stages/coreos.live-artifacts: add erofs support

stages/org.osbuild.coreos.live-artifacts.mono

@@ -83,13 +83,14 @@ def mkinitrd_pipe(tmproot, destf, compress=True):
     files = subprocess.check_output(['find', '.', '-mindepth', '1', '-print0'],
                                     cwd=tmproot)
     file_list = files.split(b'\0')
-    # If there's a root.squashfs, it _must_ be the first file in the cpio
+    # If there's a root.[squash|ero]fs, it _must_ be the first file in the cpio
     # archive, since the dracut 20live module assumes its contents are at
     # a fixed offset in the archive.
-    squashfs = b'./root.squashfs'
-    if squashfs in file_list:
-        file_list.remove(squashfs)
-        file_list.insert(0, squashfs)
+    for filename in [b'./root.squashfs', b'./root.erofs']:
+        if filename in file_list:
+            file_list.remove(filename)
+            file_list.insert(0, filename)
+            break
     cpioproc = subprocess.Popen(['cpio', '-o', '-H', 'newc', '-R', 'root:root',
                                  '--quiet', '--reproducible', '--force-local', '--null',
                                  '-D', tmproot], stdin=subprocess.PIPE, stdout=subprocess.PIPE)
@@ -544,14 +545,13 @@ boot
     return "images/efiboot.img"
 
 
-def mksquashfs_metal(paths, workdir, img_metal, loop_client):
+def mkrootfs_metal(paths, workdir, img_metal, fstype, fsoptions, loop_client):
     """
-    Mounts a copy of the metal image and modifies it accordingly to create a (squashfs) rootfs from its contents for the
-    live ISO.
+    Mounts a copy of the metal image and modifies it accordingly to create a (fstype) rootfs from its contents for the
+    live ISO. fstype must be squashfs or erofs.
 
     Returns the bls entry kernel arguments for the ISO bootloader.
     """
-    squashfs_compression = 'zstd'
     basearch = os.uname().machine
     tmp_squashfs_dir = os.path.join(workdir, 'tmp-squashfs-dir')
     os.mkdir(tmp_squashfs_dir)
@@ -601,17 +601,23 @@ def mksquashfs_metal(paths, workdir, img_metal, loop_client):
             print(f"Kernel binary linked: {tmp_squashfs_dir}/boot/{kernel_binary_basename}")
             print(f"Kernel HMAC linked: {tmp_squashfs_dir}/boot/{kernel_hmac_basename}")
             # Generate root squashfs
-            print(f'Compressing squashfs with {squashfs_compression}')
+            print(f'Creating {fstype} with {fsoptions}')
 
             # Note the filename must be exactly "root.squashfs" because the 20live
             # dracut module makes assumptions about the length of the name in sysroot.mount
             # this matches the set of flags we implicitly passed when doing this
             # through libguestfs' mksquashfs command
-            subprocess.check_call(['mksquashfs', tmp_squashfs_dir,
-                                   paths["initrd-rootfs/root.squashfs"],
-                                   '-root-becomes', tmp_squashfs_dir,
-                                   '-wildcards', '-no-recovery',
-                                   '-comp', squashfs_compression])
+            if fstype == "erofs":
+                subprocess.check_call(['mkfs.erofs',
+                                       *fsoptions.split(' '),
+                                       paths["initrd-rootfs/root.erofs"],
+                                       tmp_squashfs_dir])
+            else:
+                subprocess.check_call(['mksquashfs', tmp_squashfs_dir,
+                                       paths["initrd-rootfs/root.squashfs"],
+                                       '-root-becomes', tmp_squashfs_dir,
+                                       '-wildcards', '-no-recovery',
+                                       *fsoptions.split(' ')])
 
             # while it's mounted here, also get the kargs
             blsentry = ensure_glob(os.path.join(tmp_squashfs_dir, 'boot/loader/entries/*.conf'), n=1)[0]
@@ -776,7 +782,7 @@ def mk_osmet_files(deployed_tree, img_metal, img_metal4k, loop_client, paths, os
                 chroot.run(cmd, check=True)
 
 
-def mk_paths(workdir):
+def mk_paths(workdir, fstype):
     """
     Returns a dictionary with all the paths under workdir needed throughout multiple functions in the stage.
     """
@@ -808,7 +814,7 @@ def mk_paths(workdir):
         "initrd/etc/coreos-live-want-rootfs": "",
         "initrd/etc/coreos-live-initramfs": "",
         "initrd-rootfs": "",
-        "initrd-rootfs/root.squashfs": "",
+        f"initrd-rootfs/root.{fstype}": ""
     }
     for key in paths:
         paths[key] = os.path.join(workdir, key)
@@ -864,7 +870,9 @@ def main(workdir, tree, inputs, options, loop_client):
     os_release = osrelease.parse_files(os.path.join(deployed_tree, 'etc', 'os-release'))
     version = os_release['OSTREE_VERSION']
 
-    paths = mk_paths(workdir)
+    fstype = options.get("live_rootfs_fstype", "squashfs")
+    fsoptions = options.get("live_rootfs_fsoptions", "-comp zstd")
+    paths = mk_paths(workdir, fstype)
     mk_workdirs(paths)
 
     # Find the directory under `/usr/lib/modules/<kver>` where the
@@ -905,7 +913,7 @@ def main(workdir, tree, inputs, options, loop_client):
 
     mk_osmet_files(deployed_tree, img_metal, img_metal4k, loop_client, paths, os_release)
 
-    blsentry_kargs = mksquashfs_metal(paths, workdir, img_metal, loop_client)
+    blsentry_kargs = mkrootfs_metal(paths, workdir, img_metal, fstype, fsoptions, loop_client)
 
     # Generate rootfs image
     # The rootfs must be uncompressed because the ISO mounts root.squashfs
@@ -914,10 +922,18 @@ def main(workdir, tree, inputs, options, loop_client):
                      tree=paths["initrd-rootfs"], compress=False)
     # Check that the root.squashfs magic number is in the offset hardcoded
     # in sysroot.mount in 20live/live-generator
+    offset = 124
+    magic = b'hsqs'
+    if fstype == "erofs":
+        # The erofs's superblock starts at an absolute offset 1024 bytes
+        offset += 1024
+        magic = bytes.fromhex("e2e1f5e0")
+
     with open(paths["iso/images/pxeboot/rootfs.img"], 'rb') as fh:
-        fh.seek(124)
-        if fh.read(4) != b'hsqs':
+        fh.seek(offset)
+        if fh.read(4) != magic:
             raise ValueError("root.squashfs not at expected offset in rootfs image")
+
     # Save stream hash of rootfs for verifying out-of-band fetches
     os.makedirs(os.path.dirname(paths["initrd/etc/coreos-live-want-rootfs"]), exist_ok=True)
     make_stream_hash(paths["iso/images/pxeboot/rootfs.img"],

stages/org.osbuild.coreos.live-artifacts.mono.meta.json

@@ -38,6 +38,20 @@
         "filenames"
       ],
       "properties": {
+        "live_rootfs_fstype": {
+          "descripton": "Filesystem of live-rootfs.img",
+          "type": "string",
+          "enum": [
+            "erofs",
+            "squashfs"
+          ],
+          "default": "squashfs"
+        },
+        "live_rootfs_fsoptions": {
+          "descripton": "Parameters for generating live-rootfs.img",
+          "type": "string",
+          "default": "-comp zstd"
+        },
         "filenames": {
           "type": "object",
           "additionalProperties": false,