8139206: Add InputStream readNBytes(int len)
Reviewed-by: alanb, chegar, plevart, apetcher, rriggs, weijun
--- a/src/java.base/share/classes/java/io/InputStream.java Thu Feb 01 09:20:40 2018 -0800
+++ b/src/java.base/share/classes/java/io/InputStream.java Thu Feb 01 09:40:38 2018 -0800
@@ -63,7 +63,8 @@
*
* <p> While the stream is open, the {@code available()}, {@code read()},
* {@code read(byte[])}, {@code read(byte[], int, int)},
- * {@code readAllBytes()}, {@code readNBytes()}, {@code skip()}, and
+ * {@code readAllBytes()}, {@code readNBytes(byte[], int, int)},
+ * {@code readNBytes(int)}, {@code skip(long)}, and
* {@code transferTo()} methods all behave as if end of stream has been
* reached. After the stream has been closed, these methods all throw
* {@code IOException}.
@@ -123,6 +124,15 @@
}
@Override
+ public byte[] readNBytes(int len) throws IOException {
+ if (len < 0) {
+ throw new IllegalArgumentException("len < 0");
+ }
+ ensureOpen();
+ return new byte[0];
+ }
+
+ @Override
public long skip(long n) throws IOException {
ensureOpen();
return 0L;
@@ -233,8 +243,8 @@
* <code>b</code> and the number of bytes read before the exception
* occurred is returned. The default implementation of this method blocks
* until the requested amount of input data <code>len</code> has been read,
- * end of file is detected, or an exception is thrown. Subclasses are encouraged
- * to provide a more efficient implementation of this method.
+ * end of file is detected, or an exception is thrown. Subclasses are
+ * encouraged to provide a more efficient implementation of this method.
*
* @param b the buffer into which the data is read.
* @param off the start offset in array <code>b</code>
@@ -308,26 +318,85 @@
* It is strongly recommended that the stream be promptly closed if an I/O
* error occurs.
*
+ * @implSpec
+ * This method invokes {@link #readNBytes(int)} with a length of
+ * {@link Integer#MAX_VALUE}.
+ *
* @return a byte array containing the bytes read from this input stream
* @throws IOException if an I/O error occurs
* @throws OutOfMemoryError if an array of the required size cannot be
- * allocated. For example, if an array larger than {@code 2GB} would
- * be required to store the bytes.
+ * allocated.
*
* @since 9
*/
public byte[] readAllBytes() throws IOException {
+ return readNBytes(Integer.MAX_VALUE);
+ }
+
+ /**
+ * Reads up to a specified number of bytes from the input stream. This
+ * method blocks until the requested number of bytes have been read, end
+ * of stream is detected, or an exception is thrown. This method does not
+ * close the input stream.
+ *
+ * <p> The length of the returned array equals the number of bytes read
+ * from the stream. If {@code len} is zero, then no bytes are read and
+ * an empty byte array is returned. Otherwise, up to {@code len} bytes
+ * are read from the stream. Fewer than {@code len} bytes may be read if
+ * end of stream is encountered.
+ *
+ * <p> When this stream reaches end of stream, further invocations of this
+ * method will return an empty byte array.
+ *
+ * <p> Note that this method is intended for simple cases where it is
+ * convenient to read the specified number of bytes into a byte array. The
+ * total amount of memory allocated by this method is proportional to the
+ * number of bytes read from the stream which is bounded by {@code len}.
+ * Therefore, the method may be safely called with very large values of
+ * {@code len} provided sufficient memory is available.
+ *
+ * <p> The behavior for the case where the input stream is <i>asynchronously
+ * closed</i>, or the thread interrupted during the read, is highly input
+ * stream specific, and therefore not specified.
+ *
+ * <p> If an I/O error occurs reading from the input stream, then it may do
+ * so after some, but not all, bytes have been read. Consequently the input
+ * stream may not be at end of stream and may be in an inconsistent state.
