1 files changed, 422 insertions, 0 deletions
diff --git a/src/backend/nodes/params.c b/src/backend/nodes/params.c
new file mode 100644
index 0000000..45ebff5
--- /dev/null
+++ b/src/backend/nodes/params.c
@@ -0,0 +1,422 @@
+/*-------------------------------------------------------------------------
+ *
+ * params.c
+ *	  Support for finding the values associated with Param nodes.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/backend/nodes/params.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/xact.h"
+#include "fmgr.h"
+#include "mb/stringinfo_mb.h"
+#include "nodes/params.h"
+#include "parser/parse_node.h"
+#include "storage/shmem.h"
+#include "utils/datum.h"
+#include "utils/lsyscache.h"
+#include "utils/memutils.h"
+
+
+static void paramlist_parser_setup(ParseState *pstate, void *arg);
+static Node *paramlist_param_ref(ParseState *pstate, ParamRef *pref);
+
+
+/*
+ * Allocate and initialize a new ParamListInfo structure.
+ *
+ * To make a new structure for the "dynamic" way (with hooks), pass 0 for
+ * numParams and set numParams manually.
+ *
+ * A default parserSetup function is supplied automatically.  Callers may
+ * override it if they choose.  (Note that most use-cases for ParamListInfos
+ * will never use the parserSetup function anyway.)
+ */
+ParamListInfo
+makeParamList(int numParams)
+{
+	ParamListInfo retval;
+	Size		size;
+
+	size = offsetof(ParamListInfoData, params) +
+		numParams * sizeof(ParamExternData);
+
+	retval = (ParamListInfo) palloc(size);
+	retval->paramFetch = NULL;
+	retval->paramFetchArg = NULL;
+	retval->paramCompile = NULL;
+	retval->paramCompileArg = NULL;
+	retval->parserSetup = paramlist_parser_setup;
+	retval->parserSetupArg = (void *) retval;
+	retval->paramValuesStr = NULL;
+	retval->numParams = numParams;
+
+	return retval;
+}
+
+/*
+ * Copy a ParamListInfo structure.
+ *
+ * The result is allocated in CurrentMemoryContext.
+ *
+ * Note: the intent of this function is to make a static, self-contained
+ * set of parameter values.  If dynamic parameter hooks are present, we
+ * intentionally do not copy them into the result.  Rather, we forcibly
+ * instantiate all available parameter values and copy the datum values.
+ *
+ * paramValuesStr is not copied, either.
+ */
+ParamListInfo
+copyParamList(ParamListInfo from)
+{
+	ParamListInfo retval;
+
+	if (from == NULL || from->numParams <= 0)
+		return NULL;
+
+	retval = makeParamList(from->numParams);
+
+	for (int i = 0; i < from->numParams; i++)
+	{
+		ParamExternData *oprm;
+		ParamExternData *nprm = &retval->params[i];
+		ParamExternData prmdata;
+		int16		typLen;
+		bool		typByVal;
+
+		/* give hook a chance in case parameter is dynamic */
+		if (from->paramFetch != NULL)
+			oprm = from->paramFetch(from, i + 1, false, &prmdata);
+		else
+			oprm = &from->params[i];
+
+		/* flat-copy the parameter info */
+		*nprm = *oprm;
+
+		/* need datumCopy in case it's a pass-by-reference datatype */
+		if (nprm->isnull || !OidIsValid(nprm->ptype))
+			continue;
+		get_typlenbyval(nprm->ptype, &typLen, &typByVal);
+		nprm->value = datumCopy(nprm->value, typByVal, typLen);
+	}
+
+	return retval;
+}
+
+
+/*
+ * Set up to parse a query containing references to parameters
+ * sourced from a ParamListInfo.
+ */
+static void
+paramlist_parser_setup(ParseState *pstate, void *arg)
+{
+	pstate->p_paramref_hook = paramlist_param_ref;
+	/* no need to use p_coerce_param_hook */
+	pstate->p_ref_hook_state = arg;
+}
+
+/*
+ * Transform a ParamRef using parameter type data from a ParamListInfo.
+ */
+static Node *
+paramlist_param_ref(ParseState *pstate, ParamRef *pref)
+{
+	ParamListInfo paramLI = (ParamListInfo) pstate->p_ref_hook_state;
+	int			paramno = pref->number;
+	ParamExternData *prm;
+	ParamExternData prmdata;
+	Param	   *param;
+
+	/* check parameter number is valid */
+	if (paramno <= 0 || paramno > paramLI->numParams)
+		return NULL;
+
+	/* give hook a chance in case parameter is dynamic */
+	if (paramLI->paramFetch != NULL)
+		prm = paramLI->paramFetch(paramLI, paramno, false, &prmdata);
+	else
+		prm = &paramLI->params[paramno - 1];
+
+	if (!OidIsValid(prm->ptype))
+		return NULL;
+
+	param = makeNode(Param);
+	param->paramkind = PARAM_EXTERN;
+	param->paramid = paramno;
+	param->paramtype = prm->ptype;
+	param->paramtypmod = -1;
+	param->paramcollid = get_typcollation(param->paramtype);
+	param->location = pref->location;
+
+	return (Node *) param;
+}
+
+/*
+ * Estimate the amount of space required to serialize a ParamListInfo.
