Adding upstream version 15.4.upstream/15.4upstream

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

1 files changed, 4480 insertions, 0 deletions

diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
new file mode 100644
index 0000000..8989f71
--- /dev/null
+++ b/src/interfaces/libpq/fe-exec.c
@@ -0,0 +1,4480 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe-exec.c
+ *	  functions related to sending a query down to the backend
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/interfaces/libpq/fe-exec.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres_fe.h"
+
+#include <ctype.h>
+#include <fcntl.h>
+#include <limits.h>
+
+#ifdef WIN32
+#include "win32.h"
+#else
+#include <unistd.h>
+#endif
+
+#include "libpq-fe.h"
+#include "libpq-int.h"
+#include "mb/pg_wchar.h"
+
+/* keep this in same order as ExecStatusType in libpq-fe.h */
+char	   *const pgresStatus[] = {
+	"PGRES_EMPTY_QUERY",
+	"PGRES_COMMAND_OK",
+	"PGRES_TUPLES_OK",
+	"PGRES_COPY_OUT",
+	"PGRES_COPY_IN",
+	"PGRES_BAD_RESPONSE",
+	"PGRES_NONFATAL_ERROR",
+	"PGRES_FATAL_ERROR",
+	"PGRES_COPY_BOTH",
+	"PGRES_SINGLE_TUPLE",
+	"PGRES_PIPELINE_SYNC",
+	"PGRES_PIPELINE_ABORTED"
+};
+
+/* We return this if we're unable to make a PGresult at all */
+static const PGresult OOM_result = {
+	.resultStatus = PGRES_FATAL_ERROR,
+	.client_encoding = PG_SQL_ASCII,
+	.errMsg = "out of memory\n",
+};
+
+/*
+ * static state needed by PQescapeString and PQescapeBytea; initialize to
+ * values that result in backward-compatible behavior
+ */
+static int	static_client_encoding = PG_SQL_ASCII;
+static bool static_std_strings = false;
+
+
+static PGEvent *dupEvents(PGEvent *events, int count, size_t *memSize);
+static bool pqAddTuple(PGresult *res, PGresAttValue *tup,
+					   const char **errmsgp);
+static int	PQsendQueryInternal(PGconn *conn, const char *query, bool newQuery);
+static bool PQsendQueryStart(PGconn *conn, bool newQuery);
+static int	PQsendQueryGuts(PGconn *conn,
+							const char *command,
+							const char *stmtName,
+							int nParams,
+							const Oid *paramTypes,
+							const char *const *paramValues,
+							const int *paramLengths,
+							const int *paramFormats,
+							int resultFormat);
+static void parseInput(PGconn *conn);
+static PGresult *getCopyResult(PGconn *conn, ExecStatusType copytype);
+static bool PQexecStart(PGconn *conn);
+static PGresult *PQexecFinish(PGconn *conn);
+static int	PQsendDescribe(PGconn *conn, char desc_type,
+						   const char *desc_target);
+static int	check_field_number(const PGresult *res, int field_num);
+static void pqPipelineProcessQueue(PGconn *conn);
+static int	pqPipelineFlush(PGconn *conn);
+
+
+/* ----------------
+ * Space management for PGresult.
+ *
+ * Formerly, libpq did a separate malloc() for each field of each tuple
+ * returned by a query.  This was remarkably expensive --- malloc/free
+ * consumed a sizable part of the application's runtime.  And there is
+ * no real need to keep track of the fields separately, since they will
+ * all be freed together when the PGresult is released.  So now, we grab
+ * large blocks of storage from malloc and allocate space for query data
+ * within these blocks, using a trivially simple allocator.  This reduces
+ * the number of malloc/free calls dramatically, and it also avoids
+ * fragmentation of the malloc storage arena.
+ * The PGresult structure itself is still malloc'd separately.  We could
+ * combine it with the first allocation block, but that would waste space
+ * for the common case that no extra storage is actually needed (that is,
+ * the SQL command did not return tuples).
+ *
+ * We also malloc the top-level array of tuple pointers separately, because
+ * we need to be able to enlarge it via realloc, and our trivial space
+ * allocator doesn't handle that effectively.  (Too bad the FE/BE protocol
+ * doesn't tell us up front how many tuples will be returned.)
+ * All other subsidiary storage for a PGresult is kept in PGresult_data blocks
+ * of size PGRESULT_DATA_BLOCKSIZE.  The overhead at the start of each block
+ * is just a link to the next one, if any.  Free-space management info is
+ * kept in the owning PGresult.
+ * A query returning a small amount of data will thus require three malloc
+ * calls: one for the PGresult, one for the tuples pointer array, and one
+ * PGresult_data block.
+ *
+ * Only the most recently allocated PGresult_data block is a candidate to
+ * have more stuff added to it --- any extra space left over in older blocks
+ * is wasted.  We could be smarter and search the whole chain, but the point
+ * here is to be simple and fast.  Typical applications do not keep a PGresult
+ * around very long anyway, so some wasted space within one is not a problem.
+ *
+ * Tuning constants for the space allocator are:
+ * PGRESULT_DATA_BLOCKSIZE: size of a standard allocation block, in bytes
+ * PGRESULT_ALIGN_BOUNDARY: assumed alignment requirement for binary data
+ * PGRESULT_SEP_ALLOC_THRESHOLD: objects bigger than this are given separate
+ *	 blocks, instead of being crammed into a regular allocation block.
+ * Requirements for correct function are:
+ * PGRESULT_ALIGN_BOUNDARY must be a multiple of the alignment requirements
+ *		of all machine data types.  (Currently this is set from configure
+ *		tests, so it should be OK automatically.)
+ * PGRESULT_SEP_ALLOC_THRESHOLD + PGRESULT_BLOCK_OVERHEAD <=
+ *			PGRESULT_DATA_BLOCKSIZE
+ *		pqResultAlloc assumes an object smaller than the threshold will fit
+ *		in a new block.
+ * The amount of space wasted at the end of a block could be as much as
+ * PGRESULT_SEP_ALLOC_THRESHOLD, so it doesn't pay to make that too large.
+ * ----------------
+ */
+
+#define PGRESULT_DATA_BLOCKSIZE		2048
+#define PGRESULT_ALIGN_BOUNDARY		MAXIMUM_ALIGNOF /* from configure */
+#define PGRESULT_BLOCK_OVERHEAD		Max(sizeof(PGresult_data), PGRESULT_ALIGN_BOUNDARY)
+#define PGRESULT_SEP_ALLOC_THRESHOLD	(PGRESULT_DATA_BLOCKSIZE / 2)
+
+
+/*
+ * PQmakeEmptyPGresult
+ *	 returns a newly allocated, initialized PGresult with given status.
+ *	 If conn is not NULL and status indicates an error, the conn's
+ *	 errorMessage is copied.  Also, any PGEvents are copied from the conn.
+ *
+ * Note: the logic to copy the conn's errorMessage is now vestigial;
+ * no internal caller uses it.  However, that behavior is documented for
+ * outside callers, so we'd better keep it.
+ */
+PGresult *
+PQmakeEmptyPGresult(PGconn *conn, ExecStatusType status)
+{
+	PGresult   *result;
+
+	result = (PGresult *) malloc(sizeof(PGresult));
+	if (!result)
+		return NULL;
+
+	result->ntups = 0;
+	result->numAttributes = 0;
+	result->attDescs = NULL;
+	result->tuples = NULL;
+	result->tupArrSize = 0;
+	result->numParameters = 0;
+	result->paramDescs = NULL;
+	result->resultStatus = status;
+	result->cmdStatus[0] = '\0';
+	result->binary = 0;
+	result->events = NULL;
+	result->nEvents = 0;
+	result->errMsg = NULL;
+	result->errFields = NULL;
+	result->errQuery = NULL;
+	result->null_field[0] = '\0';
+	result->curBlock = NULL;
+	result->curOffset = 0;
+	result->spaceLeft = 0;
+	result->memorySize = sizeof(PGresult);
+
+	if (conn)
+	{
+		/* copy connection data we might need for operations on PGresult */
+		result->noticeHooks = conn->noticeHooks;
+		result->client_encoding = conn->client_encoding;
+
+		/* consider copying conn's errorMessage */
+		switch (status)
+		{
+			case PGRES_EMPTY_QUERY:
+			case PGRES_COMMAND_OK:
+			case PGRES_TUPLES_OK:
+			case PGRES_COPY_OUT:
+			case PGRES_COPY_IN:
+			case PGRES_COPY_BOTH:
+			case PGRES_SINGLE_TUPLE:
+				/* non-error cases */
+				break;
+			default:
+				/* we intentionally do not use or modify errorReported here */
+				pqSetResultError(result, &conn->errorMessage, 0);
+				break;
+		}
+
+		/* copy events last; result must be valid if we need to PQclear */
+		if (conn->nEvents > 0)
+		{
+			result->events = dupEvents(conn->events, conn->nEvents,
+									   &result->memorySize);
+			if (!result->events)
+			{
+				PQclear(result);
+				return NULL;
+			}
+			result->nEvents = conn->nEvents;
+		}
+	}
+	else
+	{
+		/* defaults... */
+		result->noticeHooks.noticeRec = NULL;
+		result->noticeHooks.noticeRecArg = NULL;
+		result->noticeHooks.noticeProc = NULL;
+		result->noticeHooks.noticeProcArg = NULL;
+		result->client_encoding = PG_SQL_ASCII;
+	}
+
+	return result;
+}
+
+/*
+ * PQsetResultAttrs
+ *
+ * Set the attributes for a given result.  This function fails if there are
+ * already attributes contained in the provided result.  The call is
+ * ignored if numAttributes is zero or attDescs is NULL.  If the
+ * function fails, it returns zero.  If the function succeeds, it
+ * returns a non-zero value.
+ */
+int
+PQsetResultAttrs(PGresult *res, int numAttributes, PGresAttDesc *attDescs)
+{
+	int			i;
+
+	/* Fail if argument is NULL or OOM_result */
+	if (!res || (const PGresult *) res == &OOM_result)
+		return false;
+
+	/* If attrs already exist, they cannot be overwritten. */
+	if (res->numAttributes > 0)
+		return false;
+
+	/* ignore no-op request */
+	if (numAttributes <= 0 || !attDescs)
+		return true;
+
+	res->attDescs = (PGresAttDesc *)
+		PQresultAlloc(res, numAttributes * sizeof(PGresAttDesc));
+
+	if (!res->attDescs)
+		return false;
+
+	res->numAttributes = numAttributes;
+	memcpy(res->attDescs, attDescs, numAttributes * sizeof(PGresAttDesc));
+
+	/* deep-copy the attribute names, and determine format */
+	res->binary = 1;
+	for (i = 0; i < res->numAttributes; i++)
+	{
+		if (res->attDescs[i].name)
+			res->attDescs[i].name = pqResultStrdup(res, res->attDescs[i].name);
+		else
+			res->attDescs[i].name = res->null_field;
+
+		if (!res->attDescs[i].name)
+			return false;
+
+		if (res->attDescs[i].format == 0)
+			res->binary = 0;
+	}
+
+	return true;
+}
+
+/*
+ * PQcopyResult
+ *
+ * Returns a deep copy of the provided 'src' PGresult, which cannot be NULL.
+ * The 'flags' argument controls which portions of the result will or will
+ * NOT be copied.  The created result is always put into the
+ * PGRES_TUPLES_OK status.  The source result error message is not copied,
+ * although cmdStatus is.
+ *
+ * To set custom attributes, use PQsetResultAttrs.  That function requires
+ * that there are no attrs contained in the result, so to use that
+ * function you cannot use the PG_COPYRES_ATTRS or PG_COPYRES_TUPLES
+ * options with this function.
+ *
+ * Options:
+ *	 PG_COPYRES_ATTRS - Copy the source result's attributes
+ *
+ *	 PG_COPYRES_TUPLES - Copy the source result's tuples.  This implies
+ *	 copying the attrs, seeing how the attrs are needed by the tuples.
+ *
+ *	 PG_COPYRES_EVENTS - Copy the source result's events.
+ *
+ *	 PG_COPYRES_NOTICEHOOKS - Copy the source result's notice hooks.
+ */
+PGresult *
+PQcopyResult(const PGresult *src, int flags)
+{
+	PGresult   *dest;
+	int			i;
+
+	if (!src)
+		return NULL;
+
+	dest = PQmakeEmptyPGresult(NULL, PGRES_TUPLES_OK);
+	if (!dest)
+		return NULL;
+
+	/* Always copy these over.  Is cmdStatus really useful here? */
+	dest->client_encoding = src->client_encoding;
+	strcpy(dest->cmdStatus, src->cmdStatus);
+
+	/* Wants attrs? */
+	if (flags & (PG_COPYRES_ATTRS | PG_COPYRES_TUPLES))
+	{
+		if (!PQsetResultAttrs(dest, src->numAttributes, src->attDescs))
+		{
+			PQclear(dest);
+			return NULL;
+		}
+	}
+
+	/* Wants to copy tuples? */
+	if (flags & PG_COPYRES_TUPLES)
+	{
+		int			tup,
+					field;
+
+		for (tup = 0; tup < src->ntups; tup++)
+		{
+			for (field = 0; field < src->numAttributes; field++)
+			{
+				if (!PQsetvalue(dest, tup, field,
+								src->tuples[tup][field].value,
+								src->tuples[tup][field].len))
+				{
+					PQclear(dest);
+					return NULL;
+				}
+			}
+		}
+	}
+
+	/* Wants to copy notice hooks? */
+	if (flags & PG_COPYRES_NOTICEHOOKS)
+		dest->noticeHooks = src->noticeHooks;
+
+	/* Wants to copy PGEvents? */
+	if ((flags & PG_COPYRES_EVENTS) && src->nEvents > 0)
+	{
+		dest->events = dupEvents(src->events, src->nEvents,
+								 &dest->memorySize);
+		if (!dest->events)
+		{
+			PQclear(dest);
+			return NULL;
+		}
+		dest->nEvents = src->nEvents;
+	}
+
+	/* Okay, trigger PGEVT_RESULTCOPY event */
+	for (i = 0; i < dest->nEvents; i++)
+	{
+		/* We don't fire events that had some previous failure */
+		if (src->events[i].resultInitialized)
+		{
+			PGEventResultCopy evt;
+
+			evt.src = src;
+			evt.dest = dest;
+			if (dest->events[i].proc(PGEVT_RESULTCOPY, &evt,
+									 dest->events[i].passThrough))
+				dest->events[i].resultInitialized = true;
+		}
+	}
+
+	return dest;
+}
+
+/*
+ * Copy an array of PGEvents (with no extra space for more).
+ * Does not duplicate the event instance data, sets this to NULL.
+ * Also, the resultInitialized flags are all cleared.
+ * The total space allocated is added to *memSize.
+ */
+static PGEvent *
+dupEvents(PGEvent *events, int count, size_t *memSize)
+{
+	PGEvent    *newEvents;
+	size_t		msize;
+	int			i;
+
+	if (!events || count <= 0)
+		return NULL;
+
+	msize = count * sizeof(PGEvent);
+	newEvents = (PGEvent *) malloc(msize);
+	if (!newEvents)
+		return NULL;
+
+	for (i = 0; i < count; i++)
+	{
+		newEvents[i].proc = events[i].proc;
+		newEvents[i].passThrough = events[i].passThrough;
+		newEvents[i].data = NULL;
+		newEvents[i].resultInitialized = false;
+		newEvents[i].name = strdup(events[i].name);
+		if (!newEvents[i].name)
+		{
+			while (--i >= 0)
+				free(newEvents[i].name);
+			free(newEvents);
+			return NULL;
+		}
+		msize += strlen(events[i].name) + 1;
+	}
+
+	*memSize += msize;
+	return newEvents;
+}
+
+
+/*
+ * Sets the value for a tuple field.  The tup_num must be less than or
+ * equal to PQntuples(res).  If it is equal, a new tuple is created and
+ * added to the result.
+ * Returns a non-zero value for success and zero for failure.
+ * (On failure, we report the specific problem via pqInternalNotice.)
+ */
+int
+PQsetvalue(PGresult *res, int tup_num, int field_num, char *value, int len)
+{
+	PGresAttValue *attval;
+	const char *errmsg = NULL;
+
+	/* Fail if argument is NULL or OOM_result */
+	if (!res || (const PGresult *) res == &OOM_result)
+		return false;
+
+	/* Invalid field_num? */
+	if (!check_field_number(res, field_num))
+		return false;
+
+	/* Invalid tup_num, must be <= ntups */
+	if (tup_num < 0 || tup_num > res->ntups)
+	{
+		pqInternalNotice(&res->noticeHooks,
+						 "row number %d is out of range 0..%d",
+						 tup_num, res->ntups);
+		return false;
+	}
+
+	/* need to allocate a new tuple? */
+	if (tup_num == res->ntups)
+	{
+		PGresAttValue *tup;
+		int			i;
+
+		tup = (PGresAttValue *)
+			pqResultAlloc(res, res->numAttributes * sizeof(PGresAttValue),
+						  true);
+
+		if (!tup)
+			goto fail;
+
+		/* initialize each column to NULL */
+		for (i = 0; i < res->numAttributes; i++)
+		{
+			tup[i].len = NULL_LEN;
+			tup[i].value = res->null_field;
+		}
+
+		/* add it to the array */
+		if (!pqAddTuple(res, tup, &errmsg))
+			goto fail;
+	}
+
+	attval = &res->tuples[tup_num][field_num];
+
+	/* treat either NULL_LEN or NULL value pointer as a NULL field */
+	if (len == NULL_LEN || value == NULL)
+	{
+		attval->len = NULL_LEN;
+		attval->value = res->null_field;
+	}
+	else if (len <= 0)
+	{
+		attval->len = 0;
+		attval->value = res->null_field;
+	}
+	else
+	{
+		attval->value = (char *) pqResultAlloc(res, len + 1, true);
+		if (!attval->value)
+			goto fail;
+		attval->len = len;
+		memcpy(attval->value, value, len);
+		attval->value[len] = '\0';
+	}
+
+	return true;
+
+	/*
+	 * Report failure via pqInternalNotice.  If preceding code didn't provide
+	 * an error message, assume "out of memory" was meant.