+ * It is strongly recommended that the stream be promptly closed if an I/O
+ * error occurs.
+ *
+ * @implNote
+ * The number of bytes allocated to read data from this stream and return
+ * the result is bounded by {@code 2*(long)len}, inclusive.
+ *
+ * @param len the maximum number of bytes to read
+ * @return a byte array containing the bytes read from this input stream
+ * @throws IllegalArgumentException if {@code length} is negative
+ * @throws IOException if an I/O error occurs
+ * @throws OutOfMemoryError if an array of the required size cannot be
+ * allocated.
+ *
+ * @since 11
+ */
+ public byte[] readNBytes(int len) throws IOException {
+ if (len < 0) {
+ throw new IllegalArgumentException("len < 0");
+ }
+
List<byte[]> bufs = null;
byte[] result = null;
int total = 0;
+ int remaining = len;
int n;
do {
- byte[] buf = new byte[DEFAULT_BUFFER_SIZE];
+ byte[] buf = new byte[Math.min(remaining, DEFAULT_BUFFER_SIZE)];
int nread = 0;
// read to EOF which may read more or less than buffer size
- while ((n = read(buf, nread, buf.length - nread)) > 0) {
+ while ((n = read(buf, nread,
+ Math.min(buf.length - nread, remaining))) > 0) {
nread += n;
+ remaining -= n;
}
if (nread > 0) {
@@ -345,7 +414,9 @@
bufs.add(buf);
}
}
- } while (n >= 0); // if the last call to read returned -1, then break
+ // if the last call to read returned -1 or the number of bytes
+ // requested have been read then break
+ } while (n >= 0 && remaining > 0);
if (bufs == null) {
if (result == null) {
@@ -357,12 +428,12 @@
result = new byte[total];
int offset = 0;
- int remaining = total;
+ remaining = total;
for (byte[] b : bufs) {
- int len = Math.min(b.length, remaining);
- System.arraycopy(b, 0, result, offset, len);
- offset += len;
- remaining -= len;
+ int count = Math.min(b.length, remaining);
+ System.arraycopy(b, 0, result, offset, count);
+ offset += count;
+ remaining -= count;
}
return result;
--- a/test/jdk/java/io/InputStream/NullInputStream.java Thu Feb 01 09:20:40 2018 -0800
+++ b/test/jdk/java/io/InputStream/NullInputStream.java Thu Feb 01 09:40:38 2018 -0800
@@ -31,7 +31,7 @@
/*
* @test
- * @bug 4358774
+ * @bug 4358774 8139206
* @run testng NullInputStream
* @summary Check for expected behavior of InputStream.nullInputStream().
*/
@@ -107,7 +107,7 @@
}
@Test(groups = "open")
- public static void testreadNBytes() {
+ public static void testReadNBytes() {
try {
assertEquals(0, openStream.readNBytes(new byte[1], 0, 1),
"readNBytes(byte[],int,int) != 0");
@@ -117,6 +117,26 @@
}
@Test(groups = "open")
+ public static void testReadNBytesWithLength() {
+ try {
+ assertEquals(0, openStream.readNBytes(-1).length,
+ "readNBytes(-1) != 0");
+ fail("Expected IllegalArgumentException not thrown");
+ } catch (IllegalArgumentException iae) {
+ } catch (IOException ioe) {
+ fail("Unexpected IOException");
+ }
+ try {
+ assertEquals(0, openStream.readNBytes(0).length,
+ "readNBytes(0, false) != 0");
+ assertEquals(0, openStream.readNBytes(1).length,
+ "readNBytes(1, false) != 0");
+ } catch (IOException ioe) {
+ fail("Unexpected IOException");
+ }
+ }
+
+ @Test(groups = "open")
public static void testSkip() {
try {
