Add resume_swapfile to handle resuming from swapfile not a swappartition

src/ugrd/fs/resume.toml

@@ -1,6 +1,6 @@
 cmdline_strings = [ "resume" ]
 
-[imports.init_main] 
+[imports.init_main]
 "ugrd.fs.resume" = [ "handle_resume" ]
 
 [import_order.before]

src/ugrd/fs/resume_swapfile.py

@@ -0,0 +1,44 @@
+__version__ = "0.4.2"
+
+
+def handle_resume_swapfile(self) -> None:
+    """Returns a shell script handling resume from hibernation with a swapfile.
+    Checks that /sys/power/resume is writable, resume_offset= is sane, resume= is set, and noresume is not set,
+    if so, checks if UUID= or PARTUUID= or LABEL= is in the resume var,
+    and tries to use blkid to find the resume device.
+    If the specified device exists, writes resume device to /sys/power/resume.
+    In the event of failure, it prints an error message, a list of block devuices, then runs rd_fail.
+
+
+    Resuming or failing to do so is potentially dangerous.
+    If the system was hibernated, and fails to resume, it will be in an inconsistent state.
+    If the system is freshly booted, it will not be able to resume, as there is no hibernation image.
+    Distinguising between a fresh boot and missing/borked hibernation image is not possible at run time.
+    """
+    return [
+        "resumeval=$(readvar resume)",  # read the cmdline resume var
+        "offset=$(readvar resume_offset)",
+        'if ! check_var noresume && [ -n "$resumeval" ] && [ -w /sys/power/resume ]; then',
+        '    if echo "$resumeval" | grep -q "UUID="     ||',      #    resolve uuid to device
+        '       echo "$resumeval" | grep -q "PARTUUID=" ||',      # or resolve partuuid to device
+        '       echo "$resumeval" | grep -q "LABEL="    ; then',  # or resolve label to device
+        '        resume=$(blkid -t "$resumeval" -o device)',
+        "    else",
+        "        resume=$resumeval",
+        "    fi",
+        '    if [ ! -n "$offset" ] || [ "$offset" -le 0 ]; then', # check for sane offset value, i.e. not empty and greater than 0
+        '        ewarn "resume_offset not set, resume from swapfile likely to fail"',
+        "    fi",
+        '    if [ -e "$resume" ]; then',  # Check if the resume device exists
+        '        einfo "Resuming from: $resume position $offset"',
+        '        printf "%s" "$resume" > /sys/power/resume',  # Attempt to resume
+        '        ewarn "Failed to resume from: $resume position $offset"',
+        "    else",
+        '        ewarn "Resume device not found: $resume)"',  # Warn if the resume device does not exist
+        r'        eerror "Block devices:\n$(blkid)"',
+        '        eerror "If you wish to continue booting, remove the resume= kernel parameter."',
+        '''        eerror " or run 'setvar noresume 1' from the recovery shell (set ugrd_recovery) to skip resuming."''',
+        '        rd_fail "Failed to resume from $(readvar resume)."',
+        "    fi",
+        "fi",
+    ]

src/ugrd/fs/resume_swapfile.toml

@@ -0,0 +1,10 @@
+cmdline_strings = [ "resume" ]
+
+[imports.init_main]
+"ugrd.fs.resume_swapfile" = [ "handle_resume_swapfile" ]
+
+[import_order.after]
+handle_resume_swapfile = [ "crypt_init", "init_lvm" ]
+
+[import_order.before]
+handle_resume_swapfile = [ "mount_root", "mount_fstab", "btrfs_scan", "md_init" ]