8010837: FileInputStream.available() throw IOException when encountering negative available values

Summary: Remove the check in the native code to allow negative values
Reviewed-by: mchung

src/solaris/native/java/io/io_util_md.c

@@ -200,12 +200,8 @@ handleAvailable(FD fd, jlong *pbytes)
             return 0;
     }
 
-    if (size >= current) {
-        *pbytes = size - current;
-        return 1;
-    } else {
-        return 0;
-    }
+    *pbytes = size - current;
+    return 1;
 }
 
 jint

test/java/io/FileInputStream/NegativeAvailable.java

+/*
+ * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8010837
+ * @summary Test if available returns correct value when skipping beyond
+ *          the end of a file.
+ * @author Dan Xu
+ */
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+public class NegativeAvailable {
+
+    public static void main(String[] args) throws IOException {
+        final int SIZE = 10;
+        final int SKIP = 5;
+
+        // Create a temporary file with size of 10 bytes.
+        Path tmp = Files.createTempFile(null, null);
+        try (BufferedWriter writer =
+            Files.newBufferedWriter(tmp, Charset.defaultCharset())) {
+            for (int i = 0; i < SIZE; i++) {
+                writer.write('1');
+            }
+        }
+
+        File tempFile = tmp.toFile();
+        try (FileInputStream fis = new FileInputStream(tempFile)) {
+            if (tempFile.length() != SIZE) {
+                throw new RuntimeException("unexpected file size = "
+                    + tempFile.length());
+            }
+            long space = skipBytes(fis, SKIP, SIZE);
+            space = skipBytes(fis, SKIP, space);
+            space = skipBytes(fis, SKIP, space);
+            space = skipBytes(fis, SKIP, space);
+        }
+        Files.deleteIfExists(tmp);
+    }
+
+    /**
+     *  Skip toSkip number of bytes and return the remaining bytes of the file.
+     */
+    private static long skipBytes(FileInputStream fis, int toSkip, long space)
+            throws IOException {
+        long skip = fis.skip(toSkip);
+        if (skip != toSkip) {
+            throw new RuntimeException("skip() returns " + skip
+                + " but expected " + toSkip);
+        }
+        long remaining = space - toSkip;
+        int avail = fis.available();
+        if (avail != remaining) {
+            throw new RuntimeException("available() returns " + avail
+                + " but expected " + remaining);
+        }
+
+        System.out.println("Skipped " + skip + " bytes "
+            + " available() returns " + avail);
+        return remaining;
+    }
+}