Resize buffer if BytesRead is less than MaxSegmentSize

src/MyFirstUDRKit.cpp

@@ -74,7 +74,7 @@
 #include <windows.h>
 #define SYSERROR()  GetLastError()
 #else
-#include <errno.h>
+#include <cerrno>
 #define SYSERROR()  errno
 #endif
 
@@ -180,6 +180,8 @@ FB_UDR_END_FUNCTION
  *	external name 'MyFirstUDRKit!MFKLoadBlobFromFile!Load file and save to Blob'
  *	engine udr;
  ***/
+// NOTE This function would be better as a procedure as that would allow it
+// to return the bytes written to the blob.
 FB_UDR_BEGIN_FUNCTION (MFK_LoadBlobFromFile)
 //BEGIN
 FB_UDR_MESSAGE(InMessage,
@@ -205,8 +207,9 @@ FB_UDR_EXECUTE_FUNCTION
 
 
 	std::ifstream FileReader;
-	FileReader.open( in->afilename.str , std::ifstream::binary );
+	FileReader.open( in->afilename.str , std::ifstream::binary | std::ifstream::in );
 	if (! FileReader.is_open()) {
+//	if (! FileReader.good()) {
 		out->ablobNull = FB_TRUE;
 		return;
 	}
@@ -238,7 +241,7 @@ FB_UDR_EXECUTE_FUNCTION
 			// What do we do with the partially written blob? Is cancel enough?
 			blob->cancel( status );
 		}
-		// ****** IT IS VITAL TO SET THIS IF WRITING  TO BLOB SUCCEEDED ********
+		// ****** IT IS VITAL TO SET THIS IF WRITING TO BLOB WAS SUCCESSFUL ******* //
 		out->ablobNull = FB_FALSE;
 
 		blob->close( status );
@@ -298,21 +301,32 @@ FB_UDR_EXECUTE_FUNCTION
 
 	/*
 	 * DOC NOTE - We do not test for existence of the file here!
+	 * This should be done prior to calling this function.
 	 */
 
-	std::ofstream FileWriter ( in->afilename.str , std::ofstream::binary );
+	std::ofstream FileWriter ( in->afilename.str , std::ofstream::binary | std::ofstream::out );
 	if (! FileWriter.is_open()) {
+//	if (! FileWriter.good()) {
 		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.
+
+		// important to set out->resultNull to false here otherwise the error
+		// code willbe 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;
-	}
+ 	}
+
+// This might be useful but doesn't work because it requires libc++ and we compile with libstdc++ on linux
+//		else {
+// 			    std::filesystem::permissions ( in->afilename.str, std::filesystem::perms::owner_all | std::filesystem::perms::group_all,
+// 																				 std::filesystem::perm_options::add );
+// 	}
 
 
 	att.reset(context->getAttachment(status));
@@ -328,6 +342,7 @@ FB_UDR_EXECUTE_FUNCTION
 
 		std::vector<std::uint8_t> Buffer (MaxSegmentSize, 0);
 		unsigned BytesRead = 0;
+		unsigned BufferSize = 0;
 
 		for (bool Eof = false; !Eof; )
 		{
@@ -336,6 +351,13 @@ FB_UDR_EXECUTE_FUNCTION
 				case IStatus::RESULT_OK:
 				case IStatus::RESULT_SEGMENT:
 				{
+					BufferSize = Buffer.size();
+					if ( BufferSize < BytesRead) {
+						BytesRead = BufferSize;
+					}
+					if ( BytesRead < MaxSegmentSize) {
+						Buffer.resize( BytesRead);
+					}
 					FileWriter.write( (char *) Buffer.data(), Buffer.size() );
 					out->result += BytesRead;
 					continue;