Implement FUSE_WRITE command in app fuse.

The CL adds a handler for FUSE_WRITE command which invokes a Java
handler.

BUG=23093747

Change-Id: I1903fca6b5663e6241ad540a89fe812310ba6810
(cherry picked from commit 35693da25af11583053d4af6a70d4acbf446978d)

5 files changed, 208 insertions, 12 deletions

diff --git a/packages/MtpDocumentsProvider/jni/com_android_mtp_AppFuse.cpp b/packages/MtpDocumentsProvider/jni/com_android_mtp_AppFuse.cpp
index 2b44d514fde7..1d4ed1dc5c5b 100644
--- a/packages/MtpDocumentsProvider/jni/com_android_mtp_AppFuse.cpp
+++ b/packages/MtpDocumentsProvider/jni/com_android_mtp_AppFuse.cpp
@@ -51,6 +51,7 @@ constexpr size_t MAX_REQUEST_SIZE = sizeof(struct fuse_in_header) +
 static jclass app_fuse_class;
 static jmethodID app_fuse_get_file_size;
 static jmethodID app_fuse_read_object_bytes;
+static jmethodID app_fuse_write_object_bytes;
 static jfieldID app_fuse_buffer;
 
 // NOTE:
@@ -140,6 +141,9 @@ public:
             case FUSE_READ:
                 invoke_handler(fd, req, &AppFuse::handle_fuse_read);
                 return true;
+            case FUSE_WRITE:
+                invoke_handler(fd, req, &AppFuse::handle_fuse_write);
+                return true;
             case FUSE_RELEASE:
                 invoke_handler(fd, req, &AppFuse::handle_fuse_release);
                 return true;
@@ -289,6 +293,29 @@ private:
         return 0;
     }
 
+    int handle_fuse_write(const fuse_in_header& /* header */,
+                          const fuse_write_in* in,
+                          FuseResponse<fuse_write_out>* out) {
+        if (in->size > MAX_WRITE) {
+            return -EINVAL;
+        }
+        const std::map<uint32_t, uint64_t>::iterator it = handles_.find(in->fh);
+        if (it == handles_.end()) {
+            return -EBADF;
+        }
+        const uint64_t offset = in->offset;
+        const uint32_t size = in->size;
+        const void* const buffer = reinterpret_cast<const uint8_t*>(in) + sizeof(fuse_write_in);
+        uint32_t written_size;
+        const int result = write_object_bytes(it->second, offset, size, buffer, &written_size);
+        if (result < 0) {
+            return result;
+        }
+        out->prepare_buffer();
+        out->data()->size = written_size;
+        return 0;
+    }
+
     int handle_fuse_release(const fuse_in_header& /* header */,
                             const fuse_release_in* in,
                             FuseResponse<void>* /* out */) {
@@ -355,6 +382,27 @@ private:
         return read_size;
     }
 
+    int write_object_bytes(int inode, uint64_t offset, uint32_t size, const void* buffer,
+                           uint32_t* written_size) {
+        ScopedLocalRef<jbyteArray> array(
+                env_,
+                static_cast<jbyteArray>(env_->GetObjectField(self_, app_fuse_buffer)));
+        {
+            ScopedByteArrayRW bytes(env_, array.get());
+            if (bytes.get() == nullptr) {
+                return -EIO;
+            }
+            memcpy(bytes.get(), buffer, size);
+        }
+        *written_size = env_->CallIntMethod(
+                self_, app_fuse_write_object_bytes, inode, offset, size, array.get());
+        if (env_->ExceptionCheck()) {
+            env_->ExceptionClear();
+            return -EIO;
+        }
+        return 0;
+    }
+
     static void fuse_reply(int fd, int unique, int reply_code, void* reply_data,
                            size_t reply_size) {
         // Don't send any data for error case.
@@ -469,6 +517,28 @@ jint JNI_OnLoad(JavaVM* vm, void* /* reserved */) {
         return -1;
     }
 
