productversionholder.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.iapi.services.info.ProductVersionHolder

   Copyright 1998, 2004 The Apache Software Foundation or its licensors, as applicable.

   Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

*/

package org.apache.derby.iapi.services.info;

import java.io.InputStream;
import java.io.IOException;
import java.util.Properties;


/**
  Class to hold a cloudscape Product version.

  This class includes the following product version features.

  <OL>
  <LI>Save the product version information this holds as a String. We call
      the string a 'product version string'.
  <LI>Construct a ProductVersionHolder from a valid 'product version string'.
  <LI>Determine if two product versions are feature compatible. This means
      products of these versions may interoperate with ***NO*** compatibility
	  problems.
  <LI>Determine if two product versions are the same. This is a stronger
      test than the test for feature compatibility.
  </OL>



  Cloudscape 5.1 and older versions used the majorVersion, minorVersion, maintVersion versions
  directly. That is a three part version number, majorVersion.minorVersion.maintVersion, e.g. 5.1.21.

  For Cloudscape 5.2 onwards a four part name is required.
	majorVersion.minorVersion.fixPack.bugVersion e.g. 5.2.1.2

	This follows the IBM standard and allows us to state that a fix pack will be 5.2.3 without worrying
	about how many maintence fixes there are between fix packs.

	We implement this using the existing format of ProductVersionHolder to reduce disruption to the
	code, however we make the maintVersion encode the {fixPack.bugVersion}. Since the maintVersion
	is represented by a int (2G values) we have plenty of room for encoding. If we assign a given
	majorVersion.minorVersion.fixPack a 10 year life, then we about the maximum number of individual releases
	it can have is 10 years * 365 days/year = 3650. Thus with the pre 5.2 scheme we would not expect a 
	5.1.x to have an x > 3650 (approximately). Usually the rate of point releases has been much less than
	one per day, 5.1.31 is released about 225 days after GA which makes around a point release every 7 days.
	But in the encoding we need to be conservative. With fix packs the maximum is about 2 per year and fix
	packs are only made to the current release, thus with a yearly minor release cycle we would imagine
	only 2 fixpacks per major.minor. However like other IBM products or release cycle may be extended thus
	we can expect up to a handful of fix packs.

	Thus we might imagine releases like

	5.2.0.12
	5.2.0.234
	5.2.1.34
	5.2.4.2445

  but highly unlikey to have

	5.2.2.59321
	5.2.23.1
	

    The encoding number must continue to increase so that the
	
		encodedMaintB > encodedMaintA

		if (fixPackB > fixPackA) || ((fixPackB == fixPackA) && (bugB > bugA))


	Selected encoding

	encodedMaint = (fixPack * 1,000,000) + (bugVersion);

	Handles many many fixpacks and upto one million bug fixes per fix pack and remains somewhat human readable.

	Special fix packs

	fixpack == 0 = alpha (version off main codeline)
	fixpack == 1 = first release of major.minor (may be marked with beta)
	fixpack == 2 = first fix pack (displayed as 1)
     

	The drdaMaintVersion is sent in the Network Server PRDID. It never displays
    but may be used by the client for version specific behaviour. It should be 
	reset to 0 with each minor release.	

  The product version string has the form:
  <PRE>
  productVendorName - ProductName - majorVersion.minorVersion.maintVersion [beta] - (buildNumber)

  </PRE>

  */
public final class ProductVersionHolder implements java.security.PrivilegedAction
{

	//
	//Used as an invalid value for numbers. This works because all
	//the numbers in a product version must be non-negative.
	private static final int BAD_NUMBER = -1;
	private static final String ALPHA = "alpha";
	private static final String BETA = "beta";

	private final static int	MAINT_ENCODING = 1000000;
	
	private String productVendorName;
	private String productName;
	private String productTechnologyName;
	private int majorVersion = BAD_NUMBER;
	private int minorVersion = BAD_NUMBER;
	private int maintVersion = BAD_NUMBER;
	private int drdaMaintVersion = BAD_NUMBER;
	private String buildNumber = "????";
	private Boolean isBeta;

