fs_mgr: Allow overriding the super partition name via the kernel commandline.

For retrofit devices where the super partition is not called "super",
this allows the correct partition to be passed via the kernel
command-line, i.e.:

  androidboot.super_partition=system

Since retrofitting is only supported for A/B devices, we assume that
a partition named this way must be slot-suffixed.

Bug: 116802789
Test: manual test
Change-Id: I930dbbd397d5552e9ded89baa5a7bb0e63c67426

1 files changed, 20 insertions, 1 deletions

diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index ae2e2fe4c..c321fe3eb 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -1588,6 +1588,25 @@ bool fs_mgr_update_verity_state(std::function<fs_mgr_verity_state_callback> call
     return true;
 }
 
-std::string fs_mgr_get_super_partition_name(int /* slot */) {
+std::string fs_mgr_get_super_partition_name(int slot) {
+    // Devices upgrading to dynamic partitions are allowed to specify a super
+    // partition name, assumed to be A/B (non-A/B retrofit is not supported).
+    // For devices launching with dynamic partition support, the partition
+    // name must be "super".
+    std::string super_partition;
+    if (fs_mgr_get_boot_config_from_kernel_cmdline("super_partition", &super_partition)) {
+        std::string suffix;
+        if (slot == 0) {
+            suffix = "_a";
+        } else if (slot == 1) {
+            suffix = "_b";
+        } else if (slot == -1) {
+            suffix = fs_mgr_get_slot_suffix();
+        }
+        if (suffix.empty()) {
+            LFATAL << "Super partition name can only be overridden on A/B devices.";
+        }
+        return super_partition + suffix;
+    }
     return LP_METADATA_DEFAULT_PARTITION_NAME;
 }