When using InputStream.skip, trying to read past the end of a BLOB failed with…

When using InputStream.skip, trying to read past the end of a BLOB failed with the exception "IO Exception: Missing lob entry: ..." [90028-...].

h2/src/main/org/h2/store/LobStorage.java

@@ -249,11 +249,34 @@ public class LobStorage {
      */
     public class LobInputStream extends InputStream {
 
-        private byte[] buffer;
+        /**
+         * The size of the blob.
+         */
         private long length;
-        private int pos;
+
+        /**
+         * The remaining bytes in the blob.
+         */
         private long remainingBytes;
+
+        /**
+         * The temporary buffer.
+         */
+        private byte[] buffer;
+
+        /**
+         * The position within the buffer.
+         */
+        private int pos;
+
+        /**
+         * The blob id.
+         */
         private long lob;
+
+        /**
+         * The blob sequence id.
+         */
         private int seq;
 
         public LobInputStream(long lob, long byteCount) {
@@ -281,7 +304,9 @@ public class LobStorage {
                         return super.skip(n);
                     }
                     seq = (int) seqPos[0];
-                    n = toPos - seqPos[1];
+                    long p = seqPos[1];
+                    remainingBytes = length - p;
+                    n = toPos - p;
                 } catch (SQLException e) {
                     throw DbException.convertToIOException(e);
                 }

h2/src/test/org/h2/test/db/TestLob.java

@@ -53,6 +53,7 @@ public class TestLob extends TestBase {
     }
 
     public void test() throws Exception {
+        testLobSkipPastEnd();
         testCreateIndexOnLob();
         testBlobInputStreamSeek(true);
         testBlobInputStreamSeek(false);
@@ -98,6 +99,42 @@ public class TestLob extends TestBase {
         IOUtils.deleteRecursive(TEMP_DIR, true);
     }
 
+    private void testLobSkipPastEnd() throws Exception {
+        if (config.memory) {
+            return;
+        }
+        deleteDb("lob");
+        Connection conn;
+        conn = getConnection("lob");
+        Statement stat = conn.createStatement();
+        stat.execute("create table test(id int, data blob)");
+        byte[] data = new byte[150000];
+        new Random(0).nextBytes(data);
+        PreparedStatement prep = conn.prepareStatement("insert into test values(1, ?)");
+        prep.setBytes(1, data);
+        prep.execute();
+        ResultSet rs = stat.executeQuery("select data from test");
+        rs.next();
+        for (int blockSize = 1; blockSize < 100000; blockSize *= 10) {
+            for (int i = 0; i < data.length; i += 1000) {
+                InputStream in = rs.getBinaryStream(1);
+                in.skip(i);
+                byte[] d2 = new byte[data.length];
+                int l = in.read(d2, i, blockSize);
+                if (i >= data.length) {
+                    assertEquals(-1, l);
+                } else if (i + blockSize >= data.length) {
+                    assertEquals(data.length - i, l);
+                }
+                for (int j = i; j < blockSize && j < d2.length; j++) {
+                    assertEquals(data[j], d2[j]);
+                }
+            }
+        }
+        stat.execute("drop table test");
+        conn.close();
+    }
+
     private void testCreateIndexOnLob() throws Exception {
         if (config.memory) {
             return;