diff --git a/src/share/classes/java/nio/file/Files.java b/src/share/classes/java/nio/file/Files.java index 586859f17dc1c6ae2180e38d6fb8fede336b32ba..721184c1533382511572e15f9f0f6bb2fa171ba6 100644 --- a/src/share/classes/java/nio/file/Files.java +++ b/src/share/classes/java/nio/file/Files.java @@ -25,10 +25,10 @@ package java.nio.file; -import java.nio.ByteBuffer; import java.nio.file.attribute.*; import java.nio.file.spi.FileSystemProvider; import java.nio.file.spi.FileTypeDetector; +import java.nio.channels.Channels; import java.nio.channels.FileChannel; import java.nio.channels.SeekableByteChannel; import java.io.Closeable; @@ -2965,7 +2965,63 @@ public final class Files { } /** - * Read all the bytes from a file. The method ensures that the file is + * The maximum size of array to allocate. + * Some VMs reserve some header words in an array. + * Attempts to allocate larger arrays may result in + * OutOfMemoryError: Requested array size exceeds VM limit + */ + private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8; + + /** + * Reads all the bytes from an input stream. Uses {@code initialSize} as a hint + * about how many bytes the stream will have. + * + * @param source + * the input stream to read from + * @param initialSize + * the initial size of the byte array to allocate + * + * @return a byte array containing the bytes read from the file + * + * @throws IOException + * if an I/O error occurs reading from the stream + * @throws OutOfMemoryError + * if an array of the required size cannot be allocated + */ + private static byte[] read(InputStream source, int initialSize) + throws IOException + { + int capacity = initialSize; + byte[] buf = new byte[capacity]; + int nread = 0; + int n; + for (;;) { + // read to EOF which may read more or less than initialSize (eg: file + // is truncated while we are reading) + while ((n = source.read(buf, nread, capacity - nread)) > 0) + nread += n; + + // if last call to source.read() returned -1, we are done + // otherwise, try to read one more byte; if that failed we're done too + if (n < 0 || (n = source.read()) < 0) + break; + + // one more byte was read; need to allocate a larger buffer + if (capacity <= MAX_BUFFER_SIZE - capacity) { + capacity = Math.max(capacity << 1, BUFFER_SIZE); + } else { + if (capacity == MAX_BUFFER_SIZE) + throw new OutOfMemoryError("Required array size too large"); + capacity = MAX_BUFFER_SIZE; + } + buf = Arrays.copyOf(buf, capacity); + buf[nread++] = (byte)n; + } + return (capacity == nread) ? buf : Arrays.copyOf(buf, nread); + } + + /** + * Reads all the bytes from a file. The method ensures that the file is * closed when all bytes have been read or an I/O error, or other runtime * exception, is thrown. * @@ -2989,22 +3045,13 @@ public final class Files { * method is invoked to check read access to the file. */ public static byte[] readAllBytes(Path path) throws IOException { - try (FileChannel fc = FileChannel.open(path)) { + try (FileChannel fc = FileChannel.open(path); + InputStream is = Channels.newInputStream(fc)) { long size = fc.size(); - if (size > (long)Integer.MAX_VALUE) + if (size > (long)MAX_BUFFER_SIZE) throw new OutOfMemoryError("Required array size too large"); - byte[] arr = new byte[(int)size]; - ByteBuffer bb = ByteBuffer.wrap(arr); - while (bb.hasRemaining()) { - if (fc.read(bb) < 0) { - // truncated - break; - } - } - - int nread = bb.position(); - return (nread == size) ? arr : Arrays.copyOf(arr, nread); + return read(is, (int)size); } } diff --git a/test/java/nio/file/Files/BytesAndLines.java b/test/java/nio/file/Files/BytesAndLines.java index 2833c99cb73ad4fcd04fff0670617390daadc46b..15fb6a4251b68f35396b44652a223d3091a285d1 100644 --- a/test/java/nio/file/Files/BytesAndLines.java +++ b/test/java/nio/file/Files/BytesAndLines.java @@ -22,7 +22,7 @@ */ /* @test - * @bug 7006126 + * @bug 7006126 8020669 * @summary Unit test for methods for Files readAllBytes, readAllLines and * and write methods. */ @@ -82,6 +82,16 @@ public class BytesAndLines { write(file, lines, Charset.defaultCharset(), opts); throw new RuntimeException("NullPointerException expected"); } catch (NullPointerException ignore) { } + + // read from procfs + if (System.getProperty("os.name").equals("Linux")) { + // Refer to the Linux proc(5) man page for details about /proc/self/stat file + // procfs reports it to be zero sized, even though data can be read from it + String statFile = "/proc/self/stat"; + Path pathStat = Paths.get(statFile); + byte[] data = Files.readAllBytes(pathStat); + assertTrue(data.length > 0, "Files.readAllBytes('" + statFile + "') failed to read"); + } } @@ -174,6 +184,16 @@ public class BytesAndLines { throw new RuntimeException("NullPointerException expected"); } catch (NullPointerException ignore) { } + // read from procfs + if (System.getProperty("os.name").equals("Linux")) { + // Refer to the Linux proc(5) man page for details about /proc/self/status file + // procfs reports this file to be zero sized, even though data can be read from it + String statusFile = "/proc/self/status"; + Path pathStatus = Paths.get(statusFile); + lines = Files.readAllLines(pathStatus, US_ASCII); + assertTrue(lines.size() > 0, "Files.readAllLines('" + pathStatus + "') failed to read"); + } + } finally { delete(tmpfile); } @@ -242,7 +262,6 @@ public class BytesAndLines { } finally { delete(tmpfile); } - } static void assertTrue(boolean expr, String errmsg) {