+	 */
+fail:
+	if (!errmsg)
+		errmsg = libpq_gettext("out of memory");
+	pqInternalNotice(&res->noticeHooks, "%s", errmsg);
+
+	return false;
+}
+
+/*
+ * pqResultAlloc - exported routine to allocate local storage in a PGresult.
+ *
+ * We force all such allocations to be maxaligned, since we don't know
+ * whether the value might be binary.
+ */
+void *
+PQresultAlloc(PGresult *res, size_t nBytes)
+{
+	/* Fail if argument is NULL or OOM_result */
+	if (!res || (const PGresult *) res == &OOM_result)
+		return NULL;
+
+	return pqResultAlloc(res, nBytes, true);
+}
+
+/*
+ * pqResultAlloc -
+ *		Allocate subsidiary storage for a PGresult.
+ *
+ * nBytes is the amount of space needed for the object.
+ * If isBinary is true, we assume that we need to align the object on
+ * a machine allocation boundary.
+ * If isBinary is false, we assume the object is a char string and can
+ * be allocated on any byte boundary.
+ */
+void *
+pqResultAlloc(PGresult *res, size_t nBytes, bool isBinary)
+{
+	char	   *space;
+	PGresult_data *block;
+
+	if (!res)
+		return NULL;
+
+	if (nBytes <= 0)
+		return res->null_field;
+
+	/*
+	 * If alignment is needed, round up the current position to an alignment
+	 * boundary.
+	 */
+	if (isBinary)
+	{
+		int			offset = res->curOffset % PGRESULT_ALIGN_BOUNDARY;
+
+		if (offset)
+		{
+			res->curOffset += PGRESULT_ALIGN_BOUNDARY - offset;
+			res->spaceLeft -= PGRESULT_ALIGN_BOUNDARY - offset;
+		}
+	}
+
+	/* If there's enough space in the current block, no problem. */
+	if (nBytes <= (size_t) res->spaceLeft)
+	{
+		space = res->curBlock->space + res->curOffset;
+		res->curOffset += nBytes;
+		res->spaceLeft -= nBytes;
+		return space;
+	}
+
+	/*
+	 * If the requested object is very large, give it its own block; this
+	 * avoids wasting what might be most of the current block to start a new
+	 * block.  (We'd have to special-case requests bigger than the block size
+	 * anyway.)  The object is always given binary alignment in this case.
+	 */
+	if (nBytes >= PGRESULT_SEP_ALLOC_THRESHOLD)
+	{
+		size_t		alloc_size = nBytes + PGRESULT_BLOCK_OVERHEAD;
+
+		block = (PGresult_data *) malloc(alloc_size);
+		if (!block)
+			return NULL;
+		res->memorySize += alloc_size;
+		space = block->space + PGRESULT_BLOCK_OVERHEAD;
+		if (res->curBlock)
+		{
+			/*
+			 * Tuck special block below the active block, so that we don't
+			 * have to waste the free space in the active block.
+			 */
+			block->next = res->curBlock->next;
+			res->curBlock->next = block;
+		}
+		else
+		{
+			/* Must set up the new block as the first active block. */
+			block->next = NULL;
+			res->curBlock = block;
+			res->spaceLeft = 0; /* be sure it's marked full */
+		}
+		return space;
+	}
+
+	/* Otherwise, start a new block. */
+	block = (PGresult_data *) malloc(PGRESULT_DATA_BLOCKSIZE);
+	if (!block)
+		return NULL;
+	res->memorySize += PGRESULT_DATA_BLOCKSIZE;
+	block->next = res->curBlock;
+	res->curBlock = block;
+	if (isBinary)
+	{
+		/* object needs full alignment */
+		res->curOffset = PGRESULT_BLOCK_OVERHEAD;
+		res->spaceLeft = PGRESULT_DATA_BLOCKSIZE - PGRESULT_BLOCK_OVERHEAD;
+	}
+	else
+	{
+		/* we can cram it right after the overhead pointer */
+		res->curOffset = sizeof(PGresult_data);
+		res->spaceLeft = PGRESULT_DATA_BLOCKSIZE - sizeof(PGresult_data);
+	}
+
+	space = block->space + res->curOffset;
+	res->curOffset += nBytes;
+	res->spaceLeft -= nBytes;
+	return space;
+}
+
+/*
+ * PQresultMemorySize -
+ *		Returns total space allocated for the PGresult.
+ */
+size_t
+PQresultMemorySize(const PGresult *res)
+{
+	if (!res)
+		return 0;
+	return res->memorySize;
+}
+
+/*
+ * pqResultStrdup -
+ *		Like strdup, but the space is subsidiary PGresult space.
+ */
+char *
+pqResultStrdup(PGresult *res, const char *str)
+{
+	char	   *space = (char *) pqResultAlloc(res, strlen(str) + 1, false);
+
+	if (space)
+		strcpy(space, str);
+	return space;
+}
+
+/*
+ * pqSetResultError -
+ *		assign a new error message to a PGresult
+ *
+ * Copy text from errorMessage buffer beginning at given offset
+ * (it's caller's responsibility that offset is valid)
+ */
+void
+pqSetResultError(PGresult *res, PQExpBuffer errorMessage, int offset)
+{
+	char	   *msg;
+
+	if (!res)
+		return;
+
+	/*
+	 * We handle two OOM scenarios here.  The errorMessage buffer might be
+	 * marked "broken" due to having previously failed to allocate enough
+	 * memory for the message, or it might be fine but pqResultStrdup fails
+	 * and returns NULL.  In either case, just make res->errMsg point directly
+	 * at a constant "out of memory" string.
+	 */
+	if (!PQExpBufferBroken(errorMessage))
+		msg = pqResultStrdup(res, errorMessage->data + offset);
+	else
+		msg = NULL;
+	if (msg)
+		res->errMsg = msg;
+	else
+		res->errMsg = libpq_gettext("out of memory\n");
+}
+
+/*
+ * PQclear -
+ *	  free's the memory associated with a PGresult
+ */
+void
+PQclear(PGresult *res)
+{
+	PGresult_data *block;
+	int			i;
+
+	/* As a convenience, do nothing for a NULL pointer */
+	if (!res)
+		return;
+	/* Also, do nothing if the argument is OOM_result */
+	if ((const PGresult *) res == &OOM_result)
+		return;
+
+	/* Close down any events we may have */
+	for (i = 0; i < res->nEvents; i++)
+	{
+		/* only send DESTROY to successfully-initialized event procs */
+		if (res->events[i].resultInitialized)
+		{
+			PGEventResultDestroy evt;
+
+			evt.result = res;
+			(void) res->events[i].proc(PGEVT_RESULTDESTROY, &evt,
+									   res->events[i].passThrough);
+		}
+		free(res->events[i].name);
+	}
+
+	if (res->events)
+		free(res->events);
+
+	/* Free all the subsidiary blocks */
+	while ((block = res->curBlock) != NULL)
+	{
+		res->curBlock = block->next;
+		free(block);
+	}
+
+	/* Free the top-level tuple pointer array */
+	if (res->tuples)
+		free(res->tuples);
+
+	/* zero out the pointer fields to catch programming errors */
+	res->attDescs = NULL;
+	res->tuples = NULL;
+	res->paramDescs = NULL;
+	res->errFields = NULL;
+	res->events = NULL;
+	res->nEvents = 0;
+	/* res->curBlock was zeroed out earlier */
+
+	/* Free the PGresult structure itself */
+	free(res);
+}
+
+/*
+ * Handy subroutine to deallocate any partially constructed async result.
+ *
+ * Any "next" result gets cleared too.
+ */
+void
+pqClearAsyncResult(PGconn *conn)
+{
+	if (conn->result)
+		PQclear(conn->result);
+	conn->result = NULL;
+	conn->error_result = false;
+	if (conn->next_result)
+		PQclear(conn->next_result);
+	conn->next_result = NULL;
+}
+
+/*
+ * pqSaveErrorResult -
+ *	  remember that we have an error condition
+ *
+ * In much of libpq, reporting an error just requires appending text to
+ * conn->errorMessage and returning a failure code to one's caller.
+ * Where returning a failure code is impractical, instead call this
+ * function to remember that an error needs to be reported.
+ *
+ * (It might seem that appending text to conn->errorMessage should be
+ * sufficient, but we can't rely on that working under out-of-memory
+ * conditions.  The OOM hazard is also why we don't try to make a new
+ * PGresult right here.)
+ */
+void
+pqSaveErrorResult(PGconn *conn)
+{
+	/* Drop any pending result ... */
+	pqClearAsyncResult(conn);
+	/* ... and set flag to remember to make an error result later */
+	conn->error_result = true;
+}
+
+/*
+ * pqSaveWriteError -
+ *	  report a write failure
+ *
+ * As above, after appending conn->write_err_msg to whatever other error we
+ * have.  This is used when we've detected a write failure and have exhausted
+ * our chances of reporting something else instead.
+ */
+static void
+pqSaveWriteError(PGconn *conn)
+{
+	/*
+	 * If write_err_msg is null because of previous strdup failure, do what we
+	 * can.  (It's likely our machinations here will get OOM failures as well,
+	 * but might as well try.)
+	 */
+	if (conn->write_err_msg)
+	{
+		appendPQExpBufferStr(&conn->errorMessage, conn->write_err_msg);
+		/* Avoid possibly appending the same message twice */
+		conn->write_err_msg[0] = '\0';
+	}
+	else
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("write to server failed\n"));
+
+	pqSaveErrorResult(conn);
+}
+
+/*
+ * pqPrepareAsyncResult -
+ *	  prepare the current async result object for return to the caller
+ *
+ * If there is not already an async result object, build an error object
+ * using whatever is in conn->errorMessage.  In any case, clear the async
+ * result storage, and update our notion of how much error text has been
+ * returned to the application.
+ */
+PGresult *
+pqPrepareAsyncResult(PGconn *conn)
+{
+	PGresult   *res;
+
+	res = conn->result;
+	if (res)
+	{
+		/*
+		 * If the pre-existing result is an ERROR (presumably something
+		 * received from the server), assume that it represents whatever is in
+		 * conn->errorMessage, and advance errorReported.
+		 */
+		if (res->resultStatus == PGRES_FATAL_ERROR)
+			conn->errorReported = conn->errorMessage.len;
+	}
+	else
+	{
+		/*
+		 * We get here after internal-to-libpq errors.  We should probably
+		 * always have error_result = true, but if we don't, gin up some error
+		 * text.
+		 */
+		if (!conn->error_result)
+			appendPQExpBufferStr(&conn->errorMessage,
+								 libpq_gettext("no error text available\n"));
+
+		/* Paranoia: be sure errorReported offset is sane */
+		if (conn->errorReported < 0 ||
+			conn->errorReported >= conn->errorMessage.len)
+			conn->errorReported = 0;
+
+		/*
+		 * Make a PGresult struct for the error.  We temporarily lie about the
+		 * result status, so that PQmakeEmptyPGresult doesn't uselessly copy
+		 * all of conn->errorMessage.
+		 */
+		res = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY);
+		if (res)
+		{
+			/*
+			 * Report whatever new error text we have, and advance
+			 * errorReported.
+			 */
+			res->resultStatus = PGRES_FATAL_ERROR;
+			pqSetResultError(res, &conn->errorMessage, conn->errorReported);
+			conn->errorReported = conn->errorMessage.len;
+		}
+		else
+		{
+			/*
+			 * Ouch, not enough memory for a PGresult.  Fortunately, we have a
+			 * card up our sleeve: we can use the static OOM_result.  Casting
+			 * away const here is a bit ugly, but it seems best to declare
+			 * OOM_result as const, in hopes it will be allocated in read-only
+			 * storage.
+			 */
+			res = unconstify(PGresult *, &OOM_result);
+
+			/*
+			 * Don't advance errorReported.  Perhaps we'll be able to report
+			 * the text later.
+			 */
+		}
+	}
+
+	/*
+	 * Replace conn->result with next_result, if any.  In the normal case
+	 * there isn't a next result and we're just dropping ownership of the
+	 * current result.  In single-row mode this restores the situation to what
+	 * it was before we created the current single-row result.
+	 */
+	conn->result = conn->next_result;
+	conn->error_result = false; /* next_result is never an error */
+	conn->next_result = NULL;
+
+	return res;
+}
+
+/*
+ * pqInternalNotice - produce an internally-generated notice message
+ *
+ * A format string and optional arguments can be passed.  Note that we do
+ * libpq_gettext() here, so callers need not.
+ *
+ * The supplied text is taken as primary message (ie., it should not include
+ * a trailing newline, and should not be more than one line).
+ */
+void
+pqInternalNotice(const PGNoticeHooks *hooks, const char *fmt,...)
+{
+	char		msgBuf[1024];
+	va_list		args;
+	PGresult   *res;
+
+	if (hooks->noticeRec == NULL)
+		return;					/* nobody home to receive notice? */
+
+	/* Format the message */
+	va_start(args, fmt);
+	vsnprintf(msgBuf, sizeof(msgBuf), libpq_gettext(fmt), args);
+	va_end(args);
+	msgBuf[sizeof(msgBuf) - 1] = '\0';	/* make real sure it's terminated */
+
+	/* Make a PGresult to pass to the notice receiver */
+	res = PQmakeEmptyPGresult(NULL, PGRES_NONFATAL_ERROR);
+	if (!res)
+		return;
+	res->noticeHooks = *hooks;
+
+	/*
+	 * Set up fields of notice.
+	 */
+	pqSaveMessageField(res, PG_DIAG_MESSAGE_PRIMARY, msgBuf);
+	pqSaveMessageField(res, PG_DIAG_SEVERITY, libpq_gettext("NOTICE"));
+	pqSaveMessageField(res, PG_DIAG_SEVERITY_NONLOCALIZED, "NOTICE");
+	/* XXX should provide a SQLSTATE too? */
+
+	/*
+	 * Result text is always just the primary message + newline.  If we can't
+	 * allocate it, substitute "out of memory", as in pqSetResultError.
+	 */
+	res->errMsg = (char *) pqResultAlloc(res, strlen(msgBuf) + 2, false);
+	if (res->errMsg)
+		sprintf(res->errMsg, "%s\n", msgBuf);
+	else
+		res->errMsg = libpq_gettext("out of memory\n");
+
+	/*
+	 * Pass to receiver, then free it.
+	 */
+	res->noticeHooks.noticeRec(res->noticeHooks.noticeRecArg, res);
+	PQclear(res);
+}
+
+/*
+ * pqAddTuple
+ *	  add a row pointer to the PGresult structure, growing it if necessary
+ *	  Returns true if OK, false if an error prevented adding the row
+ *
+ * On error, *errmsgp can be set to an error string to be returned.
+ * If it is left NULL, the error is presumed to be "out of memory".
+ */
+static bool
+pqAddTuple(PGresult *res, PGresAttValue *tup, const char **errmsgp)
+{
+	if (res->ntups >= res->tupArrSize)
+	{
+		/*
+		 * Try to grow the array.
+		 *
+		 * We can use realloc because shallow copying of the structure is
+		 * okay. Note that the first time through, res->tuples is NULL. While
+		 * ANSI says that realloc() should act like malloc() in that case,
+		 * some old C libraries (like SunOS 4.1.x) coredump instead. On
+		 * failure realloc is supposed to return NULL without damaging the
+		 * existing allocation. Note that the positions beyond res->ntups are
+		 * garbage, not necessarily NULL.
+		 */
+		int			newSize;
+		PGresAttValue **newTuples;
+
+		/*
+		 * Since we use integers for row numbers, we can't support more than
+		 * INT_MAX rows.  Make sure we allow that many, though.
+		 */
+		if (res->tupArrSize <= INT_MAX / 2)
+			newSize = (res->tupArrSize > 0) ? res->tupArrSize * 2 : 128;
+		else if (res->tupArrSize < INT_MAX)
+			newSize = INT_MAX;
+		else
+		{
+			*errmsgp = libpq_gettext("PGresult cannot support more than INT_MAX tuples");
+			return false;
+		}
+
+		/*
+		 * Also, on 32-bit platforms we could, in theory, overflow size_t even
+		 * before newSize gets to INT_MAX.  (In practice we'd doubtless hit
+		 * OOM long before that, but let's check.)
