QcomModulePkg: avb: Allow system partition to be absent

On devices with dynamic partitions, 'system' partition might not exist.
Therefore, we should not add root=$(ANDROID_SYSTEM_PARTUUID) in kernel
cmdline and resolve it for devices without system partition.

Bug: 119551429
Test: m libavb_host_unittest &&
      ../../out/host/linux-x86/nativetest64/libavb_host_unittest/libavb_host_unittest

Git-repo: https://source.codeaurora.org/quic/la/platform/external/avb
Git-Commit: 5abd6bc2578968d24406d834471adfd995a0c2e9

Change-Id: I767fb1b18182663d8401cf0e8d19930d45c4b83a

1 files changed, 39 insertions, 5 deletions

diff --git a/QcomModulePkg/Library/avb/libavb/avb_slot_verify.c b/QcomModulePkg/Library/avb/libavb/avb_slot_verify.c
index db650e094c..b410fec3d6 100644
--- a/QcomModulePkg/Library/avb/libavb/avb_slot_verify.c
+++ b/QcomModulePkg/Library/avb/libavb/avb_slot_verify.c
@@ -1280,6 +1280,35 @@ out:
   return ret;
 }
 
+static bool has_system_partition(AvbOps* ops, const char* ab_suffix) {
+  char part_name[PART_NAME_MAX_SIZE];
+  char* system_part_name = "system";
+  char guid_buf[37];
+  AvbIOResult io_ret;
+
+  if (!avb_str_concat(part_name,
+                      sizeof part_name,
+                      system_part_name,
+                      avb_strlen(system_part_name),
+                      ab_suffix,
+                      avb_strlen(ab_suffix))) {
+    avb_error("System partition name and suffix does not fit.\n");
+    return false;
+  }
+
+  io_ret = ops->get_unique_guid_for_partition(
+      ops, part_name, guid_buf, sizeof guid_buf);
+  if (io_ret == AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION) {
+    avb_debug("No system partition.\n");
+    return false;
+  } else if (io_ret != AVB_IO_RESULT_OK) {
+    avb_error("Error getting unique GUID for system partition.\n");
+    return false;
+  }
+
+  return true;
+}
+
 AvbSlotVerifyResult avb_slot_verify(AvbOps* ops,
                                     const char* const* requested_partitions,
                                     const char* ab_suffix,
@@ -1382,11 +1411,16 @@ AvbSlotVerifyResult avb_slot_verify(AvbOps* ops,
        * that the system partition is mounted.
        */
       avb_assert(slot_data->cmdline == NULL);
-      slot_data->cmdline =
-          avb_strdup("root=PARTUUID=$(ANDROID_SYSTEM_PARTUUID)");
-      if (slot_data->cmdline == NULL) {
-        ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
-        goto fail;
+      // Devices with dynamic partitions won't have system partition.
+      // Instead, it has a large super partition to accommodate *.img files.
+      // See b/119551429 for details.
+      if (has_system_partition(ops, ab_suffix)) {
+        slot_data->cmdline =
+            avb_strdup("root=PARTUUID=$(ANDROID_SYSTEM_PARTUUID)");
+        if (slot_data->cmdline == NULL) {
+          ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
+          goto fail;
+        }
       }
     } else {
       /* Add options - any failure in append_options() is either an