Seek in temporary blob level 0 makes read return wrong data

[asfernandes]

Without line blob->seek(&status, 0, 0); data is returned correctly.

#include "ifaceExamples.h"
#include <firebird/Message.h>

static IMaster* master = fb_get_master_interface();

static void errPrint(IStatus* status)
{
	char buf[256];
	master->getUtilInterface()->formatStatus(buf, sizeof(buf), status);
	fprintf(stderr, "%s\n", buf);
}

static void drop(IAttachment** att)
{
	// With CheckStatusWrapper passed as status interface noting is thrown on error
	// You should check status yourself
	CheckStatusWrapper status(master->getStatus());

	// drop database (will close interface)
	(*att)->dropDatabase(&status);
	if (status.getState() & IStatus::STATE_ERRORS)
	{
		errPrint(&status);
		fprintf(stderr, "*** Drop database failed - do it manually before next run ***\n");
	}
	else
		*att = nullptr;

	// cleanup
	status.dispose();
}

int main()
{
	int rc = 0;

	// set default password if none specified in environment
	setenv("ISC_USER", "sysdba", 0);
	setenv("ISC_PASSWORD", "masterkey", 0);

	// With ThrowStatusWrapper passed as status interface FbException will be thrown on error
	ThrowStatusWrapper status(master->getStatus());

	// Declare pointers to required interfaces
	IProvider* prov = master->getDispatcher();
	IAttachment* att = nullptr;
	ITransaction* tra = nullptr;
	IBlob* blob = nullptr;

	try
	{
		att = prov->createDatabase(&status, "blob_test.fdb", 0, nullptr);
		tra = att->startTransaction(&status, 0, nullptr);

		FB_MESSAGE(Msg, ThrowStatusWrapper,
			(FB_BLOB, b)
		) message(&status, master);

		message.clear();
		att->execute(&status, tra, 0, "select blob_append(null, '1234567890') from rdb$database", SAMPLES_DIALECT,
			nullptr, nullptr, message.getMetadata(), message.getData());
		blob = att->openBlob(&status, tra, &message->b, 0, nullptr);

		blob->seek(&status, 0, 0);

		int bufOver = 0;
		for (bool eof = false; !eof; )
		{
			const char* lineFeed = "\n";
			char buf[3];
			unsigned l = 0;

			switch (blob->getSegment(&status, sizeof(buf) - 1, buf, &l))
			{
				case IStatus::RESULT_OK:
					break;
				case IStatus::RESULT_SEGMENT:
					lineFeed = "";
					bufOver++;
					break;
				default:
					eof = true;
					continue;
			}

			buf[l] = 0;
			printf("%s%s", buf, lineFeed);
		}

		blob->close(&status);
		blob = nullptr;

		tra->commit(&status);
		tra = nullptr;

		drop(&att);
	}
	catch (const FbException& error)
	{
		// handle error
		rc = 1;
		errPrint(error.getStatus());

		if (att)
			drop(&att);
	}

	// release interfaces after error caught
	if (blob)
		blob->release();

	if (tra)
		tra->release();

	if (att)
		att->release();

	status.dispose();
	prov->release();

	return rc;
}

[hvlad]

BLOB_APPEND have nothing comon with this test.
Just replace it by base64_encode(cast('1234567890' as blob sub_type text)).

[aafemt]

That would produce a segmented BLOB, no? Seek is supposed not to work with segmented BLOBs at all.

[hvlad]

No.
Why do you think I use base64_encode ?