char *svptcmd = NULL;
+
+		transaction_status = PQtransactionStatus(pset.db);
+
+		switch (transaction_status)
+		{
+			case PQTRANS_INERROR:
+				/* We always rollback on an error */
+				svptcmd = "ROLLBACK TO pg_psql_temporary_savepoint";
+				break;
+
+			case PQTRANS_IDLE:
+				/* If they are no longer in a transaction, then do nothing */
+				break;
+
+			case PQTRANS_INTRANS:
+
+				/*
+				 * Release our savepoint, but do nothing if they are messing
+				 * with savepoints themselves
+				 */
+				if (!svpt_gone)
+					svptcmd = "RELEASE pg_psql_temporary_savepoint";
+				break;
+
+			case PQTRANS_ACTIVE:
+			case PQTRANS_UNKNOWN:
+			default:
+				OK = false;
+				/* PQTRANS_UNKNOWN is expected given a broken connection. */
+				if (transaction_status != PQTRANS_UNKNOWN || ConnectionUp())
+					pg_log_error("unexpected transaction status (%d)",
+								 transaction_status);
+				break;
+		}
+
+		if (svptcmd)
+		{
+			PGresult   *svptres;
+
+			svptres = PQexec(pset.db, svptcmd);
+			if (PQresultStatus(svptres) != PGRES_COMMAND_OK)
+			{
+				pg_log_info("%s", PQerrorMessage(pset.db));
+				ClearOrSaveResult(svptres);
+				OK = false;
+
+				goto sendquery_cleanup;
+			}
+			PQclear(svptres);
+		}
+	}
+
+	/* Possible microtiming output */
+	if (timing)
+		PrintTiming(elapsed_msec);
+
+	/* check for events that may occur during query execution */
+
+	if (pset.encoding != PQclientEncoding(pset.db) &&
+		PQclientEncoding(pset.db) >= 0)
+	{
+		/* track effects of SET CLIENT_ENCODING */
+		pset.encoding = PQclientEncoding(pset.db);
+		pset.popt.topt.encoding = pset.encoding;
+		SetVariable(pset.vars, "ENCODING",
+					pg_encoding_to_char(pset.encoding));
+	}
+
+	PrintNotifications();
+
+	/* perform cleanup that should occur after any attempted query */
+
+sendquery_cleanup:
+
+	/* global cancellation reset */
+	ResetCancelConn();
+
+	/* reset \g's output-to-filename trigger */
+	if (pset.gfname)
+	{
+		free(pset.gfname);
+		pset.gfname = NULL;
+	}
+
+	/* restore print settings if \g changed them */
+	if (pset.gsavepopt)
+	{
+		restorePsetInfo(&pset.popt, pset.gsavepopt);
+		pset.gsavepopt = NULL;
+	}
+
+	/* reset \gset trigger */
+	if (pset.gset_prefix)
+	{
+		free(pset.gset_prefix);
+		pset.gset_prefix = NULL;
+	}
+
+	/* reset \gdesc trigger */
+	pset.gdesc_flag = false;
+
+	/* reset \gexec trigger */
+	pset.gexec_flag = false;
+
+	/* reset \crosstabview trigger */
+	pset.crosstab_flag = false;
+	for (i = 0; i < lengthof(pset.ctv_args); i++)
+	{
+		pg_free(pset.ctv_args[i]);
+		pset.ctv_args[i] = NULL;
+	}
+
+	return OK;
+}
+
+
+/*
+ * DescribeQuery: describe the result columns of a query, without executing it
+ *
+ * Returns true if the operation executed successfully, false otherwise.
+ *
+ * If pset.timing is on, total query time (exclusive of result-printing) is
+ * stored into *elapsed_msec.
+ */
+static bool
+DescribeQuery(const char *query, double *elapsed_msec)
+{
+	bool		timing = pset.timing;
+	PGresult   *result;
+	bool		OK;
+	instr_time	before,
+				after;
+
+	*elapsed_msec = 0;
+
+	if (timing)
+		INSTR_TIME_SET_CURRENT(before);
+
+	/*
+	 * To parse the query but not execute it, we prepare it, using the unnamed
+	 * prepared statement.  This is invisible to psql users, since there's no
+	 * way to access the unnamed prepared statement from psql user space. The
+	 * next Parse or Query protocol message would overwrite the statement
+	 * anyway.  (So there's no great need to clear it when done, which is a
+	 * good thing because libpq provides no easy way to do that.)
