/*
* PROGRAM: Object oriented API samples.
* MODULE: 05.user_metadata.cpp
* DESCRIPTION: A sample of user-implemented IMessageMetadata.
* Prints firebird user name (SYSDBA by default).
*
* Example for the following interfaces:
*
* IOffsetsCallback - callback for IUtil::setOffsets()
* IMessageMetadata - how to implement it yourself
*
* The contents of this file are subject to the Initial
* Developer's Public License Version 1.0 (the "License");
* you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
* http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_idpl.
*
* Software distributed under the License is distributed AS IS,
* WITHOUT WARRANTY OF ANY KIND, either express or implied.
* See the License for the specific language governing rights
* and limitations under the License.
*
* The Original Code was created by Alexander Peshkoff
* for the Firebird Open Source RDBMS project.
*
* Copyright (c) 2016 Alexander Peshkoff <peshkoff@mail.ru>
* and all contributors signed below.
*
* All Rights Reserved.
* Contributor(s): ______________________________________.
*/
#include "ifaceExamples.h"
static IMaster* master = fb_get_master_interface();
/*
* Trivial sample of IMessageMetadata implementation.
* Metadata is created for a fixed output format with single char field.
* Therefore index parameter in all functions is ignored.
* Because the only possible error is index out of bounds status parameter is ignored too.
* Atomic operation is not used in IReferenceCounted cause we do not plan MT support.
* Non-array vars used to represent offset and nullOffset of that single field.
*/
class MyMetadata : public IMessageMetadataImpl<MyMetadata, ThrowStatusWrapper>
{
private:
class Callback : public IOffsetsCallbackImpl<Callback, ThrowStatusWrapper>
{
private:
MyMetadata* metadata;
public:
Callback(MyMetadata* pmeta)
: metadata(pmeta)
{ }
//IOffsetsCallback implementation
void setOffset(ThrowStatusWrapper* status, unsigned /*index*/, unsigned offset, unsigned nullOffset)
{
// Typically setOffset() function should save passed offsets
// in your implementation of message metadata.
metadata->offset = offset;
metadata->nullOffset = nullOffset;
}
};
FbSampleAtomic referenceCounter;
// we are using only single field (varchar) in a sample, therefore no strong alignment requirements.
// In general message alignment is the maximum field alignment in that message.
static const unsigned messageAlignment = sizeof(ISC_SHORT);
public:
unsigned offset, nullOffset, length;
MyMetadata()
: referenceCounter(0)
{
IUtil* utl = master->getUtilInterface();
ThrowStatusWrapper s(master->getStatus());
try
{
Callback cb(this);
length = utl->setOffsets(&s, this, &cb);
}
catch(...)
{
s.dispose();
throw;
}
s.dispose();
}
void addRef()
{
++referenceCounter;
}
int release()
{
int rc = --referenceCounter;
if (!rc)
delete this;
return rc;
}
// IMessageMetadata implementation
unsigned getCount(ThrowStatusWrapper* /*status*/)
{
return 1;
}
const char* getField(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return NULL;
}
const char* getRelation(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return NULL;
}
const char* getOwner(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return NULL;
}
const char* getAlias(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return NULL;
}
unsigned getType(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return SQL_VARYING;
}
FB_BOOLEAN isNullable(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return false;
}
int getSubType(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return 0;
}
unsigned getLength(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return 20; // Want to make it fit
}
int getScale(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return 0;
}
unsigned getCharSet(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return 0;
}
unsigned getOffset(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return offset;
}
unsigned getNullOffset(ThrowStatusWrapper* /*status*/, unsigned /*index*/)
{
return nullOffset;
}
IMetadataBuilder* getBuilder(ThrowStatusWrapper* status)
{
ISC_STATUS err[] = {isc_arg_gds, isc_wish_list, isc_arg_end};
status->setErrors(err);
return NULL;
}
unsigned getMessageLength(ThrowStatusWrapper* /*status*/)
{
return length;
}
unsigned getAlignment(ThrowStatusWrapper* /*status*/)
{
return messageAlignment;
}
unsigned getAlignedLength(ThrowStatusWrapper* /*status*/)
{
return ((length / messageAlignment) + (length % messageAlignment ? 1 : 0)) * messageAlignment;
}
};
template <typename T>
T to(const unsigned char* b, unsigned o)
{
return *((T*) (b + o));
}
int main()
{
int rc = 0;
unsigned char* buffer = NULL;
// set default password if none specified in environment
setenv("ISC_USER", "sysdba", 0);
setenv("ISC_PASSWORD", "masterkey", 0);
// status vector and main dispatcher
ThrowStatusWrapper status(master->getStatus());
IProvider* prov = master->getDispatcher();
// declare pointers to required interfaces
IAttachment* att = NULL;
ITransaction* tra = NULL;
IResultSet* curs = NULL;
MyMetadata* meta = NULL;
try
{
// Instance of our metadata
meta = new MyMetadata;
meta->addRef();
// allocate output buffer
buffer = new unsigned char[meta->length];
// attach employee db
att = prov->attachDatabase(&status, "employee", 0, NULL);
// start default transaction
tra = att->startTransaction(&status, 0, NULL);
// open cursor
curs = att->openCursor(&status, tra, 0, "select current_user from rdb$database",
SAMPLES_DIALECT, NULL, NULL, meta, NULL, 0);
// fetch record from cursor and print it
curs->fetchNext(&status, buffer);
ISC_SHORT l = to<ISC_SHORT>(buffer, meta->offset);
printf("<%*.*s>\n", l, l, buffer + meta->offset + sizeof(ISC_SHORT));
// close interfaces
curs->close(&status);
curs = NULL;
tra->commit(&status);
tra = NULL;
att->detach(&status);
att = NULL;
}
catch (const FbException& error)
{
// handle error
rc = 1;
char buf[256];
master->getUtilInterface()->formatStatus(buf, sizeof(buf), error.getStatus());
fprintf(stderr, "%s\n", buf);
}
// release interfaces after error caught
if (curs)
curs->release();
if (tra)
tra->release();
if (att)
att->release();
// generic cleanup
if (meta)
meta->release();
prov->release();
status.dispose();
delete[] buffer;
return rc;
}