Merge "Have AssetFileDescriptor.AutoCloseInputStream use pread"

1 files changed, 36 insertions, 35 deletions

diff --git a/core/java/android/content/res/AssetFileDescriptor.java b/core/java/android/content/res/AssetFileDescriptor.java
index e93ec00468f5..c622ca461c05 100644
--- a/core/java/android/content/res/AssetFileDescriptor.java
+++ b/core/java/android/content/res/AssetFileDescriptor.java
@@ -21,6 +21,8 @@ import android.os.Bundle;
 import android.os.Parcel;
 import android.os.ParcelFileDescriptor;
 import android.os.Parcelable;
+import android.system.ErrnoException;
+import android.system.Os;
 
 import java.io.Closeable;
 import java.io.FileDescriptor;
@@ -203,19 +205,22 @@ public class AssetFileDescriptor implements Parcelable, Closeable {
      */
     public static class AutoCloseInputStream
             extends ParcelFileDescriptor.AutoCloseInputStream {
-        private long mRemaining;
+        private long mTotalSize;
+        private final long mFileOffset;
+        private long mOffset;
         
         public AutoCloseInputStream(AssetFileDescriptor fd) throws IOException {
             super(fd.getParcelFileDescriptor());
-            super.skip(fd.getStartOffset());
-            mRemaining = (int)fd.getLength();
+            mTotalSize = fd.getLength();
+            mFileOffset = fd.getStartOffset();
         }
 
         @Override
         public int available() throws IOException {
-            return mRemaining >= 0
-                    ? (mRemaining < 0x7fffffff ? (int)mRemaining : 0x7fffffff)
-                    : super.available();
+            long available = mTotalSize - mOffset;
+            return available >= 0
+                    ? (available < 0x7fffffff ? (int) available : 0x7fffffff)
+                    : 0;
         }
 
         @Override
@@ -227,15 +232,21 @@ public class AssetFileDescriptor implements Parcelable, Closeable {
 
         @Override
         public int read(byte[] buffer, int offset, int count) throws IOException {
-            if (mRemaining >= 0) {
-                if (mRemaining == 0) return -1;
-                if (count > mRemaining) count = (int)mRemaining;
-                int res = super.read(buffer, offset, count);
-                if (res >= 0) mRemaining -= res;
+            int available = available();
+            if (available <= 0) {
+                return -1;
+            }
+
+            if (count > available) count = available;
+            try {
+                int res = Os.pread(getFD(), buffer, offset, count, mFileOffset + mOffset);
+                // pread returns 0 at end of file, while java's InputStream interface requires -1
+                if (res == 0) res = -1;
+                if (res >= 0) mOffset += res;
                 return res;
+            } catch (ErrnoException e) {
+                throw new IOException(e);
             }
-            
-            return super.read(buffer, offset, count);
         }
 
         @Override
@@ -245,41 +256,31 @@ public class AssetFileDescriptor implements Parcelable, Closeable {
 
         @Override
         public long skip(long count) throws IOException {
-            if (mRemaining >= 0) {
-                if (mRemaining == 0) return -1;
-                if (count > mRemaining) count = mRemaining;
-                long res = super.skip(count);
-                if (res >= 0) mRemaining -= res;
-                return res;
+            int available = available();
+            if (available <= 0) {
+                return -1;
             }
-            
-            return super.skip(count);
+
+            if (count > available) count = available;
+            mOffset += count;
+            return count;
         }
 
         @Override
         public void mark(int readlimit) {
-            if (mRemaining >= 0) {
-                // Not supported.
-                return;
-            }
-            super.mark(readlimit);
+            // Not supported.
+            return;
         }
 
         @Override
         public boolean markSupported() {
-            if (mRemaining >= 0) {
-                return false;
-            }
-            return super.markSupported();
+            return false;
         }
 
         @Override
         public synchronized void reset() throws IOException {
-            if (mRemaining >= 0) {
-                // Not supported.
-                return;
-            }
-            super.reset();
+            // Not supported.
+            return;
         }
     }