+	 */
+	result = PQprepare(pset.db, "", query, 0, NULL);
+	if (PQresultStatus(result) != PGRES_COMMAND_OK)
+	{
+		pg_log_info("%s", PQerrorMessage(pset.db));
+		SetResultVariables(result, false);
+		ClearOrSaveResult(result);
+		return false;
+	}
+	PQclear(result);
+
+	result = PQdescribePrepared(pset.db, "");
+	OK = AcceptResult(result, true) &&
+		(PQresultStatus(result) == PGRES_COMMAND_OK);
+	if (OK && result)
+	{
+		if (PQnfields(result) > 0)
+		{
+			PQExpBufferData buf;
+			int			i;
+
+			initPQExpBuffer(&buf);
+
+			printfPQExpBuffer(&buf,
+							  "SELECT name AS \"%s\", pg_catalog.format_type(tp, tpm) AS \"%s\"\n"
+							  "FROM (VALUES ",
+							  gettext_noop("Column"),
+							  gettext_noop("Type"));
+
+			for (i = 0; i < PQnfields(result); i++)
+			{
+				const char *name;
+				char	   *escname;
+
+				if (i > 0)
+					appendPQExpBufferStr(&buf, ",");
+
+				name = PQfname(result, i);
+				escname = PQescapeLiteral(pset.db, name, strlen(name));
+
+				if (escname == NULL)
+				{
+					pg_log_info("%s", PQerrorMessage(pset.db));
+					PQclear(result);
+					termPQExpBuffer(&buf);
+					return false;
+				}
+
+				appendPQExpBuffer(&buf, "(%s, '%u'::pg_catalog.oid, %d)",
+								  escname,
+								  PQftype(result, i),
+								  PQfmod(result, i));
+
+				PQfreemem(escname);
+			}
+
+			appendPQExpBufferStr(&buf, ") s(name, tp, tpm)");
+			PQclear(result);
+
+			result = PQexec(pset.db, buf.data);
+			OK = AcceptResult(result, true);
+
+			if (timing)
+			{
+				INSTR_TIME_SET_CURRENT(after);
+				INSTR_TIME_SUBTRACT(after, before);
+				*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
+			}
+
+			if (OK && result)
+				OK = PrintQueryResult(result, true, NULL, NULL, NULL);
+
+			termPQExpBuffer(&buf);
+		}
+		else
+			fprintf(pset.queryFout,
+					_("The command has no result, or the result has no columns.\n"));
+	}
+
+	SetResultVariables(result, OK);
+	ClearOrSaveResult(result);
+
+	return OK;
+}
+
+
+/*
+ * ExecQueryAndProcessResults: utility function for use by SendQuery()
+ * and PSQLexecWatch().
+ *
+ * Sends query and cycles through PGresult objects.
+ *
+ * If our command string contained a COPY FROM STDIN or COPY TO STDOUT, the
+ * PGresult associated with these commands must be processed by providing an
+ * input or output stream.  In that event, we'll marshal data for the COPY.
+ *
+ * For other commands, the results are processed normally, depending on their
+ * status.
+ *
+ * Returns 1 on complete success, 0 on interrupt and -1 or errors.  Possible
+ * failure modes include purely client-side problems; check the transaction
+ * status for the server-side opinion.
+ *
+ * Note that on a combined query, failure does not mean that nothing was
+ * committed.
+ */
+static int
+ExecQueryAndProcessResults(const char *query,
+						   double *elapsed_msec, bool *svpt_gone_p,
+						   bool is_watch,
+						   const printQueryOpt *opt, FILE *printQueryFout)
+{
+	bool		timing = pset.timing;
+	bool		success;
+	instr_time	before,
+				after;
+	PGresult   *result;
+	FILE	   *gfile_fout = NULL;
+	bool		gfile_is_pipe = false;
+
+	if (timing)
+		INSTR_TIME_SET_CURRENT(before);
+
+	success = PQsendQuery(pset.db, query);
+
+	if (!success)
+	{
+		const char *error = PQerrorMessage(pset.db);
+
+		if (strlen(error))
+			pg_log_info("%s", error);
+
+		CheckConnection();
+
+		return -1;
+	}
+
+	/*
+	 * If SIGINT is sent while the query is processing, the interrupt will be
+	 * consumed.  The user's intention, though, is to cancel the entire watch
+	 * process, so detect a sent cancellation request and exit in this case.
+	 */
+	if (is_watch && cancel_pressed)
+	{
+		ClearOrSaveAllResults();
+		return 0;
+	}
+
+	/* first result */
+	result = PQgetResult(pset.db);
+
+	while (result != NULL)
+	{
+		ExecStatusType result_status;
+		PGresult   *next_result;
+		bool		last;
+
+		if (!AcceptResult(result, false))
+		{
+			/*
+			 * Some error occured, either a server-side failure or a failure
+			 * to submit the command string.  Record that.
