import json
import os
import re
import select
import subprocess
import sys
class Watcher:
def __init__(self, path):
self.inotify = Inotify()
self.path = path
self.setup()
def setup(self):
self.wd = self.inotify.add_watch(self.path, IN_CLOSE_WRITE)
def process(self, callback=None):
def event(_wd, mask, name):
if callback:
callback()
if mask & IN_IGNORED:
self.setup()
self.inotify.process(event)
def field_escape(field):
return field.replace("\\", r"\134").replace(" ", r"\040").replace("\t", r"\011")
def field_unescape(field):
return re.sub(r"\\([0-7]{1,3})", lambda m: chr(int(m.group(1), 8)), field)
def parse_tab(name):
entries = []
with open(name, "r") as f:
for line in f:
sline = line.strip()
if sline == "" or sline[0] == "#":
continue
fields = list(map(field_unescape, re.split(r"[ \t]+", sline)))
if len(fields) > 2 and ":" in fields[0] and fields[2].startswith("nfs"):
entries.append(fields)
return entries
def index_tab(tab):
by_remote = {}
for t in tab:
if t[0] not in by_remote:
by_remote[t[0]] = []
by_remote[t[0]].append(t)
return by_remote
def modify_tab(name, modify):
with open(name) as f:
lines = f.read().splitlines()
new_lines = []
for line in lines:
sline = line.strip()
if sline == "" or sline[0] == "#":
new_lines.append(line)
else:
fields = list(map(field_unescape, re.split(r"[ \t]+", sline)))
if len(fields) > 0 and ":" in fields[0]:
new_fields = modify(fields)
if new_fields:
if new_fields == fields:
new_lines.append(line)
else:
new_lines.append(" ".join(map(field_escape, new_fields)))
else:
new_lines.append(line)
new_fields = modify(None)
if new_fields:
new_lines.append(" ".join(map(field_escape, new_fields)))
with open(name + ".tmp", "w") as f:
f.write("\n".join(new_lines) + "\n")
f.flush()
os.fsync(f.fileno())
os.rename(name + ".tmp", name)
fstab = []
fstab_by_remote = {}
mtab = []
mtab_by_remote = {}
def process_fstab():
global fstab, fstab_by_remote
fstab = parse_tab("/etc/fstab")
fstab_by_remote = index_tab(fstab)
def process_mtab():
global mtab, mtab_by_remote
mtab = parse_tab("/proc/self/mounts")
mtab_by_remote = index_tab(mtab)
def find_in_tab(tab_by_remote, fields):
for t in tab_by_remote.get(fields[0], []):
if t[0] == fields[0] and t[1] == fields[1]:
return t
return None
def report():
data = []
for f in fstab:
m = find_in_tab(mtab_by_remote, f)
data.append({"fstab": True, "fields": f, "mounted": m is not None})
for m in mtab:
if not find_in_tab(fstab_by_remote, m):
data.append({"fstab": False, "fields": m, "mounted": True})
sys.stdout.write(json.dumps(data) + "\n")
sys.stdout.flush()
def monitor():
process_mtab()
process_fstab()
report()
fstab_watcher = Watcher("/etc/fstab")
with open("/proc/self/mounts", "r") as mtab_file:
while True:
r, _w, x = select.select([fstab_watcher.inotify.fd], [], [mtab_file])
if mtab_file in x:
process_mtab()
report()
if fstab_watcher.inotify.fd in r:
fstab_watcher.process()
process_fstab()
report()
def mkdir_if_necessary(path):
if not os.path.exists(path):
os.makedirs(path)
def rmdir_maybe(path):
try:
os.rmdir(path)
except OSError:
pass
def update(entry, new_fields):
old_fields = entry["fields"]
if old_fields[1] != new_fields[1]:
mkdir_if_necessary(new_fields[1])
if entry["mounted"]:
if (new_fields[0] == old_fields[0] and
new_fields[1] == old_fields[1] and
new_fields[2] == old_fields[2]):
remount(new_fields)
else:
try:
unmount(entry)
if old_fields[1] != new_fields[1]:
rmdir_maybe(old_fields[1])
except subprocess.CalledProcessError:
pass
mount({"fields": new_fields})
else:
if old_fields[1] != new_fields[1]:
rmdir_maybe(old_fields[1])
modify_tab("/etc/fstab", lambda fields: new_fields if fields == old_fields else fields)
def add(new_fields):
mkdir_if_necessary(new_fields[1])
mount({"fields": new_fields})
modify_tab("/etc/fstab", lambda fields: new_fields if fields is None else fields)
def remove(entry):
old_fields = entry["fields"]
if entry["mounted"]:
unmount(entry)
rmdir_maybe(old_fields[1])
modify_tab("/etc/fstab", lambda fields: None if fields == old_fields else fields)
def mount(entry):
fields = entry["fields"]
mkdir_if_necessary(fields[1])
subprocess.check_call(["mount",
"-t", fields[2],
"-o", fields[3],
fields[0],
fields[1]])
def remount(fields):
subprocess.check_call(["mount",
"-o", "remount," + fields[3],
fields[0],
fields[1]])
def unmount(entry):
subprocess.check_call(["umount", entry["fields"][1]])
def dispatch(argv):
if argv[1] == "monitor":
monitor()
elif argv[1] == "update":
update(json.loads(argv[2]), json.loads(argv[3]))
elif argv[1] == "add":
add(json.loads(argv[2]))
elif argv[1] == "remove":
remove(json.loads(argv[2]))
elif argv[1] == "mount":
mount(json.loads(argv[2]))
elif argv[1] == "unmount":
unmount(json.loads(argv[2]))
try:
dispatch(sys.argv)
except subprocess.CalledProcessError as e:
sys.exit(e.returncode)
except Exception as e:
sys.stderr.write(str(e) + "\n")
sys.exit(1)