assertEquals(0, openStream.skip(1), "skip() != 0");
@@ -181,6 +201,15 @@
}
@Test(groups = "closed")
+ public static void testReadNBytesWithLengthClosed() {
+ try {
+ closedStream.readNBytes(1);
+ fail("Expected IOException not thrown");
+ } catch (IOException e) {
+ }
+ }
+
+ @Test(groups = "closed")
public static void testSkipClosed() {
try {
closedStream.skip(1);
--- a/test/jdk/java/io/InputStream/ReadNBytes.java Thu Feb 01 09:20:40 2018 -0800
+++ b/test/jdk/java/io/InputStream/ReadNBytes.java Thu Feb 01 09:40:38 2018 -0800
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2018, 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
@@ -31,7 +31,7 @@
/*
* @test
- * @bug 8080835
+ * @bug 8080835 8139206
* @library /test/lib
* @build jdk.test.lib.RandomFactory
* @run main ReadNBytes
@@ -46,15 +46,19 @@
public static void main(String[] args) throws IOException {
test(new byte[]{1, 2, 3});
test(createRandomBytes(1024));
- test(createRandomBytes((1 << 13) - 1));
- test(createRandomBytes((1 << 13)));
- test(createRandomBytes((1 << 13) + 1));
- test(createRandomBytes((1 << 15) - 1));
- test(createRandomBytes((1 << 15)));
- test(createRandomBytes((1 << 15) + 1));
- test(createRandomBytes((1 << 17) - 1));
- test(createRandomBytes((1 << 17)));
- test(createRandomBytes((1 << 17) + 1));
+ for (int shift : new int[] {13, 15, 17}) {
+ for (int offset : new int[] {-1, 0, 1}) {
+ test(createRandomBytes((1 << shift) + offset));
+ }
+ }
+
+ test(-1);
+ test(0);
+ for (int shift : new int[] {13, 15, 17}) {
+ for (int offset : new int[] {-1, 0, 1}) {
+ test((1 << shift) + offset);
+ }
+ }
}
static void test(byte[] inputBytes) throws IOException {
@@ -91,6 +95,46 @@
check(!in.isClosed(), "Stream unexpectedly closed");
}
+ static void test(int max) throws IOException {
+ byte[] inputBytes = max <= 0 ? new byte[0] : createRandomBytes(max);
+ WrapperInputStream in =
+ new WrapperInputStream(new ByteArrayInputStream(inputBytes));
+
+ if (max < 0) {
+ try {
+ in.readNBytes(max);
+ check(false, "Expected IllegalArgumentException not thrown");
+ } catch (IllegalArgumentException iae) {
+ return;
+ }
+ } else if (max == 0) {
+ int x;
+ check((x = in.readNBytes(max).length) == 0,
+ "Expected zero bytes, got " + x);
+ return;
+ }
+
+ int off = Math.toIntExact(in.skip(generator.nextInt(max/2)));
+ int len = generator.nextInt(max - 1 - off);
+ byte[] readBytes = in.readNBytes(len);
+ check(readBytes.length == len,
+ "Expected " + len + " bytes, got " + readBytes.length);
+ check(Arrays.equals(inputBytes, off, off + len, readBytes, 0, len),
+ "Expected[" + Arrays.copyOfRange(inputBytes, off, off + len) +
+ "], got:[" + readBytes + "]");
+
+ int remaining = max - (off + len);
+ readBytes = in.readNBytes(remaining);
+ check(readBytes.length == remaining,
+ "Expected " + remaining + "bytes, got " + readBytes.length);
+ check(Arrays.equals(inputBytes, off + len, max,
+ readBytes, 0, remaining),
+ "Expected[" + Arrays.copyOfRange(inputBytes, off + len, max) +
+ "], got:[" + readBytes + "]");
+
+ check(!in.isClosed(), "Stream unexpectedly closed");
+ }
+
static byte[] createRandomBytes(int size) {
byte[] bytes = new byte[size];
generator.nextBytes(bytes);