refactor packages.py, register qemu-binfmt manually

binfmt.py

@@ -0,0 +1,77 @@
+# modifed from pmbootstrap's binfmt.py, Copyright 2018 Oliver Smith, GPL-licensed
+
+import os
+import logging
+import subprocess
+
+from utils import mount
+
+
+def binfmt_info():
+    # Parse the info file
+    full = {}
+    info = "/usr/lib/binfmt.d/qemu-static.conf"
+    logging.debug("parsing: " + info)
+    with open(info, "r") as handle:
+        for line in handle:
+            if line.startswith('#') or ":" not in line:
+                continue
+            splitted = line.split(":")
+            result = {
+                # _ = splitted[0] # empty
+                'name': splitted[1],
+                'type': splitted[2],
+                'offset': splitted[3],
+                'magic': splitted[4],
+                'mask': splitted[5],
+                'interpreter': splitted[6],
+                'flags': splitted[7],
+                'line': line,
+            }
+            if not result['name'].startswith('qemu-'):
+                logging.fatal(f'Unknown binfmt handler "{result["name"]}"')
+                logging.debug(f'binfmt line: {line}')
+                continue
+            arch = ''.join(result['name'].split('-')[1:])
+            full[arch] = result
+
+    return full
+
+
+def is_registered(arch: str) -> bool:
+    return os.path.exists("/proc/sys/fs/binfmt_misc/qemu-" + arch)
+
+
+def register(arch):
+    if is_registered(arch):
+        return
+
+    lines = binfmt_info()
+
+    # Build registration string
+    # https://en.wikipedia.org/wiki/Binfmt_misc
+    # :name:type:offset:magic:mask:interpreter:flags
+    info = lines[arch]
+    code = info['line']
+    binfmt = '/proc/sys/fs/binfmt_misc'
+    register = binfmt + '/register'
+    if not os.path.exists(register):
+        logging.info('mounting binfmt_misc')
+        result = mount('binfmt_misc', binfmt, options=[], fs_type='binfmt_misc')
+        if result.returncode != 0:
+            raise Exception(f'Failed mounting binfmt_misc to {binfmt}')
+
+    # Register in binfmt_misc
+    logging.info(f"Registering qemu binfmt ({arch})")
+    subprocess.run(["sh", "-c", 'echo "' + code + '" > ' + register + ' 2>/dev/null'])
+    if not is_registered(arch):
+        logging.debug(f'binfmt line: {code}')
+        raise Exception(f'Failed to register qemu-user for {arch} with binfmt_misc, {binfmt}/{info["name"]} not found')
+
+
+def unregister(args, arch):
+    binfmt_file = "/proc/sys/fs/binfmt_misc/qemu-" + arch
+    if not os.path.exists(binfmt_file):
+        return
+    logging.info(f"Unregistering qemu binfmt ({arch})")
+    subprocess.run(["sh", "-c", "echo -1 > " + binfmt_file])