From 48e2d3207618a75a6f8a042a8568bde889a8c5e7 Mon Sep 17 00:00:00 2001
From: Dimitry Sibiryakov <sd@ibphoenix.com>
Date: Mon, 19 May 2025 16:11:05 +0200
Subject: [PATCH] Recognize message format with a real data length for
 dtype_text

---
 src/dsql/ExprNodes.cpp | 39 +++++++++++++++++++++++++++++++++++----
 src/dsql/ExprNodes.h   |  1 +
 2 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/src/dsql/ExprNodes.cpp b/src/dsql/ExprNodes.cpp
index 31973dfcd4e..c2f2eb4905e 100644
--- a/src/dsql/ExprNodes.cpp
+++ b/src/dsql/ExprNodes.cpp
@@ -9881,6 +9881,19 @@ ParameterNode* ParameterNode::pass1(thread_db* tdbb, CompilerScratch* csb)
 			status_exception::raise(Arg::Gds(isc_ctxnotdef) << Arg::Gds(isc_random) << Arg::Str("Outer parameter has no outer scratch"));
 	}
 
+	const dsc& desc = format->fmt_desc[argNumber];
+	if (desc.isText())
+	{
+		// Remember expected maximum length in characters to be able to recognize format of the real data buffer later
+		const CharSet* charSet = INTL_charset_lookup(tdbb, desc.getCharSet());
+		USHORT length = TEXT_LEN(&desc);
+		if (charSet->isMultiByte())
+		{
+			length /= charSet->maxBytesPerChar();
+		}
+		maxCharLength = length;
+	}
+
 	return this;
 }
 
@@ -9944,9 +9957,6 @@ dsc* ParameterNode::execute(thread_db* tdbb, Request* request) const
 	{
 		if (impureForOuter)
 			EVL_make_value(tdbb, retDesc, impureForOuter);
-
-		if (retDesc->dsc_dtype == dtype_text)
-			INTL_adjust_text_descriptor(tdbb, retDesc);
 	}
 
 	auto impureFlags = paramRequest->getImpure<USHORT>(
@@ -9984,7 +9994,9 @@ dsc* ParameterNode::execute(thread_db* tdbb, Request* request) const
 				auto charSet = INTL_charset_lookup(tdbb, DSC_GET_CHARSET(retDesc));
 
 				EngineCallbacks::instance->validateData(charSet, len, p);
-				EngineCallbacks::instance->validateLength(charSet, DSC_GET_CHARSET(retDesc), len, p, maxLen);
+
+				// Validation of length for user-provided data against user-provided metadata makes a little sense here. Leave it to the real assignment.
+				// Besides in some cases overlong values are valid. For example `field like ?`
 			}
 			else if (retDesc->isBlob())
 			{
@@ -10013,6 +10025,25 @@ dsc* ParameterNode::execute(thread_db* tdbb, Request* request) const
 		*impureFlags |= VLU_checked;
 	}
 
+	// This block is after validation because having here a malformed data would produce a wrong result
+	if (!(request->req_flags & req_null) && retDesc->dsc_dtype == dtype_text && maxCharLength != 0)
+	{
+		// Data in the message buffer can be in a padded Firebird format or in an application-defined format with real length.
+		// API provides no way to distinguish these cases so we must use some heuristics:
+		// perform the adjustment only if the data length matches the length that would be expected in the padded format.
+
+		const CharSet* charSet = INTL_charset_lookup(tdbb, retDesc->getCharSet());
+
+		if (charSet->isMultiByte() && maxCharLength * charSet->maxBytesPerChar() == retDesc->dsc_length)
+		{
+			Firebird::HalfStaticArray<UCHAR, BUFFER_SMALL> buffer;
+
+			retDesc->dsc_length = charSet->substring(retDesc->dsc_length, retDesc->dsc_address,
+				retDesc->dsc_length, buffer.getBuffer(retDesc->dsc_length), 0,
+				maxCharLength);
+		}
+	}
+
 	return (request->req_flags & req_null) ? nullptr : retDesc;
 }
 
diff --git a/src/dsql/ExprNodes.h b/src/dsql/ExprNodes.h
index 9a7166740fe..906eda67290 100644
--- a/src/dsql/ExprNodes.h
+++ b/src/dsql/ExprNodes.h
@@ -1671,6 +1671,7 @@ class ParameterNode final : public TypedNode<ValueExprNode, ExprNode::TYPE_PARAM
 	// Message can be modified during merge of SP/view subtrees
 	USHORT messageNumber = MAX_USHORT;
 	USHORT argNumber = 0;
+	USHORT maxCharLength = 0;
 	bool outerDecl = false;
 };