install: verify pmaports branch supporting fs (MR 2011)

Do not attempt to install with a filesystem that is not supported by the
initramfs code in the checked out pmaports branch.

Previously we would have increased the pmaports.cfg version and require
that new version by pmbootstrap, however this will break compatibility
with release branches where we won't roll out this feature (v20.05).
Therefore don't change the version, but add a new
"supported_root_filesystems" key to pmaports.cfg, which defaults to
"ext4".

Related: https://postmarketos.org/pmaports.cfg

pmb/helpers/frontend.py

@@ -308,6 +308,9 @@ def install(args):
                              " packages found. Consider 'pmbootstrap zap -p'"
                              " to delete them.")
 
+    # Verify that the root filesystem is supported by current pmaports branch
+    pmb.install.get_root_filesystem(args)
+
     pmb.install.install(args)
 
 

pmb/install/__init__.py

@@ -4,4 +4,5 @@ from pmb.install._install import install
 from pmb.install._install import get_kernel_package
 from pmb.install.partition import partition
 from pmb.install.format import format
+from pmb.install.format import get_root_filesystem
 from pmb.install.partition import partitions_mount

pmb/install/format.py

@@ -67,6 +67,22 @@ def format_luks_root(args, device):
         raise RuntimeError("Failed to open cryptdevice!")
 
 
+def get_root_filesystem(args):
+    ret = args.filesystem or args.deviceinfo["root_filesystem"] or "ext4"
+    pmaports_cfg = pmb.config.pmaports.read_config(args)
+
+    supported = pmaports_cfg.get("supported_root_filesystems", "ext4")
+    supported_list = supported.split(",")
+
+    if ret not in supported_list:
+        raise ValueError(f"Root filesystem {ret} is not supported by your"
+                         " currently checked out pmaports branch. Update your"
+                         " branch ('pmbootstrap pull'), change it"
+                         " ('pmbootstrap init'), or select one of these"
+                         f" filesystems: {', '.join(supported_list)}")
+    return ret
+
+
 def format_and_mount_root(args, device, root_label, sdcard):
     """
     :param device: root partition on install block device (e.g. /dev/installp2)
@@ -75,8 +91,7 @@ def format_and_mount_root(args, device, root_label, sdcard):
     """
     # Format
     if not args.rsync:
-        filesystem = (args.filesystem or args.deviceinfo["root_filesystem"] or
+        filesystem = get_root_filesystem(args)
-                      "ext4")
 
         if filesystem == "ext4":
             # Some downstream kernels don't support metadata_csum (#1364).