+    app_fuse_write_object_bytes = env->GetMethodID(app_fuse_class, "writeObjectBytes", "(IJI[B)I");
+    if (app_fuse_write_object_bytes == nullptr) {
+        ALOGE("Can't find getWriteObjectBytes");
+        return -1;
+    }
+
+    app_fuse_buffer = env->GetFieldID(app_fuse_class, "mBuffer", "[B");
+    if (app_fuse_buffer == nullptr) {
+        ALOGE("Can't find mBuffer");
+        return -1;
+    }
+
+    const jfieldID read_max_fied = env->GetStaticFieldID(app_fuse_class, "MAX_READ", "I");
+    if (static_cast<int>(env->GetStaticIntField(app_fuse_class, read_max_fied)) != MAX_READ) {
+        return -1;
+    }
+
+    const jfieldID write_max_fied = env->GetStaticFieldID(app_fuse_class, "MAX_WRITE", "I");
+    if (static_cast<int>(env->GetStaticIntField(app_fuse_class, write_max_fied)) != MAX_WRITE) {
+        return -1;
+    }
+
     const int result = android::AndroidRuntime::registerNativeMethods(
             env, "com/android/mtp/AppFuse", gMethods, NELEM(gMethods));
     if (result < 0) {
diff --git a/packages/MtpDocumentsProvider/src/com/android/mtp/AppFuse.java b/packages/MtpDocumentsProvider/src/com/android/mtp/AppFuse.java
index 38435f4afa47..1fd471cb48e2 100644
--- a/packages/MtpDocumentsProvider/src/com/android/mtp/AppFuse.java
+++ b/packages/MtpDocumentsProvider/src/com/android/mtp/AppFuse.java
@@ -38,8 +38,12 @@ public class AppFuse {
      * Max read amount specified at the FUSE kernel implementation.
      * The value is copied from sdcard.c.
      */
+    @UsedByNative("com_android_mtp_AppFuse.cpp")
     static final int MAX_READ = 128 * 1024;
 
+    @UsedByNative("com_android_mtp_AppFuse.cpp")
+    static final int MAX_WRITE = 256 * 1024;
+
     private final String mName;
     private final Callback mCallback;
 
@@ -47,7 +51,7 @@ public class AppFuse {
      * Buffer for read bytes request.
      * Don't use the buffer from the out of AppFuseMessageThread.
      */
-    private byte[] mBuffer = new byte[MAX_READ];
+    private byte[] mBuffer = new byte[Math.max(MAX_READ, MAX_WRITE)];
 
     private Thread mMessageThread;
     private ParcelFileDescriptor mDeviceFd;
@@ -79,11 +83,22 @@ public class AppFuse {
         }
     }
 
-    public ParcelFileDescriptor openFile(int i) throws FileNotFoundException {
+    /**
+     * Opens a file on app fuse and returns ParcelFileDescriptor.
+     *
+     * @param i ID for opened file.
+     * @param mode Mode for opening file.
+     * @see ParcelFileDescriptor#MODE_READ_ONLY
+     * @see ParcelFileDescriptor#MODE_WRITE_ONLY
+     */
+    public ParcelFileDescriptor openFile(int i, int mode) throws FileNotFoundException {
+        Preconditions.checkArgument(
+                mode == ParcelFileDescriptor.MODE_READ_ONLY ||
+                mode == ParcelFileDescriptor.MODE_WRITE_ONLY);
         return ParcelFileDescriptor.open(new File(
                 getMountPoint(),
                 Integer.toString(i)),
-                ParcelFileDescriptor.MODE_READ_ONLY);
+                mode);
     }
 
     File getMountPoint() {
@@ -100,7 +115,7 @@ public class AppFuse {
         long getFileSize(int inode) throws FileNotFoundException;
 
         /**
-         * Returns flie bytes for the give inode.
+         * Returns file bytes for the give inode.
          * @param inode
          * @param offset Offset for file bytes.
          * @param size Size for file bytes.
@@ -109,6 +124,17 @@ public class AppFuse {
          * @throws IOException
          */
         long readObjectBytes(int inode, long offset, long size, byte[] bytes) throws IOException;
+
+        /**
+         * Handles writing bytes for the give inode.
+         * @param inode
+         * @param offset Offset for file bytes.
+         * @param size Size for file bytes.
+         * @param bytes Buffer to store file bytes.
+         * @return Number of read bytes. Must not be negative.
+         * @throws IOException
+         */
+        int writeObjectBytes(int inode, long offset, int size, byte[] bytes) throws IOException;
     }
 