	private ProductVersionHolder() {
	}
	
	/**
	  Create a ProductVersionHolder

	  <P>Please see the documentation for the varient of getProductVesionHolder
	  that takes the same parameters as this for a description of the parameters.
	  */
	private ProductVersionHolder(String productVendorName,
								 String productName,
								 String productTechnologyName,
								 int majorVersion,
								 int minorVersion,
								 int maintVersion,
								 int drdaMaintVersion,
								 String buildNumber,
								 Boolean isBeta)
	{
		if (productVendorName != null)
			this.productVendorName = productVendorName.trim();
		if (productName != null)
			this.productName = productName.trim();
		if (productTechnologyName != null)
			this.productTechnologyName = productTechnologyName.trim();
		this.majorVersion = majorVersion;
		this.minorVersion = minorVersion;
		this.maintVersion = maintVersion;
		this.drdaMaintVersion = drdaMaintVersion;
		this.buildNumber = buildNumber;
		this.isBeta = isBeta;
	}

	/**
	  Create a valid ProductVersionHolder. If any of the
	  parameters provided is invalid, this returns null.
	  @param productName The name of the product. productName.length()
	  must be greater than 0. The syntax for a product name is
	  'productGenus[:productSpecies]'. 
	  @param majorVersion The most significant portion of a 3 
	  part product version.  Must be non-negative.
	  @param minorVersion The second portion of a 3 part 
	  product version. Must be non-negative.
	  @param maintVersion The least significant portion of a 3 part
	  product version. Must be non-negative.
	  @param drdaMaintVersion The protocol modification number for minor release.
	  @param buildNumber The buildNumber for a product. 
	  @param isBeta true iff the product is beta.
	  @return A valid ProductVersionHolder of null if any of the parameters
	  provided are not valid.
	  */
	public static ProductVersionHolder
	getProductVersionHolder(
						   String productVendorName,
						   String productName,
						   String productTechnologyName,
						   int majorVersion,
						   int minorVersion,
						   int maintVersion,
						   int drdaMaintVersion,
						   String buildNumber,
						   Boolean isBeta)
	{
		ProductVersionHolder pvh =
			new ProductVersionHolder(productVendorName,
									 productName,
									 productTechnologyName,
									 majorVersion,
									 minorVersion,
									 maintVersion,
									 drdaMaintVersion,
									 buildNumber,
									 isBeta);
		return pvh;
	}
	
	/**
	  Get a ProductVersionHolder for a product of a given genus,
	  that is available in the caller's environment. 
	  Even though this uses a priv bock, it may stil fail when
	  the jar the version is being fetched from, is different to the
	  one that loaded this class, AND the jars are in different security contexts.

	  @param productGenus The genus for the product.
	  @return The ProductVersionHolder or null if
	  a product with the given genus is not available in the
	  caller's environment.
	  */
	public static ProductVersionHolder
	getProductVersionHolderFromMyEnv(String productGenus)
	{

		ProductVersionHolder tempPVH = new ProductVersionHolder();

		tempPVH.productGenus = productGenus;
		Properties p = (Properties) java.security.AccessController.doPrivileged(tempPVH);

		if (p == null)
			return null;

		return getProductVersionHolder(p);
	}


	/**
		Load the version info from the already opened properties files.
		We need to do this because if the jar files (e.g. db2jtools and db2j)
		are in different security contexts (entries in the policy files) then
		we cannot load the version information for one of them correctly.
		This is because the this class will either have been loaded from
		only one of the jars and hence can only access the resource in its own jar.
		By making code specific to the jar open the resource we are guaranteed it will work.
	*/
	public static ProductVersionHolder
	getProductVersionHolderFromMyEnv(InputStream propertiesStream)
	{

		if (propertiesStream == null)
			return null;

		Properties p = new Properties();
		try {
			p.load(propertiesStream);
		}
		catch (IOException ioe) {

			System.out.println("IOE " + ioe.getMessage());
			//
			//This case is a bit ugly. If we get an IOException, we return
			//null. Though this correctly reflects that the product is not
			//available for use, it may be confusing to users that we swallow
			//the IO error here.
			return null;
		} finally {
			try {
				propertiesStream.close();
			} catch (IOException ioe2) {
			}
		}

		return getProductVersionHolder(p);
	}

	/**
	  Get a ProductVersionHolder based on the information in