+		 */
+#if INT_MAX >= (SIZE_MAX / 2)
+		if (newSize > SIZE_MAX / sizeof(PGresAttValue *))
+		{
+			*errmsgp = libpq_gettext("size_t overflow");
+			return false;
+		}
+#endif
+
+		if (res->tuples == NULL)
+			newTuples = (PGresAttValue **)
+				malloc(newSize * sizeof(PGresAttValue *));
+		else
+			newTuples = (PGresAttValue **)
+				realloc(res->tuples, newSize * sizeof(PGresAttValue *));
+		if (!newTuples)
+			return false;		/* malloc or realloc failed */
+		res->memorySize +=
+			(newSize - res->tupArrSize) * sizeof(PGresAttValue *);
+		res->tupArrSize = newSize;
+		res->tuples = newTuples;
+	}
+	res->tuples[res->ntups] = tup;
+	res->ntups++;
+	return true;
+}
+
+/*
+ * pqSaveMessageField - save one field of an error or notice message
+ */
+void
+pqSaveMessageField(PGresult *res, char code, const char *value)
+{
+	PGMessageField *pfield;
+
+	pfield = (PGMessageField *)
+		pqResultAlloc(res,
+					  offsetof(PGMessageField, contents) +
+					  strlen(value) + 1,
+					  true);
+	if (!pfield)
+		return;					/* out of memory? */
+	pfield->code = code;
+	strcpy(pfield->contents, value);
+	pfield->next = res->errFields;
+	res->errFields = pfield;
+}
+
+/*
+ * pqSaveParameterStatus - remember parameter status sent by backend
+ */
+void
+pqSaveParameterStatus(PGconn *conn, const char *name, const char *value)
+{
+	pgParameterStatus *pstatus;
+	pgParameterStatus *prev;
+
+	/*
+	 * Forget any old information about the parameter
+	 */
+	for (pstatus = conn->pstatus, prev = NULL;
+		 pstatus != NULL;
+		 prev = pstatus, pstatus = pstatus->next)
+	{
+		if (strcmp(pstatus->name, name) == 0)
+		{
+			if (prev)
+				prev->next = pstatus->next;
+			else
+				conn->pstatus = pstatus->next;
+			free(pstatus);		/* frees name and value strings too */
+			break;
+		}
+	}
+
+	/*
+	 * Store new info as a single malloc block
+	 */
+	pstatus = (pgParameterStatus *) malloc(sizeof(pgParameterStatus) +
+										   strlen(name) + strlen(value) + 2);
+	if (pstatus)
+	{
+		char	   *ptr;
+
+		ptr = ((char *) pstatus) + sizeof(pgParameterStatus);
+		pstatus->name = ptr;
+		strcpy(ptr, name);
+		ptr += strlen(name) + 1;
+		pstatus->value = ptr;
+		strcpy(ptr, value);
+		pstatus->next = conn->pstatus;
+		conn->pstatus = pstatus;
+	}
+
+	/*
+	 * Save values of settings that are of interest to libpq in fields of the
+	 * PGconn object.  We keep client_encoding and standard_conforming_strings
+	 * in static variables as well, so that PQescapeString and PQescapeBytea
+	 * can behave somewhat sanely (at least in single-connection-using
+	 * programs).
+	 */
+	if (strcmp(name, "client_encoding") == 0)
+	{
+		conn->client_encoding = pg_char_to_encoding(value);
+		/* if we don't recognize the encoding name, fall back to SQL_ASCII */
+		if (conn->client_encoding < 0)
+			conn->client_encoding = PG_SQL_ASCII;
+		static_client_encoding = conn->client_encoding;
+	}
+	else if (strcmp(name, "standard_conforming_strings") == 0)
+	{
+		conn->std_strings = (strcmp(value, "on") == 0);
+		static_std_strings = conn->std_strings;
+	}
+	else if (strcmp(name, "server_version") == 0)
+	{
+		/* We convert the server version to numeric form. */
+		int			cnt;
+		int			vmaj,
+					vmin,
+					vrev;
+
+		cnt = sscanf(value, "%d.%d.%d", &vmaj, &vmin, &vrev);
+
+		if (cnt == 3)
+		{
+			/* old style, e.g. 9.6.1 */
+			conn->sversion = (100 * vmaj + vmin) * 100 + vrev;
+		}
+		else if (cnt == 2)
+		{
+			if (vmaj >= 10)
+			{
+				/* new style, e.g. 10.1 */
+				conn->sversion = 100 * 100 * vmaj + vmin;
+			}
+			else
+			{
+				/* old style without minor version, e.g. 9.6devel */
+				conn->sversion = (100 * vmaj + vmin) * 100;
+			}
+		}
+		else if (cnt == 1)
+		{
+			/* new style without minor version, e.g. 10devel */
+			conn->sversion = 100 * 100 * vmaj;
+		}
+		else
+			conn->sversion = 0; /* unknown */
+	}
+	else if (strcmp(name, "default_transaction_read_only") == 0)
+	{
+		conn->default_transaction_read_only =
+			(strcmp(value, "on") == 0) ? PG_BOOL_YES : PG_BOOL_NO;
+	}
+	else if (strcmp(name, "in_hot_standby") == 0)
+	{
+		conn->in_hot_standby =
+			(strcmp(value, "on") == 0) ? PG_BOOL_YES : PG_BOOL_NO;
+	}
+}
+
+
+/*
+ * pqRowProcessor
+ *	  Add the received row to the current async result (conn->result).
+ *	  Returns 1 if OK, 0 if error occurred.
+ *
+ * On error, *errmsgp can be set to an error string to be returned.
+ * (Such a string should already be translated via libpq_gettext().)
+ * If it is left NULL, the error is presumed to be "out of memory".
+ *
+ * In single-row mode, we create a new result holding just the current row,
+ * stashing the previous result in conn->next_result so that it becomes
+ * active again after pqPrepareAsyncResult().  This allows the result metadata
+ * (column descriptions) to be carried forward to each result row.
+ */
+int
+pqRowProcessor(PGconn *conn, const char **errmsgp)
+{
+	PGresult   *res = conn->result;
+	int			nfields = res->numAttributes;
+	const PGdataValue *columns = conn->rowBuf;
+	PGresAttValue *tup;
+	int			i;
+
+	/*
+	 * In single-row mode, make a new PGresult that will hold just this one
+	 * row; the original conn->result is left unchanged so that it can be used
+	 * again as the template for future rows.
+	 */
+	if (conn->singleRowMode)
+	{
+		/* Copy everything that should be in the result at this point */
+		res = PQcopyResult(res,
+						   PG_COPYRES_ATTRS | PG_COPYRES_EVENTS |
+						   PG_COPYRES_NOTICEHOOKS);
+		if (!res)
+			return 0;
+	}
+
+	/*
+	 * Basically we just allocate space in the PGresult for each field and
+	 * copy the data over.
+	 *
+	 * Note: on malloc failure, we return 0 leaving *errmsgp still NULL, which
+	 * caller will take to mean "out of memory".  This is preferable to trying
+	 * to set up such a message here, because evidently there's not enough
+	 * memory for gettext() to do anything.
+	 */
+	tup = (PGresAttValue *)
+		pqResultAlloc(res, nfields * sizeof(PGresAttValue), true);
+	if (tup == NULL)
+		goto fail;
+
+	for (i = 0; i < nfields; i++)
+	{
+		int			clen = columns[i].len;
+
+		if (clen < 0)
+		{
+			/* null field */
+			tup[i].len = NULL_LEN;
+			tup[i].value = res->null_field;
+		}
+		else
+		{
+			bool		isbinary = (res->attDescs[i].format != 0);
+			char	   *val;
+
+			val = (char *) pqResultAlloc(res, clen + 1, isbinary);
+			if (val == NULL)
+				goto fail;
+
+			/* copy and zero-terminate the data (even if it's binary) */
+			memcpy(val, columns[i].value, clen);
+			val[clen] = '\0';
+
+			tup[i].len = clen;
+			tup[i].value = val;
+		}
+	}
+
+	/* And add the tuple to the PGresult's tuple array */
+	if (!pqAddTuple(res, tup, errmsgp))
+		goto fail;
+
+	/*
+	 * Success.  In single-row mode, make the result available to the client
+	 * immediately.
+	 */
+	if (conn->singleRowMode)
+	{
+		/* Change result status to special single-row value */
+		res->resultStatus = PGRES_SINGLE_TUPLE;
+		/* Stash old result for re-use later */
+		conn->next_result = conn->result;
+		conn->result = res;
+		/* And mark the result ready to return */
+		conn->asyncStatus = PGASYNC_READY_MORE;
+	}
+
+	return 1;
+
+fail:
+	/* release locally allocated PGresult, if we made one */
+	if (res != conn->result)
+		PQclear(res);
+	return 0;
+}
+
+
+/*
+ * pqAllocCmdQueueEntry
+ *		Get a command queue entry for caller to fill.
+ *
+ * If the recycle queue has a free element, that is returned; if not, a
+ * fresh one is allocated.  Caller is responsible for adding it to the
+ * command queue (pqAppendCmdQueueEntry) once the struct is filled in, or
+ * releasing the memory (pqRecycleCmdQueueEntry) if an error occurs.
+ *
+ * If allocation fails, sets the error message and returns NULL.
+ */
+static PGcmdQueueEntry *
+pqAllocCmdQueueEntry(PGconn *conn)
+{
+	PGcmdQueueEntry *entry;
+
+	if (conn->cmd_queue_recycle == NULL)
+	{
+		entry = (PGcmdQueueEntry *) malloc(sizeof(PGcmdQueueEntry));
+		if (entry == NULL)
+		{
+			appendPQExpBufferStr(&conn->errorMessage,
+								 libpq_gettext("out of memory\n"));
+			return NULL;
+		}
+	}
+	else
+	{
+		entry = conn->cmd_queue_recycle;
+		conn->cmd_queue_recycle = entry->next;
+	}
+	entry->next = NULL;
+	entry->query = NULL;
+
+	return entry;
+}
+
+/*
+ * pqAppendCmdQueueEntry
+ *		Append a caller-allocated entry to the command queue, and update
+ *		conn->asyncStatus to account for it.
+ *
+ * The query itself must already have been put in the output buffer by the
+ * caller.
+ */
+static void
+pqAppendCmdQueueEntry(PGconn *conn, PGcmdQueueEntry *entry)
+{
+	Assert(entry->next == NULL);
+
+	if (conn->cmd_queue_head == NULL)
+		conn->cmd_queue_head = entry;
+	else
+		conn->cmd_queue_tail->next = entry;
+
+	conn->cmd_queue_tail = entry;
+
+	switch (conn->pipelineStatus)
+	{
+		case PQ_PIPELINE_OFF:
+		case PQ_PIPELINE_ON:
+
+			/*
+			 * When not in pipeline aborted state, if there's a result ready
+			 * to be consumed, let it be so (that is, don't change away from
+			 * READY or READY_MORE); otherwise set us busy to wait for
+			 * something to arrive from the server.
+			 */
+			if (conn->asyncStatus == PGASYNC_IDLE)
+				conn->asyncStatus = PGASYNC_BUSY;
+			break;
+
+		case PQ_PIPELINE_ABORTED:
+
+			/*
+			 * In aborted pipeline state, we don't expect anything from the
+			 * server (since we don't send any queries that are queued).
+			 * Therefore, if IDLE then do what PQgetResult would do to let
+			 * itself consume commands from the queue; if we're in any other
+			 * state, we don't have to do anything.
+			 */
+			if (conn->asyncStatus == PGASYNC_IDLE ||
+				conn->asyncStatus == PGASYNC_PIPELINE_IDLE)
+				pqPipelineProcessQueue(conn);
+			break;
+	}
+}
+
+/*
+ * pqRecycleCmdQueueEntry
+ *		Push a command queue entry onto the freelist.
+ */
+static void
+pqRecycleCmdQueueEntry(PGconn *conn, PGcmdQueueEntry *entry)
+{
+	if (entry == NULL)
+		return;
+
+	/* recyclable entries should not have a follow-on command */
+	Assert(entry->next == NULL);
+
+	if (entry->query)
+	{
+		free(entry->query);
+		entry->query = NULL;
+	}
+
+	entry->next = conn->cmd_queue_recycle;
+	conn->cmd_queue_recycle = entry;
+}
+
+
+/*
+ * PQsendQuery
+ *	 Submit a query, but don't wait for it to finish
+ *
+ * Returns: 1 if successfully submitted
+ *			0 if error (conn->errorMessage is set)
+ *
+ * PQsendQueryContinue is a non-exported version that behaves identically
+ * except that it doesn't reset conn->errorMessage.
+ */
+int
+PQsendQuery(PGconn *conn, const char *query)
+{
+	return PQsendQueryInternal(conn, query, true);
+}
+
+int
+PQsendQueryContinue(PGconn *conn, const char *query)
+{
+	return PQsendQueryInternal(conn, query, false);
+}
+
+static int
+PQsendQueryInternal(PGconn *conn, const char *query, bool newQuery)
+{
+	PGcmdQueueEntry *entry = NULL;
+
+	if (!PQsendQueryStart(conn, newQuery))
+		return 0;
+
+	/* check the argument */
+	if (!query)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("command string is a null pointer\n"));
+		return 0;
+	}
+
+	if (conn->pipelineStatus != PQ_PIPELINE_OFF)
+	{
+		appendPQExpBuffer(&conn->errorMessage,
+						  libpq_gettext("%s not allowed in pipeline mode\n"),
+						  "PQsendQuery");
+		return 0;
+	}
+
+	entry = pqAllocCmdQueueEntry(conn);
+	if (entry == NULL)
+		return 0;				/* error msg already set */
+
+	/* Send the query message(s) */
+	/* construct the outgoing Query message */
+	if (pqPutMsgStart('Q', conn) < 0 ||
+		pqPuts(query, conn) < 0 ||
+		pqPutMsgEnd(conn) < 0)
+	{
+		/* error message should be set up already */
+		pqRecycleCmdQueueEntry(conn, entry);
+		return 0;
+	}
+
+	/* remember we are using simple query protocol */
+	entry->queryclass = PGQUERY_SIMPLE;
+	/* and remember the query text too, if possible */
+	entry->query = strdup(query);
+
+	/*
+	 * Give the data a push.  In nonblock mode, don't complain if we're unable
+	 * to send it all; PQgetResult() will do any additional flushing needed.
+	 */
+	if (pqFlush(conn) < 0)
+		goto sendFailed;
+
+	/* OK, it's launched! */
+	pqAppendCmdQueueEntry(conn, entry);
+
+	return 1;
+
+sendFailed:
+	pqRecycleCmdQueueEntry(conn, entry);
+	/* error message should be set up already */
+	return 0;
+}
+
+/*
+ * PQsendQueryParams
+ *		Like PQsendQuery, but use extended query protocol so we can pass parameters
+ */
+int
+PQsendQueryParams(PGconn *conn,
+				  const char *command,
+				  int nParams,
+				  const Oid *paramTypes,
+				  const char *const *paramValues,
+				  const int *paramLengths,
+				  const int *paramFormats,
+				  int resultFormat)
+{
+	if (!PQsendQueryStart(conn, true))
+		return 0;
+
+	/* check the arguments */
+	if (!command)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("command string is a null pointer\n"));
+		return 0;
+	}
+	if (nParams < 0 || nParams > PQ_QUERY_PARAM_MAX_LIMIT)
+	{
+		appendPQExpBuffer(&conn->errorMessage,
+						  libpq_gettext("number of parameters must be between 0 and %d\n"),
+						  PQ_QUERY_PARAM_MAX_LIMIT);
+		return 0;
+	}
+
+	return PQsendQueryGuts(conn,
+						   command,
+						   "",	/* use unnamed statement */
+						   nParams,
+						   paramTypes,
+						   paramValues,
+						   paramLengths,
+						   paramFormats,
+						   resultFormat);
+}
+
+/*
+ * PQsendPrepare
+ *	 Submit a Parse message, but don't wait for it to finish
+ *
+ * Returns: 1 if successfully submitted
+ *			0 if error (conn->errorMessage is set)
+ */
+int
+PQsendPrepare(PGconn *conn,
+			  const char *stmtName, const char *query,
+			  int nParams, const Oid *paramTypes)
+{
+	PGcmdQueueEntry *entry = NULL;
+
+	if (!PQsendQueryStart(conn, true))
+		return 0;
+
+	/* check the arguments */
+	if (!stmtName)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("statement name is a null pointer\n"));
+		return 0;
+	}
+	if (!query)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("command string is a null pointer\n"));
+		return 0;
+	}
+	if (nParams < 0 || nParams > PQ_QUERY_PARAM_MAX_LIMIT)
+	{
+		appendPQExpBuffer(&conn->errorMessage,
+						  libpq_gettext("number of parameters must be between 0 and %d\n"),
+						  PQ_QUERY_PARAM_MAX_LIMIT);
+		return 0;
+	}
+
+	entry = pqAllocCmdQueueEntry(conn);
+	if (entry == NULL)
+		return 0;				/* error msg already set */
+
+	/* construct the Parse message */
+	if (pqPutMsgStart('P', conn) < 0 ||
+		pqPuts(stmtName, conn) < 0 ||
+		pqPuts(query, conn) < 0)
+		goto sendFailed;
+
+	if (nParams > 0 && paramTypes)
+	{
+		int			i;
+
+		if (pqPutInt(nParams, 2, conn) < 0)
+			goto sendFailed;
+		for (i = 0; i < nParams; i++)
+		{
+			if (pqPutInt(paramTypes[i], 4, conn) < 0)
+				goto sendFailed;
+		}
+	}
+	else
+	{
+		if (pqPutInt(0, 2, conn) < 0)
+			goto sendFailed;
+	}
+	if (pqPutMsgEnd(conn) < 0)
+		goto sendFailed;
+
+	/* Add a Sync, unless in pipeline mode. */
+	if (conn->pipelineStatus == PQ_PIPELINE_OFF)
+	{
+		if (pqPutMsgStart('S', conn) < 0 ||
+			pqPutMsgEnd(conn) < 0)
+			goto sendFailed;
+	}
+
+	/* remember we are doing just a Parse */
+	entry->queryclass = PGQUERY_PREPARE;
+
+	/* and remember the query text too, if possible */
+	/* if insufficient memory, query just winds up NULL */
+	entry->query = strdup(query);
+
+	/*
+	 * Give the data a push (in pipeline mode, only if we're past the size
+	 * threshold).  In nonblock mode, don't complain if we're unable to send
+	 * it all; PQgetResult() will do any additional flushing needed.
