add "flasher flash_vbmeta" command (!1885)

Flashes device vbmeta partition (can be overriden with
"flash_fastboot_partition_vbmeta" setting in deviceinfo)
with custom vbmeta.img which has verity flag disabled,
so device can boot postmarketOS with no problems.

pmb/config/__init__.py

@@ -273,6 +273,7 @@ deviceinfo_attributes = [
     "flash_heimdall_partition_system",
     "flash_fastboot_partition_kernel",
     "flash_fastboot_partition_system",
+    "flash_fastboot_partition_vbmeta",
     "generate_legacy_uboot_initfs",
     "kernel_cmdline",
     "generate_bootimg",
@@ -351,13 +352,21 @@ uuu specific: $UUU_SCRIPT
 """
 flashers = {
     "fastboot": {
-        "depends": ["android-tools"],
+        "depends": ["android-tools", "avbtool"],
         "actions": {
             "list_devices": [["fastboot", "devices", "-l"]],
             "flash_rootfs": [["fastboot", "flash", "$PARTITION_SYSTEM",
                               "$IMAGE"]],
             "flash_kernel": [["fastboot", "flash", "$PARTITION_KERNEL",
                               "$BOOT/boot.img-$FLAVOR"]],
+            "flash_vbmeta": [
+                # Generate vbmeta image with "disable verification" flag
+                ["avbtool", "make_vbmeta_image", "--flags", "2",
+                    "--padding_size", "$FLASH_PAGESIZE",
+                    "--output", "/vbmeta.img"],
+                ["fastboot", "flash", "$PARTITION_VBMETA", "/vbmeta.img"],
+                ["rm", "-f", "/vbmeta.img"]
+            ],
             "boot": [["fastboot", "--cmdline", "$KERNEL_CMDLINE",
                       "boot", "$BOOT/boot.img-$FLAVOR"]],
         },

pmb/flasher/frontend.py

@@ -70,6 +70,11 @@ def rootfs(args):
     pmb.flasher.run(args, "flash_rootfs")
 
 
+def flash_vbmeta(args):
+    logging.info("(native) flash vbmeta.img with verity disabled flag")
+    pmb.flasher.run(args, "flash_vbmeta")
+
+
 def list_devices(args):
     pmb.flasher.run(args, "list_devices")
 
@@ -115,6 +120,8 @@ def frontend(args):
         kernel(args)
     if action == "flash_rootfs":
         rootfs(args)
+    if action == "flash_vbmeta":
+        flash_vbmeta(args)
     if action == "list_flavors":
         list_flavors(args)
     if action == "list_devices":

pmb/flasher/run.py

@@ -32,6 +32,15 @@ def run(args, action, flavor=None):
     # Variable setup
     vars = pmb.flasher.variables(args, flavor, method)
 
+    # vbmeta flasher requires vbmeta partition to be explicitly specified
+    if action == "flash_vbmeta" and not vars["$PARTITION_VBMETA"]:
+        raise RuntimeError("Your device does not have 'vbmeta' partition"
+                           " specified; set"
+                           " 'deviceinfo_flash_fastboot_partition_vbmeta'"
+                           " in deviceinfo file. See also:"
+                           " <https://wiki.postmarketos.org/wiki/"
+                           "Deviceinfo_reference>")
+
     # Run the commands of each action
     for command in cfg["actions"][action]:
         # Variable replacement

pmb/flasher/variables.py

@@ -7,17 +7,21 @@ def variables(args, flavor, method):
     if "cmdline" in args and args.cmdline:
         _cmdline = args.cmdline
 
+    flash_pagesize = args.deviceinfo['flash_pagesize']
+
     if method.startswith("fastboot"):
         _partition_kernel = args.deviceinfo["flash_fastboot_partition_kernel"] or "boot"
         _partition_system = args.deviceinfo["flash_fastboot_partition_system"] or "system"
+        _partition_vbmeta = args.deviceinfo["flash_fastboot_partition_vbmeta"] or None
     else:
         _partition_kernel = args.deviceinfo["flash_heimdall_partition_kernel"] or "KERNEL"
         _partition_system = args.deviceinfo["flash_heimdall_partition_system"] or "SYSTEM"
 
     if "partition" in args and args.partition:
-        # Only one of two operations is done at same time so it doesn't matter sharing the arg
+        # Only one of operations is done at same time so it doesn't matter sharing the arg
         _partition_kernel = args.partition
         _partition_system = args.partition
+        _partition_vbmeta = args.partition
 
     vars = {
         "$BOOT": "/mnt/rootfs_" + args.device + "/boot",
@@ -29,6 +33,8 @@ def variables(args, flavor, method):
         "$PARTITION_KERNEL": _partition_kernel,
         "$PARTITION_INITFS": args.deviceinfo["flash_heimdall_partition_initfs"] or "RECOVERY",
         "$PARTITION_SYSTEM": _partition_system,
+        "$PARTITION_VBMETA": _partition_vbmeta,
+        "$FLASH_PAGESIZE": flash_pagesize,
         "$RECOVERY_ZIP": "/mnt/buildroot_" + args.deviceinfo["arch"] +
                          "/var/lib/postmarketos-android-recovery-installer"
                          "/pmos-" + args.device + ".zip",

pmb/parse/arguments.py

@@ -70,6 +70,15 @@ def arguments_flasher(subparser):
                                    " 'userdata' on Android may have more"
                                    " space)")
 
+    # Flash vbmeta
+    flash_vbmeta = sub.add_parser("flash_vbmeta",
+                                  help="generate and flash AVB 2.0 image with disable"
+                                       " verification flag set to a partition on the"
+                                       " device (typically called vbmeta)")
+    flash_vbmeta.add_argument("--partition", default=None,
+                              help="partition to flash the vbmeta to (defaults"
+                                   " to deviceinfo_flash_*_partition_vbmeta")
+
     # Actions without extra arguments
     sub.add_parser("sideload", help="sideload recovery zip")
     sub.add_parser("list_flavors", help="list installed kernel flavors" +