From ee01cfcbf58a868b6ae561d277625b47640286f5 Mon Sep 17 00:00:00 2001
From: Craig Raw <craigraw@gmail.com>
Date: Thu, 1 Apr 2021 10:15:23 +0200
Subject: [PATCH] fix findNominalFragmentLength edge case

---
 .../hummingbird/fountain/FountainEncoder.java              | 2 +-
 src/test/java/com/sparrowwallet/hummingbird/URTest.java    | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainEncoder.java b/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainEncoder.java
index 9b20859..d1faad4 100644
--- a/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainEncoder.java
+++ b/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainEncoder.java
@@ -101,7 +101,7 @@ public class FountainEncoder {
     }
 
     static int findNominalFragmentLength(int messageLen, int minFragmentLen, int maxFragmentLen) {
-        int maxFragmentCount = messageLen / minFragmentLen;
+        int maxFragmentCount = Math.max(1, messageLen / minFragmentLen);
         int fragmentLen = 0;
         for(int fragmentCount = 1; fragmentCount <= maxFragmentCount; fragmentCount++) {
             fragmentLen = (int)Math.ceil((double)messageLen / (double)fragmentCount);
diff --git a/src/test/java/com/sparrowwallet/hummingbird/URTest.java b/src/test/java/com/sparrowwallet/hummingbird/URTest.java
index 345077b..4cc86bd 100644
--- a/src/test/java/com/sparrowwallet/hummingbird/URTest.java
+++ b/src/test/java/com/sparrowwallet/hummingbird/URTest.java
@@ -110,6 +110,13 @@ public class URTest {
         Assert.assertEquals("ur:bytes/gdaebycpeofygoiyktlonlpkrksfutwyzmwmfyeozs", encoded);
     }
 
+    @Test
+    public void testFindNominalFragmentLength() throws UR.InvalidCBORException, UR.InvalidTypeException {
+        byte[] message = "Hello".getBytes();
+        UR ur = UR.fromBytes(message);
+        UREncoder urEncoder = new UREncoder(ur, 200, 100, 0);
+    }
+
     @Test
     public void testLegacyEncode() throws UR.InvalidTypeException, UR.InvalidCBORException {
         String random = "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";