+			 */
+			const char *error = PQresultErrorMessage(result);
+
+			if (strlen(error))
+				pg_log_info("%s", error);
+
+			CheckConnection();
+			if (!is_watch)
+				SetResultVariables(result, false);
+
+			/* keep the result status before clearing it */
+			result_status = PQresultStatus(result);
+			ClearOrSaveResult(result);
+			success = false;
+
+			/*
+			 * switch to next result
+			 */
+			if (result_status == PGRES_COPY_BOTH ||
+				result_status == PGRES_COPY_OUT ||
+				result_status == PGRES_COPY_IN)
+
+				/*
+				 * For some obscure reason PQgetResult does *not* return a
+				 * NULL in copy cases despite the result having been cleared,
+				 * but keeps returning an "empty" result that we have to
+				 * ignore manually.
+				 */
+				result = NULL;
+			else
+				result = PQgetResult(pset.db);
+
+			/*
+			 * Get current timing measure in case an error occurs
+			 */
+			if (timing)
+			{
+				INSTR_TIME_SET_CURRENT(after);
+				INSTR_TIME_SUBTRACT(after, before);
+				*elapsed_msec = INSTR_TIME_GET_MILLISEC(after);
+			}
+
+			continue;
+		}
+		else if (svpt_gone_p && !*svpt_gone_p)
+		{
+			/*
+			 * Check if the user ran any command that would destroy our
+			 * internal savepoint: If the user did COMMIT AND CHAIN, RELEASE
+			 * or ROLLBACK, our savepoint is gone. If they issued a SAVEPOINT,
+			 * releasing ours would remove theirs.
+			 */
+			const char *cmd = PQcmdStatus(result);
+
+			*svpt_gone_p = (strcmp(cmd, "COMMIT") == 0 ||
+							strcmp(cmd, "SAVEPOINT") == 0 ||
+							strcmp(cmd, "RELEASE") == 0 ||
+							strcmp(cmd, "ROLLBACK") == 0);
+		}
+
+		result_status = PQresultStatus(result);
+
+		/* must handle COPY before changing the current result */
+		Assert(result_status != PGRES_COPY_BOTH);
+		if (result_status == PGRES_COPY_IN ||
+			result_status == PGRES_COPY_OUT)
+		{
+			FILE	   *copy_stream = NULL;
+
+			/*
+			 * For COPY OUT, direct the output to the default place (probably
+			 * a pager pipe) for \watch, or to pset.copyStream for \copy,
+			 * otherwise to pset.gfname if that's set, otherwise to
+			 * pset.queryFout.
+			 */
+			if (result_status == PGRES_COPY_OUT)
+			{
+				if (is_watch)
+				{
+					/* invoked by \watch */
+					copy_stream = printQueryFout ? printQueryFout : pset.queryFout;
+				}
+				else if (pset.copyStream)
+				{
+					/* invoked by \copy */
+					copy_stream = pset.copyStream;
+				}
+				else if (pset.gfname)
+				{
+					/* send to \g file, which we may have opened already */
+					if (gfile_fout == NULL)
+					{
+						if (openQueryOutputFile(pset.gfname,
+												&gfile_fout, &gfile_is_pipe))
+						{
+							if (gfile_is_pipe)
+								disable_sigpipe_trap();
+							copy_stream = gfile_fout;
+						}
+						else
+							success = false;
+					}
+					else
+						copy_stream = gfile_fout;
+				}
+				else
+				{
+					/* fall back to the generic query output stream */
+					copy_stream = pset.queryFout;
+				}
+			}
+
+			/*
+			 * Even if the output stream could not be opened, we call
+			 * HandleCopyResult() with a NULL output stream to collect and
+			 * discard the COPY data.
+			 */
+			success &= HandleCopyResult(&result, copy_stream);
+		}
+
+		/*
+		 * Check PQgetResult() again.  In the typical case of a single-command
+		 * string, it will return NULL.  Otherwise, we'll have other results
+		 * to process.  We need to do that to check whether this is the last.
+		 */
+		next_result = PQgetResult(pset.db);
+		last = (next_result == NULL);
+
+		/*
+		 * Update current timing measure.
+		 *
+		 * It will include the display of previous results, if any. This
+		 * cannot be helped because the server goes on processing further
+		 * queries anyway while the previous ones are being displayed. The
+		 * parallel execution of the client display hides the server time when
+		 * it is shorter.
+		 *
+		 * With combined queries, timing must be understood as an upper bound
+		 * of the time spent processing them.
