Add Export command

pgpainless-cert-d-cli/src/main/java/pgp/cert_d/cli/PGPCertDCli.java

@@ -8,6 +8,7 @@ import org.pgpainless.certificate_store.CertificateReader;
 import org.pgpainless.certificate_store.SharedPGPCertificateDirectoryAdapter;
 import pgp.cert_d.BaseDirectoryProvider;
 import pgp.cert_d.SharedPGPCertificateDirectoryImpl;
+import pgp.cert_d.cli.commands.Export;
 import pgp.cert_d.cli.commands.Get;
 import pgp.cert_d.cli.commands.Insert;
 import pgp.cert_d.cli.commands.Import;
@@ -25,6 +26,7 @@ import java.sql.SQLException;
         name = "certificate-store",
         description = "Store and manage public OpenPGP certificates",
         subcommands = {
+                Export.class,
                 Insert.class,
                 Import.class,
                 Get.class,

pgpainless-cert-d-cli/src/main/java/pgp/cert_d/cli/commands/Export.java

@@ -0,0 +1,40 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package pgp.cert_d.cli.commands;
+
+import org.bouncycastle.util.io.Streams;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import pgp.cert_d.cli.PGPCertDCli;
+import pgp.certificate_store.Certificate;
+import picocli.CommandLine;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Iterator;
+
+@CommandLine.Command(name = "export",
+        description = "Export all certificates in the store to Standard Output")
+public class Export implements Runnable {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(Get.class);
+
+    @Override
+    public void run() {
+        Iterator<Certificate> certificates = PGPCertDCli.getCertificateDirectory()
+                .getCertificates();
+        while (certificates.hasNext()) {
+            try {
+                Certificate certificate = certificates.next();
+                InputStream inputStream = certificate.getInputStream();
+                Streams.pipeAll(inputStream, System.out);
+                inputStream.close();
+            } catch (IOException e) {
+                LOGGER.error("IO Error", e);
+                System.exit(-1);
+            }
+        }
+    }
+}

pgpainless-cert-d-cli/src/main/java/pgp/cert_d/cli/commands/Import.java

@@ -20,7 +20,7 @@ import java.io.ByteArrayInputStream;
 import java.io.IOException;
 
 @CommandLine.Command(name = "import",
-        description = "Import certificates into the store from stdin")
+        description = "Import certificates into the store from Standard Input")
 public class Import implements Runnable {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(Import.class);