[MDEP-972] copy-dependencies: copy signatures alongside artifacts

pom.xml

@@ -405,6 +405,17 @@ under the License.
       <version>${slf4jVersion}</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.apache.maven.resolver</groupId>
+      <artifactId>maven-resolver-api</artifactId>
+      <version>1.9.22</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.maven.resolver</groupId>
+      <artifactId>maven-resolver-util</artifactId>
+      <version>1.9.22</version>
+    </dependency>
   </dependencies>
 
   <build>

src/main/java/org/apache/maven/plugins/dependency/fromDependencies/CopyDependenciesMojo.java

@@ -97,6 +97,14 @@ public class CopyDependenciesMojo extends AbstractFromDependenciesMojo {
     @Parameter(property = "mdep.addParentPoms", defaultValue = "false")
     protected boolean addParentPoms;
 
+    /**
+     * Also copy the signature files (.asc) of each artifact.
+     *
+     * @since 3.2.0
+     */
+    @Parameter(property = "mdep.copySignatures", defaultValue = "false")
+    protected boolean copySignatures;
+
     @Inject
     // CHECKSTYLE_OFF: ParameterNumber
     public CopyDependenciesMojo(
@@ -240,6 +248,8 @@ protected void copyArtifact(
      * @see CopyUtil#copyArtifactFile(Artifact, File)
      * @see DependencyUtil#getFormattedOutputDirectory(boolean, boolean, boolean, boolean, boolean, boolean, File, Artifact)
      */
+    private static final String SIGNATURE_EXTENSION = ".asc";
+
     protected void copyArtifact(
             Artifact artifact,
             boolean removeVersion,
@@ -266,12 +276,53 @@ protected void copyArtifact(
         }
         try {
             copyUtil.copyArtifactFile(artifact, destFile);
+
+            // Copy the signature file if the copySignatures flag is true
+            if (copySignatures) {
+                copySignatureFile(artifact, destDir, destFileName);
+            }
+
         } catch (IOException e) {
             throw new MojoExecutionException(
                     "Failed to copy artifact '" + artifact + "' (" + artifact.getFile() + ") to " + destFile, e);
         }
     }
 
+    /**
+     * Copies the signature file of the artifact to the destination directory, if it exists or can be resolved.
+     * If the signature file does not exist and cannot be resolved, a warning is logged.
+     * @param artifact the artifact whose signature file should be copied
+     * @param destDir the destination directory
+     * @param destFileName the destination file name without the extension
+     */
+    private void copySignatureFile(Artifact artifact, File destDir, String destFileName) {
+        File signatureFile = new File(artifact.getFile().getAbsolutePath() + SIGNATURE_EXTENSION);
+
+        if (!signatureFile.exists()) {
+            try {
+                org.eclipse.aether.artifact.Artifact aArtifact = RepositoryUtils.toArtifact(artifact);
+                org.eclipse.aether.artifact.Artifact aSignatureArtifact =
+                        new SubArtifact(aArtifact, null, "jar" + SIGNATURE_EXTENSION);
+                org.eclipse.aether.artifact.Artifact resolvedSignature = getResolverUtil()
+                        .resolveArtifact(aSignatureArtifact, getProject().getRemoteProjectRepositories());
+                signatureFile = resolvedSignature.getFile();
+            } catch (ArtifactResolutionException e) {
+                getLog().warn("Failed to resolve signature file for artifact: " + artifact, e);
+            }
+        }
+
+        if (signatureFile != null && signatureFile.exists()) {
+            File signatureDestFile = new File(destDir, destFileName + SIGNATURE_EXTENSION);
+            try {
+                copyUtil.copyFile(signatureFile, signatureDestFile);
+            } catch (IOException e) {
+                getLog().warn("Failed to copy signature file: " + signatureFile, e);
+            }
+        } else {
+            getLog().warn("Signature file for artifact " + artifact + " not found and could not be resolved.");
+        }
+    }
+
     /**
      * Copy the pom files associated with the artifacts.
      *

src/main/java/org/apache/maven/plugins/dependency/utils/CopyUtil.java

@@ -72,4 +72,19 @@ public void copyArtifactFile(Artifact sourceArtifact, File destination) throws I
         FileUtils.copyFile(source, destination);
         buildContext.refresh(destination);
     }
+
+    /**
+     * Copies a file to a destination and refreshes the build context for the new file.
+     *
+     * @param source the source file to copy
+     * @param destination the destination file
+     * @throws IOException if copy has failed
+     *
+     * @since 3.2.0
+     */
+    public void copyFile(File source, File destination) throws IOException {
+        logger.debug("Copying file '{}' to {}", source, destination);
+        FileUtils.copyFile(source, destination);
+        buildContext.refresh(destination);
+    }
 }

src/test/java/org/apache/maven/plugins/dependency/fromDependencies/TestCopyDependenciesMojo.java

@@ -101,6 +101,66 @@ public void testCopyArtifactFile() throws Exception {
         assertTrue(dest.exists());
     }
 
+    /**
+     * Tests the copying of signature files associated with artifacts.
+     *
+     * @throws Exception if an error occurs during the test
+     */
+    public void testCopySignatureFiles() throws Exception {
+        // Enable the copySignatures parameter
+        mojo.copySignatures = true;
+
+        if (!mojo.outputDirectory.exists()) {
+            assertTrue("Failed to create output directory", mojo.outputDirectory.mkdirs());
+        }
+
+        File sourceDirectory =
+                new File(System.getProperty("java.io.tmpdir"), "test-source-" + System.currentTimeMillis());
+        if (!sourceDirectory.exists()) {
+            assertTrue("Failed to create source directory", sourceDirectory.mkdirs());
+        }
+
+        File artifactFile = new File(sourceDirectory, "maven-dependency-plugin-1.0.jar");
+        if (!artifactFile.getParentFile().exists()) {
+            assertTrue(
+                    "Failed to create parent directory",
+                    artifactFile.getParentFile().mkdirs());
+        }
+        if (artifactFile.exists()) {
+            assertTrue("Failed to delete existing artifact file", artifactFile.delete());
+        }
+        assertTrue("Failed to create artifact file", artifactFile.createNewFile());
+
+        File signatureFile = new File(sourceDirectory, "maven-dependency-plugin-1.0.jar.asc");
+        if (!signatureFile.getParentFile().exists()) {
+            assertTrue(
+                    "Failed to create parent directory",
+                    signatureFile.getParentFile().mkdirs());
+        }
+        if (signatureFile.exists()) {
+            assertTrue("Failed to delete existing signature file", signatureFile.delete());
+        }
+        assertTrue("Failed to create signature file", signatureFile.createNewFile());
+
+        Artifact artifact = stubFactory.createArtifact(
+                "org.apache.maven.plugins", "maven-dependency-plugin", "1.0", Artifact.SCOPE_COMPILE);
+        artifact.setFile(artifactFile);
+
+        Set<Artifact> artifacts = new HashSet<>();
+        artifacts.add(artifact);
+        mojo.getProject().setArtifacts(artifacts);
+
+        mojo.execute();
+
+        File copiedSignatureFile = new File(mojo.outputDirectory, "maven-dependency-plugin-1.0.jar.asc");
+        assertTrue("Signature file was not copied", copiedSignatureFile.exists());
+
+        // Clean up
+        artifactFile.delete();
+        signatureFile.delete();
+        sourceDirectory.delete();
+    }
+
     /**
      * Tests the proper discovery and configuration of the mojo.
      *