     @UsedByNative("com_android_mtp_AppFuse.cpp")
@@ -138,6 +164,15 @@ public class AppFuse {
         }
     }
 
+    @UsedByNative("com_android_mtp_AppFuse.cpp")
+    @WorkerThread
+    private /* unsgined */ int writeObjectBytes(int inode,
+                                                /* unsigned */ long offset,
+                                                /* unsigned */ int size,
+                                                byte[] bytes) throws IOException {
+        return mCallback.writeObjectBytes(inode, offset, size, bytes);
+    }
+
     private native boolean native_start_app_fuse_loop(int fd);
 
     private class AppFuseMessageThread extends Thread {
diff --git a/packages/MtpDocumentsProvider/src/com/android/mtp/MtpDocumentsProvider.java b/packages/MtpDocumentsProvider/src/com/android/mtp/MtpDocumentsProvider.java
index cf5bee5d727d..4152d1e84de1 100644
--- a/packages/MtpDocumentsProvider/src/com/android/mtp/MtpDocumentsProvider.java
+++ b/packages/MtpDocumentsProvider/src/com/android/mtp/MtpDocumentsProvider.java
@@ -242,7 +242,8 @@ public class MtpDocumentsProvider extends DocumentsProvider {
                     // extension.
                     if (MtpDeviceRecord.isPartialReadSupported(
                             device.operationsSupported, fileSize)) {
-                        return mAppFuse.openFile(Integer.parseInt(documentId));
+                        return mAppFuse.openFile(
+                                Integer.parseInt(documentId), ParcelFileDescriptor.MODE_READ_ONLY);
                     } else {
                         return getPipeManager(identifier).readDocument(mMtpManager, identifier);
                     }
@@ -606,5 +607,12 @@ public class MtpDocumentsProvider extends DocumentsProvider {
         public long getFileSize(int inode) throws FileNotFoundException {
             return MtpDocumentsProvider.this.getFileSize(String.valueOf(inode));
         }
+
+        @Override
+        public int writeObjectBytes(int inode, long offset, int size, byte[] bytes)
+                throws IOException {
+            // TODO: Implement it.
+            throw new IOException();
+        }
     }
 }
diff --git a/packages/MtpDocumentsProvider/src/com/android/mtp/annotations/UsedByNative.java b/packages/MtpDocumentsProvider/src/com/android/mtp/annotations/UsedByNative.java
index a7f295f670b3..2ded92540627 100644
--- a/packages/MtpDocumentsProvider/src/com/android/mtp/annotations/UsedByNative.java
+++ b/packages/MtpDocumentsProvider/src/com/android/mtp/annotations/UsedByNative.java
@@ -22,7 +22,7 @@ import java.lang.annotation.Target;
 /**
  * Annotation that shows the method is used by JNI.
  */
-@Target(ElementType.METHOD)
+@Target({ElementType.METHOD, ElementType.FIELD})
 public @interface UsedByNative {
     /**
      * JNI file name that uses the method.
diff --git a/packages/MtpDocumentsProvider/tests/src/com/android/mtp/AppFuseTest.java b/packages/MtpDocumentsProvider/tests/src/com/android/mtp/AppFuseTest.java
index c0973bd73514..3b925068c50c 100644
--- a/packages/MtpDocumentsProvider/tests/src/com/android/mtp/AppFuseTest.java
+++ b/packages/MtpDocumentsProvider/tests/src/com/android/mtp/AppFuseTest.java
@@ -56,7 +56,8 @@ public class AppFuseTest extends AndroidTestCase {
                     }
                 });
         appFuse.mount(storageManager);
-        final ParcelFileDescriptor fd = appFuse.openFile(INODE);
+        final ParcelFileDescriptor fd = appFuse.openFile(
+                INODE, ParcelFileDescriptor.MODE_READ_ONLY);
         fd.close();
         appFuse.close();
     }
@@ -67,11 +68,21 @@ public class AppFuseTest extends AndroidTestCase {
         final AppFuse appFuse = new AppFuse("test", new TestCallback());
         appFuse.mount(storageManager);
         try {
-            appFuse.openFile(INODE);
+            appFuse.openFile(INODE, ParcelFileDescriptor.MODE_READ_ONLY);
             fail();
-        } catch (Throwable t) {
-            assertTrue(t instanceof FileNotFoundException);
-        }
+        } catch (FileNotFoundException exp) {}
+        appFuse.close();
+    }
+
+    public void testOpenFile_illegalMode() throws IOException {
+        final StorageManager storageManager = getContext().getSystemService(StorageManager.class);
+        final int INODE = 10;
+        final AppFuse appFuse = new AppFuse("test", new TestCallback());
+        appFuse.mount(storageManager);
+        try {
+            appFuse.openFile(INODE, ParcelFileDescriptor.MODE_READ_WRITE);
+            fail();
+        } catch (IllegalArgumentException exp) {}
         appFuse.close();
     }
 