+ */
+Size
+EstimateParamListSpace(ParamListInfo paramLI)
+{
+	int			i;
+	Size		sz = sizeof(int);
+
+	if (paramLI == NULL || paramLI->numParams <= 0)
+		return sz;
+
+	for (i = 0; i < paramLI->numParams; i++)
+	{
+		ParamExternData *prm;
+		ParamExternData prmdata;
+		Oid			typeOid;
+		int16		typLen;
+		bool		typByVal;
+
+		/* give hook a chance in case parameter is dynamic */
+		if (paramLI->paramFetch != NULL)
+			prm = paramLI->paramFetch(paramLI, i + 1, false, &prmdata);
+		else
+			prm = &paramLI->params[i];
+
+		typeOid = prm->ptype;
+
+		sz = add_size(sz, sizeof(Oid)); /* space for type OID */
+		sz = add_size(sz, sizeof(uint16));	/* space for pflags */
+
+		/* space for datum/isnull */
+		if (OidIsValid(typeOid))
+			get_typlenbyval(typeOid, &typLen, &typByVal);
+		else
+		{
+			/* If no type OID, assume by-value, like copyParamList does. */
+			typLen = sizeof(Datum);
+			typByVal = true;
+		}
+		sz = add_size(sz,
+					  datumEstimateSpace(prm->value, prm->isnull, typByVal, typLen));
+	}
+
+	return sz;
+}
+
+/*
+ * Serialize a ParamListInfo structure into caller-provided storage.
+ *
+ * We write the number of parameters first, as a 4-byte integer, and then
+ * write details for each parameter in turn.  The details for each parameter
+ * consist of a 4-byte type OID, 2 bytes of flags, and then the datum as
+ * serialized by datumSerialize().  The caller is responsible for ensuring
+ * that there is enough storage to store the number of bytes that will be
+ * written; use EstimateParamListSpace to find out how many will be needed.
+ * *start_address is updated to point to the byte immediately following those
+ * written.
+ *
+ * RestoreParamList can be used to recreate a ParamListInfo based on the
+ * serialized representation; this will be a static, self-contained copy
+ * just as copyParamList would create.
+ *
+ * paramValuesStr is not included.
+ */
+void
+SerializeParamList(ParamListInfo paramLI, char **start_address)
+{
+	int			nparams;
+	int			i;
+
+	/* Write number of parameters. */
+	if (paramLI == NULL || paramLI->numParams <= 0)
+		nparams = 0;
+	else
+		nparams = paramLI->numParams;
+	memcpy(*start_address, &nparams, sizeof(int));
+	*start_address += sizeof(int);
+
+	/* Write each parameter in turn. */
+	for (i = 0; i < nparams; i++)
+	{
+		ParamExternData *prm;
+		ParamExternData prmdata;
+		Oid			typeOid;
+		int16		typLen;
+		bool		typByVal;
+
+		/* give hook a chance in case parameter is dynamic */
+		if (paramLI->paramFetch != NULL)
+			prm = paramLI->paramFetch(paramLI, i + 1, false, &prmdata);
+		else
+			prm = &paramLI->params[i];
+
+		typeOid = prm->ptype;
+
+		/* Write type OID. */
+		memcpy(*start_address, &typeOid, sizeof(Oid));
+		*start_address += sizeof(Oid);
+
+		/* Write flags. */
+		memcpy(*start_address, &prm->pflags, sizeof(uint16));
+		*start_address += sizeof(uint16);
+
+		/* Write datum/isnull. */
+		if (OidIsValid(typeOid))
+			get_typlenbyval(typeOid, &typLen, &typByVal);
+		else
+		{
+			/* If no type OID, assume by-value, like copyParamList does. */
+			typLen = sizeof(Datum);
+			typByVal = true;
+		}
+		datumSerialize(prm->value, prm->isnull, typByVal, typLen,
+					   start_address);
+	}
+}
+
+/*
+ * Copy a ParamListInfo structure.
+ *
+ * The result is allocated in CurrentMemoryContext.
