fastbootd: Add an update-super command to sync the super partition.

This change introduces an "update-super" command to the fastboot
protocol. Unlike the "flash" command, which copies raw or sparse data to
a partition, the "update-super" command requires the data to be a super
image generated by lpmake.

If the super partition is not yet formatted (or is corrupt), then it
will be formatted using the given image. Otherwise, "update-super" will
preserve the existing partition layout, and only ensure that logical
partition entries exist for all the new partitions in the given image.
All new partitions added this way will have a zero size, and it is the
host's responsibility to size them as needed afterwards with the
"resize-logical-partition" command.

In addition, the "update-super" command supports a "wipe" argument,
which will force the super partition to be reformatted with the given
image, overwriting any existing partition tables.

Bug: 78793464
Test: fastboot flashall with a super partition
Change-Id: If37d839a03e396e11b6c08a9c32984106613d1dc

fastboot/README.md

@@ -186,10 +186,45 @@ The various currently defined names are:
                         bootloader requiring a signature before
                         it will install or boot images.
 
+    is-userspace        If the value is "yes", the device is running
+                        fastbootd. Otherwise, it is running fastboot
+                        in the bootloader.
+
 Names starting with a lowercase character are reserved by this
 specification.  OEM-specific names should not start with lowercase
 characters.
 
+## Logical Partitions
+
+There are a number of commands to interact with logical partitions:
+
+    update-super:%s:%s  Write the previously downloaded image to a super
+                        partition. Unlike the "flash" command, this has
+                        special rules. The image must have been created by
+                        the lpmake command, and must not be a sparse image.
+                        If the last argument is "wipe", then all existing
+                        logical partitions are deleted. If no final argument
+                        is specified, the partition tables are merged. Any
+                        partition in the new image that does not exist in the
+                        old image is created with a zero size.
+
+                        In all cases, this will cause the temporary "scratch"
+                        partition to be deleted if it exists.
+
+    create-logical-partition:%s:%d
+                        Create a logical partition with the given name and
+                        size, in the super partition.
+
+    delete-logical-partition:%s
+                        Delete a logical partition with the given name.
+
+    resize-logical-partition:%s:%d
+                        Change the size of the named logical partition.
+
+In addition, there is a variable to test whether a partition is logical:
+
+    is-logical:%s       If the value is "yes", the partition is logical.
+                        Otherwise the partition is physical.
 
 ## TCP Protocol v1
 

fastboot/constants.h

@@ -33,6 +33,7 @@
 #define FB_CMD_CREATE_PARTITION "create-logical-partition"
 #define FB_CMD_DELETE_PARTITION "delete-logical-partition"
 #define FB_CMD_RESIZE_PARTITION "resize-logical-partition"
+#define FB_CMD_UPDATE_SUPER "update-super"
 
 #define RESPONSE_OKAY "OKAY"
 #define RESPONSE_FAIL "FAIL"

fastboot/device/commands.cpp

@@ -336,3 +336,11 @@ bool ResizePartitionHandler(FastbootDevice* device, const std::vector<std::strin
     }
     return device->WriteOkay("Partition resized");
 }
+
+bool UpdateSuperHandler(FastbootDevice* device, const std::vector<std::string>& args) {
+    if (args.size() < 2) {
+        return device->WriteFail("Invalid arguments");
+    }
+    bool wipe = (args.size() >= 3 && args[2] == "wipe");
+    return UpdateSuper(device, args[1], wipe);
+}

fastboot/device/commands.h

@@ -44,3 +44,4 @@ bool FlashHandler(FastbootDevice* device, const std::vector<std::string>& args);
 bool CreatePartitionHandler(FastbootDevice* device, const std::vector<std::string>& args);
 bool DeletePartitionHandler(FastbootDevice* device, const std::vector<std::string>& args);
 bool ResizePartitionHandler(FastbootDevice* device, const std::vector<std::string>& args);
+bool UpdateSuperHandler(FastbootDevice* device, const std::vector<std::string>& args);

fastboot/device/fastboot_device.cpp

@@ -46,6 +46,7 @@ FastbootDevice::FastbootDevice()
               {FB_CMD_CREATE_PARTITION, CreatePartitionHandler},
               {FB_CMD_DELETE_PARTITION, DeletePartitionHandler},
               {FB_CMD_RESIZE_PARTITION, ResizePartitionHandler},
+              {FB_CMD_UPDATE_SUPER, UpdateSuperHandler},
       }),
       transport_(std::make_unique<ClientUsbTransport>()),
       boot_control_hal_(IBootControl::getService()) {}

fastboot/device/flashing.cpp

@@ -25,6 +25,8 @@
 #include <android-base/logging.h>
 #include <android-base/strings.h>
 #include <ext4_utils/ext4_utils.h>
+#include <liblp/builder.h>
+#include <liblp/liblp.h>
 #include <sparse/sparse.h>
 