+	 */
+	if (pqPipelineFlush(conn) < 0)
+		goto sendFailed;
+
+	/* OK, it's launched! */
+	pqAppendCmdQueueEntry(conn, entry);
+
+	return 1;
+
+sendFailed:
+	pqRecycleCmdQueueEntry(conn, entry);
+	/* error message should be set up already */
+	return 0;
+}
+
+/*
+ * PQsendQueryPrepared
+ *		Like PQsendQuery, but execute a previously prepared statement,
+ *		using extended query protocol so we can pass parameters
+ */
+int
+PQsendQueryPrepared(PGconn *conn,
+					const char *stmtName,
+					int nParams,
+					const char *const *paramValues,
+					const int *paramLengths,
+					const int *paramFormats,
+					int resultFormat)
+{
+	if (!PQsendQueryStart(conn, true))
+		return 0;
+
+	/* check the arguments */
+	if (!stmtName)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("statement name is a null pointer\n"));
+		return 0;
+	}
+	if (nParams < 0 || nParams > PQ_QUERY_PARAM_MAX_LIMIT)
+	{
+		appendPQExpBuffer(&conn->errorMessage,
+						  libpq_gettext("number of parameters must be between 0 and %d\n"),
+						  PQ_QUERY_PARAM_MAX_LIMIT);
+		return 0;
+	}
+
+	return PQsendQueryGuts(conn,
+						   NULL,	/* no command to parse */
+						   stmtName,
+						   nParams,
+						   NULL,	/* no param types */
+						   paramValues,
+						   paramLengths,
+						   paramFormats,
+						   resultFormat);
+}
+
+/*
+ * PQsendQueryStart
+ *	Common startup code for PQsendQuery and sibling routines
+ */
+static bool
+PQsendQueryStart(PGconn *conn, bool newQuery)
+{
+	if (!conn)
+		return false;
+
+	/*
+	 * If this is the beginning of a query cycle, reset the error state.
+	 * However, in pipeline mode with something already queued, the error
+	 * buffer belongs to that command and we shouldn't clear it.
+	 */
+	if (newQuery && conn->cmd_queue_head == NULL)
+		pqClearConnErrorState(conn);
+
+	/* Don't try to send if we know there's no live connection. */
+	if (conn->status != CONNECTION_OK)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("no connection to the server\n"));
+		return false;
+	}
+
+	/* Can't send while already busy, either, unless enqueuing for later */
+	if (conn->asyncStatus != PGASYNC_IDLE &&
+		conn->pipelineStatus == PQ_PIPELINE_OFF)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("another command is already in progress\n"));
+		return false;
+	}
+
+	if (conn->pipelineStatus != PQ_PIPELINE_OFF)
+	{
+		/*
+		 * When enqueuing commands we don't change much of the connection
+		 * state since it's already in use for the current command. The
+		 * connection state will get updated when pqPipelineProcessQueue()
+		 * advances to start processing the queued message.
+		 *
+		 * Just make sure we can safely enqueue given the current connection
+		 * state. We can enqueue behind another queue item, or behind a
+		 * non-queue command (one that sends its own sync), but we can't
+		 * enqueue if the connection is in a copy state.
+		 */
+		switch (conn->asyncStatus)
+		{
+			case PGASYNC_IDLE:
+			case PGASYNC_PIPELINE_IDLE:
+			case PGASYNC_READY:
+			case PGASYNC_READY_MORE:
+			case PGASYNC_BUSY:
+				/* ok to queue */
+				break;
+
+			case PGASYNC_COPY_IN:
+			case PGASYNC_COPY_OUT:
+			case PGASYNC_COPY_BOTH:
+				appendPQExpBufferStr(&conn->errorMessage,
+									 libpq_gettext("cannot queue commands during COPY\n"));
+				return false;
+		}
+	}
+	else
+	{
+		/*
+		 * This command's results will come in immediately. Initialize async
+		 * result-accumulation state
+		 */
+		pqClearAsyncResult(conn);
+
+		/* reset single-row processing mode */
+		conn->singleRowMode = false;
+	}
+
+	/* ready to send command message */
+	return true;
+}
+
+/*
+ * PQsendQueryGuts
+ *		Common code for sending a query with extended query protocol
+ *		PQsendQueryStart should be done already
+ *
+ * command may be NULL to indicate we use an already-prepared statement
+ */
+static int
+PQsendQueryGuts(PGconn *conn,
+				const char *command,
+				const char *stmtName,
+				int nParams,
+				const Oid *paramTypes,
+				const char *const *paramValues,
+				const int *paramLengths,
+				const int *paramFormats,
+				int resultFormat)
+{
+	int			i;
+	PGcmdQueueEntry *entry;
+
+	entry = pqAllocCmdQueueEntry(conn);
+	if (entry == NULL)
+		return 0;				/* error msg already set */
+
+	/*
+	 * We will send Parse (if needed), Bind, Describe Portal, Execute, Sync
+	 * (if not in pipeline mode), using specified statement name and the
+	 * unnamed portal.
+	 */
+
+	if (command)
+	{
+		/* construct the Parse message */
+		if (pqPutMsgStart('P', conn) < 0 ||
+			pqPuts(stmtName, conn) < 0 ||
+			pqPuts(command, conn) < 0)
+			goto sendFailed;
+		if (nParams > 0 && paramTypes)
+		{
+			if (pqPutInt(nParams, 2, conn) < 0)
+				goto sendFailed;
+			for (i = 0; i < nParams; i++)
+			{
+				if (pqPutInt(paramTypes[i], 4, conn) < 0)
+					goto sendFailed;
+			}
+		}
+		else
+		{
+			if (pqPutInt(0, 2, conn) < 0)
+				goto sendFailed;
+		}
+		if (pqPutMsgEnd(conn) < 0)
+			goto sendFailed;
+	}
+
+	/* Construct the Bind message */
+	if (pqPutMsgStart('B', conn) < 0 ||
+		pqPuts("", conn) < 0 ||
+		pqPuts(stmtName, conn) < 0)
+		goto sendFailed;
+
+	/* Send parameter formats */
+	if (nParams > 0 && paramFormats)
+	{
+		if (pqPutInt(nParams, 2, conn) < 0)
+			goto sendFailed;
+		for (i = 0; i < nParams; i++)
+		{
+			if (pqPutInt(paramFormats[i], 2, conn) < 0)
+				goto sendFailed;
+		}
+	}
+	else
+	{
+		if (pqPutInt(0, 2, conn) < 0)
+			goto sendFailed;
+	}
+
+	if (pqPutInt(nParams, 2, conn) < 0)
+		goto sendFailed;
+
+	/* Send parameters */
+	for (i = 0; i < nParams; i++)
+	{
+		if (paramValues && paramValues[i])
+		{
+			int			nbytes;
+
+			if (paramFormats && paramFormats[i] != 0)
+			{
+				/* binary parameter */
+				if (paramLengths)
+					nbytes = paramLengths[i];
+				else
+				{
+					appendPQExpBufferStr(&conn->errorMessage,
+										 libpq_gettext("length must be given for binary parameter\n"));
+					goto sendFailed;
+				}
+			}
+			else
+			{
+				/* text parameter, do not use paramLengths */
+				nbytes = strlen(paramValues[i]);
+			}
+			if (pqPutInt(nbytes, 4, conn) < 0 ||
+				pqPutnchar(paramValues[i], nbytes, conn) < 0)
+				goto sendFailed;
+		}
+		else
+		{
+			/* take the param as NULL */
+			if (pqPutInt(-1, 4, conn) < 0)
+				goto sendFailed;
+		}
+	}
+	if (pqPutInt(1, 2, conn) < 0 ||
+		pqPutInt(resultFormat, 2, conn))
+		goto sendFailed;
+	if (pqPutMsgEnd(conn) < 0)
+		goto sendFailed;
+
+	/* construct the Describe Portal message */
+	if (pqPutMsgStart('D', conn) < 0 ||
+		pqPutc('P', conn) < 0 ||
+		pqPuts("", conn) < 0 ||
+		pqPutMsgEnd(conn) < 0)
+		goto sendFailed;
+
+	/* construct the Execute message */
+	if (pqPutMsgStart('E', conn) < 0 ||
+		pqPuts("", conn) < 0 ||
+		pqPutInt(0, 4, conn) < 0 ||
+		pqPutMsgEnd(conn) < 0)
+		goto sendFailed;
+
+	/* construct the Sync message if not in pipeline mode */
+	if (conn->pipelineStatus == PQ_PIPELINE_OFF)
+	{
+		if (pqPutMsgStart('S', conn) < 0 ||
+			pqPutMsgEnd(conn) < 0)
+			goto sendFailed;
+	}
+
+	/* remember we are using extended query protocol */
+	entry->queryclass = PGQUERY_EXTENDED;
+
+	/* and remember the query text too, if possible */
+	/* if insufficient memory, query just winds up NULL */
+	if (command)
+		entry->query = strdup(command);
+
+	/*
+	 * Give the data a push (in pipeline mode, only if we're past the size
+	 * threshold).  In nonblock mode, don't complain if we're unable to send
+	 * it all; PQgetResult() will do any additional flushing needed.
+	 */
+	if (pqPipelineFlush(conn) < 0)
+		goto sendFailed;
+
+	/* OK, it's launched! */
+	pqAppendCmdQueueEntry(conn, entry);
+
+	return 1;
+
+sendFailed:
+	pqRecycleCmdQueueEntry(conn, entry);
+	/* error message should be set up already */
+	return 0;
+}
+
+/*
+ * Select row-by-row processing mode
+ */
+int
+PQsetSingleRowMode(PGconn *conn)
+{
+	/*
+	 * Only allow setting the flag when we have launched a query and not yet
+	 * received any results.
+	 */
+	if (!conn)
+		return 0;
+	if (conn->asyncStatus != PGASYNC_BUSY)
+		return 0;
+	if (!conn->cmd_queue_head ||
+		(conn->cmd_queue_head->queryclass != PGQUERY_SIMPLE &&
+		 conn->cmd_queue_head->queryclass != PGQUERY_EXTENDED))
+		return 0;
+	if (pgHavePendingResult(conn))
+		return 0;
+
+	/* OK, set flag */
+	conn->singleRowMode = true;
+	return 1;
+}
+
+/*
+ * Consume any available input from the backend
+ * 0 return: some kind of trouble
+ * 1 return: no problem
+ */
+int
+PQconsumeInput(PGconn *conn)
+{
+	if (!conn)
+		return 0;
+
+	/*
+	 * for non-blocking connections try to flush the send-queue, otherwise we
+	 * may never get a response for something that may not have already been
+	 * sent because it's in our write buffer!
+	 */
+	if (pqIsnonblocking(conn))
+	{
+		if (pqFlush(conn) < 0)
+			return 0;
+	}
+
+	/*
+	 * Load more data, if available. We do this no matter what state we are
+	 * in, since we are probably getting called because the application wants
+	 * to get rid of a read-select condition. Note that we will NOT block
+	 * waiting for more input.
+	 */
+	if (pqReadData(conn) < 0)
+		return 0;
+
+	/* Parsing of the data waits till later. */
+	return 1;
+}
+
+
+/*
+ * parseInput: if appropriate, parse input data from backend
+ * until input is exhausted or a stopping state is reached.
+ * Note that this function will NOT attempt to read more data from the backend.
+ */
+static void
+parseInput(PGconn *conn)
+{
+	pqParseInput3(conn);
+}
+
+/*
+ * PQisBusy
+ *	 Return true if PQgetResult would block waiting for input.
+ */
+
+int
+PQisBusy(PGconn *conn)
+{
+	if (!conn)
+		return false;
+
+	/* Parse any available data, if our state permits. */
+	parseInput(conn);
+
+	/*
+	 * PQgetResult will return immediately in all states except BUSY.  Also,
+	 * if we've detected read EOF and dropped the connection, we can expect
+	 * that PQgetResult will fail immediately.  Note that we do *not* check
+	 * conn->write_failed here --- once that's become set, we know we have
+	 * trouble, but we need to keep trying to read until we have a complete
+	 * server message or detect read EOF.
+	 */
+	return conn->asyncStatus == PGASYNC_BUSY && conn->status != CONNECTION_BAD;
+}
+
+/*
+ * PQgetResult
+ *	  Get the next PGresult produced by a query.  Returns NULL if no
+ *	  query work remains or an error has occurred (e.g. out of
+ *	  memory).
+ *
+ *	  In pipeline mode, once all the result of a query have been returned,
+ *	  PQgetResult returns NULL to let the user know that the next
+ *	  query is being processed.  At the end of the pipeline, returns a
+ *	  result with PQresultStatus(result) == PGRES_PIPELINE_SYNC.
+ */
+PGresult *
+PQgetResult(PGconn *conn)
+{
+	PGresult   *res;
+
+	if (!conn)
+		return NULL;
+
+	/* Parse any available data, if our state permits. */
+	parseInput(conn);
+
+	/* If not ready to return something, block until we are. */
+	while (conn->asyncStatus == PGASYNC_BUSY)
+	{
+		int			flushResult;
+
+		/*
+		 * If data remains unsent, send it.  Else we might be waiting for the
+		 * result of a command the backend hasn't even got yet.
+		 */
+		while ((flushResult = pqFlush(conn)) > 0)
+		{
+			if (pqWait(false, true, conn))
+			{
+				flushResult = -1;
+				break;
+			}
+		}
+
+		/*
+		 * Wait for some more data, and load it.  (Note: if the connection has
+		 * been lost, pqWait should return immediately because the socket
+		 * should be read-ready, either with the last server data or with an
+		 * EOF indication.  We expect therefore that this won't result in any
+		 * undue delay in reporting a previous write failure.)
+		 */
+		if (flushResult ||
+			pqWait(true, false, conn) ||
+			pqReadData(conn) < 0)
+		{
+			/* Report the error saved by pqWait or pqReadData */
+			pqSaveErrorResult(conn);
+			conn->asyncStatus = PGASYNC_IDLE;
+			return pqPrepareAsyncResult(conn);
+		}
+
+		/* Parse it. */
+		parseInput(conn);
+
+		/*
+		 * If we had a write error, but nothing above obtained a query result
+		 * or detected a read error, report the write error.
+		 */
+		if (conn->write_failed && conn->asyncStatus == PGASYNC_BUSY)
+		{
+			pqSaveWriteError(conn);
+			conn->asyncStatus = PGASYNC_IDLE;
+			return pqPrepareAsyncResult(conn);
+		}
+	}
+
+	/* Return the appropriate thing. */
+	switch (conn->asyncStatus)
+	{
+		case PGASYNC_IDLE:
+			res = NULL;			/* query is complete */
+			break;
+		case PGASYNC_PIPELINE_IDLE:
+			Assert(conn->pipelineStatus != PQ_PIPELINE_OFF);
+
+			/*
+			 * We're about to return the NULL that terminates the round of
+			 * results from the current query; prepare to send the results
+			 * of the next query, if any, when we're called next.  If there's
+			 * no next element in the command queue, this gets us in IDLE
+			 * state.
+			 */
+			pqPipelineProcessQueue(conn);
+			res = NULL;			/* query is complete */
+			break;
+
+		case PGASYNC_READY:
+
+			/*
+			 * For any query type other than simple query protocol, we advance
+			 * the command queue here.  This is because for simple query
+			 * protocol we can get the READY state multiple times before the
+			 * command is actually complete, since the command string can
+			 * contain many queries.  In simple query protocol, the queue
+			 * advance is done by fe-protocol3 when it receives ReadyForQuery.
+			 */
+			if (conn->cmd_queue_head &&
+				conn->cmd_queue_head->queryclass != PGQUERY_SIMPLE)
+				pqCommandQueueAdvance(conn);
+			res = pqPrepareAsyncResult(conn);
+			if (conn->pipelineStatus != PQ_PIPELINE_OFF)
+			{
+				/*
+				 * We're about to send the results of the current query.  Set
+				 * us idle now, and ...