+		 */
+		if (timing)
+		{
+			INSTR_TIME_SET_CURRENT(after);
+			INSTR_TIME_SUBTRACT(after, before);
+			*elapsed_msec = INSTR_TIME_GET_MILLISEC(after);
+		}
+
+		/* this may or may not print something depending on settings */
+		if (result != NULL)
+		{
+			/*
+			 * If results need to be printed into the file specified by \g,
+			 * open it, unless we already did.  Note that when pset.gfname is
+			 * set, the passed-in value of printQueryFout is not used for
+			 * tuple output, but it's still used for status output.
+			 */
+			FILE	   *tuples_fout = printQueryFout;
+			bool		do_print = true;
+
+			if (PQresultStatus(result) == PGRES_TUPLES_OK &&
+				pset.gfname)
+			{
+				if (gfile_fout == NULL)
+				{
+					if (openQueryOutputFile(pset.gfname,
+											&gfile_fout, &gfile_is_pipe))
+					{
+						if (gfile_is_pipe)
+							disable_sigpipe_trap();
+					}
+					else
+						success = do_print = false;
+				}
+				tuples_fout = gfile_fout;
+			}
+			if (do_print)
+				success &= PrintQueryResult(result, last, opt,
+											tuples_fout, printQueryFout);
+		}
+
+		/* set variables on last result if all went well */
+		if (!is_watch && last && success)
+			SetResultVariables(result, true);
+
+		ClearOrSaveResult(result);
+		result = next_result;
+
+		if (cancel_pressed)
+		{
+			ClearOrSaveAllResults();
+			break;
+		}
+	}
+
+	/* close \g file if we opened it */
+	if (gfile_fout)
+	{
+		if (gfile_is_pipe)
+		{
+			pclose(gfile_fout);
+			restore_sigpipe_trap();
+		}
+		else
+			fclose(gfile_fout);
+	}
+
+	/* may need this to recover from conn loss during COPY */
+	if (!CheckConnection())
+		return -1;
+
+	return cancel_pressed ? 0 : success ? 1 : -1;
+}
+
+
+/*
+ * ExecQueryUsingCursor: run a SELECT-like query using a cursor
+ *
+ * This feature allows result sets larger than RAM to be dealt with.
+ *
+ * Returns true if the query executed successfully, false otherwise.
+ *
+ * If pset.timing is on, total query time (exclusive of result-printing) is
+ * stored into *elapsed_msec.
+ */
+static bool
+ExecQueryUsingCursor(const char *query, double *elapsed_msec)
+{
+	bool		OK = true;
+	PGresult   *result;
+	PQExpBufferData buf;
+	printQueryOpt my_popt = pset.popt;
+	bool		timing = pset.timing;
+	FILE	   *fout;
+	bool		is_pipe;
+	bool		is_pager = false;
+	bool		started_txn = false;
+	int64		total_tuples = 0;
+	int			ntuples;
+	int			fetch_count;
+	char		fetch_cmd[64];
+	instr_time	before,
+				after;
+	int			flush_error;
+
+	*elapsed_msec = 0;
+
+	/* initialize print options for partial table output */
+	my_popt.topt.start_table = true;
+	my_popt.topt.stop_table = false;
+	my_popt.topt.prior_records = 0;
+
+	if (timing)
+		INSTR_TIME_SET_CURRENT(before);
+
+	/* if we're not in a transaction, start one */
+	if (PQtransactionStatus(pset.db) == PQTRANS_IDLE)
+	{
+		result = PQexec(pset.db, "BEGIN");
+		OK = AcceptResult(result, true) &&
+			(PQresultStatus(result) == PGRES_COMMAND_OK);
+		ClearOrSaveResult(result);
+		if (!OK)
+			return false;
+		started_txn = true;
+	}
+
+	/* Send DECLARE CURSOR */
+	initPQExpBuffer(&buf);
+	appendPQExpBuffer(&buf, "DECLARE _psql_cursor NO SCROLL CURSOR FOR\n%s",
+					  query);
+
+	result = PQexec(pset.db, buf.data);
+	OK = AcceptResult(result, true) &&
+		(PQresultStatus(result) == PGRES_COMMAND_OK);
+	if (!OK)
+		SetResultVariables(result, OK);
+	ClearOrSaveResult(result);
+	termPQExpBuffer(&buf);
+	if (!OK)
+		goto cleanup;
+
+	if (timing)
+	{
+		INSTR_TIME_SET_CURRENT(after);
+		INSTR_TIME_SUBTRACT(after, before);
+		*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
+	}
+
+	/*
+	 * In \gset mode, we force the fetch count to be 2, so that we will throw
+	 * the appropriate error if the query returns more than one row.