@@ -105,7 +116,8 @@ public class AppFuseTest extends AndroidTestCase {
                     }
                 });
         appFuse.mount(storageManager);
-        final ParcelFileDescriptor fd = appFuse.openFile(fileInode);
+        final ParcelFileDescriptor fd = appFuse.openFile(
+                fileInode, ParcelFileDescriptor.MODE_READ_ONLY);
         try (final ParcelFileDescriptor.AutoCloseInputStream stream =
                 new ParcelFileDescriptor.AutoCloseInputStream(fd)) {
             final byte[] buffer = new byte[1024];
@@ -115,6 +127,71 @@ public class AppFuseTest extends AndroidTestCase {
         appFuse.close();
     }
 
+    public void testWriteFile() throws IOException {
+        final StorageManager storageManager = getContext().getSystemService(StorageManager.class);
+        final int INODE = 10;
+        final byte[] resultBytes = new byte[5];
+        final AppFuse appFuse = new AppFuse(
+                "test",
+                new TestCallback() {
+                    @Override
+                    public long getFileSize(int inode) throws FileNotFoundException {
+                        if (inode != INODE) {
+                            throw new FileNotFoundException();
+                        }
+                        return resultBytes.length;
+                    }
+
+                    @Override
+                    public int writeObjectBytes(int inode, long offset, int size, byte[] bytes) {
+                        for (int i = 0; i < size; i++) {
+                            resultBytes[(int)(offset + i)] = bytes[i];
+                        }
+                        return size;
+                    }
+                });
+        appFuse.mount(storageManager);
+        final ParcelFileDescriptor fd = appFuse.openFile(
+                INODE, ParcelFileDescriptor.MODE_WRITE_ONLY);
+        try (final ParcelFileDescriptor.AutoCloseOutputStream stream =
+                new ParcelFileDescriptor.AutoCloseOutputStream(fd)) {
+            stream.write('a');
+            stream.write('b');
+            stream.write('c');
+            stream.write('d');
+            stream.write('e');
+        }
+        final byte[] BYTES = new byte[] { 'a', 'b', 'c', 'd', 'e' };
+        assertTrue(Arrays.equals(BYTES, resultBytes));
+        appFuse.close();
+    }
+
+    public void testWriteFile_writeError() throws IOException {
+        final StorageManager storageManager = getContext().getSystemService(StorageManager.class);
+        final int INODE = 10;
+        final AppFuse appFuse = new AppFuse(
+                "test",
+                new TestCallback() {
+                    @Override
+                    public long getFileSize(int inode) throws FileNotFoundException {
+                        if (inode != INODE) {
+                            throw new FileNotFoundException();
+                        }
+                        return 5;
+                    }
+                });
+        appFuse.mount(storageManager);
+        final ParcelFileDescriptor fd = appFuse.openFile(
+                INODE, ParcelFileDescriptor.MODE_WRITE_ONLY);
+        try (final ParcelFileDescriptor.AutoCloseOutputStream stream =
+                new ParcelFileDescriptor.AutoCloseOutputStream(fd)) {
+            stream.write('a');
+            fail();
+        } catch (IOException e) {
+        }
+        appFuse.close();
+    }
+
     private static class TestCallback implements AppFuse.Callback {
         @Override
         public long getFileSize(int inode) throws FileNotFoundException {
@@ -126,5 +203,11 @@ public class AppFuseTest extends AndroidTestCase {
                 throws IOException {
             throw new IOException();
         }
+
+        @Override
+        public int writeObjectBytes(int inode, long offset, int size, byte[] bytes)
+                throws IOException {
+            throw new IOException();
+        }
     }
 }