 #include "fastboot_device.h"
@@ -36,6 +38,8 @@ constexpr uint32_t SPARSE_HEADER_MAGIC = 0xed26ff3a;
 
 }  // namespace
 
+using namespace android::fs_mgr;
+
 int FlashRawDataChunk(int fd, const char* data, size_t len) {
     size_t ret = 0;
     while (ret < len) {
@@ -99,3 +103,74 @@ int Flash(FastbootDevice* device, const std::string& partition_name) {
     }
     return FlashBlockDevice(handle.fd(), data);
 }
+
+bool UpdateSuper(FastbootDevice* device, const std::string& partition_name, bool wipe) {
+    std::optional<std::string> super = FindPhysicalPartition(partition_name);
+    if (!super) {
+        return device->WriteFail("Could not find partition: " + partition_name);
+    }
+
+    std::vector<char> data = std::move(device->download_data());
+    if (data.empty()) {
+        return device->WriteFail("No data available");
+    }
+
+    std::unique_ptr<LpMetadata> new_metadata = ReadFromImageBlob(data.data(), data.size());
+    if (!new_metadata) {
+        return device->WriteFail("Data is not a valid logical partition metadata image");
+    }
+
+    // If we are unable to read the existing metadata, then the super partition
+    // is corrupt. In this case we reflash the whole thing using the provided
+    // image.
+    std::string slot_suffix = device->GetCurrentSlot();
+    uint32_t slot_number = SlotNumberForSlotSuffix(slot_suffix);
+    std::unique_ptr<LpMetadata> metadata = ReadMetadata(super->c_str(), slot_number);
+    if (!metadata || wipe) {
+        if (!FlashPartitionTable(super.value(), *new_metadata.get())) {
+            return device->WriteFail("Unable to flash new partition table");
+        }
+        return device->WriteOkay("Successfully flashed partition table");
+    }
+
+    // There's a working super partition, and we don't want to wipe it - it may
+    // may contain partitions created for the user. Instead, we create a zero-
+    // sized partition for each entry in the new partition table. It is then
+    // the host's responsibility to size it correctly via resize-logical-partition.
+    std::unique_ptr<MetadataBuilder> builder = MetadataBuilder::New(*metadata.get());
+    if (!builder) {
+        return device->WriteFail("Unable to create a metadata builder");
+    }
+    for (const auto& partition : new_metadata->partitions) {
+        std::string name = GetPartitionName(partition);
+        if (builder->FindPartition(name)) {
+            continue;
+        }
+        std::string guid = GetPartitionGuid(partition);
+        if (!builder->AddPartition(name, guid, partition.attributes)) {
+            return device->WriteFail("Unable to add partition: " + name);
+        }
+    }
+
+    // The scratch partition may exist as temporary storage, created for
+    // use by adb remount for overlayfs. If we're performing a flashall
+    // operation then we want to start over with a clean slate, so we
+    // remove the scratch partition until it is requested again.
+    builder->RemovePartition("scratch");
+
+    new_metadata = builder->Export();
+    if (!new_metadata) {
+        return device->WriteFail("Unable to export new partition table");
+    }
+
+    // Write the new table to every metadata slot.
+    bool ok = true;
+    for (size_t i = 0; i < new_metadata->geometry.metadata_slot_count; i++) {
+        ok &= UpdatePartitionTable(super.value(), *new_metadata.get(), i);
+    }
+
+    if (!ok) {
+        return device->WriteFail("Unable to write new partition table");
+    }
+    return device->WriteOkay("Successfully updated partition table");
+}

fastboot/device/flashing.h

@@ -22,3 +22,4 @@
 class FastbootDevice;
 
 int Flash(FastbootDevice* device, const std::string& partition_name);
+bool UpdateSuper(FastbootDevice* device, const std::string& partition_name, bool wipe);