+	 */
+	if (pset.gset_prefix)
+		fetch_count = 2;
+	else
+		fetch_count = pset.fetch_count;
+
+	snprintf(fetch_cmd, sizeof(fetch_cmd),
+			 "FETCH FORWARD %d FROM _psql_cursor",
+			 fetch_count);
+
+	/* prepare to write output to \g argument, if any */
+	if (pset.gfname)
+	{
+		if (!openQueryOutputFile(pset.gfname, &fout, &is_pipe))
+		{
+			OK = false;
+			goto cleanup;
+		}
+		if (is_pipe)
+			disable_sigpipe_trap();
+	}
+	else
+	{
+		fout = pset.queryFout;
+		is_pipe = false;		/* doesn't matter */
+	}
+
+	/* clear any pre-existing error indication on the output stream */
+	clearerr(fout);
+
+	for (;;)
+	{
+		if (timing)
+			INSTR_TIME_SET_CURRENT(before);
+
+		/* get fetch_count tuples at a time */
+		result = PQexec(pset.db, fetch_cmd);
+
+		if (timing)
+		{
+			INSTR_TIME_SET_CURRENT(after);
+			INSTR_TIME_SUBTRACT(after, before);
+			*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
+		}
+
+		if (PQresultStatus(result) != PGRES_TUPLES_OK)
+		{
+			/* shut down pager before printing error message */
+			if (is_pager)
+			{
+				ClosePager(fout);
+				is_pager = false;
+			}
+
+			OK = AcceptResult(result, true);
+			Assert(!OK);
+			SetResultVariables(result, OK);
+			ClearOrSaveResult(result);
+			break;
+		}
+
+		if (pset.gset_prefix)
+		{
+			/* StoreQueryTuple will complain if not exactly one row */
+			OK = StoreQueryTuple(result);
+			ClearOrSaveResult(result);
+			break;
+		}
+
+		/*
+		 * Note we do not deal with \gdesc, \gexec or \crosstabview modes here
+		 */
+
+		ntuples = PQntuples(result);
+		total_tuples += ntuples;
+
+		if (ntuples < fetch_count)
+		{
+			/* this is the last result set, so allow footer decoration */
+			my_popt.topt.stop_table = true;
+		}
+		else if (fout == stdout && !is_pager)
+		{
+			/*
+			 * If query requires multiple result sets, hack to ensure that
+			 * only one pager instance is used for the whole mess
+			 */
+			fout = PageOutput(INT_MAX, &(my_popt.topt));
+			is_pager = true;
+		}
+
+		printQuery(result, &my_popt, fout, is_pager, pset.logfile);
+
+		ClearOrSaveResult(result);
+
+		/* after the first result set, disallow header decoration */
+		my_popt.topt.start_table = false;
+		my_popt.topt.prior_records += ntuples;
+
+		/*
+		 * Make sure to flush the output stream, so intermediate results are
+		 * visible to the client immediately.  We check the results because if
+		 * the pager dies/exits/etc, there's no sense throwing more data at
+		 * it.
+		 */
+		flush_error = fflush(fout);
+
+		/*
+		 * Check if we are at the end, if a cancel was pressed, or if there
+		 * were any errors either trying to flush out the results, or more
+		 * generally on the output stream at all.  If we hit any errors
+		 * writing things to the stream, we presume $PAGER has disappeared and
+		 * stop bothering to pull down more data.
+		 */
+		if (ntuples < fetch_count || cancel_pressed || flush_error ||
+			ferror(fout))
+			break;
+	}
+
+	if (pset.gfname)
+	{
+		/* close \g argument file/pipe */
+		if (is_pipe)
+		{
+			pclose(fout);
+			restore_sigpipe_trap();
+		}
+		else
+			fclose(fout);
+	}
+	else if (is_pager)
+	{
+		/* close transient pager */
+		ClosePager(fout);
+	}
+
+	if (OK)
+	{
+		/*
+		 * We don't have a PGresult here, and even if we did it wouldn't have
+		 * the right row count, so fake SetResultVariables().  In error cases,
+		 * we already set the result variables above.
+		 */
+		char		buf[32];
+
+		SetVariable(pset.vars, "ERROR", "false");
+		SetVariable(pset.vars, "SQLSTATE", "00000");
+		snprintf(buf, sizeof(buf), INT64_FORMAT, total_tuples);
+		SetVariable(pset.vars, "ROW_COUNT", buf);
+	}
+
+cleanup:
+	if (timing)
+		INSTR_TIME_SET_CURRENT(before);
+
+	/*
+	 * We try to close the cursor on either success or failure, but on failure
+	 * ignore the result (it's probably just a bleat about being in an aborted
+	 * transaction)
+	 */
+	result = PQexec(pset.db, "CLOSE _psql_cursor");
+	if (OK)
+	{
+		OK = AcceptResult(result, true) &&
+			(PQresultStatus(result) == PGRES_COMMAND_OK);
+		ClearOrSaveResult(result);
+	}
+	else
+		PQclear(result);
+
+	if (started_txn)
+	{
+		result = PQexec(pset.db, OK ? "COMMIT" : "ROLLBACK");
+		OK &= AcceptResult(result, true) &&
+			(PQresultStatus(result) == PGRES_COMMAND_OK);
+		ClearOrSaveResult(result);
+	}
+
+	if (timing)
+	{
+		INSTR_TIME_SET_CURRENT(after);
+		INSTR_TIME_SUBTRACT(after, before);
+		*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
+	}
+
+	return OK;
+}
+
+
+/*
+ * Advance the given char pointer over white space and SQL comments.
