fastboot: Implement helper commands for Virtual A/B.

This introduces two new commands to the fastboot protocol:

  - getvar snapshot-update-status - Return "none", "snapshotted", or
    "merging" depending on the current status set by the boot control
    HAL.
  - snapshot-update [cancel] - Cancel any pending snapshot-based updates
    via the boot control HAL. After this, the HAL should return
    MergeStatus::CANCELLED and "update-merge-status" should be "none".
    If no argument is specified, the snapshot-update-status is returned
    via an INFO response.

Bootloaders are expected to implement this in a manner consistent with
the boot control HAL.

Fastboot-based tooling should expect wipes of userdata to fail when
update-merge-status returns "merging". Thus, the force flag now cancel
any pending snapshots.

Bug: 139154945
Test: fastboot getvar snapshot-update-status
      fastboot snapshot-update cancel
      fastboot snapshot-update

Change-Id: Idc423fe7656b212e929e64eb0e6b85b453e0e8dc

1 files changed, 34 insertions, 0 deletions

diff --git a/fastboot/device/variables.cpp b/fastboot/device/variables.cpp
index 130a3cf34..6e613d647 100644
--- a/fastboot/device/variables.cpp
+++ b/fastboot/device/variables.cpp
@@ -23,6 +23,7 @@
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
+#include <android/hardware/boot/1.1/IBootControl.h>
 #include <ext4_utils/ext4_utils.h>
 #include <fs_mgr.h>
 #include <healthhalutils/HealthHalUtils.h>
@@ -34,9 +35,11 @@
 
 using ::android::hardware::boot::V1_0::BoolResult;
 using ::android::hardware::boot::V1_0::Slot;
+using ::android::hardware::boot::V1_1::MergeStatus;
 using ::android::hardware::fastboot::V1_0::FileSystemType;
 using ::android::hardware::fastboot::V1_0::Result;
 using ::android::hardware::fastboot::V1_0::Status;
+using IBootControl1_1 = ::android::hardware::boot::V1_1::IBootControl;
 using namespace android::fs_mgr;
 
 constexpr char kFastbootProtocolVersion[] = "0.4";
@@ -424,3 +427,34 @@ bool GetSuperPartitionName(FastbootDevice* device, const std::vector<std::string
     *message = fs_mgr_get_super_partition_name(slot_number);
     return true;
 }
+
+bool GetSnapshotUpdateStatus(FastbootDevice* device, const std::vector<std::string>& /* args */,
+                             std::string* message) {
+    // Note that we use the HAL rather than mounting /metadata, since we want
+    // our results to match the bootloader.
+    auto hal = device->boot_control_hal();
+    if (!hal) {
+        *message = "not supported";
+        return false;
+    }
+
+    android::sp<IBootControl1_1> hal11 = IBootControl1_1::castFrom(hal);
+    if (!hal11) {
+        *message = "not supported";
+        return false;
+    }
+
+    MergeStatus status = hal11->getSnapshotMergeStatus();
+    switch (status) {
+        case MergeStatus::SNAPSHOTTED:
+            *message = "snapshotted";
+            break;
+        case MergeStatus::MERGING:
+            *message = "merging";
+            break;
+        default:
+            *message = "none";
+            break;
+    }
+    return true;
+}