+ *
+ * Note: the intent of this function is to make a static, self-contained
+ * set of parameter values.  If dynamic parameter hooks are present, we
+ * intentionally do not copy them into the result.  Rather, we forcibly
+ * instantiate all available parameter values and copy the datum values.
+ */
+ParamListInfo
+RestoreParamList(char **start_address)
+{
+	ParamListInfo paramLI;
+	int			nparams;
+
+	memcpy(&nparams, *start_address, sizeof(int));
+	*start_address += sizeof(int);
+
+	paramLI = makeParamList(nparams);
+
+	for (int i = 0; i < nparams; i++)
+	{
+		ParamExternData *prm = &paramLI->params[i];
+
+		/* Read type OID. */
+		memcpy(&prm->ptype, *start_address, sizeof(Oid));
+		*start_address += sizeof(Oid);
+
+		/* Read flags. */
+		memcpy(&prm->pflags, *start_address, sizeof(uint16));
+		*start_address += sizeof(uint16);
+
+		/* Read datum/isnull. */
+		prm->value = datumRestore(start_address, &prm->isnull);
+	}
+
+	return paramLI;
+}
+
+/*
+ * BuildParamLogString
+ *		Return a string that represents the parameter list, for logging.
+ *
+ * If caller already knows textual representations for some parameters, it can
+ * pass an array of exactly params->numParams values as knownTextValues, which
+ * can contain NULLs for any unknown individual values.  NULL can be given if
+ * no parameters are known.
+ *
+ * If maxlen is >= 0, that's the maximum number of bytes of any one
+ * parameter value to be printed; an ellipsis is added if the string is
+ * longer.  (Added quotes are not considered in this calculation.)
+ */
+char *
+BuildParamLogString(ParamListInfo params, char **knownTextValues, int maxlen)
+{
+	MemoryContext tmpCxt,
+				oldCxt;
+	StringInfoData buf;
+
+	/*
+	 * NB: think not of returning params->paramValuesStr!  It may have been
+	 * generated with a different maxlen, and so be unsuitable.  Besides that,
+	 * this is the function used to create that string.
+	 */
+
+	/*
+	 * No work if the param fetch hook is in use.  Also, it's not possible to
+	 * do this in an aborted transaction.  (It might be possible to improve on
+	 * this last point when some knownTextValues exist, but it seems tricky.)
+	 */
+	if (params->paramFetch != NULL ||
+		IsAbortedTransactionBlockState())
+		return NULL;
+
+	/* Initialize the output stringinfo, in caller's memory context */
+	initStringInfo(&buf);
+
+	/* Use a temporary context to call output functions, just in case */
+	tmpCxt = AllocSetContextCreate(CurrentMemoryContext,
+								   "BuildParamLogString",
+								   ALLOCSET_DEFAULT_SIZES);
+	oldCxt = MemoryContextSwitchTo(tmpCxt);
+
+	for (int paramno = 0; paramno < params->numParams; paramno++)
+	{
+		ParamExternData *param = &params->params[paramno];
+
+		appendStringInfo(&buf,
+						 "%s$%d = ",
+						 paramno > 0 ? ", " : "",
+						 paramno + 1);
+
+		if (param->isnull || !OidIsValid(param->ptype))
+			appendStringInfoString(&buf, "NULL");
+		else
+		{
+			if (knownTextValues != NULL && knownTextValues[paramno] != NULL)
+				appendStringInfoStringQuoted(&buf, knownTextValues[paramno],
+											 maxlen);
+			else
+			{
+				Oid			typoutput;
+				bool		typisvarlena;
+				char	   *pstring;
+
+				getTypeOutputInfo(param->ptype, &typoutput, &typisvarlena);
+				pstring = OidOutputFunctionCall(typoutput, param->value);
+				appendStringInfoStringQuoted(&buf, pstring, maxlen);
+			}
+		}
+	}
+
+	MemoryContextSwitchTo(oldCxt);
+	MemoryContextDelete(tmpCxt);
+
+	return buf.data;
+}
+
+/*
+ * ParamsErrorCallback - callback for printing parameters in error context
+ *
+ * Note that this is a no-op unless BuildParamLogString has been called
+ * beforehand.
+ */
+void
+ParamsErrorCallback(void *arg)
+{
+	ParamsErrorCbData *data = (ParamsErrorCbData *) arg;
+
+	if (data == NULL ||
+		data->params == NULL ||
+		data->params->paramValuesStr == NULL)
+		return;
+
+	if (data->portalName && data->portalName[0] != '\0')
+		errcontext("portal \"%s\" with parameters: %s",
+				   data->portalName, data->params->paramValuesStr);
+	else
+		errcontext("unnamed portal with parameters: %s",
+				   data->params->paramValuesStr);
+}