+ */
+static const char *
+skip_white_space(const char *query)
+{
+	int			cnestlevel = 0; /* slash-star comment nest level */
+
+	while (*query)
+	{
+		int			mblen = PQmblenBounded(query, pset.encoding);
+
+		/*
+		 * Note: we assume the encoding is a superset of ASCII, so that for
+		 * example "query[0] == '/'" is meaningful.  However, we do NOT assume
+		 * that the second and subsequent bytes of a multibyte character
+		 * couldn't look like ASCII characters; so it is critical to advance
+		 * by mblen, not 1, whenever we haven't exactly identified the
+		 * character we are skipping over.
+		 */
+		if (isspace((unsigned char) *query))
+			query += mblen;
+		else if (query[0] == '/' && query[1] == '*')
+		{
+			cnestlevel++;
+			query += 2;
+		}
+		else if (cnestlevel > 0 && query[0] == '*' && query[1] == '/')
+		{
+			cnestlevel--;
+			query += 2;
+		}
+		else if (cnestlevel == 0 && query[0] == '-' && query[1] == '-')
+		{
+			query += 2;
+
+			/*
+			 * We have to skip to end of line since any slash-star inside the
+			 * -- comment does NOT start a slash-star comment.
+			 */
+			while (*query)
+			{
+				if (*query == '\n')
+				{
+					query++;
+					break;
+				}
+				query += PQmblenBounded(query, pset.encoding);
+			}
+		}
+		else if (cnestlevel > 0)
+			query += mblen;
+		else
+			break;				/* found first token */
+	}
+
+	return query;
+}
+
+
+/*
+ * Check whether a command is one of those for which we should NOT start
+ * a new transaction block (ie, send a preceding BEGIN).
+ *
+ * These include the transaction control statements themselves, plus
+ * certain statements that the backend disallows inside transaction blocks.
+ */
+static bool
+command_no_begin(const char *query)
+{
+	int			wordlen;
+
+	/*
+	 * First we must advance over any whitespace and comments.
+	 */
+	query = skip_white_space(query);
+
+	/*
+	 * Check word length (since "beginx" is not "begin").
+	 */
+	wordlen = 0;
+	while (isalpha((unsigned char) query[wordlen]))
+		wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+	/*
+	 * Transaction control commands.  These should include every keyword that
+	 * gives rise to a TransactionStmt in the backend grammar, except for the
+	 * savepoint-related commands.
+	 *
+	 * (We assume that START must be START TRANSACTION, since there is
+	 * presently no other "START foo" command.)
+	 */
+	if (wordlen == 5 && pg_strncasecmp(query, "abort", 5) == 0)
+		return true;
+	if (wordlen == 5 && pg_strncasecmp(query, "begin", 5) == 0)
+		return true;
+	if (wordlen == 5 && pg_strncasecmp(query, "start", 5) == 0)
+		return true;
+	if (wordlen == 6 && pg_strncasecmp(query, "commit", 6) == 0)
+		return true;
+	if (wordlen == 3 && pg_strncasecmp(query, "end", 3) == 0)
+		return true;
+	if (wordlen == 8 && pg_strncasecmp(query, "rollback", 8) == 0)
+		return true;
+	if (wordlen == 7 && pg_strncasecmp(query, "prepare", 7) == 0)
+	{
+		/* PREPARE TRANSACTION is a TC command, PREPARE foo is not */
+		query += wordlen;
+
+		query = skip_white_space(query);
+
+		wordlen = 0;
+		while (isalpha((unsigned char) query[wordlen]))
+			wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+		if (wordlen == 11 && pg_strncasecmp(query, "transaction", 11) == 0)
+			return true;
+		return false;
+	}
+
+	/*
+	 * Commands not allowed within transactions.  The statements checked for
+	 * here should be exactly those that call PreventInTransactionBlock() in
+	 * the backend.