+				 */
+				conn->asyncStatus = PGASYNC_PIPELINE_IDLE;
+
+				/*
+				 * ... in cases when we're sending a pipeline-sync result,
+				 * move queue processing forwards immediately, so that next
+				 * time we're called, we're prepared to return the next result
+				 * received from the server.  In all other cases, leave the
+				 * queue state change for next time, so that a terminating
+				 * NULL result is sent.
+				 *
+				 * (In other words: we don't return a NULL after a pipeline
+				 * sync.)
+				 */
+				if (res && res->resultStatus == PGRES_PIPELINE_SYNC)
+					pqPipelineProcessQueue(conn);
+			}
+			else
+			{
+				/* Set the state back to BUSY, allowing parsing to proceed. */
+				conn->asyncStatus = PGASYNC_BUSY;
+			}
+			break;
+		case PGASYNC_READY_MORE:
+			res = pqPrepareAsyncResult(conn);
+			/* Set the state back to BUSY, allowing parsing to proceed. */
+			conn->asyncStatus = PGASYNC_BUSY;
+			break;
+		case PGASYNC_COPY_IN:
+			res = getCopyResult(conn, PGRES_COPY_IN);
+			break;
+		case PGASYNC_COPY_OUT:
+			res = getCopyResult(conn, PGRES_COPY_OUT);
+			break;
+		case PGASYNC_COPY_BOTH:
+			res = getCopyResult(conn, PGRES_COPY_BOTH);
+			break;
+		default:
+			appendPQExpBuffer(&conn->errorMessage,
+							  libpq_gettext("unexpected asyncStatus: %d\n"),
+							  (int) conn->asyncStatus);
+			pqSaveErrorResult(conn);
+			conn->asyncStatus = PGASYNC_IDLE;	/* try to restore valid state */
+			res = pqPrepareAsyncResult(conn);
+			break;
+	}
+
+	/* Time to fire PGEVT_RESULTCREATE events, if there are any */
+	if (res && res->nEvents > 0)
+		(void) PQfireResultCreateEvents(conn, res);
+
+	return res;
+}
+
+/*
+ * getCopyResult
+ *	  Helper for PQgetResult: generate result for COPY-in-progress cases
+ */
+static PGresult *
+getCopyResult(PGconn *conn, ExecStatusType copytype)
+{
+	/*
+	 * If the server connection has been lost, don't pretend everything is
+	 * hunky-dory; instead return a PGRES_FATAL_ERROR result, and reset the
+	 * asyncStatus to idle (corresponding to what we'd do if we'd detected I/O
+	 * error in the earlier steps in PQgetResult).  The text returned in the
+	 * result is whatever is in conn->errorMessage; we hope that was filled
+	 * with something relevant when the lost connection was detected.
+	 */
+	if (conn->status != CONNECTION_OK)
+	{
+		pqSaveErrorResult(conn);
+		conn->asyncStatus = PGASYNC_IDLE;
+		return pqPrepareAsyncResult(conn);
+	}
+
+	/* If we have an async result for the COPY, return that */
+	if (conn->result && conn->result->resultStatus == copytype)
+		return pqPrepareAsyncResult(conn);
+
+	/* Otherwise, invent a suitable PGresult */
+	return PQmakeEmptyPGresult(conn, copytype);
+}
+
+
+/*
+ * PQexec
+ *	  send a query to the backend and package up the result in a PGresult
+ *
+ * If the query was not even sent, return NULL; conn->errorMessage is set to
+ * a relevant message.
+ * If the query was sent, a new PGresult is returned (which could indicate
+ * either success or failure).
+ * The user is responsible for freeing the PGresult via PQclear()
+ * when done with it.
+ */
+PGresult *
+PQexec(PGconn *conn, const char *query)
+{
+	if (!PQexecStart(conn))
+		return NULL;
+	if (!PQsendQuery(conn, query))
+		return NULL;
+	return PQexecFinish(conn);
+}
+
+/*
+ * PQexecParams
+ *		Like PQexec, but use extended query protocol so we can pass parameters
+ */
+PGresult *
+PQexecParams(PGconn *conn,
+			 const char *command,
+			 int nParams,
+			 const Oid *paramTypes,
+			 const char *const *paramValues,
+			 const int *paramLengths,
+			 const int *paramFormats,
+			 int resultFormat)
+{
+	if (!PQexecStart(conn))
+		return NULL;
+	if (!PQsendQueryParams(conn, command,
+						   nParams, paramTypes, paramValues, paramLengths,
+						   paramFormats, resultFormat))
+		return NULL;
+	return PQexecFinish(conn);
+}
+
+/*
+ * PQprepare
+ *	  Creates a prepared statement by issuing a Parse message.
+ *
+ * If the query was not even sent, return NULL; conn->errorMessage is set to
+ * a relevant message.
+ * If the query was sent, a new PGresult is returned (which could indicate
+ * either success or failure).
+ * The user is responsible for freeing the PGresult via PQclear()
+ * when done with it.
+ */
+PGresult *
+PQprepare(PGconn *conn,
+		  const char *stmtName, const char *query,
+		  int nParams, const Oid *paramTypes)
+{
+	if (!PQexecStart(conn))
+		return NULL;
+	if (!PQsendPrepare(conn, stmtName, query, nParams, paramTypes))
+		return NULL;
+	return PQexecFinish(conn);
+}
+
+/*
+ * PQexecPrepared
+ *		Like PQexec, but execute a previously prepared statement,
+ *		using extended query protocol so we can pass parameters
+ */
+PGresult *
+PQexecPrepared(PGconn *conn,
+			   const char *stmtName,
+			   int nParams,
+			   const char *const *paramValues,
+			   const int *paramLengths,
+			   const int *paramFormats,
+			   int resultFormat)
+{
+	if (!PQexecStart(conn))
+		return NULL;
+	if (!PQsendQueryPrepared(conn, stmtName,
+							 nParams, paramValues, paramLengths,
+							 paramFormats, resultFormat))
+		return NULL;
+	return PQexecFinish(conn);
+}
+
+/*
+ * Common code for PQexec and sibling routines: prepare to send command
+ */
+static bool
+PQexecStart(PGconn *conn)
+{
+	PGresult   *result;
+
+	if (!conn)
+		return false;
+
+	/*
+	 * Since this is the beginning of a query cycle, reset the error state.
+	 * However, in pipeline mode with something already queued, the error
+	 * buffer belongs to that command and we shouldn't clear it.
+	 */
+	if (conn->cmd_queue_head == NULL)
+		pqClearConnErrorState(conn);
+
+	if (conn->pipelineStatus != PQ_PIPELINE_OFF)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("synchronous command execution functions are not allowed in pipeline mode\n"));
+		return false;
+	}
+
+	/*
+	 * Silently discard any prior query result that application didn't eat.
+	 * This is probably poor design, but it's here for backward compatibility.
+	 */
+	while ((result = PQgetResult(conn)) != NULL)
+	{
+		ExecStatusType resultStatus = result->resultStatus;
+
+		PQclear(result);		/* only need its status */
+		if (resultStatus == PGRES_COPY_IN)
+		{
+			/* get out of a COPY IN state */
+			if (PQputCopyEnd(conn,
+							 libpq_gettext("COPY terminated by new PQexec")) < 0)
+				return false;
+			/* keep waiting to swallow the copy's failure message */
+		}
+		else if (resultStatus == PGRES_COPY_OUT)
+		{
+			/*
+			 * Get out of a COPY OUT state: we just switch back to BUSY and
+			 * allow the remaining COPY data to be dropped on the floor.
+			 */
+			conn->asyncStatus = PGASYNC_BUSY;
+			/* keep waiting to swallow the copy's completion message */
+		}
+		else if (resultStatus == PGRES_COPY_BOTH)
+		{
+			/* We don't allow PQexec during COPY BOTH */
+			appendPQExpBufferStr(&conn->errorMessage,
+								 libpq_gettext("PQexec not allowed during COPY BOTH\n"));
+			return false;
+		}
+		/* check for loss of connection, too */
+		if (conn->status == CONNECTION_BAD)
+			return false;
+	}
+
+	/* OK to send a command */
+	return true;
+}
+
+/*
+ * Common code for PQexec and sibling routines: wait for command result
+ */
+static PGresult *
+PQexecFinish(PGconn *conn)
+{
+	PGresult   *result;
+	PGresult   *lastResult;
+
+	/*
+	 * For backwards compatibility, return the last result if there are more
+	 * than one.  (We used to have logic here to concatenate successive error
+	 * messages, but now that happens automatically, since conn->errorMessage
+	 * will continue to accumulate errors throughout this loop.)
+	 *
+	 * We have to stop if we see copy in/out/both, however. We will resume
+	 * parsing after application performs the data transfer.
+	 *
+	 * Also stop if the connection is lost (else we'll loop infinitely).
+	 */
+	lastResult = NULL;
+	while ((result = PQgetResult(conn)) != NULL)
+	{
+		if (lastResult)
+			PQclear(lastResult);
+		lastResult = result;
+		if (result->resultStatus == PGRES_COPY_IN ||
+			result->resultStatus == PGRES_COPY_OUT ||
+			result->resultStatus == PGRES_COPY_BOTH ||
+			conn->status == CONNECTION_BAD)
+			break;
+	}
+
+	return lastResult;
+}
+
+/*
+ * PQdescribePrepared
+ *	  Obtain information about a previously prepared statement
+ *
+ * If the query was not even sent, return NULL; conn->errorMessage is set to
+ * a relevant message.
+ * If the query was sent, a new PGresult is returned (which could indicate
+ * either success or failure).  On success, the PGresult contains status
+ * PGRES_COMMAND_OK, and its parameter and column-heading fields describe
+ * the statement's inputs and outputs respectively.
+ * The user is responsible for freeing the PGresult via PQclear()
+ * when done with it.
+ */
+PGresult *
+PQdescribePrepared(PGconn *conn, const char *stmt)
+{
+	if (!PQexecStart(conn))
+		return NULL;
+	if (!PQsendDescribe(conn, 'S', stmt))
+		return NULL;
+	return PQexecFinish(conn);
+}
+
+/*
+ * PQdescribePortal
+ *	  Obtain information about a previously created portal
+ *
+ * This is much like PQdescribePrepared, except that no parameter info is
+ * returned.  Note that at the moment, libpq doesn't really expose portals
+ * to the client; but this can be used with a portal created by a SQL
+ * DECLARE CURSOR command.
+ */
+PGresult *
+PQdescribePortal(PGconn *conn, const char *portal)
+{
+	if (!PQexecStart(conn))
+		return NULL;
+	if (!PQsendDescribe(conn, 'P', portal))
+		return NULL;
+	return PQexecFinish(conn);
+}
+
+/*
+ * PQsendDescribePrepared
+ *	 Submit a Describe Statement command, but don't wait for it to finish
+ *
+ * Returns: 1 if successfully submitted
+ *			0 if error (conn->errorMessage is set)
+ */
+int
+PQsendDescribePrepared(PGconn *conn, const char *stmt)
+{
+	return PQsendDescribe(conn, 'S', stmt);
+}
+
+/*
+ * PQsendDescribePortal
+ *	 Submit a Describe Portal command, but don't wait for it to finish
+ *
+ * Returns: 1 if successfully submitted
+ *			0 if error (conn->errorMessage is set)
+ */
+int
+PQsendDescribePortal(PGconn *conn, const char *portal)
+{
+	return PQsendDescribe(conn, 'P', portal);
+}
+
+/*
+ * PQsendDescribe
+ *	 Common code to send a Describe command
+ *
+ * Available options for desc_type are
+ *	 'S' to describe a prepared statement; or
+ *	 'P' to describe a portal.
+ * Returns 1 on success and 0 on failure.
+ */
+static int
+PQsendDescribe(PGconn *conn, char desc_type, const char *desc_target)
+{
+	PGcmdQueueEntry *entry = NULL;
+
+	/* Treat null desc_target as empty string */
+	if (!desc_target)
+		desc_target = "";
+
+	if (!PQsendQueryStart(conn, true))
+		return 0;
+
+	entry = pqAllocCmdQueueEntry(conn);
+	if (entry == NULL)
+		return 0;				/* error msg already set */
+
+	/* construct the Describe message */
+	if (pqPutMsgStart('D', conn) < 0 ||
+		pqPutc(desc_type, conn) < 0 ||
+		pqPuts(desc_target, conn) < 0 ||
+		pqPutMsgEnd(conn) < 0)
+		goto sendFailed;
+
+	/* construct the Sync message */
+	if (conn->pipelineStatus == PQ_PIPELINE_OFF)
+	{
+		if (pqPutMsgStart('S', conn) < 0 ||
+			pqPutMsgEnd(conn) < 0)
+			goto sendFailed;
+	}
+
+	/* remember we are doing a Describe */
+	entry->queryclass = PGQUERY_DESCRIBE;
+
+	/*
+	 * Give the data a push (in pipeline mode, only if we're past the size
+	 * threshold).  In nonblock mode, don't complain if we're unable to send
+	 * it all; PQgetResult() will do any additional flushing needed.
+	 */
+	if (pqPipelineFlush(conn) < 0)
+		goto sendFailed;
+
+	/* OK, it's launched! */
+	pqAppendCmdQueueEntry(conn, entry);
+
+	return 1;
+
+sendFailed:
+	pqRecycleCmdQueueEntry(conn, entry);
+	/* error message should be set up already */
+	return 0;
+}
+
+/*
+ * PQnotifies
+ *	  returns a PGnotify* structure of the latest async notification
+ * that has not yet been handled
+ *
+ * returns NULL, if there is currently
+ * no unhandled async notification from the backend
+ *
+ * the CALLER is responsible for FREE'ing the structure returned
+ *
+ * Note that this function does not read any new data from the socket;
+ * so usually, caller should call PQconsumeInput() first.
+ */
+PGnotify *
+PQnotifies(PGconn *conn)
+{
+	PGnotify   *event;
+
+	if (!conn)
+		return NULL;
+
+	/* Parse any available data to see if we can extract NOTIFY messages. */
+	parseInput(conn);
+
+	event = conn->notifyHead;
+	if (event)
+	{
+		conn->notifyHead = event->next;
+		if (!conn->notifyHead)
+			conn->notifyTail = NULL;
+		event->next = NULL;		/* don't let app see the internal state */
+	}
+	return event;
+}
+
+/*
+ * PQputCopyData - send some data to the backend during COPY IN or COPY BOTH
+ *
+ * Returns 1 if successful, 0 if data could not be sent (only possible
+ * in nonblock mode), or -1 if an error occurs.
+ */
+int
+PQputCopyData(PGconn *conn, const char *buffer, int nbytes)
+{
+	if (!conn)
+		return -1;
+	if (conn->asyncStatus != PGASYNC_COPY_IN &&
+		conn->asyncStatus != PGASYNC_COPY_BOTH)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("no COPY in progress\n"));
+		return -1;
+	}
+
+	/*
+	 * Process any NOTICE or NOTIFY messages that might be pending in the
+	 * input buffer.  Since the server might generate many notices during the
+	 * COPY, we want to clean those out reasonably promptly to prevent
+	 * indefinite expansion of the input buffer.  (Note: the actual read of
+	 * input data into the input buffer happens down inside pqSendSome, but
+	 * it's not authorized to get rid of the data again.)
+	 */
+	parseInput(conn);
+
+	if (nbytes > 0)
+	{
+		/*
+		 * Try to flush any previously sent data in preference to growing the
+		 * output buffer.  If we can't enlarge the buffer enough to hold the
+		 * data, return 0 in the nonblock case, else hard error. (For
+		 * simplicity, always assume 5 bytes of overhead.)
+		 */
+		if ((conn->outBufSize - conn->outCount - 5) < nbytes)
+		{
+			if (pqFlush(conn) < 0)
+				return -1;
+			if (pqCheckOutBufferSpace(conn->outCount + 5 + (size_t) nbytes,
+									  conn))
+				return pqIsnonblocking(conn) ? 0 : -1;
+		}
+		/* Send the data (too simple to delegate to fe-protocol files) */
+		if (pqPutMsgStart('d', conn) < 0 ||
+			pqPutnchar(buffer, nbytes, conn) < 0 ||
+			pqPutMsgEnd(conn) < 0)
+			return -1;
+	}
+	return 1;
+}
+
+/*
+ * PQputCopyEnd - send EOF indication to the backend during COPY IN
+ *
+ * After calling this, use PQgetResult() to check command completion status.
+ *
+ * Returns 1 if successful, 0 if data could not be sent (only possible
+ * in nonblock mode), or -1 if an error occurs.
+ */
+int
+PQputCopyEnd(PGconn *conn, const char *errormsg)
+{
+	if (!conn)
+		return -1;
+	if (conn->asyncStatus != PGASYNC_COPY_IN &&
+		conn->asyncStatus != PGASYNC_COPY_BOTH)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("no COPY in progress\n"));
+		return -1;
+	}
+
+	/*
+	 * Send the COPY END indicator.  This is simple enough that we don't
+	 * bother delegating it to the fe-protocol files.
