recovery: Allow "Mount /system" for system_root_image.

When system images contain the root directory, there is no entry of
"/system" in the fstab. Change it to look for "/" instead if
ro.build.system_root_image is true. We actually mount the partition
to /system_root instead, and create a symlink to /system_root/system
for /system. This allows "adb shell" to work properly.

Bug: 22855115
Change-Id: Ibac493a5a9320c98ee3b60bd2cc635b925f5454a

1 files changed, 17 insertions, 2 deletions

diff --git a/recovery.cpp b/recovery.cpp
index d5b0157..b7f1e4a 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -863,9 +863,24 @@ prompt_and_wait(Device* device, int status) {
                 break;
 
             case Device::MOUNT_SYSTEM:
-                if (ensure_path_mounted("/system") != -1) {
-                    ui->Print("Mounted /system.\n");
+                char system_root_image[PROPERTY_VALUE_MAX];
+                property_get("ro.build.system_root_image", system_root_image, "");
+
+                // For a system image built with the root directory (i.e.
+                // system_root_image == "true"), we mount it to /system_root, and symlink /system
+                // to /system_root/system to make adb shell work (the symlink is created through
+                // the build system).
+                // Bug: 22855115
+                if (strcmp(system_root_image, "true") == 0) {
+                    if (ensure_path_mounted_at("/", "/system_root") != -1) {
+                        ui->Print("Mounted /system.\n");
+                    }
+                } else {
+                    if (ensure_path_mounted("/system") != -1) {
+                        ui->Print("Mounted /system.\n");
+                    }
                 }
+
                 break;
         }
     }