Add addDependencyBasedRequires Parameter

To avoid duplication of dependency information from the Maven pom file towards the <requires> list of the rpm-maven-plugin configuration a new Parameter is added: addDependencyBasedRequires.

The idea of this feature is that the rpm-maven-plugin itself inspects the dependencies of the project in which it is executed and adds a Require: [rpm-name] >= [rpm-version] for each found RPM dependency.

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 +1078,67 @@ 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 = getRpmAttribute(rpmFile, "NAME");
+                String rpmVersion = getRpmAttribute(rpmFile, "VERSION");
+                String rpmRelease = getRpmAttribute(rpmFile, "RELEASE");
+                require.append(rpmName)
+                        .append(" >= ")
+                        .append(rpmVersion)
+                        .append("-")
+                        .append(rpmRelease);
+                getLog().info("Add dependency-based require: " + require.toString());
+                requires.add(require.toString());
+            }
+        }
+    }
+
+    private String getRpmAttribute(File rpmFile, String attribute) throws MojoExecutionException {
+        String attributeValue = null;
+        try {
+            Process rpmQuery = Runtime.getRuntime().exec(new String[]{"rpm", "--query", "--package", rpmFile.getAbsolutePath(),
+                    "--queryformat", "%{" + attribute + "}"});
+            if (rpmQuery.waitFor() == 0) {
+                attributeValue = new BufferedReader(new InputStreamReader(rpmQuery.getInputStream())).readLine().trim();
+            } else {
+                StringBuilder errorMsg = new StringBuilder();
+                BufferedReader errorStreamReader = new BufferedReader(new InputStreamReader(rpmQuery.getErrorStream()));
+                String line = errorStreamReader.readLine();
+                while (line != null) {
+                    errorMsg.append(line).append("\n");
+                    line = errorStreamReader.readLine();
+                }
+                throw new MojoExecutionException("Failed to get attribute '" + attribute + "' from rpm '" + rpmFile + "'\n" + errorMsg);
+            }
+        } catch (InterruptedException e) {
+            throw new MojoExecutionException("Failed to get attribute '" + attribute + "' from rpm '" + rpmFile + "'", e);
+        } catch (IOException e) {
+            throw new MojoExecutionException("Failed to get attribute '" + attribute + "' from rpm '" + rpmFile + "'", e);
+        }
+        // read stdout, and return as String
+        return attributeValue;
     }
 
     /**

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.>>