+	 */
+	if (errormsg)
+	{
+		/* Send COPY FAIL */
+		if (pqPutMsgStart('f', conn) < 0 ||
+			pqPuts(errormsg, conn) < 0 ||
+			pqPutMsgEnd(conn) < 0)
+			return -1;
+	}
+	else
+	{
+		/* Send COPY DONE */
+		if (pqPutMsgStart('c', 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->cmd_queue_head &&
+		conn->cmd_queue_head->queryclass != PGQUERY_SIMPLE)
+	{
+		if (pqPutMsgStart('S', conn) < 0 ||
+			pqPutMsgEnd(conn) < 0)
+			return -1;
+	}
+
+	/* Return to active duty */
+	if (conn->asyncStatus == PGASYNC_COPY_BOTH)
+		conn->asyncStatus = PGASYNC_COPY_OUT;
+	else
+		conn->asyncStatus = PGASYNC_BUSY;
+
+	/* Try to flush data */
+	if (pqFlush(conn) < 0)
+		return -1;
+
+	return 1;
+}
+
+/*
+ * PQgetCopyData - read a row of data from the backend during COPY OUT
+ * or COPY BOTH
+ *
+ * If successful, sets *buffer to point to a malloc'd row of data, and
+ * returns row length (always > 0) as result.
+ * Returns 0 if no row available yet (only possible if async is true),
+ * -1 if end of copy (consult PQgetResult), or -2 if error (consult
+ * PQerrorMessage).
+ */
+int
+PQgetCopyData(PGconn *conn, char **buffer, int async)
+{
+	*buffer = NULL;				/* for all failure cases */
+	if (!conn)
+		return -2;
+	if (conn->asyncStatus != PGASYNC_COPY_OUT &&
+		conn->asyncStatus != PGASYNC_COPY_BOTH)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("no COPY in progress\n"));
+		return -2;
+	}
+	return pqGetCopyData3(conn, buffer, async);
+}
+
+/*
+ * PQgetline - gets a newline-terminated string from the backend.
+ *
+ * Chiefly here so that applications can use "COPY <rel> to stdout"
+ * and read the output string.  Returns a null-terminated string in s.
+ *
+ * XXX this routine is now deprecated, because it can't handle binary data.
+ * If called during a COPY BINARY we return EOF.
+ *
+ * PQgetline reads up to maxlen-1 characters (like fgets(3)) but strips
+ * the terminating \n (like gets(3)).
+ *
+ * CAUTION: the caller is responsible for detecting the end-of-copy signal
+ * (a line containing just "\.") when using this routine.
+ *
+ * RETURNS:
+ *		EOF if error (eg, invalid arguments are given)
+ *		0 if EOL is reached (i.e., \n has been read)
+ *				(this is required for backward-compatibility -- this
+ *				 routine used to always return EOF or 0, assuming that
+ *				 the line ended within maxlen bytes.)
+ *		1 in other cases (i.e., the buffer was filled before \n is reached)
+ */
+int
+PQgetline(PGconn *conn, char *s, int maxlen)
+{
+	if (!s || maxlen <= 0)
+		return EOF;
+	*s = '\0';
+	/* maxlen must be at least 3 to hold the \. terminator! */
+	if (maxlen < 3)
+		return EOF;
+
+	if (!conn)
+		return EOF;
+
+	return pqGetline3(conn, s, maxlen);
+}
+
+/*
+ * PQgetlineAsync - gets a COPY data row without blocking.
+ *
+ * This routine is for applications that want to do "COPY <rel> to stdout"
+ * asynchronously, that is without blocking.  Having issued the COPY command
+ * and gotten a PGRES_COPY_OUT response, the app should call PQconsumeInput
+ * and this routine until the end-of-data signal is detected.  Unlike
+ * PQgetline, this routine takes responsibility for detecting end-of-data.
+ *
+ * On each call, PQgetlineAsync will return data if a complete data row
+ * is available in libpq's input buffer.  Otherwise, no data is returned
+ * until the rest of the row arrives.
+ *
+ * If -1 is returned, the end-of-data signal has been recognized (and removed
+ * from libpq's input buffer).  The caller *must* next call PQendcopy and
+ * then return to normal processing.
+ *
+ * RETURNS:
+ *	 -1    if the end-of-copy-data marker has been recognized
+ *	 0	   if no data is available
+ *	 >0    the number of bytes returned.
+ *
+ * The data returned will not extend beyond a data-row boundary.  If possible
+ * a whole row will be returned at one time.  But if the buffer offered by
+ * the caller is too small to hold a row sent by the backend, then a partial
+ * data row will be returned.  In text mode this can be detected by testing
+ * whether the last returned byte is '\n' or not.
+ *
+ * The returned data is *not* null-terminated.
+ */
+
+int
+PQgetlineAsync(PGconn *conn, char *buffer, int bufsize)
+{
+	if (!conn)
+		return -1;
+
+	return pqGetlineAsync3(conn, buffer, bufsize);
+}
+
+/*
+ * PQputline -- sends a string to the backend during COPY IN.
+ * Returns 0 if OK, EOF if not.
+ *
+ * This is deprecated primarily because the return convention doesn't allow
+ * caller to tell the difference between a hard error and a nonblock-mode
+ * send failure.
+ */
+int
+PQputline(PGconn *conn, const char *s)
+{
+	return PQputnbytes(conn, s, strlen(s));
+}
+
+/*
+ * PQputnbytes -- like PQputline, but buffer need not be null-terminated.
+ * Returns 0 if OK, EOF if not.
+ */
+int
+PQputnbytes(PGconn *conn, const char *buffer, int nbytes)
+{
+	if (PQputCopyData(conn, buffer, nbytes) > 0)
+		return 0;
+	else
+		return EOF;
+}
+
+/*
+ * PQendcopy
+ *		After completing the data transfer portion of a copy in/out,
+ *		the application must call this routine to finish the command protocol.
+ *
+ * This is deprecated; it's cleaner to use PQgetResult to get the transfer
+ * status.
+ *
+ * RETURNS:
+ *		0 on success
+ *		1 on failure
+ */
+int
+PQendcopy(PGconn *conn)
+{
+	if (!conn)
+		return 0;
+
+	return pqEndcopy3(conn);
+}
+
+
+/* ----------------
+ *		PQfn -	Send a function call to the POSTGRES backend.
+ *
+ *		conn			: backend connection
+ *		fnid			: OID of function to be called
+ *		result_buf		: pointer to result buffer
+ *		result_len		: actual length of result is returned here
+ *		result_is_int	: If the result is an integer, this must be 1,
+ *						  otherwise this should be 0
+ *		args			: pointer to an array of function arguments
+ *						  (each has length, if integer, and value/pointer)
+ *		nargs			: # of arguments in args array.
+ *
+ * RETURNS
+ *		PGresult with status = PGRES_COMMAND_OK if successful.
+ *			*result_len is > 0 if there is a return value, 0 if not.
+ *		PGresult with status = PGRES_FATAL_ERROR if backend returns an error.
+ *		NULL on communications failure.  conn->errorMessage will be set.
+ * ----------------
+ */
+
+PGresult *
+PQfn(PGconn *conn,
+	 int fnid,
+	 int *result_buf,
+	 int *result_len,
+	 int result_is_int,
+	 const PQArgBlock *args,
+	 int nargs)
+{
+	*result_len = 0;
+
+	if (!conn)
+		return NULL;
+
+	/*
+	 * Since this is the beginning of a query cycle, reset the error state.
+	 * However, in pipeline mode with something already queued, the error
+	 * buffer belongs to that command and we shouldn't clear it.
+	 */
+	if (conn->cmd_queue_head == NULL)
+		pqClearConnErrorState(conn);
+
+	if (conn->pipelineStatus != PQ_PIPELINE_OFF)
+	{
+		appendPQExpBuffer(&conn->errorMessage,
+						  libpq_gettext("%s not allowed in pipeline mode\n"),
+						  "PQfn");
+		return NULL;
+	}
+
+	if (conn->sock == PGINVALID_SOCKET || conn->asyncStatus != PGASYNC_IDLE ||
+		pgHavePendingResult(conn))
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("connection in wrong state\n"));
+		return NULL;
+	}
+
+	return pqFunctionCall3(conn, fnid,
+						   result_buf, result_len,
+						   result_is_int,
+						   args, nargs);
+}
+
+/* ====== Pipeline mode support ======== */
+
+/*
+ * PQenterPipelineMode
+ *		Put an idle connection in pipeline mode.
+ *
+ * Returns 1 on success. On failure, errorMessage is set and 0 is returned.
+ *
+ * Commands submitted after this can be pipelined on the connection;
+ * there's no requirement to wait for one to finish before the next is
+ * dispatched.
+ *
+ * Queuing of a new query or syncing during COPY is not allowed.
+ *
+ * A set of commands is terminated by a PQpipelineSync.  Multiple sync
+ * points can be established while in pipeline mode.  Pipeline mode can
+ * be exited by calling PQexitPipelineMode() once all results are processed.
+ *
+ * This doesn't actually send anything on the wire, it just puts libpq
+ * into a state where it can pipeline work.
+ */
+int
+PQenterPipelineMode(PGconn *conn)
+{
+	if (!conn)
+		return 0;
+
+	/* succeed with no action if already in pipeline mode */
+	if (conn->pipelineStatus != PQ_PIPELINE_OFF)
+		return 1;
+
+	if (conn->asyncStatus != PGASYNC_IDLE)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("cannot enter pipeline mode, connection not idle\n"));
+		return 0;
+	}
+
+	conn->pipelineStatus = PQ_PIPELINE_ON;
+
+	return 1;
+}
+
+/*
+ * PQexitPipelineMode
+ *		End pipeline mode and return to normal command mode.
+ *
+ * Returns 1 in success (pipeline mode successfully ended, or not in pipeline
+ * mode).
+ *
+ * Returns 0 if in pipeline mode and cannot be ended yet.  Error message will
+ * be set.
+ */
+int
+PQexitPipelineMode(PGconn *conn)
+{
+	if (!conn)
+		return 0;
+
+	if (conn->pipelineStatus == PQ_PIPELINE_OFF &&
+		(conn->asyncStatus == PGASYNC_IDLE ||
+		 conn->asyncStatus == PGASYNC_PIPELINE_IDLE) &&
+		conn->cmd_queue_head == NULL)
+		return 1;
+
+	switch (conn->asyncStatus)
+	{
+		case PGASYNC_READY:
+		case PGASYNC_READY_MORE:
+			/* there are some uncollected results */
+			appendPQExpBufferStr(&conn->errorMessage,
+								 libpq_gettext("cannot exit pipeline mode with uncollected results\n"));
+			return 0;
+
+		case PGASYNC_BUSY:
+			appendPQExpBufferStr(&conn->errorMessage,
+								 libpq_gettext("cannot exit pipeline mode while busy\n"));
+			return 0;
+
+		case PGASYNC_IDLE:
+		case PGASYNC_PIPELINE_IDLE:
+			/* OK */
+			break;
+
+		case PGASYNC_COPY_IN:
+		case PGASYNC_COPY_OUT:
+		case PGASYNC_COPY_BOTH:
+			appendPQExpBufferStr(&conn->errorMessage,
+								 libpq_gettext("cannot exit pipeline mode while in COPY\n"));
+	}
+
+	/* still work to process */
+	if (conn->cmd_queue_head != NULL)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("cannot exit pipeline mode with uncollected results\n"));
+		return 0;
+	}
+
+	conn->pipelineStatus = PQ_PIPELINE_OFF;
+	conn->asyncStatus = PGASYNC_IDLE;
+
+	/* Flush any pending data in out buffer */
+	if (pqFlush(conn) < 0)
+		return 0;				/* error message is setup already */
+	return 1;
+}
+
+/*
+ * pqCommandQueueAdvance
+ *		Remove one query from the command queue, when we receive
+ *		all results from the server that pertain to it.
+ */
+void
+pqCommandQueueAdvance(PGconn *conn)
+{
+	PGcmdQueueEntry *prevquery;
+
+	if (conn->cmd_queue_head == NULL)
+		return;
+
+	/* delink from queue */
+	prevquery = conn->cmd_queue_head;
+	conn->cmd_queue_head = conn->cmd_queue_head->next;
+
+	/* If the queue is now empty, reset the tail too */
+	if (conn->cmd_queue_head == NULL)
+		conn->cmd_queue_tail = NULL;
+
+	/* and make it recyclable */
+	prevquery->next = NULL;
+	pqRecycleCmdQueueEntry(conn, prevquery);
+}
+
+/*
+ * pqPipelineProcessQueue: subroutine for PQgetResult
+ *		In pipeline mode, start processing the results of the next query in the queue.
+ */
+static void
+pqPipelineProcessQueue(PGconn *conn)
+{
+	switch (conn->asyncStatus)
+	{
+		case PGASYNC_COPY_IN:
+		case PGASYNC_COPY_OUT:
+		case PGASYNC_COPY_BOTH:
+		case PGASYNC_READY:
+		case PGASYNC_READY_MORE:
+		case PGASYNC_BUSY:
+			/* client still has to process current query or results */
+			return;
+
+		case PGASYNC_IDLE:
+			/*
+			 * If we're in IDLE mode and there's some command in the queue,
+			 * get us into PIPELINE_IDLE mode and process normally.  Otherwise
+			 * there's nothing for us to do.
+			 */
+			if (conn->cmd_queue_head != NULL)
+			{
+				conn->asyncStatus = PGASYNC_PIPELINE_IDLE;
+				break;
+			}
+			return;
+
+		case PGASYNC_PIPELINE_IDLE:
+			Assert(conn->pipelineStatus != PQ_PIPELINE_OFF);
+			/* next query please */
+			break;
+	}
+
+	/*
+	 * Reset single-row processing mode.  (Client has to set it up for each
+	 * query, if desired.)
+	 */
+	conn->singleRowMode = false;
+
+	/*
+	 * If there are no further commands to process in the queue, get us in
+	 * "real idle" mode now.
+	 */
+	if (conn->cmd_queue_head == NULL)
+	{
+		conn->asyncStatus = PGASYNC_IDLE;
+		return;
+	}
+
+	/*
+	 * Reset the error state.  This and the next couple of steps correspond to
+	 * what PQsendQueryStart didn't do for this query.
+	 */
+	pqClearConnErrorState(conn);
+
+	/* Initialize async result-accumulation state */
+	pqClearAsyncResult(conn);
+
+	if (conn->pipelineStatus == PQ_PIPELINE_ABORTED &&
+		conn->cmd_queue_head->queryclass != PGQUERY_SYNC)
+	{
+		/*
+		 * In an aborted pipeline we don't get anything from the server for
+		 * each result; we're just discarding commands from the queue until we
+		 * get to the next sync from the server.
+		 *
+		 * The PGRES_PIPELINE_ABORTED results tell the client that its queries
+		 * got aborted.
+		 */
+		conn->result = PQmakeEmptyPGresult(conn, PGRES_PIPELINE_ABORTED);
+		if (!conn->result)
+		{
+			appendPQExpBufferStr(&conn->errorMessage,
+								 libpq_gettext("out of memory\n"));
+			pqSaveErrorResult(conn);
+			return;
+		}
+		conn->asyncStatus = PGASYNC_READY;
+	}
+	else
+	{
+		/* allow parsing to continue */
+		conn->asyncStatus = PGASYNC_BUSY;
+	}
+}
+
+/*
+ * PQpipelineSync
+ *		Send a Sync message as part of a pipeline, and flush to server
+ *
+ * It's legal to start submitting more commands in the pipeline immediately,
+ * without waiting for the results of the current pipeline. There's no need to
+ * end pipeline mode and start it again.
+ *
+ * If a command in a pipeline fails, every subsequent command up to and including
+ * the result to the Sync message sent by PQpipelineSync gets set to
+ * PGRES_PIPELINE_ABORTED state. If the whole pipeline is processed without
+ * error, a PGresult with PGRES_PIPELINE_SYNC is produced.
+ *
+ * Queries can already have been sent before PQpipelineSync is called, but
+ * PQpipelineSync need to be called before retrieving command results.
+ *
+ * The connection will remain in pipeline mode and unavailable for new
+ * synchronous command execution functions until all results from the pipeline
+ * are processed by the client.
+ */
+int
+PQpipelineSync(PGconn *conn)
+{
+	PGcmdQueueEntry *entry;
+
+	if (!conn)
+		return 0;
+
+	if (conn->pipelineStatus == PQ_PIPELINE_OFF)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("cannot send pipeline when not in pipeline mode\n"));
+		return 0;
+	}
+
+	switch (conn->asyncStatus)
+	{
+		case PGASYNC_COPY_IN:
+		case PGASYNC_COPY_OUT:
+		case PGASYNC_COPY_BOTH:
+			/* should be unreachable */
+			appendPQExpBufferStr(&conn->errorMessage,
+								 "internal error: cannot send pipeline while in COPY\n");
+			return 0;
+		case PGASYNC_READY:
+		case PGASYNC_READY_MORE:
+		case PGASYNC_BUSY:
+		case PGASYNC_IDLE:
+		case PGASYNC_PIPELINE_IDLE:
+			/* OK to send sync */
+			break;
+	}
+
+	entry = pqAllocCmdQueueEntry(conn);
+	if (entry == NULL)
+		return 0;				/* error msg already set */
+
+	entry->queryclass = PGQUERY_SYNC;
+	entry->query = NULL;
+
+	/* construct the Sync message */
+	if (pqPutMsgStart('S', conn) < 0 ||
+		pqPutMsgEnd(conn) < 0)
+		goto sendFailed;
+
+	/*
+	 * Give the data a push.  In nonblock mode, don't complain if we're unable
+	 * to send it all; PQgetResult() will do any additional flushing needed.
