From 52fa7e4d46331bacb6839b73012d612d147d6bfa Mon Sep 17 00:00:00 2001
From: Paul Schaub <vanitasvitae@fsfe.org>
Date: Mon, 1 May 2023 09:35:28 +0200
Subject: [PATCH] OpenPgpMessageInputStream: Return -1 instead of throwing
 MalformedOpenPgpMessageException when calling read() on drained stream

---
 .../OpenPgpMessageInputStream.java              |  2 ++
 .../syntax_check/OpenPgpMessageSyntax.java      |  4 ++++
 .../OpenPgpMessageInputStreamTest.java          | 17 +++++++++++++++++
 3 files changed, 23 insertions(+)

diff --git a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStream.java b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStream.java
index 19a01fbf..d51a6cf7 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStream.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStream.java
@@ -744,6 +744,7 @@ public class OpenPgpMessageInputStream extends DecryptionStream {
             throws IOException {
         if (nestedInputStream == null) {
             if (packetInputStream != null) {
+                syntaxVerifier.next(InputSymbol.EndOfSequence);
                 syntaxVerifier.assertValid();
             }
             return -1;
@@ -774,6 +775,7 @@ public class OpenPgpMessageInputStream extends DecryptionStream {
         super.close();
         if (closed) {
             if (packetInputStream != null) {
+                syntaxVerifier.next(InputSymbol.EndOfSequence);
                 syntaxVerifier.assertValid();
             }
             return;
diff --git a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/OpenPgpMessageSyntax.java b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/OpenPgpMessageSyntax.java
index 6abb507a..9d20e0a8 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/OpenPgpMessageSyntax.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/OpenPgpMessageSyntax.java
@@ -132,6 +132,10 @@ public class OpenPgpMessageSyntax implements Syntax {
     @Nonnull
     Transition fromValid(@Nonnull InputSymbol input, @Nullable StackSymbol stackItem)
             throws MalformedOpenPgpMessageException {
+        if (input == InputSymbol.EndOfSequence) {
+            // allow subsequent read() calls.
+            return new Transition(State.Valid);
+        }
         // There is no applicable transition rule out of Valid
         throw new MalformedOpenPgpMessageException(State.Valid, input, stackItem);
     }
diff --git a/pgpainless-core/src/test/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStreamTest.java b/pgpainless-core/src/test/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStreamTest.java
index 01966bbe..a0ec7c25 100644
--- a/pgpainless-core/src/test/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStreamTest.java
+++ b/pgpainless-core/src/test/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStreamTest.java
@@ -34,6 +34,7 @@ import org.bouncycastle.openpgp.PGPSignature;
 import org.bouncycastle.util.io.Streams;
 import org.junit.JUtils;
 import org.junit.jupiter.api.Named;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -652,6 +653,22 @@ public class OpenPgpMessageInputStreamTest {
         assertTrue(metadata.getRejectedInlineSignatures().isEmpty());
     }
 
+    @Test
+    public void readAfterCloseTest() throws PGPException, IOException {
+        OpenPgpMessageInputStream pgpIn = get(SENC_LIT, ConsumerOptions.get()
+                .addDecryptionPassphrase(Passphrase.fromPassword(PASSPHRASE)));
+        Streams.drain(pgpIn); // read all
+
+        byte[] buf = new byte[1024];
+        assertEquals(-1, pgpIn.read(buf));
+        assertEquals(-1, pgpIn.read());
+        assertEquals(-1, pgpIn.read(buf));
+        assertEquals(-1, pgpIn.read());
+
+        pgpIn.close();
+        pgpIn.getMetadata();
+    }
+
     private static Tuple<String, MessageMetadata> processReadBuffered(String armoredMessage, ConsumerOptions options)
             throws PGPException, IOException {
         OpenPgpMessageInputStream in = get(armoredMessage, options);