Merge pull request #83 from desultory/resume

Add proper resume support

Author: desultory

src/ugrd/fs/resume.py

@@ -1,31 +1,37 @@
-__version__ = "0.3.1"
+__version__ = "0.4.0"
 
 
 def handle_resume(self) -> None:
     """Returns a bash script handling resume from hibernation.
     Checks that /sys/power/resume is writable, resume= is set, and noresume is not set, if so,
-    it checks ifthe specified device exists, then echo's the resume device to /sys/power/resume.
-    In the event of failure, it prints an error message and a list of block devices.
+    checks if PARTUUID= 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.
     """
-    out_str = [
-        'if ! check_var noresume && [ -n "$(readvar resume)" ] && [ -w /sys/power/resume ]; then',
-        '    if [ -e "$(readvar resume)" ]; then',
-        '        einfo "Resuming from: $(readvar resume)"',
-        "        readvar resume > /sys/power/resume",
-        '        eerror "Failed to resume from $(readvar resume)"',
-        '        eerror "Resume device not found: $(readvar resume)"',
+    return [
+        "resumeval=$(readvar resume)",  # read the cmdline resume var
+        'if ! check_var noresume && [ -n "$resumeval" ] && [ -w /sys/power/resume ]; then',
+        '    if echo "$resumeval" | grep -q "PARTUUID="; then',  # resolve partuuid to device
+        '        resume=$(blkid -t "$resumeval" -o device)',
+        "    else",
+        "        resume=$resumeval",
+        "    fi",
+        '    if [ -e "$resume" ]; then',  # Check if the resume device exists
+        '        einfo "Resuming from: $resume"',
+        '        echo -n "$resume" > /sys/power/resume',  # Attempt to resume
+        '        ewarn "Failed to resume from: $resume"',
+        "    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 to skip resuming."''',
+        '        rd_fail "Failed to resume from $(readvar resume)."',
         "    fi",
-        r'    eerror "Block devices:\n$(blkid)"',
+        "fi",
     ]
-    if self["safe_resume"]:
-        out_str += [
-            '    eerror "If you wish to continue booting, remove the resume= kernel parameter."',
-            '''    eerror " or run 'setvar noresume 1' to skip resuming."''',
-            '    rd_fail "Failed to resume from $(readvar resume)."',
-        ]
-    else:
-        out_str += ['   eerror "Failed to resume from $(readvar resume)"']
-
-    out_str += ["fi"]
-
-    return out_str

src/ugrd/fs/resume.toml

@@ -2,6 +2,3 @@ cmdline_strings = [ "resume" ]
 
 [imports.init_early] 
 "ugrd.fs.resume" = [ "handle_resume" ]
-
-[custom_parameters]
-safe_resume = "bool"  # Fail if resume is not possible