+	 */
+	if (PQflush(conn) < 0)
+		goto sendFailed;
+
+	/* OK, it's launched! */
+	pqAppendCmdQueueEntry(conn, entry);
+
+	return 1;
+
+sendFailed:
+	pqRecycleCmdQueueEntry(conn, entry);
+	/* error message should be set up already */
+	return 0;
+}
+
+/*
+ * PQsendFlushRequest
+ *		Send request for server to flush its buffer.  Useful in pipeline
+ *		mode when a sync point is not desired.
+ */
+int
+PQsendFlushRequest(PGconn *conn)
+{
+	if (!conn)
+		return 0;
+
+	/* Don't try to send if we know there's no live connection. */
+	if (conn->status != CONNECTION_OK)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("no connection to the server\n"));
+		return 0;
+	}
+
+	/* Can't send while already busy, either, unless enqueuing for later */
+	if (conn->asyncStatus != PGASYNC_IDLE &&
+		conn->pipelineStatus == PQ_PIPELINE_OFF)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("another command is already in progress\n"));
+		return 0;
+	}
+
+	if (pqPutMsgStart('H', conn) < 0 ||
+		pqPutMsgEnd(conn) < 0)
+	{
+		return 0;
+	}
+
+	return 1;
+}
+
+/* ====== accessor funcs for PGresult ======== */
+
+ExecStatusType
+PQresultStatus(const PGresult *res)
+{
+	if (!res)
+		return PGRES_FATAL_ERROR;
+	return res->resultStatus;
+}
+
+char *
+PQresStatus(ExecStatusType status)
+{
+	if ((unsigned int) status >= lengthof(pgresStatus))
+		return libpq_gettext("invalid ExecStatusType code");
+	return pgresStatus[status];
+}
+
+char *
+PQresultErrorMessage(const PGresult *res)
+{
+	if (!res || !res->errMsg)
+		return "";
+	return res->errMsg;
+}
+
+char *
+PQresultVerboseErrorMessage(const PGresult *res,
+							PGVerbosity verbosity,
+							PGContextVisibility show_context)
+{
+	PQExpBufferData workBuf;
+
+	/*
+	 * Because the caller is expected to free the result string, we must
+	 * strdup any constant result.  We use plain strdup and document that
+	 * callers should expect NULL if out-of-memory.
+	 */
+	if (!res ||
+		(res->resultStatus != PGRES_FATAL_ERROR &&
+		 res->resultStatus != PGRES_NONFATAL_ERROR))
+		return strdup(libpq_gettext("PGresult is not an error result\n"));
+
+	initPQExpBuffer(&workBuf);
+
+	pqBuildErrorMessage3(&workBuf, res, verbosity, show_context);
+
+	/* If insufficient memory to format the message, fail cleanly */
+	if (PQExpBufferDataBroken(workBuf))
+	{
+		termPQExpBuffer(&workBuf);
+		return strdup(libpq_gettext("out of memory\n"));
+	}
+
+	return workBuf.data;
+}
+
+char *
+PQresultErrorField(const PGresult *res, int fieldcode)
+{
+	PGMessageField *pfield;
+
+	if (!res)
+		return NULL;
+	for (pfield = res->errFields; pfield != NULL; pfield = pfield->next)
+	{
+		if (pfield->code == fieldcode)
+			return pfield->contents;
+	}
+	return NULL;
+}
+
+int
+PQntuples(const PGresult *res)
+{
+	if (!res)
+		return 0;
+	return res->ntups;
+}
+
+int
+PQnfields(const PGresult *res)
+{
+	if (!res)
+		return 0;
+	return res->numAttributes;
+}
+
+int
+PQbinaryTuples(const PGresult *res)
+{
+	if (!res)
+		return 0;
+	return res->binary;
+}
+
+/*
+ * Helper routines to range-check field numbers and tuple numbers.
+ * Return true if OK, false if not
+ */
+
+static int
+check_field_number(const PGresult *res, int field_num)
+{
+	if (!res)
+		return false;			/* no way to display error message... */
+	if (field_num < 0 || field_num >= res->numAttributes)
+	{
+		pqInternalNotice(&res->noticeHooks,
+						 "column number %d is out of range 0..%d",
+						 field_num, res->numAttributes - 1);
+		return false;
+	}
+	return true;
+}
+
+static int
+check_tuple_field_number(const PGresult *res,
+						 int tup_num, int field_num)
+{
+	if (!res)
+		return false;			/* no way to display error message... */
+	if (tup_num < 0 || tup_num >= res->ntups)
+	{
+		pqInternalNotice(&res->noticeHooks,
+						 "row number %d is out of range 0..%d",
+						 tup_num, res->ntups - 1);
+		return false;
+	}
+	if (field_num < 0 || field_num >= res->numAttributes)
+	{
+		pqInternalNotice(&res->noticeHooks,
+						 "column number %d is out of range 0..%d",
+						 field_num, res->numAttributes - 1);
+		return false;
+	}
+	return true;
+}
+
+static int
+check_param_number(const PGresult *res, int param_num)
+{
+	if (!res)
+		return false;			/* no way to display error message... */
+	if (param_num < 0 || param_num >= res->numParameters)
+	{
+		pqInternalNotice(&res->noticeHooks,
+						 "parameter number %d is out of range 0..%d",
+						 param_num, res->numParameters - 1);
+		return false;
+	}
+
+	return true;
+}
+
+/*
+ * returns NULL if the field_num is invalid
+ */
+char *
+PQfname(const PGresult *res, int field_num)
+{
+	if (!check_field_number(res, field_num))
+		return NULL;
+	if (res->attDescs)
+		return res->attDescs[field_num].name;
+	else
+		return NULL;
+}
+
+/*
+ * PQfnumber: find column number given column name
+ *
+ * The column name is parsed as if it were in a SQL statement, including
+ * case-folding and double-quote processing.  But note a possible gotcha:
+ * downcasing in the frontend might follow different locale rules than
+ * downcasing in the backend...
+ *
+ * Returns -1 if no match.  In the present backend it is also possible
+ * to have multiple matches, in which case the first one is found.
+ */
+int
+PQfnumber(const PGresult *res, const char *field_name)
+{
+	char	   *field_case;
+	bool		in_quotes;
+	bool		all_lower = true;
+	const char *iptr;
+	char	   *optr;
+	int			i;
+
+	if (!res)
+		return -1;
+
+	/*
+	 * Note: it is correct to reject a zero-length input string; the proper
+	 * input to match a zero-length field name would be "".
+	 */
+	if (field_name == NULL ||
+		field_name[0] == '\0' ||
+		res->attDescs == NULL)
+		return -1;
+
+	/*
+	 * Check if we can avoid the strdup() and related work because the
+	 * passed-in string wouldn't be changed before we do the check anyway.
+	 */
+	for (iptr = field_name; *iptr; iptr++)
+	{
+		char		c = *iptr;
+
+		if (c == '"' || c != pg_tolower((unsigned char) c))
+		{
+			all_lower = false;
+			break;
+		}
+	}
+
+	if (all_lower)
+		for (i = 0; i < res->numAttributes; i++)
+			if (strcmp(field_name, res->attDescs[i].name) == 0)
+				return i;
+
+	/* Fall through to the normal check if that didn't work out. */
+
+	/*
+	 * Note: this code will not reject partially quoted strings, eg
+	 * foo"BAR"foo will become fooBARfoo when it probably ought to be an error
+	 * condition.
+	 */
+	field_case = strdup(field_name);
+	if (field_case == NULL)
+		return -1;				/* grotty */
+
+	in_quotes = false;
+	optr = field_case;
+	for (iptr = field_case; *iptr; iptr++)
+	{
+		char		c = *iptr;
+
+		if (in_quotes)
+		{
+			if (c == '"')
+			{
+				if (iptr[1] == '"')
+				{
+					/* doubled quotes become a single quote */
+					*optr++ = '"';
+					iptr++;
+				}
+				else
+					in_quotes = false;
+			}
+			else
+				*optr++ = c;
+		}
+		else if (c == '"')
+			in_quotes = true;
+		else
+		{
+			c = pg_tolower((unsigned char) c);
+			*optr++ = c;
+		}
+	}
+	*optr = '\0';
+
+	for (i = 0; i < res->numAttributes; i++)
+	{
+		if (strcmp(field_case, res->attDescs[i].name) == 0)
+		{
+			free(field_case);
+			return i;
+		}
+	}
+	free(field_case);
+	return -1;
+}
+
+Oid
+PQftable(const PGresult *res, int field_num)
+{
+	if (!check_field_number(res, field_num))
+		return InvalidOid;
+	if (res->attDescs)
+		return res->attDescs[field_num].tableid;
+	else
+		return InvalidOid;
+}
+
+int
+PQftablecol(const PGresult *res, int field_num)
+{
+	if (!check_field_number(res, field_num))
+		return 0;
+	if (res->attDescs)
+		return res->attDescs[field_num].columnid;
+	else
+		return 0;
+}
+
+int
+PQfformat(const PGresult *res, int field_num)
+{
+	if (!check_field_number(res, field_num))
+		return 0;
+	if (res->attDescs)
+		return res->attDescs[field_num].format;
+	else
+		return 0;
+}
+
+Oid
+PQftype(const PGresult *res, int field_num)
+{
+	if (!check_field_number(res, field_num))
+		return InvalidOid;
+	if (res->attDescs)
+		return res->attDescs[field_num].typid;
+	else
+		return InvalidOid;
+}
+
+int
+PQfsize(const PGresult *res, int field_num)
+{
+	if (!check_field_number(res, field_num))
+		return 0;
+	if (res->attDescs)
+		return res->attDescs[field_num].typlen;
+	else
+		return 0;
+}
+
+int
+PQfmod(const PGresult *res, int field_num)
+{
+	if (!check_field_number(res, field_num))
+		return 0;
+	if (res->attDescs)
+		return res->attDescs[field_num].atttypmod;
+	else
+		return 0;
+}
+
+char *
+PQcmdStatus(PGresult *res)
+{
+	if (!res)
+		return NULL;
+	return res->cmdStatus;
+}
+
+/*
+ * PQoidStatus -
+ *	if the last command was an INSERT, return the oid string
+ *	if not, return ""
+ */
+char *
+PQoidStatus(const PGresult *res)
+{
+	/*
+	 * This must be enough to hold the result. Don't laugh, this is better
+	 * than what this function used to do.
+	 */
+	static char buf[24];
+
+	size_t		len;
+
+	if (!res || strncmp(res->cmdStatus, "INSERT ", 7) != 0)
+		return "";
+
+	len = strspn(res->cmdStatus + 7, "0123456789");
+	if (len > sizeof(buf) - 1)
+		len = sizeof(buf) - 1;
+	memcpy(buf, res->cmdStatus + 7, len);
+	buf[len] = '\0';
+
+	return buf;
+}
+
+/*
+ * PQoidValue -
+ *	a perhaps preferable form of the above which just returns
+ *	an Oid type
+ */
+Oid
+PQoidValue(const PGresult *res)
+{
+	char	   *endptr = NULL;
+	unsigned long result;
+
+	if (!res ||
+		strncmp(res->cmdStatus, "INSERT ", 7) != 0 ||
+		res->cmdStatus[7] < '0' ||
+		res->cmdStatus[7] > '9')
+		return InvalidOid;
+
+	result = strtoul(res->cmdStatus + 7, &endptr, 10);
+
+	if (!endptr || (*endptr != ' ' && *endptr != '\0'))
+		return InvalidOid;
+	else
+		return (Oid) result;
+}
+
+
+/*
+ * PQcmdTuples -
+ *	If the last command was INSERT/UPDATE/DELETE/MERGE/MOVE/FETCH/COPY,
+ *	return a string containing the number of inserted/affected tuples.
+ *	If not, return "".
+ *
+ *	XXX: this should probably return an int
+ */
+char *
+PQcmdTuples(PGresult *res)
+{
+	char	   *p,
+			   *c;
+
+	if (!res)
+		return "";
+
+	if (strncmp(res->cmdStatus, "INSERT ", 7) == 0)
+	{
+		p = res->cmdStatus + 7;
+		/* INSERT: skip oid and space */
+		while (*p && *p != ' ')
+			p++;
+		if (*p == 0)
+			goto interpret_error;	/* no space? */
+		p++;
+	}
+	else if (strncmp(res->cmdStatus, "SELECT ", 7) == 0 ||
+			 strncmp(res->cmdStatus, "DELETE ", 7) == 0 ||
+			 strncmp(res->cmdStatus, "UPDATE ", 7) == 0)
+		p = res->cmdStatus + 7;
+	else if (strncmp(res->cmdStatus, "FETCH ", 6) == 0 ||
+			 strncmp(res->cmdStatus, "MERGE ", 6) == 0)
+		p = res->cmdStatus + 6;
+	else if (strncmp(res->cmdStatus, "MOVE ", 5) == 0 ||
+			 strncmp(res->cmdStatus, "COPY ", 5) == 0)
+		p = res->cmdStatus + 5;
+	else
+		return "";
+
+	/* check that we have an integer (at least one digit, nothing else) */
+	for (c = p; *c; c++)
+	{
+		if (!isdigit((unsigned char) *c))
+			goto interpret_error;
+	}
+	if (c == p)
+		goto interpret_error;
+
+	return p;
+
+interpret_error:
+	pqInternalNotice(&res->noticeHooks,
+					 "could not interpret result from server: %s",
+					 res->cmdStatus);
+	return "";
+}
+
+/*
+ * PQgetvalue:
+ *	return the value of field 'field_num' of row 'tup_num'
+ */
+char *
+PQgetvalue(const PGresult *res, int tup_num, int field_num)
+{
+	if (!check_tuple_field_number(res, tup_num, field_num))
+		return NULL;
+	return res->tuples[tup_num][field_num].value;
+}
+
+/* PQgetlength:
+ *	returns the actual length of a field value in bytes.
+ */
+int
+PQgetlength(const PGresult *res, int tup_num, int field_num)
+{
+	if (!check_tuple_field_number(res, tup_num, field_num))
+		return 0;
+	if (res->tuples[tup_num][field_num].len != NULL_LEN)
+		return res->tuples[tup_num][field_num].len;
+	else
+		return 0;
+}
+
+/* PQgetisnull:
+ *	returns the null status of a field value.
+ */
+int
+PQgetisnull(const PGresult *res, int tup_num, int field_num)
+{
+	if (!check_tuple_field_number(res, tup_num, field_num))
+		return 1;				/* pretend it is null */
+	if (res->tuples[tup_num][field_num].len == NULL_LEN)
+		return 1;
+	else
+		return 0;
+}
+
+/* PQnparams:
+ *	returns the number of input parameters of a prepared statement.
+ */
+int
+PQnparams(const PGresult *res)
+{
+	if (!res)
+		return 0;
+	return res->numParameters;
+}
+
+/* PQparamtype:
+ *	returns type Oid of the specified statement parameter.
+ */
+Oid
+PQparamtype(const PGresult *res, int param_num)
+{
+	if (!check_param_number(res, param_num))
+		return InvalidOid;
+	if (res->paramDescs)
+		return res->paramDescs[param_num].typid;
+	else
+		return InvalidOid;
+}
+
+
+/* PQsetnonblocking:
+ *	sets the PGconn's database connection non-blocking if the arg is true
+ *	or makes it blocking if the arg is false, this will not protect
+ *	you from PQexec(), you'll only be safe when using the non-blocking API.
+ *	Needs to be called only on a connected database connection.
+ */
+int
+PQsetnonblocking(PGconn *conn, int arg)
+{
+	bool		barg;
+
+	if (!conn || conn->status == CONNECTION_BAD)
+		return -1;
+
+	barg = (arg ? true : false);
+
+	/* early out if the socket is already in the state requested */
+	if (barg == conn->nonblocking)
+		return 0;
+
+	/*
+	 * to guarantee constancy for flushing/query/result-polling behavior we
+	 * need to flush the send queue at this point in order to guarantee proper
+	 * behavior. this is ok because either they are making a transition _from_
+	 * or _to_ blocking mode, either way we can block them.
+	 *
+	 * Clear error state in case pqFlush adds to it, unless we're actively
+	 * pipelining, in which case it seems best not to.
+	 */
+	if (conn->cmd_queue_head == NULL)
+		pqClearConnErrorState(conn);
+
+	/* if we are going from blocking to non-blocking flush here */
+	if (pqFlush(conn))
+		return -1;
+
+	conn->nonblocking = barg;
+
+	return 0;
+}
+
+/*
+ * return the blocking status of the database connection
+ *		true == nonblocking, false == blocking
+ */
+int
+PQisnonblocking(const PGconn *conn)
+{
+	if (!conn || conn->status == CONNECTION_BAD)
+		return false;
+	return pqIsnonblocking(conn);
+}
+
+/* libpq is thread-safe? */
+int
+PQisthreadsafe(void)
+{
+#ifdef ENABLE_THREAD_SAFETY
+	return true;
+#else
+	return false;
+#endif
+}
+
+
+/* try to force data out, really only useful for non-blocking users */
+int
+PQflush(PGconn *conn)
+{
+	if (!conn || conn->status == CONNECTION_BAD)
+		return -1;
+	return pqFlush(conn);
+}
+
+/*
+ * pqPipelineFlush
+ *
+ * In pipeline mode, data will be flushed only when the out buffer reaches the
+ * threshold value.  In non-pipeline mode, it behaves as stock pqFlush.