+	 */
+	if (wordlen == 6 && pg_strncasecmp(query, "vacuum", 6) == 0)
+		return true;
+	if (wordlen == 7 && pg_strncasecmp(query, "cluster", 7) == 0)
+	{
+		/* CLUSTER with any arguments is allowed in transactions */
+		query += wordlen;
+
+		query = skip_white_space(query);
+
+		if (isalpha((unsigned char) query[0]))
+			return false;		/* has additional words */
+		return true;			/* it's CLUSTER without arguments */
+	}
+
+	if (wordlen == 6 && pg_strncasecmp(query, "create", 6) == 0)
+	{
+		query += wordlen;
+
+		query = skip_white_space(query);
+
+		wordlen = 0;
+		while (isalpha((unsigned char) query[wordlen]))
+			wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+		if (wordlen == 8 && pg_strncasecmp(query, "database", 8) == 0)
+			return true;
+		if (wordlen == 10 && pg_strncasecmp(query, "tablespace", 10) == 0)
+			return true;
+
+		/* CREATE [UNIQUE] INDEX CONCURRENTLY isn't allowed in xacts */
+		if (wordlen == 6 && pg_strncasecmp(query, "unique", 6) == 0)
+		{
+			query += wordlen;
+
+			query = skip_white_space(query);
+
+			wordlen = 0;
+			while (isalpha((unsigned char) query[wordlen]))
+				wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+		}
+
+		if (wordlen == 5 && pg_strncasecmp(query, "index", 5) == 0)
+		{
+			query += wordlen;
+
+			query = skip_white_space(query);
+
+			wordlen = 0;
+			while (isalpha((unsigned char) query[wordlen]))
+				wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+			if (wordlen == 12 && pg_strncasecmp(query, "concurrently", 12) == 0)
+				return true;
+		}
+
+		return false;
+	}
+
+	if (wordlen == 5 && pg_strncasecmp(query, "alter", 5) == 0)
+	{
+		query += wordlen;
+
+		query = skip_white_space(query);
+
+		wordlen = 0;
+		while (isalpha((unsigned char) query[wordlen]))
+			wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+		/* ALTER SYSTEM isn't allowed in xacts */
+		if (wordlen == 6 && pg_strncasecmp(query, "system", 6) == 0)
+			return true;
+
+		return false;
+	}
+
+	/*
+	 * Note: these tests will match DROP SYSTEM and REINDEX TABLESPACE, which
+	 * aren't really valid commands so we don't care much. The other four
+	 * possible matches are correct.
+	 */
+	if ((wordlen == 4 && pg_strncasecmp(query, "drop", 4) == 0) ||
+		(wordlen == 7 && pg_strncasecmp(query, "reindex", 7) == 0))
+	{
+		query += wordlen;
+
+		query = skip_white_space(query);
+
+		wordlen = 0;
+		while (isalpha((unsigned char) query[wordlen]))
+			wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+		if (wordlen == 8 && pg_strncasecmp(query, "database", 8) == 0)
+			return true;
+		if (wordlen == 6 && pg_strncasecmp(query, "system", 6) == 0)
+			return true;
+		if (wordlen == 10 && pg_strncasecmp(query, "tablespace", 10) == 0)
+			return true;
+		if (wordlen == 5 && (pg_strncasecmp(query, "index", 5) == 0 ||
+							 pg_strncasecmp(query, "table", 5) == 0))
+		{
+			query += wordlen;
+			query = skip_white_space(query);
+			wordlen = 0;
+			while (isalpha((unsigned char) query[wordlen]))
+				wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+			/*
+			 * REINDEX [ TABLE | INDEX ] CONCURRENTLY are not allowed in
+			 * xacts.
+			 */
+			if (wordlen == 12 && pg_strncasecmp(query, "concurrently", 12) == 0)
+				return true;
+		}
+
+		/* DROP INDEX CONCURRENTLY isn't allowed in xacts */
+		if (wordlen == 5 && pg_strncasecmp(query, "index", 5) == 0)
+		{
+			query += wordlen;
+
+			query = skip_white_space(query);
+
+			wordlen = 0;
+			while (isalpha((unsigned char) query[wordlen]))
+				wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+			if (wordlen == 12 && pg_strncasecmp(query, "concurrently", 12) == 0)
+				return true;
+
+			return false;
+		}
+
+		return false;
+	}
+
+	/* DISCARD ALL isn't allowed in xacts, but other variants are allowed. */
+	if (wordlen == 7 && pg_strncasecmp(query, "discard", 7) == 0)
+	{
+		query += wordlen;
+
+		query = skip_white_space(query);
+
+		wordlen = 0;
+		while (isalpha((unsigned char) query[wordlen]))
+			wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+		if (wordlen == 3 && pg_strncasecmp(query, "all", 3) == 0)
+			return true;
+		return false;
+	}
+
+	return false;
+}
+
+
+/*
+ * Check whether the specified command is a SELECT (or VALUES).
