Use libcore Posix class for StatFs implementation

Remove some JNI and duplicated functionality and use libcore's Posix
class for the statfs function instead.

Change-Id: Ic1e161dc10c18c2c6ee81d895a0efd8910086dbf

Author: kruton

core/java/android/os/StatFs.java

@@ -16,59 +16,77 @@
 
 package android.os;
 
+import libcore.io.ErrnoException;
+import libcore.io.Libcore;
+import libcore.io.StructStatFs;
+
 /**
- * Retrieve overall information about the space on a filesystem.  This is a
- * Wrapper for Unix statfs().
+ * Retrieve overall information about the space on a filesystem. This is a
+ * wrapper for Unix statfs().
  */
 public class StatFs {
+    private StructStatFs mStat;
+
     /**
-     * Construct a new StatFs for looking at the stats of the
-     * filesystem at <var>path</var>.  Upon construction, the stat of
-     * the file system will be performed, and the values retrieved available
-     * from the methods on this class.
-     * 
-     * @param path A path in the desired file system to state.
+     * Construct a new StatFs for looking at the stats of the filesystem at
+     * {@code path}. Upon construction, the stat of the file system will be
+     * performed, and the values retrieved available from the methods on this
+     * class.
+     *
+     * @param path path in the desired file system to stat.
      */
-    public StatFs(String path) { native_setup(path); }
-    
+    public StatFs(String path) {
+        mStat = doStat(path);
+    }
+
+    private static StructStatFs doStat(String path) {
+        try {
+            return Libcore.os.statfs(path);
+        } catch (ErrnoException e) {
+            throw new IllegalArgumentException("Invalid path: " + path, e);
+        }
+    }
+
     /**
-     * Perform a restat of the file system referenced by this object.  This
-     * is the same as re-constructing the object with the same file system
-     * path, and the new stat values are available upon return.
+     * Perform a restat of the file system referenced by this object. This is
+     * the same as re-constructing the object with the same file system path,
+     * and the new stat values are available upon return.
      */
-    public void restat(String path) { native_restat(path); }
-
-    @Override
-    protected void finalize() { native_finalize(); }
+    public void restat(String path) {
+        mStat = doStat(path);
+    }
 
     /**
-     * The size, in bytes, of a block on the file system.  This corresponds
-     * to the Unix statfs.f_bsize field.
+     * The size, in bytes, of a block on the file system. This corresponds to
+     * the Unix {@code statfs.f_bsize} field.
      */
-    public native int getBlockSize();
+    public int getBlockSize() {
+        return (int) mStat.f_bsize;
+    }
 
     /**
-     * The total number of blocks on the file system.  This corresponds
-     * to the Unix statfs.f_blocks field.
+     * The total number of blocks on the file system. This corresponds to the
+     * Unix {@code statfs.f_blocks} field.
      */
-    public native int getBlockCount();
+    public int getBlockCount() {
+        return (int) mStat.f_blocks;
+    }
 
     /**
      * The total number of blocks that are free on the file system, including
-     * reserved blocks (that are not available to normal applications).  This
-     * corresponds to the Unix statfs.f_bfree field.  Most applications will
-     * want to use {@link #getAvailableBlocks()} instead.
+     * reserved blocks (that are not available to normal applications). This
+     * corresponds to the Unix {@code statfs.f_bfree} field. Most applications
+     * will want to use {@link #getAvailableBlocks()} instead.
      */
-    public native int getFreeBlocks();
+    public int getFreeBlocks() {
+        return (int) mStat.f_bfree;
+    }
 
     /**
      * The number of blocks that are free on the file system and available to
-     * applications.  This corresponds to the Unix statfs.f_bavail field.
+     * applications. This corresponds to the Unix {@code statfs.f_bavail} field.
      */
-    public native int getAvailableBlocks();    
-    
-    private int mNativeContext;
-    private native void native_restat(String path);
-    private native void native_setup(String path);
-    private native void native_finalize();
+    public int getAvailableBlocks() {
+        return (int) mStat.f_bavail;
+    }
 }

core/jni/Android.mk

@@ -67,7 +67,6 @@ LOCAL_SRC_FILES:= \
 	android_os_ParcelFileDescriptor.cpp \
 	android_os_Parcel.cpp \
 	android_os_SELinux.cpp \
-	android_os_StatFs.cpp \
 	android_os_SystemClock.cpp \
 	android_os_SystemProperties.cpp \
 	android_os_Trace.cpp \