Generify the IO requirements for writing a dex file

The DexWriter implementations now write to a generic "DexDataStore", instead
of writing directly to a file.

Also, writing of the DebugItems and CodeItems are linked, with the code
items being written to a temporary location, and then the entire code item
section is written as a batch after the debug item section.

1 files changed, 50 insertions, 0 deletions

diff --git a/util/src/main/java/org/jf/util/RandomAccessFileInputStream.java b/util/src/main/java/org/jf/util/RandomAccessFileInputStream.java
new file mode 100644
index 00000000..4c62aed7
--- /dev/null
+++ b/util/src/main/java/org/jf/util/RandomAccessFileInputStream.java
@@ -0,0 +1,50 @@
+package org.jf.util;
+
+import javax.annotation.Nonnull;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.RandomAccessFile;
+
+public class RandomAccessFileInputStream extends InputStream {
+    private int filePosition;
+    @Nonnull private final RandomAccessFile raf;
+
+    public RandomAccessFileInputStream(@Nonnull RandomAccessFile raf, int filePosition) {
+        this.filePosition = filePosition;
+        this.raf = raf;
+    }
+
+    @Override public int read() throws IOException {
+        raf.seek(filePosition);
+        filePosition++;
+        return raf.read();
+    }
+
+    @Override public int read(byte[] bytes) throws IOException {
+        raf.seek(filePosition);
+        int bytesRead = raf.read(bytes);
+        filePosition += bytesRead;
+        return bytesRead;
+    }
+
+    @Override public int read(byte[] bytes, int offset, int length) throws IOException {
+        raf.seek(filePosition);
+        int bytesRead = raf.read(bytes, offset, length);
+        filePosition += bytesRead;
+        return bytesRead;
+    }
+
+    @Override public long skip(long l) throws IOException {
+        int skipBytes = Math.min((int)l, available());
+        filePosition += skipBytes;
+        return skipBytes;
+    }
+
+    @Override public int available() throws IOException {
+        return (int)raf.length() - filePosition;
+    }
+
+    @Override public boolean markSupported() {
+        return false;
+    }
+}