+ */
+static bool
+is_select_command(const char *query)
+{
+	int			wordlen;
+
+	/*
+	 * First advance over any whitespace, comments and left parentheses.
+	 */
+	for (;;)
+	{
+		query = skip_white_space(query);
+		if (query[0] == '(')
+			query++;
+		else
+			break;
+	}
+
+	/*
+	 * Check word length (since "selectx" is not "select").
+	 */
+	wordlen = 0;
+	while (isalpha((unsigned char) query[wordlen]))
+		wordlen += PQmblenBounded(&query[wordlen], pset.encoding);
+
+	if (wordlen == 6 && pg_strncasecmp(query, "select", 6) == 0)
+		return true;
+
+	if (wordlen == 6 && pg_strncasecmp(query, "values", 6) == 0)
+		return true;
+
+	return false;
+}
+
+
+/*
+ * Test if the current user is a database superuser.
+ */
+bool
+is_superuser(void)
+{
+	const char *val;
+
+	if (!pset.db)
+		return false;
+
+	val = PQparameterStatus(pset.db, "is_superuser");
+
+	if (val && strcmp(val, "on") == 0)
+		return true;
+
+	return false;
+}
+
+
+/*
+ * Test if the current session uses standard string literals.
+ */
+bool
+standard_strings(void)
+{
+	const char *val;
+
+	if (!pset.db)
+		return false;
+
+	val = PQparameterStatus(pset.db, "standard_conforming_strings");
+
+	if (val && strcmp(val, "on") == 0)
+		return true;
+
+	return false;
+}
+
+
+/*
+ * Return the session user of the current connection.
+ */
+const char *
+session_username(void)
+{
+	const char *val;
+
+	if (!pset.db)
+		return NULL;
+
+	val = PQparameterStatus(pset.db, "session_authorization");
+	if (val)
+		return val;
+	else
+		return PQuser(pset.db);
+}
+
+
+/* expand_tilde
+ *
+ * substitute '~' with HOME or '~username' with username's home dir
+ *
+ */
+void
+expand_tilde(char **filename)
+{
+	if (!filename || !(*filename))
+		return;
+
+	/*
+	 * WIN32 doesn't use tilde expansion for file names. Also, it uses tilde
+	 * for short versions of long file names, though the tilde is usually
+	 * toward the end, not at the beginning.
+	 */
+#ifndef WIN32
+
+	/* try tilde expansion */
+	if (**filename == '~')
+	{
+		char	   *fn;
+		char		oldp,
+				   *p;
+		struct passwd *pw;
+		char		home[MAXPGPATH];
+
+		fn = *filename;
+		*home = '\0';
+
+		p = fn + 1;
+		while (*p != '/' && *p != '\0')
+			p++;
+
+		oldp = *p;
+		*p = '\0';
+
+		if (*(fn + 1) == '\0')
+			get_home_path(home);	/* ~ or ~/ only */
+		else if ((pw = getpwnam(fn + 1)) != NULL)
+			strlcpy(home, pw->pw_dir, sizeof(home));	/* ~user */
+
+		*p = oldp;
+		if (strlen(home) != 0)
+		{
+			char	   *newfn;
+
+			newfn = psprintf("%s%s", home, p);
+			free(fn);
+			*filename = newfn;
+		}
+	}
+#endif
+}
+
+/*
+ * Checks if connection string starts with either of the valid URI prefix
+ * designators.
+ *
+ * Returns the URI prefix length, 0 if the string doesn't contain a URI prefix.
+ *
+ * XXX This is a duplicate of the eponymous libpq function.
+ */
+static int
+uri_prefix_length(const char *connstr)
+{
+	/* The connection URI must start with either of the following designators: */
+	static const char uri_designator[] = "postgresql://";
+	static const char short_uri_designator[] = "postgres://";
+
+	if (strncmp(connstr, uri_designator,
+				sizeof(uri_designator) - 1) == 0)
+		return sizeof(uri_designator) - 1;
+
+	if (strncmp(connstr, short_uri_designator,
+				sizeof(short_uri_designator) - 1) == 0)
+		return sizeof(short_uri_designator) - 1;
+
+	return 0;
+}
+
+/*
+ * Recognized connection string either starts with a valid URI prefix or
+ * contains a "=" in it.
+ *
+ * Must be consistent with parse_connection_string: anything for which this
+ * returns true should at least look like it's parseable by that routine.
+ *
+ * XXX This is a duplicate of the eponymous libpq function.
+ */
+bool
+recognized_connection_string(const char *connstr)
+{
+	return uri_prefix_length(connstr) != 0 || strchr(connstr, '=') != NULL;
+}