pmbootstrap install: support size_reserve (MR 1946)

Create an empty partition between boot and root. This will be used by
the on-device installer, as explained in detail here:
https://wiki.postmarketos.org/wiki/On-device_installer

pmb/helpers/frontend.py

@@ -137,8 +137,9 @@ def chroot(args):
     if args.install_blockdev:
         size_boot = 128  # 128 MiB
         size_root = 4096  # 4 GiB
+        size_reserve = 2048  # 2 GiB
         pmb.install.blockdevice.create_and_mount_image(args, size_boot,
-                                                       size_root)
+                                                       size_root, size_reserve)
 
     # Run the command as user/root
     if args.user:

pmb/install/_install.py

@@ -366,17 +366,22 @@ def sanity_check_sdcard(device):
             raise RuntimeError("{} is read-only, is the sdcard locked?".format(device))
 
 
-def install_system_image(args):
+def install_system_image(args, size_reserve=0):
+    """
+    :param size_reserve: empty partition between root and boot in MiB (pma#463)
+    """
     # Partition and fill image/sdcard
     logging.info("*** (3/5) PREPARE INSTALL BLOCKDEVICE ***")
     pmb.chroot.shutdown(args, True)
     (size_boot, size_root) = get_subpartitions_size(args)
     if not args.rsync:
-        pmb.install.blockdevice.create(args, size_boot, size_root)
+        pmb.install.blockdevice.create(args, size_boot, size_root,
+                                       size_reserve)
         if not args.split:
-            pmb.install.partition(args, size_boot)
+            pmb.install.partition(args, size_boot, size_reserve)
     if not args.split:
-        pmb.install.partitions_mount(args)
+        root_id = 3 if size_reserve else 2
+        pmb.install.partitions_mount(args, root_id)
 
     if args.full_disk_encryption:
         logging.info("WARNING: Full disk encryption is enabled!")
@@ -386,7 +391,7 @@ def install_system_image(args):
         logging.info("FDE by re-running the install command without '--fde' until")
         logging.info("you have properly configured osk-sdl. More information:")
         logging.info("<https://postmarketos.org/osk-port>")
-    pmb.install.format(args)
+    pmb.install.format(args, size_reserve)
 
     # Just copy all the files
     logging.info("*** (4/5) FILL INSTALL BLOCKDEVICE ***")

pmb/install/blockdevice.py

@@ -54,12 +54,14 @@ def mount_sdcard(args):
             raise RuntimeError("Aborted.")
 
 
-def create_and_mount_image(args, size_boot, size_root, split=False):
+def create_and_mount_image(args, size_boot, size_root, size_reserve,
+                           split=False):
     """
     Create a new image file, and mount it as /dev/install.
 
     :param size_boot: size of the boot partition in MiB
     :param size_root: size of the root partition in MiB
+    :param size_reserve: empty partition between root and boot in MiB (pma#463)
     :param split: create separate images for boot and root partitions
     """
 
@@ -79,7 +81,7 @@ def create_and_mount_image(args, size_boot, size_root, split=False):
             pmb.chroot.root(args, ["rm", img_path])
 
     # Make sure there is enough free space
-    size_mb = round(size_boot + size_root)
+    size_mb = round(size_boot + size_reserve + size_root)
     disk_data = os.statvfs(args.work)
     free = round((disk_data.f_bsize * disk_data.f_bavail) / (1024**2))
     if size_mb > free:
@@ -113,16 +115,18 @@ def create_and_mount_image(args, size_boot, size_root, split=False):
                                     args.work + "/chroot_native" + mount_point)
 
 
-def create(args, size_boot, size_root):
+def create(args, size_boot, size_root, size_reserve):
     """
     Create /dev/install (the "install blockdevice").
 
