From e27090859f2a5d2ef5997059e37024fcb9179c4f Mon Sep 17 00:00:00 2001 From: Nick Burch Date: Wed, 9 Jan 2008 16:31:25 +0000 Subject: [PATCH] Tweak comments, layout and exceptions in IOUtils and RawDataBlock. It should now be clearer exactly what they do, and when they become unhappy. Also include a test that ensures that when reading from a slow inputstream (as per bug #42834), we really are ok with the data dribbling in, and do not require it to all come in in blocksize chunks at one git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@610439 13f79535-47bb-0310-9956-ffa450edef68 --- .../poi/poifs/storage/RawDataBlock.java | 46 ++++--- src/java/org/apache/poi/util/IOUtils.java | 16 ++- .../poi/poifs/storage/TestRawDataBlock.java | 113 ++++++++++++++++++ 3 files changed, 150 insertions(+), 25 deletions(-) diff --git a/src/java/org/apache/poi/poifs/storage/RawDataBlock.java b/src/java/org/apache/poi/poifs/storage/RawDataBlock.java index 4403966343..d554298400 100644 --- a/src/java/org/apache/poi/poifs/storage/RawDataBlock.java +++ b/src/java/org/apache/poi/poifs/storage/RawDataBlock.java @@ -42,34 +42,44 @@ public class RawDataBlock * @param stream the InputStream from which the data will be read * * @exception IOException on I/O errors, and if an insufficient - * amount of data is read + * amount of data is read (the InputStream must + * be an exact multiple of the block size) */ - public RawDataBlock(final InputStream stream) - throws IOException - { - _data = new byte[ POIFSConstants.BIG_BLOCK_SIZE ]; + throws IOException { + this(stream, POIFSConstants.BIG_BLOCK_SIZE); + } + /** + * Constructor RawDataBlock + * + * @param stream the InputStream from which the data will be read + * @param blockSize the size of the POIFS blocks, normally 512 bytes {@link POIFSConstants#BIG_BLOCK_SIZE} + * + * @exception IOException on I/O errors, and if an insufficient + * amount of data is read (the InputStream must + * be an exact multiple of the block size) + */ + public RawDataBlock(final InputStream stream, int blockSize) + throws IOException { + _data = new byte[ blockSize ]; int count = IOUtils.readFully(stream, _data); - if (count == -1) - { + if (count == -1) { _eof = true; } - else if (count != POIFSConstants.BIG_BLOCK_SIZE) - { - if (count == -1) - //Cant have -1 bytes read in the error message! - count = 0; - + else if (count != blockSize) { + // IOUtils.readFully will always read the + // requested number of bytes, unless it hits + // an EOF + _eof = true; String type = " byte" + ((count == 1) ? ("") : ("s")); throw new IOException("Unable to read entire block; " + count - + type + " read; expected " - + POIFSConstants.BIG_BLOCK_SIZE + " bytes"); + + type + " read before EOF; expected " + + blockSize + " bytes"); } - else - { + else { _eof = false; } } @@ -82,7 +92,6 @@ public class RawDataBlock * * @exception IOException */ - public boolean eof() throws IOException { @@ -98,7 +107,6 @@ public class RawDataBlock * * @exception IOException if there is no data */ - public byte [] getData() throws IOException { diff --git a/src/java/org/apache/poi/util/IOUtils.java b/src/java/org/apache/poi/util/IOUtils.java index 42b69c850b..c3aa8695e2 100644 --- a/src/java/org/apache/poi/util/IOUtils.java +++ b/src/java/org/apache/poi/util/IOUtils.java @@ -58,11 +58,16 @@ public class IOUtils } /** - * Same as the normal in.read(b, off, len), but tries to ensure that - * the entire len number of bytes is read. + * Same as the normal in.read(b, off, len), but + * tries to ensure that the entire len number of bytes + * is read. *

- * If the end of file is reached before any bytes are read, returns -1. - * Otherwise, returns the number of bytes read. + * If the end of file is reached before any bytes + * are read, returns -1. + * If the end of the file is reached after some bytes are + * read, returns the number of bytes read. + * If the end of the file isn't reached before len + * bytes have been read, will return len bytes. */ public static int readFully(InputStream in, byte[] b, int off, int len) throws IOException @@ -79,5 +84,4 @@ public class IOUtils } } } -} - +} \ No newline at end of file diff --git a/src/testcases/org/apache/poi/poifs/storage/TestRawDataBlock.java b/src/testcases/org/apache/poi/poifs/storage/TestRawDataBlock.java index 4756629e7a..1473fa82ea 100644 --- a/src/testcases/org/apache/poi/poifs/storage/TestRawDataBlock.java +++ b/src/testcases/org/apache/poi/poifs/storage/TestRawDataBlock.java @@ -20,6 +20,7 @@ package org.apache.poi.poifs.storage; import java.io.*; +import java.util.Random; import junit.framework.*; @@ -124,6 +125,118 @@ public class TestRawDataBlock } } } + + /** + * Tests that when using a slow input stream, which + * won't return a full block at a time, we don't + * incorrectly think that there's not enough data + */ + public void testSlowInputStream() throws Exception { + for (int k = 1; k < 512; k++) { + byte[] data = new byte[ 512 ]; + for (int j = 0; j < data.length; j++) { + data[j] = (byte) j; + } + + // Shouldn't complain, as there is enough data, + // even if it dribbles through + RawDataBlock block = + new RawDataBlock(new SlowInputStream(data, k)); + assertFalse(block.eof()); + } + + // But if there wasn't enough data available, will + // complain + for (int k = 1; k < 512; k++) { + byte[] data = new byte[ 511 ]; + for (int j = 0; j < data.length; j++) { + data[j] = (byte) j; + } + + // Shouldn't complain, as there is enough data + try { + RawDataBlock block = + new RawDataBlock(new SlowInputStream(data, k)); + fail(); + } catch(IOException e) { + // as expected + } + } + } + + /** + * An input stream which will return a maximum of + * a given number of bytes to read, and often claims + * not to have any data + */ + public static class SlowInputStream extends InputStream { + private Random rnd = new Random(); + private byte[] data; + private int chunkSize; + private int pos = 0; + + public SlowInputStream(byte[] data, int chunkSize) { + this.chunkSize = chunkSize; + this.data = data; + } + + /** + * 75% of the time, claim there's no data available + */ + private boolean claimNoData() { + if(rnd.nextFloat() < 0.25f) { + return false; + } + return true; + } + + public int read() throws IOException { + if(pos >= data.length) { + return -1; + } + int ret = data[pos]; + pos++; + + if(ret < 0) ret += 256; + return ret; + } + + /** + * Reads the requested number of bytes, or the chunk + * size, whichever is lower. + * Quite often will simply claim to have no data + */ + public int read(byte[] b, int off, int len) throws IOException { + // Keep the length within the chunk size + if(len > chunkSize) { + len = chunkSize; + } + // Don't read off the end of the data + if(pos + len > data.length) { + len = data.length - pos; + + // Spot when we're out of data + if(len == 0) { + return -1; + } + } + + // 75% of the time, claim there's no data + if(claimNoData()) { + return 0; + } + + // Copy, and return what we read + System.arraycopy(data, pos, b, off, len); + pos += len; + return len; + } + + public int read(byte[] b) throws IOException { + return read(b, 0, b.length); + } + + } /** * main method to run the unit tests -- 2.39.5