1 files changed, 91 insertions, 0 deletions
diff --git a/src/com/google/common/io/protocol/BoundInputStream.java b/src/com/google/common/io/protocol/BoundInputStream.java
new file mode 100644
index 0000000..dbccca7
--- /dev/null
+++ b/src/com/google/common/io/protocol/BoundInputStream.java
@@ -0,0 +1,91 @@
+// Copyright 2008 Google Inc. All Rights Reserved.
+
+package com.google.common.io.protocol;
+
+import java.io.*;
+
+/**
+ * An input stream backed by another input stream, where reading from the
+ * underlying input stream is limited to a fixed number of bytes. Also does
+ * some buffering.
+ *
+ */
+public class BoundInputStream extends InputStream {
+
+  /** Buffer size */
+  static final int BUF_SIZE = 4096;
+
+  /** Number of bytes that may still be read from the underlying stream */
+  private int remaining;
+
+  /** Small buffer to avoid making OS calls for each byte read. */
+  private byte[] buf;
+
+  /** Current position in the buffer */
+  private int bufPos;
+
+  /** Filled size of the buffer */
+  private int bufSize;
+
+  /** Underlying stream to read from */
+  private InputStream base;
+
+  public BoundInputStream(InputStream base, int len) {
+    this.base = base;
+    this.remaining = len;
+
+    buf = new byte[Math.min(len, BUF_SIZE)];
+  }
+
+  /**
+   * Make sure there is at least one byte in the buffer. If not possible,
+   * return false.
+   */
+  private boolean checkBuf() throws IOException {
+    if (remaining <= 0) {
+      return false;
+    }
+
+    if (bufPos >= bufSize) {
+      bufSize = base.read(buf, 0, Math.min(remaining, buf.length));
+      if (bufSize <= 0) {
+        remaining = 0;
+        return false;
+      }
+      bufPos = 0;
+    }
+    return true;
+  }
+
+  public int available() {
+    return bufSize - bufPos;
+  }
+
+  public int read() throws IOException {
+    if (!checkBuf()) {
+      return -1;
+    }
+    remaining--;
+    return buf[bufPos++] & 255;
+  }
+
+  public int read(byte[] data, int start, int count) throws IOException {
+    if (!checkBuf()) {
+      return -1;
+    }
+    count = Math.min(count, bufSize - bufPos);
+    System.arraycopy(buf, bufPos, data, start, count);
+    bufPos += count;
+    remaining -= count;
+    return count;
+  }
+
+  /**
+   * How many bytes are remaining, based on the length provided to the
+   * constructor. The underlying stream may terminate earlier. Provided mainly
+   * for testing purposes.
+   */
+  public int getRemaining() {
+    return remaining;
+  }
+}