Add addDependencyBasedRequires configuration option

src/main/java/org/codehaus/mojo/rpm/AbstractRPMMojo.java

@@ -23,6 +23,7 @@
 import java.io.File;
 import java.io.FileReader;
 import java.io.FileWriter;
+import java.io.InputStreamReader;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.ArrayList;
@@ -608,6 +609,14 @@ public abstract class AbstractRPMMojo
     @Parameter( required = true, defaultValue = "rpm.release" )
     private String releaseProperty;
 
+    /**
+     * When enabled, automatically generates requires for all (transitive) rpm-dependencies.
+     * 
+     * @since 2.2.1
+     */
+    @Parameter
+    private boolean addDependencyBasedRequires;
+
     /**
      * The changelog file. If the file does not exist, it is ignored.
      *
@@ -1069,6 +1078,47 @@ else if ( "true".equalsIgnoreCase( needarch ) )
         }
 
         processDefineStatements();
+
+        if ( addDependencyBasedRequires )
+        {
+            appendDependencyBasedRequires();
+        }
+    }
+
+    /**
+     * Extends this.requires with additional require for each immediate rpm-type dependency
+     * of the project, requiring the same or a higher version as the resolved-dependency-version.
+     *
+     * @throws MojoExecutionException if the projects dependency-tree cannot be generated.
+     * @since 2.2.1
+     */
+    private void appendDependencyBasedRequires()
+        throws MojoExecutionException
+    {
+        if ( this.requires == null )
+        {
+            this.requires = new LinkedHashSet();
+        }
+        for ( Object dependency : project.getDependencyArtifacts() )
+        {
+            Artifact dependencyArtifact = (Artifact) dependency;
+            if ( "rpm".equals( dependencyArtifact.getType() ) )
+            {
+                StringBuilder require = new StringBuilder();
+                getLog().debug( "Determining rpm name and version of rpm-dependency " + dependencyArtifact);
+                File rpmFile = dependencyArtifact.getFile();
+                String rpmName = helper.getRpmAttribute( rpmFile, "NAME" );
+                String rpmVersion = helper.getRpmAttribute( rpmFile, "VERSION" );
+                String rpmRelease = helper.getRpmAttribute( rpmFile, "RELEASE" );
+                require.append( rpmName )
+                        .append( " >= " )
+                        .append( rpmVersion )
+                        .append( "-" )
+                        .append( rpmRelease );
+                getLog().info( "Add dependency-based require: " + require.toString() );
+                requires.add( require.toString() );
+            }
+        }
     }
 
     /**

src/main/java/org/codehaus/mojo/rpm/RPMHelper.java

@@ -19,7 +19,10 @@
  * under the License.
  */
 
+import java.io.BufferedReader;
 import java.io.File;
+import java.io.IOException;
+import java.io.InputStreamReader;
 
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugin.logging.Log;
@@ -250,4 +253,48 @@ public String getArch()
 
         return stdConsumer.getOutput().trim();
     }
+
+    /**
+     * Gets the value of the RPM attribute for the given RPM file..
+     * @param rpmFile The full path of the RPM file.
+     * @param attribute The attribute to get the value for.
+     * @return A String containing the value of the requested attribute.
+     * @throws MojoExecutionException if the attribute could not be read.
+     */
+    public String getRpmAttribute( File rpmFile, String attribute )
+        throws MojoExecutionException
+    {
+        final Commandline cl = new Commandline();
+        cl.setExecutable( "rpm" );
+        cl.createArg().setValue( "--query" );
+        cl.createArg().setValue( "--package" );
+        cl.createArg().setValue( rpmFile.getAbsolutePath() );
+        cl.createArg().setValue( "--queryformat" );
+        cl.createArg().setValue( "%{" + attribute + "}" );
+
+        final Log log = mojo.getLog();
+
+        final StringStreamConsumer stdout = new StringStreamConsumer();
+        final StreamConsumer stderr = new LogStreamConsumer( LogStreamConsumer.INFO, log );
+        try
+        {
+            if ( log.isDebugEnabled() )
+            {
+                log.debug( "About to execute \'" + cl.toString() + "\'" );
+            }
+
+            int result = CommandLineUtils.executeCommandLine( cl, stdout, stderr );
+            if ( result != 0 )
+            {
+                throw new MojoExecutionException( "rpm -query returned: \'" + result + "\' executing \'"
+                        + cl.toString() + "\'" );
+            }
+        }
+        catch ( CommandLineException e )
+        {
+            throw new MojoExecutionException( "Unable to get " + attribute + " from rpm", e );
+        }
+
+        return stdout.getOutput().trim();
+    }
 }

src/site/apt/adv-params.apt

@@ -76,6 +76,17 @@ Advanced Parameters
 </conflicts>
 +-----+
 
+* addDependencyBasedRequires
+
+  If you set the boolean property <<<addDependencyBasedRequires>>> to <<<true>>>, 
+  all Maven dependencies of type <<<rpm>>> in the current project will be added as 
+  a dependency to the generated RPM.
+
+  Using this option, you don't need to specify the <<<requires>>> option (see above)
+  for the direct RPM dependencies that you specified in your pom.xml.
+
+  This option defaults to <<<false>>>.
+
 * RPM Build Dependency Management
 
   <<These parameters relate to the dependencies required to build the RPM package contents.>>