Introduce a library to contain gsid's image creation logic.

README.md contains a full explanation. GsiInstaller's logic will be
removed in a follow-up CL.

Bug: 134536978
Test: libgsi_image_test gtest
Change-Id: I76f273e06bd8633c6c16e3f3c76ade28e59efe6f

3 files changed, 96 insertions, 0 deletions

diff --git a/aidl/android/gsi/IGsiService.aidl b/aidl/android/gsi/IGsiService.aidl
index 4ffdf62..4468eb7 100644
--- a/aidl/android/gsi/IGsiService.aidl
+++ b/aidl/android/gsi/IGsiService.aidl
@@ -18,6 +18,7 @@ package android.gsi;
 
 import android.gsi.GsiInstallParams;
 import android.gsi.GsiProgress;
+import android.gsi.IImageManager;
 import android.os.ParcelFileDescriptor;
 
 /** {@hide} */
@@ -181,4 +182,13 @@ interface IGsiService {
      * @return              0 on success, an error code on failure.
      */
     int wipeGsiUserdata();
+
+    /**
+     * Open a handle to an IImageManager for the given metadata and data storage paths.
+     *
+     * @param prefix        A prefix used to organize images. The data path will become
+     *                      /data/gsi/{prefix} and the metadata path will become
+     *                      /metadata/gsi/{prefix}.
+     */
+    IImageManager openImageManager(@utf8InCpp String prefix);
 }
diff --git a/aidl/android/gsi/IImageManager.aidl b/aidl/android/gsi/IImageManager.aidl
new file mode 100644
index 0000000..526b08a
--- /dev/null
+++ b/aidl/android/gsi/IImageManager.aidl
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.gsi;
+
+import android.gsi.MappedImage;
+
+/** {@hide} */
+interface IImageManager {
+    /**
+     * Create an image that can be mapped as a block device.
+     *
+     * This call will fail if running a GSI.
+     *
+     * @param name          Image name. If the image already exists, the call will fail.
+     * @param size          Image size, in bytes. If too large, or not enough space is
+     *                      free, the call will fail.
+     * @param readonly      If readonly, MapBackingImage() will configure the device as
+     *                      readonly.
+     * @return              True on success, false otherwise.
+     */
+    void createBackingImage(@utf8InCpp String name, long size, boolean readonly);
+
+    /**
+     * Delete an image created with createBackingImage.
+     *
+     * @param name          Image name as passed to createBackingImage().
+     * @return              True on success, false otherwise.
+     */
+    void deleteBackingImage(@utf8InCpp String name);
+
+    /**
+     * Map an image, created with createBackingImage, such that it is accessible as a
+     * block device.
+     *
+     * @param name          Image name as passed to createBackingImage().
+     * @param timeout_ms    Time to wait for a valid mapping, in milliseconds. This must be more
+     *                      than zero; 10 seconds is recommended.
+     * @param mapping       Information about the newly mapped block device.
+     */
+    void mapImageDevice(@utf8InCpp String name, int timeout_ms, out MappedImage mapping);
+
+    /**
+     * Unmap a block device previously mapped with mapBackingImage. This step is necessary before
+     * calling deleteBackingImage.
+     *
+     * @param name          Image name as passed to createBackingImage().
+     */
+    void unmapImageDevice(@utf8InCpp String name);
+}
diff --git a/aidl/android/gsi/MappedImage.aidl b/aidl/android/gsi/MappedImage.aidl
new file mode 100644
index 0000000..aa5af0d
--- /dev/null
+++ b/aidl/android/gsi/MappedImage.aidl
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.gsi;
+
+/** {@hide} */
+parcelable MappedImage {
+    /* Path to the block device. */
+    @utf8InCpp String path;
+}