fix NPE in available() (#40)

dldnhf · web-flow · commit af57e230ed21 · 2026-01-21T14:05:21.000+01:00
diff --git a/src/java/net/jpountz/lz4/LZ4FrameInputStream.java b/src/java/net/jpountz/lz4/LZ4FrameInputStream.java
@@ -383,6 +383,9 @@ public long skip(long n) throws IOException {
 
   @Override
   public int available() throws IOException {
+    if (!firstFrameHeaderRead) {
+      return 0;
+    }
     return buffer.remaining();
   }
 
diff --git a/src/test/net/jpountz/lz4/LZ4FrameIOStreamTest.java b/src/test/net/jpountz/lz4/LZ4FrameIOStreamTest.java
@@ -551,4 +551,29 @@ public void testPrematureMagicNb() throws IOException {
       lz4File.delete();
     }
   }
+
+  @Test
+  public void testAvailable() throws IOException {
+    final File lz4File = Files.createTempFile("lz4test", ".lz4").toFile();
+    try {
+      try (OutputStream os = new LZ4FrameOutputStream(new FileOutputStream(lz4File))) {
+        try (InputStream is = new FileInputStream(tmpFile)) {
+          copy(is, os);
+        }
+      }
+
+      try (InputStream is = new LZ4FrameInputStream(new FileInputStream(lz4File))) {
+        Assert.assertEquals("available() should be 0 before first read", 0, is.available());
+
+        if (is.read() != -1 && testSize > 1) {
+          Assert.assertTrue(
+            "After reading 1 byte, available() should report > 0 bytes ready in the buffer",
+            is.available() > 0
+          );
+        }
+      }
+    } finally {
+      lz4File.delete();
+    }
+  }
 }

Original file line number	Diff line number	Diff line change
`@@ -383,6 +383,9 @@ public long skip(long n) throws IOException {`
`383`	`383`
`384`	`384`	`@Override`
`385`	`385`	`public int available() throws IOException {`
	`386`	`+ if (!firstFrameHeaderRead) {`
	`387`	`+ return 0;`
	`388`	`+ }`
`386`	`389`	`return buffer.remaining();`
`387`	`390`	`}`
`388`	`391`