+ *
+ * Returns 0 on success.
+ */
+static int
+pqPipelineFlush(PGconn *conn)
+{
+	if ((conn->pipelineStatus != PQ_PIPELINE_ON) ||
+		(conn->outCount >= OUTBUFFER_THRESHOLD))
+		return pqFlush(conn);
+	return 0;
+}
+
+
+/*
+ *		PQfreemem - safely frees memory allocated
+ *
+ * Needed mostly by Win32, unless multithreaded DLL (/MD in VC6)
+ * Used for freeing memory from PQescapeBytea()/PQunescapeBytea()
+ */
+void
+PQfreemem(void *ptr)
+{
+	free(ptr);
+}
+
+/*
+ * PQfreeNotify - free's the memory associated with a PGnotify
+ *
+ * This function is here only for binary backward compatibility.
+ * New code should use PQfreemem().  A macro will automatically map
+ * calls to PQfreemem.  It should be removed in the future.  bjm 2003-03-24
+ */
+
+#undef PQfreeNotify
+void		PQfreeNotify(PGnotify *notify);
+
+void
+PQfreeNotify(PGnotify *notify)
+{
+	PQfreemem(notify);
+}
+
+
+/*
+ * Escaping arbitrary strings to get valid SQL literal strings.
+ *
+ * Replaces "'" with "''", and if not std_strings, replaces "\" with "\\".
+ *
+ * length is the length of the source string.  (Note: if a terminating NUL
+ * is encountered sooner, PQescapeString stops short of "length"; the behavior
+ * is thus rather like strncpy.)
+ *
+ * For safety the buffer at "to" must be at least 2*length + 1 bytes long.
+ * A terminating NUL character is added to the output string, whether the
+ * input is NUL-terminated or not.
+ *
+ * Returns the actual length of the output (not counting the terminating NUL).
+ */
+static size_t
+PQescapeStringInternal(PGconn *conn,
+					   char *to, const char *from, size_t length,
+					   int *error,
+					   int encoding, bool std_strings)
+{
+	const char *source = from;
+	char	   *target = to;
+	size_t		remaining = length;
+
+	if (error)
+		*error = 0;
+
+	while (remaining > 0 && *source != '\0')
+	{
+		char		c = *source;
+		int			len;
+		int			i;
+
+		/* Fast path for plain ASCII */
+		if (!IS_HIGHBIT_SET(c))
+		{
+			/* Apply quoting if needed */
+			if (SQL_STR_DOUBLE(c, !std_strings))
+				*target++ = c;
+			/* Copy the character */
+			*target++ = c;
+			source++;
+			remaining--;
+			continue;
+		}
+
+		/* Slow path for possible multibyte characters */
+		len = pg_encoding_mblen(encoding, source);
+
+		/* Copy the character */
+		for (i = 0; i < len; i++)
+		{
+			if (remaining == 0 || *source == '\0')
+				break;
+			*target++ = *source++;
+			remaining--;
+		}
+
+		/*
+		 * If we hit premature end of string (ie, incomplete multibyte
+		 * character), try to pad out to the correct length with spaces. We
+		 * may not be able to pad completely, but we will always be able to
+		 * insert at least one pad space (since we'd not have quoted a
+		 * multibyte character).  This should be enough to make a string that
+		 * the server will error out on.
+		 */
+		if (i < len)
+		{
+			if (error)
+				*error = 1;
+			if (conn)
+				appendPQExpBufferStr(&conn->errorMessage,
+									 libpq_gettext("incomplete multibyte character\n"));
+			for (; i < len; i++)
+			{
+				if (((size_t) (target - to)) / 2 >= length)
+					break;
+				*target++ = ' ';
+			}
+			break;
+		}
+	}
+
+	/* Write the terminating NUL character. */
+	*target = '\0';
+
+	return target - to;
+}
+
+size_t
+PQescapeStringConn(PGconn *conn,
+				   char *to, const char *from, size_t length,
+				   int *error)
+{
+	if (!conn)
+	{
+		/* force empty-string result */
+		*to = '\0';
+		if (error)
+			*error = 1;
+		return 0;
+	}
+
+	if (conn->cmd_queue_head == NULL)
+		pqClearConnErrorState(conn);
+
+	return PQescapeStringInternal(conn, to, from, length, error,
+								  conn->client_encoding,
+								  conn->std_strings);
+}
+
+size_t
+PQescapeString(char *to, const char *from, size_t length)
+{
+	return PQescapeStringInternal(NULL, to, from, length, NULL,
+								  static_client_encoding,
+								  static_std_strings);
+}
+
+
+/*
+ * Escape arbitrary strings.  If as_ident is true, we escape the result
+ * as an identifier; if false, as a literal.  The result is returned in
+ * a newly allocated buffer.  If we fail due to an encoding violation or out
+ * of memory condition, we return NULL, storing an error message into conn.
+ */
+static char *
+PQescapeInternal(PGconn *conn, const char *str, size_t len, bool as_ident)
+{
+	const char *s;
+	char	   *result;
+	char	   *rp;
+	int			num_quotes = 0; /* single or double, depending on as_ident */
+	int			num_backslashes = 0;
+	int			input_len;
+	int			result_size;
+	char		quote_char = as_ident ? '"' : '\'';
+
+	/* We must have a connection, else fail immediately. */
+	if (!conn)
+		return NULL;
+
+	if (conn->cmd_queue_head == NULL)
+		pqClearConnErrorState(conn);
+
+	/* Scan the string for characters that must be escaped. */
+	for (s = str; (s - str) < len && *s != '\0'; ++s)
+	{
+		if (*s == quote_char)
+			++num_quotes;
+		else if (*s == '\\')
+			++num_backslashes;
+		else if (IS_HIGHBIT_SET(*s))
+		{
+			int			charlen;
+
+			/* Slow path for possible multibyte characters */
+			charlen = pg_encoding_mblen(conn->client_encoding, s);
+
+			/* Multibyte character overruns allowable length. */
+			if ((s - str) + charlen > len || memchr(s, 0, charlen) != NULL)
+			{
+				appendPQExpBufferStr(&conn->errorMessage,
+									 libpq_gettext("incomplete multibyte character\n"));
+				return NULL;
+			}
+
+			/* Adjust s, bearing in mind that for loop will increment it. */
+			s += charlen - 1;
+		}
+	}
+
+	/* Allocate output buffer. */
+	input_len = s - str;
+	result_size = input_len + num_quotes + 3;	/* two quotes, plus a NUL */
+	if (!as_ident && num_backslashes > 0)
+		result_size += num_backslashes + 2;
+	result = rp = (char *) malloc(result_size);
+	if (rp == NULL)
+	{
+		appendPQExpBufferStr(&conn->errorMessage,
+							 libpq_gettext("out of memory\n"));
+		return NULL;
+	}
+
+	/*
+	 * If we are escaping a literal that contains backslashes, we use the
+	 * escape string syntax so that the result is correct under either value
+	 * of standard_conforming_strings.  We also emit a leading space in this
+	 * case, to guard against the possibility that the result might be
+	 * interpolated immediately following an identifier.
+	 */
+	if (!as_ident && num_backslashes > 0)
+	{
+		*rp++ = ' ';
+		*rp++ = 'E';
+	}
+
+	/* Opening quote. */
+	*rp++ = quote_char;
+
+	/*
+	 * Use fast path if possible.
+	 *
+	 * We've already verified that the input string is well-formed in the
+	 * current encoding.  If it contains no quotes and, in the case of
+	 * literal-escaping, no backslashes, then we can just copy it directly to
+	 * the output buffer, adding the necessary quotes.
+	 *
+	 * If not, we must rescan the input and process each character
+	 * individually.
+	 */
+	if (num_quotes == 0 && (num_backslashes == 0 || as_ident))
+	{
+		memcpy(rp, str, input_len);
+		rp += input_len;
+	}
+	else
+	{
+		for (s = str; s - str < input_len; ++s)
+		{
+			if (*s == quote_char || (!as_ident && *s == '\\'))
+			{
+				*rp++ = *s;
+				*rp++ = *s;
+			}
+			else if (!IS_HIGHBIT_SET(*s))
+				*rp++ = *s;
+			else
+			{
+				int			i = pg_encoding_mblen(conn->client_encoding, s);
+
+				while (1)
+				{
+					*rp++ = *s;
+					if (--i == 0)
+						break;
+					++s;		/* for loop will provide the final increment */
+				}
+			}
+		}
+	}
+
+	/* Closing quote and terminating NUL. */
+	*rp++ = quote_char;
+	*rp = '\0';
+
+	return result;
+}
+
+char *
+PQescapeLiteral(PGconn *conn, const char *str, size_t len)
+{
+	return PQescapeInternal(conn, str, len, false);
+}
+
+char *
+PQescapeIdentifier(PGconn *conn, const char *str, size_t len)
+{
+	return PQescapeInternal(conn, str, len, true);
+}
+
+/* HEX encoding support for bytea */
+static const char hextbl[] = "0123456789abcdef";
+
+static const int8 hexlookup[128] = {
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
+	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+};
+
+static inline char
+get_hex(char c)
+{
+	int			res = -1;
+
+	if (c > 0 && c < 127)
+		res = hexlookup[(unsigned char) c];
+
+	return (char) res;
+}
+
+
+/*
+ *		PQescapeBytea	- converts from binary string to the
+ *		minimal encoding necessary to include the string in an SQL
+ *		INSERT statement with a bytea type column as the target.
+ *
+ *		We can use either hex or escape (traditional) encoding.
+ *		In escape mode, the following transformations are applied:
+ *		'\0' == ASCII  0 == \000
+ *		'\'' == ASCII 39 == ''
+ *		'\\' == ASCII 92 == \\
+ *		anything < 0x20, or > 0x7e ---> \ooo
+ *										(where ooo is an octal expression)
+ *
+ *		If not std_strings, all backslashes sent to the output are doubled.
+ */
+static unsigned char *
+PQescapeByteaInternal(PGconn *conn,
+					  const unsigned char *from, size_t from_length,
+					  size_t *to_length, bool std_strings, bool use_hex)
+{
+	const unsigned char *vp;
+	unsigned char *rp;
+	unsigned char *result;
+	size_t		i;
+	size_t		len;
+	size_t		bslash_len = (std_strings ? 1 : 2);
+
+	/*
+	 * empty string has 1 char ('\0')
+	 */
+	len = 1;
+
+	if (use_hex)
+	{
+		len += bslash_len + 1 + 2 * from_length;
+	}
+	else
+	{
+		vp = from;
+		for (i = from_length; i > 0; i--, vp++)
+		{
+			if (*vp < 0x20 || *vp > 0x7e)
+				len += bslash_len + 3;
+			else if (*vp == '\'')
+				len += 2;
+			else if (*vp == '\\')
+				len += bslash_len + bslash_len;
+			else
+				len++;
+		}
+	}
+
+	*to_length = len;
+	rp = result = (unsigned char *) malloc(len);
+	if (rp == NULL)
+	{
+		if (conn)
+			appendPQExpBufferStr(&conn->errorMessage,
+								 libpq_gettext("out of memory\n"));
+		return NULL;
+	}
+
+	if (use_hex)
+	{
+		if (!std_strings)
+			*rp++ = '\\';
+		*rp++ = '\\';
+		*rp++ = 'x';
+	}
+
+	vp = from;
+	for (i = from_length; i > 0; i--, vp++)
+	{
+		unsigned char c = *vp;
+
+		if (use_hex)
+		{
+			*rp++ = hextbl[(c >> 4) & 0xF];
+			*rp++ = hextbl[c & 0xF];
+		}
+		else if (c < 0x20 || c > 0x7e)
+		{
+			if (!std_strings)
+				*rp++ = '\\';
+			*rp++ = '\\';
+			*rp++ = (c >> 6) + '0';
+			*rp++ = ((c >> 3) & 07) + '0';
+			*rp++ = (c & 07) + '0';
+		}
+		else if (c == '\'')
+		{
+			*rp++ = '\'';
+			*rp++ = '\'';
+		}
+		else if (c == '\\')
+		{
+			if (!std_strings)
+			{
+				*rp++ = '\\';
+				*rp++ = '\\';
+			}
+			*rp++ = '\\';
+			*rp++ = '\\';
+		}
+		else
+			*rp++ = c;
+	}
+	*rp = '\0';
+
+	return result;
+}
+
+unsigned char *
+PQescapeByteaConn(PGconn *conn,
+				  const unsigned char *from, size_t from_length,
+				  size_t *to_length)
+{
+	if (!conn)
+		return NULL;
+
+	if (conn->cmd_queue_head == NULL)
+		pqClearConnErrorState(conn);
+
+	return PQescapeByteaInternal(conn, from, from_length, to_length,
+								 conn->std_strings,
+								 (conn->sversion >= 90000));
+}
+
+unsigned char *
+PQescapeBytea(const unsigned char *from, size_t from_length, size_t *to_length)
+{
+	return PQescapeByteaInternal(NULL, from, from_length, to_length,
+								 static_std_strings,
+								 false /* can't use hex */ );
+}
+
+
+#define ISFIRSTOCTDIGIT(CH) ((CH) >= '0' && (CH) <= '3')
+#define ISOCTDIGIT(CH) ((CH) >= '0' && (CH) <= '7')
+#define OCTVAL(CH) ((CH) - '0')
+
+/*
+ *		PQunescapeBytea - converts the null terminated string representation
+ *		of a bytea, strtext, into binary, filling a buffer. It returns a
+ *		pointer to the buffer (or NULL on error), and the size of the
+ *		buffer in retbuflen. The pointer may subsequently be used as an
+ *		argument to the function PQfreemem.
+ *
+ *		The following transformations are made:
+ *		\\	 == ASCII 92 == \
+ *		\ooo == a byte whose value = ooo (ooo is an octal number)
+ *		\x	 == x (x is any character not matched by the above transformations)
+ */
+unsigned char *
+PQunescapeBytea(const unsigned char *strtext, size_t *retbuflen)
+{
+	size_t		strtextlen,
+				buflen;
+	unsigned char *buffer,
+			   *tmpbuf;
+	size_t		i,
+				j;
+
+	if (strtext == NULL)
+		return NULL;
+
+	strtextlen = strlen((const char *) strtext);
+
+	if (strtext[0] == '\\' && strtext[1] == 'x')
+	{
+		const unsigned char *s;
+		unsigned char *p;
+
+		buflen = (strtextlen - 2) / 2;
+		/* Avoid unportable malloc(0) */
+		buffer = (unsigned char *) malloc(buflen > 0 ? buflen : 1);
+		if (buffer == NULL)
+			return NULL;
+
+		s = strtext + 2;
+		p = buffer;
+		while (*s)
+		{
+			char		v1,
+						v2;
+
+			/*
+			 * Bad input is silently ignored.  Note that this includes
+			 * whitespace between hex pairs, which is allowed by byteain.
+			 */
+			v1 = get_hex(*s++);
+			if (!*s || v1 == (char) -1)
+				continue;
+			v2 = get_hex(*s++);
+			if (v2 != (char) -1)
+				*p++ = (v1 << 4) | v2;
+		}
+
+		buflen = p - buffer;
+	}
+	else
+	{
+		/*
+		 * Length of input is max length of output, but add one to avoid
+		 * unportable malloc(0) if input is zero-length.
+		 */
+		buffer = (unsigned char *) malloc(strtextlen + 1);
+		if (buffer == NULL)
+			return NULL;
+
+		for (i = j = 0; i < strtextlen;)
+		{
+			switch (strtext[i])
+			{
+				case '\\':
+					i++;
+					if (strtext[i] == '\\')
+						buffer[j++] = strtext[i++];
+					else
+					{
+						if ((ISFIRSTOCTDIGIT(strtext[i])) &&
+							(ISOCTDIGIT(strtext[i + 1])) &&
+							(ISOCTDIGIT(strtext[i + 2])))
+						{
+							int			byte;
+
+							byte = OCTVAL(strtext[i++]);
+							byte = (byte << 3) + OCTVAL(strtext[i++]);
+							byte = (byte << 3) + OCTVAL(strtext[i++]);
+							buffer[j++] = byte;
+						}
+					}
+
+					/*
+					 * Note: if we see '\' followed by something that isn't a
+					 * recognized escape sequence, we loop around having done
+					 * nothing except advance i.  Therefore the something will
+					 * be emitted as ordinary data on the next cycle. Corner
+					 * case: '\' at end of string will just be discarded.
+					 */
+					break;
+
+				default:
+					buffer[j++] = strtext[i++];
+					break;
+			}
+		}
+		buflen = j;				/* buflen is the length of the dequoted data */
+	}
+
+	/* Shrink the buffer to be no larger than necessary */
+	/* +1 avoids unportable behavior when buflen==0 */
+	tmpbuf = realloc(buffer, buflen + 1);
+
+	/* It would only be a very brain-dead realloc that could fail, but... */
+	if (!tmpbuf)
+	{
+		free(buffer);
+		return NULL;
+	}
+
+	*retbuflen = buflen;
+	return tmpbuf;
+}