SaveBlobToFile (WIP)

src/MyFirstUDRKit.cpp

@@ -70,6 +70,14 @@
 
 #include <limits>
 
+#ifdef _WIN32
+#include <windows.h>
+#define SYSERROR()  GetLastError()
+#else
+#include <errno.h>
+#define SYSERROR()  errno
+#endif
+
 using namespace Firebird;
 
 
@@ -243,8 +251,7 @@ FB_UDR_EXECUTE_FUNCTION
 		throw Firebird::FbException(status, statusVector);
 	}
 	catch (...) {
-		// This generates an unrecognised C++ exception, which is insufficient.
-		throw std::runtime_error("Error writing stream to BLOB.");
+		throw std::runtime_error("Error writing file to BLOB.");
 	}
 
 }
@@ -267,7 +274,7 @@ engine udr;
 FB_UDR_BEGIN_FUNCTION(MFK_SaveBlobToFile)
 //BEGIN
 FB_UDR_MESSAGE(InMessage,
-							 (FB_CHAR(8191), afilename)
+							 (FB_VARCHAR(8191), afilename)
 							 (FB_BLOB, ablob)
 );
 
@@ -277,7 +284,8 @@ FB_UDR_MESSAGE(OutMessage,
 
 AutoRelease<IAttachment> att;
 AutoRelease<ITransaction> tra;
-AutoRelease<IBlob> Blob;
+AutoRelease<IBlob> blob;
+ISC_STATUS_ARRAY statusVector = {0};
 
 
 FB_UDR_EXECUTE_FUNCTION
@@ -292,47 +300,68 @@ FB_UDR_EXECUTE_FUNCTION
 	 * DOC NOTE - We do not test for existence of the file here!
 	 */
 
-	std::fstream File ( in->afilename.str , std::fstream::out | std::fstream::binary | std::fstream::app );
-	if (! File.is_open()) {
-		out->result = -2;
+	std::ofstream FileWriter ( in->afilename.str , std::ofstream::binary );
+	if (! FileWriter.is_open()) {
+		out->resultNull = FB_TRUE;
+		// Convert system error to a negative value and assign to result
+		out->result = ( SYSERROR() * -1 );
+		// important to set this to false here otherwise the error code will
+		// be hidden and NULL returned to the firebird engine. This is because
+		// the test for out->resultNull has precedence.
+		if ( out->result < 0 ) {
+			out->resultNull = FB_FALSE;
+		}
 		return;
 	}
 
 
-	Blob.reset(att->openBlob(status, tra, &in->ablob, 0, nullptr));
-	if (Blob == nullptr) {
-		out->result = -1;
-		return;
-	}
+	att.reset(context->getAttachment(status));
+	tra.reset(context->getTransaction(status));
+	blob.reset(att->openBlob(status, tra, &in->ablob, 0, nullptr));
+	try {
 
+		if (blob == nullptr) {
+			out->resultNull = FB_TRUE;
+			out->result = -1;
+			return;
+		}
 
-	std::vector<char> Buffer (MaxSegmentSize, 0);
+		std::vector<std::uint8_t> Buffer (MaxSegmentSize, 0);
+		unsigned BytesRead = 0;
 
-	unsigned BytesRead = 0;
-
-	for (bool Eof = false; !Eof; )
-	{
-		switch (Blob->getSegment( status, MaxSegmentSize, Buffer.data(), &BytesRead))
+		for (bool Eof = false; !Eof; )
 		{
-			case IStatus::RESULT_OK:
-			case IStatus::RESULT_SEGMENT:
+			switch ( blob->getSegment ( status, MaxSegmentSize, Buffer.data(), &BytesRead))
 			{
-				File.write( Buffer.data(), Buffer.size() );
-				out->result += BytesRead;
-				continue;
-			}
-			default:
-			{
-				Blob->close( status ); // will close interface
-				Blob.release();
-				Eof = true;
-				break;
+				case IStatus::RESULT_OK:
+				case IStatus::RESULT_SEGMENT:
+				{
+					FileWriter.write( (char *) Buffer.data(), Buffer.size() );
+					out->result += BytesRead;
+					continue;
+				}
+				default:
+				{
+					blob->close( status ); // will close interface
+					blob->release();
+					Eof = true;
+					break;
+				}
 			}
 		}
+		// If we have got this far then we have written the blob.
+		// out->resultNULL ***must*** be set to false or else the function will return NULL
+		out->resultNull = FB_FALSE;
+		Buffer.clear();
+		FileWriter.close();
+	}
+	catch ( const FbException& error )
+	{
+		throw Firebird::FbException(status, statusVector);
+	}
+	catch (...) {
+		throw std::runtime_error("Error writing BLOB to file.");
 	}
-
-	Buffer.clear();
-	File.close();
 
 }
 

test/testudrkit-tests.dml

@@ -20,15 +20,33 @@ execute procedure load_blob(3);
 execute procedure load_blob(4);
 commit;
 
-select cast ( description as varchar(32) ) as DESCRIPTION
+select cast ( description as varchar(16) ) as DESCRIPTION
  , file_type
  , cast (left(source_file,32)  as varchar(32)) as source_file
  , source_status
--- , source_bytes D_BIGINT
--- , target_file D_PATH
--- , target_status D_STATUS
--- , target_bytes D_BIGINT
--- , the_blob D_BLOB
+ , cast (left(target_file,32)  as varchar(32)) as target_file
+ , target_status
+ , target_bytes
 from test_blobs;
 commit;
 
+set term ^;
+shell
+  mkdir --verbose /tmp/testudrkit
+  ls /tmp/testudrkit
+^
+set term ;^
+
+execute procedure save_blob(1, '/tmp/testudrkit/fb.conf' );
+execute procedure save_blob(2, '/tmp/testudrkit/fb.log' );
+commit;
+
+select cast ( description as varchar(16) ) as DESCRIPTION
+ , file_type
+ , cast (left(source_file,32)  as varchar(32)) as source_file
+ , source_status
+ , cast (left(target_file,32)  as varchar(32)) as target_file
+ , target_status
+ , cast (target_bytes as varchar(16) ) as target_bytes
+from test_blobs;
+commit;

test/testudrkit.ddl

@@ -85,10 +85,39 @@ begin
 		EXCEPTION E_BLOB_EXCEPTION 'Error updating test_blobs';
 	end
 
+end ^
+
+set term ;^
+
+
+set term ^;
+create or alter procedure save_blob ( a_test_blob_id D_ID, atarget_file D_PATH )  sql security definer
+as
+  declare theblob D_BLOB;
+  declare result D_BIGINT;
+  declare status D_STATUS;
+begin
+
+	select the_blob from test_blobs where test_blobs_id = :a_test_blob_id into :theblob;
+	select SaveBlobToFile( :atarget_file, :theblob ) from rdb$database into :result;
+
+	if ( result >= 0 ) then
+		status = 'W';
+	else
+		status = 'F';
+
+	update test_blobs
+		set target_file = :atarget_file
+		, target_bytes = :result
+		, target_status = :status
+	where test_blobs_id = :a_test_blob_id;
+	when any do begin
+		EXCEPTION E_BLOB_EXCEPTION 'Error updating test_blobs';
+	end
+
 
 
 end ^
 
 set term ;^
 
-