     :param size_boot: size of the boot partition in MiB
     :param size_root: size of the root partition in MiB
+    :param size_reserve: empty partition between root and boot in MiB (pma#463)
     """
     pmb.helpers.mount.umount_all(
         args, args.work + "/chroot_native/dev/install")
     if args.sdcard:
         mount_sdcard(args)
     else:
-        create_and_mount_image(args, size_boot, size_root, args.split)
+        create_and_mount_image(args, size_boot, size_root, size_reserve,
+                               args.split)

pmb/install/format.py

@@ -23,9 +23,11 @@ def format_and_mount_boot(args):
     pmb.chroot.root(args, ["mount", device, mountpoint])
 
 
-def format_and_mount_root(args):
+def format_and_mount_root(args, device):
+    """
+    :param device: root partition on install block device (e.g. /dev/installp2)
+    """
     mountpoint = "/dev/mapper/pm_crypt"
-    device = "/dev/installp2"
     if args.full_disk_encryption:
         logging.info("(native) format " + device + " (root, luks), mount to " +
                      mountpoint)
@@ -41,12 +43,13 @@ def format_and_mount_root(args):
             raise RuntimeError("Failed to open cryptdevice!")
 
 
-def format_and_mount_pm_crypt(args):
+def format_and_mount_pm_crypt(args, device):
+    """
+    :param device: root partition on install block device (e.g. /dev/installp2)
+    """
     # Block device
     if args.full_disk_encryption:
         device = "/dev/mapper/pm_crypt"
-    else:
-        device = "/dev/installp2"
 
     # Format
     if not args.rsync:
@@ -72,7 +75,11 @@ def format_and_mount_pm_crypt(args):
     pmb.chroot.root(args, ["mount", device, mountpoint])
 
 
-def format(args):
+def format(args, size_reserve):
-    format_and_mount_root(args)
+    """
-    format_and_mount_pm_crypt(args)
+    :param size_reserve: empty partition between root and boot in MiB (pma#463)
+    """
+    root_dev = "/dev/installp3" if size_reserve else "/dev/installp2"
+    format_and_mount_root(args, root_dev)
+    format_and_mount_pm_crypt(args, root_dev)
     format_and_mount_boot(args)

pmb/install/partition.py

@@ -8,9 +8,10 @@ import pmb.config
 import pmb.install.losetup
 
 
-def partitions_mount(args):
+def partitions_mount(args, root_id):
     """
     Mount blockdevices of partitions inside native chroot
+    :param root_id: root partition id
     """
     prefix = args.sdcard
     if not args.sdcard:
@@ -35,22 +36,28 @@ def partitions_mount(args):
                            prefix + " to be located at " + prefix +
                            "1 or " + prefix + "p1!")
 
-    for i in [1, 2]:
+    for i in [1, root_id]:
         source = prefix + partition_prefix + str(i)
         target = args.work + "/chroot_native/dev/installp" + str(i)
         pmb.helpers.mount.bind_file(args, source, target)
 
 
-def partition(args, size_boot):
+def partition(args, size_boot, size_reserve):
     """
-    Partition /dev/install and create /dev/install{p1,p2}
+    Partition /dev/install and create /dev/install{p1,p2,p3}:
+    * /dev/installp1: boot
+    * /dev/installp2: root (or reserved space)
+    * /dev/installp3: (root, if reserved space > 0)
 
     :param size_boot: size of the boot partition in MiB
+    :param size_reserve: empty partition between root and boot in MiB (pma#463)
     """
     # Convert to MB and print info
-    mb_boot = str(round(size_boot)) + "M"
+    mb_boot = f"{round(size_boot)}M"
-    logging.info("(native) partition /dev/install (boot: " + mb_boot +
+    mb_reserved = f"{round(size_reserve)}M"
-                 ", root: the rest)")
+    mb_root_start = f"{round(size_boot) + round(size_reserve)}M"
+    logging.info(f"(native) partition /dev/install (boot: {mb_boot},"
+                 f" reserved: {mb_reserved}, root: the rest)")
 
     filesystem = args.deviceinfo["boot_filesystem"] or "ext2"
 
@@ -63,9 +70,16 @@ def partition(args, size_boot):
     commands = [
         ["mktable", "msdos"],
         ["mkpart", "primary", filesystem, boot_part_start + 's', mb_boot],
-        ["mkpart", "primary", mb_boot, "100%"],
+    ]
+
+    if size_reserve:
+        commands += [["mkpart", "primary", mb_boot, mb_reserved]]
+
+    commands += [
+        ["mkpart", "primary", mb_root_start, "100%"],
         ["set", "1", "boot", "on"]
     ]
+
     for command in commands:
         pmb.chroot.root(args, ["parted", "-s", "/dev/install"] +
                         command, check=False)