SourceLob.java
/*
** Module : SourceLob.java
** Abstract : Source parameter of a converted COPY-LOB statement.
**
** Copyright (c) 2019-2023, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description---------------------------------------
** 001 ECF 20190510 Created initial version.
** 002 ECF 20190628 Implemented COPY-LOB runtime.
** 003 CA 20191119 unknown values are allowed as source lob.
** 004 CA 20191203 Fixed overlay and unknown COPY-LOB related bugs.
** 005 CA 20200427 I18nOps.convmap2Java uses uppercase keys.
** 006 OM 20210328 Improved copy lob engine and validations.
** 007 HC 20230118 Eliminated some of the uses of String.toUpperCase and/or String.toLowerCase
** for performance.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
** are non-permissive additional terms allowed under Section 7 of the GNU
** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
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**
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*/
package com.goldencode.p2j.util;
import java.io.*;
/**
* Concrete implementation of a converted COPY-LOB source parameter, corresponding with the
* {@code FROM [ OBJECT ] source-lob} phrase.
*/
public class SourceLob
extends LobCopyInput
{
/** Large object which is the source of the copy operation */
private final LargeObject lob;
/**
* Constructor which takes a LOB.
*
* @param lob
* Large object which is the source of the copy operation.
*/
public SourceLob(LargeObject lob)
{
this.lob = lob;
}
/**
* Constructor which takes an object that is expected to be a LOB. Intended to handle the
* converted POLY case.
*
* @param lob
* Large object which is the source of the copy operation.
*
* @throws ConditionException
* if {@code lob} is not an instance of @LargeObject@.
*/
public SourceLob(Object lob)
{
this(LobCopy.assertParameterType(lob));
}
/**
* Checks if the optional offset is valid.
*
* @param targetType
* The type of the target object. The error messages are different in some cases.
*
* @return {@code true} if the optional offset is valid.
*/
@Override
public boolean validateOffset(int targetType)
{
if (offset != null)
{
if (offset.isUnknown() || offset.intValue() <= 0)
{
ErrorManager.recordOrThrowError(11332);
// Invalid offset specified in COPY-LOB statement. (11332)
return false;
}
int objectType = getObjectType();
if (getSize() < offset.longValue())
{
if (objectType == TYPE_LONGCHAR || objectType == TYPE_MEMPTR)
{
return true; // this is not an error, an empty string will be returned/used
}
if (targetType == TYPE_FILE)
{
ErrorManager.recordOrThrowError(11265);
// Attempt to access blob beyond its end. (11265)
}
else
{
// NOTE: sometimes 11332 is thrown instead for: (targetType == MEMPTR && objectType == CLOB)
ErrorManager.recordOrThrowError(11334);
// Offset supplied for source large object is greater than object size. (11334)
}
}
}
return true;
}
/**
* Indicate whether this object is a valid large object data type. It is possible to pass a
* POLY which is not a valid LOB type as a COPY-LOB parameter, and this error must be
* determined at runtime.
*
* @return {@code true} if valid, else {@code false}. The default implementation assumes
* validity; implementors which must handle runtime type verification must override
* this method.
*/
@Override
public boolean isLargeObject()
{
return lob != null;
}
/**
* Obtain the type of the object wrapped by this parameter
*
* @return The numerical id of a type declared as one of the TYPE static constants from
* {@code LobCopyParameter} interface.
*/
@Override
public int getObjectType()
{
return (lob instanceof clob) ? TYPE_CLOB : // must be checked first
(lob instanceof blob) ? TYPE_BLOB :
(lob instanceof memptr) ? TYPE_MEMPTR :
(lob instanceof longchar) ? TYPE_LONGCHAR : TYPE_UNKNOWN;
}
/**
* Indicate whether the large object represented by this parameter natively represents
* encoded character data, as opposed to binary data.
*
* @return {@code true} if character data; {@code false} if binary data.
*/
@Override
public boolean isCharacterData()
{
return lob != null && lob.isCharacterData();
}
/**
* Get the size of the object to be copied.
*
* @return Size of object, in bytes or characters, as appropriate to the object type.
*/
@Override
protected int getSize()
{
// cast is ok; max 4GL LOB size fits in integer
return (int) lob.lengthOf();
}
/**
* Get the code page of this parameter, if any.
*
* @return 4GL code page name or {@code null} if parameter represents non-character data.
*/
@Override
public String getCodePage()
{
return LobCopy.getLobDefaultCodePage(lob);
}
/**
* Read the content of the backing LOB from the starting offset up to the length and return
* it as a string using the given encoding.
*
* @param codePage
* Name of the 4GL code page to be used to encode the read string. If {@code null},
* the large object's explicit code page (if any) will be used. If none, the value
* of {@code -cpinternal} will be used.
*
* @return The data as described above.
*/
@Override
protected String readString(String codePage)
{
// NOTE: this implementation is wasteful in the case that the entire content of the LOB
// is not needed, in that we encode the entire byte array into a String, then pluck out
// the substring we are interested in. However, I'm not sure how else to do this to ensure
// we are getting the proper character offset and length, since the number of bytes per
// character can vary by charset.
if (isLargeObject() && lob.isUnknown())
{
return isCharacterData() ? null : "";
}
long size = lob.lengthOf();
String all;
if (codePage != null && I18nOps.isSupported(codePage))
{
String charset = I18nOps.convmap2Java.get(codePage);
try
{
byte[] data = lob.asByteArray(0, size);
if (!I18nOps.prevalidateData(data, 0, data.length, codePage))
{
ErrorManager.recordOrThrowError(12008, codePage.toUpperCase(), "");
// Invalid character code found in data for codepage (12008)
return ""; // if ever
}
all = new String(data, charset);
}
catch (UnsupportedEncodingException exc)
{
ErrorManager.recordOrThrowError(12008);
// Invalid character code found in data for codepage (12008)
return null;
}
}
else
{
byte[] data = lob.asByteArray(0, size);
if (!I18nOps.prevalidateData(data, 0, data.length, codePage))
{
String cp = (codePage == null) ? I18nOps._getCPInternal() : codePage.toUpperCase();
ErrorManager.recordOrThrowError(12008, cp, "");
// Invalid character code found in data for codepage (12008)
return ""; // if ever
}
all = new String(data);
}
int off = getOffset();
int len = getLength();
if (off == 0 && len == size)
{
return all;
}
// in case of LONGCHAR it is legal to 'read' off the available data; the result is the empty string
if (off >= size)
{
return "";
}
// adjust the length overflow: 'read' all remaining data from the input LOB
if (off + len > size)
{
return all.substring(off);
}
return all.substring(off, off + len);
}
/**
* Read the content of the backing LOB from the starting offset up to the length and return
* it as a byte buffer.
* <p>
* Note that the returned buffer must not be modified, as it could either be a copy of the LOB's data or
* its real backing data.
*
* @return The data as described above.
*/
@Override
protected byte[] readBytes()
{
int off = getOffset();
int len = getLength();
return lob.asByteArray(off, len);
}
}