liblp: Auto-suffix group names.

This is needed for update_engine to properly clean old partitions on
retrofit devices.

Bug: 119687874
Test: liblp_test gtest
Change-Id: Ida9483ad3c127e357f45789540ebbedc9d3d3883

Former-commit-id: 7256eaa1b421ea792c908ad158038d46de07ed4b

fs_mgr/liblp/builder.cpp

@@ -623,6 +623,9 @@ std::unique_ptr<LpMetadata> MetadataBuilder::Export() {
             LERROR << "Partition group name is too long: " << group->name();
             return nullptr;
         }
+        if (auto_slot_suffixing_ && group->name() != "default") {
+            out.flags |= LP_GROUP_SLOT_SUFFIXED;
+        }
         strncpy(out.name, group->name().c_str(), sizeof(out.name));
         out.maximum_size = group->maximum_size();
 

fs_mgr/liblp/include/liblp/metadata_format.h

@@ -38,7 +38,7 @@ extern "C" {
 #define LP_METADATA_HEADER_MAGIC 0x414C5030
 
 /* Current metadata version. */
-#define LP_METADATA_MAJOR_VERSION 9
+#define LP_METADATA_MAJOR_VERSION 10
 #define LP_METADATA_MINOR_VERSION 0
 
 /* Attributes for the LpMetadataPartition::attributes field.
@@ -267,10 +267,19 @@ typedef struct LpMetadataPartitionGroup {
     /*  0: Name of this group. Any unused characters must be 0. */
     char name[36];
 
-    /* 36: Maximum size in bytes. If 0, the group has no maximum size. */
+    /* 36: Flags (see LP_GROUP_*). */
+    uint32_t flags;
+
+    /* 40: Maximum size in bytes. If 0, the group has no maximum size. */
     uint64_t maximum_size;
 } LpMetadataPartitionGroup;
 
+/* This flag is only intended to be used with super_empty.img and super.img on
+ * retrofit devices. If set, the group needs a slot suffix to be interpreted
+ * correctly. The suffix is automatically applied by ReadMetadata().
+ */
+#define LP_GROUP_SLOT_SUFFIXED (1 << 0)
+
 /* This struct defines an entry in the block_devices table. There must be at
  * least one device, and the first device must represent the partition holding
  * the super metadata.

fs_mgr/liblp/io_test.cpp

@@ -622,6 +622,7 @@ TEST(liblp, AutoSlotSuffixing) {
     unique_ptr<MetadataBuilder> builder = CreateDefaultBuilder();
     ASSERT_NE(builder, nullptr);
     ASSERT_TRUE(AddDefaultPartitions(builder.get()));
+    ASSERT_TRUE(builder->AddGroup("example", 0));
     builder->SetAutoSlotSuffixing();
 
     auto fd = CreateFakeDisk();
@@ -641,13 +642,23 @@ TEST(liblp, AutoSlotSuffixing) {
     EXPECT_EQ(GetPartitionName(metadata->partitions[0]), "system_b");
     ASSERT_EQ(metadata->block_devices.size(), static_cast<size_t>(1));
     EXPECT_EQ(GetBlockDevicePartitionName(metadata->block_devices[0]), "super_b");
+    ASSERT_EQ(metadata->groups.size(), static_cast<size_t>(2));
+    EXPECT_EQ(GetPartitionGroupName(metadata->groups[0]), "default");
+    EXPECT_EQ(GetPartitionGroupName(metadata->groups[1]), "example_b");
+    EXPECT_EQ(metadata->groups[0].flags, 0);
+    EXPECT_EQ(metadata->groups[1].flags, 0);
 
     metadata = ReadMetadata(opener, "super_a", 0);
     ASSERT_NE(metadata, nullptr);
     ASSERT_EQ(metadata->partitions.size(), static_cast<size_t>(1));
     EXPECT_EQ(GetPartitionName(metadata->partitions[0]), "system_a");
     ASSERT_EQ(metadata->block_devices.size(), static_cast<size_t>(1));
     EXPECT_EQ(GetBlockDevicePartitionName(metadata->block_devices[0]), "super_a");
+    ASSERT_EQ(metadata->groups.size(), static_cast<size_t>(2));
+    EXPECT_EQ(GetPartitionGroupName(metadata->groups[0]), "default");
+    EXPECT_EQ(GetPartitionGroupName(metadata->groups[1]), "example_a");
+    EXPECT_EQ(metadata->groups[0].flags, 0);
+    EXPECT_EQ(metadata->groups[1].flags, 0);
 }
 
 TEST(liblp, UpdateRetrofit) {

fs_mgr/liblp/reader.cpp

@@ -375,6 +375,18 @@ bool AdjustMetadataForSlot(LpMetadata* metadata, uint32_t slot_number) {
         }
         block_device.flags &= ~LP_BLOCK_DEVICE_SLOT_SUFFIXED;
     }
+    for (auto& group : metadata->groups) {
+        if (!(group.flags & LP_GROUP_SLOT_SUFFIXED)) {
+            continue;
+        }
+        std::string group_name = GetPartitionGroupName(group) + slot_suffix;
+        if (group_name.size() > sizeof(group.name)) {
+            LERROR << __PRETTY_FUNCTION__ << " group name too long: " << group_name;
+            return false;
+        }
+        strncpy(group.name, group_name.c_str(), sizeof(group.name));
+        group.flags &= ~LP_GROUP_SLOT_SUFFIXED;
+    }
     return true;
 }