1 files changed, 101 insertions, 0 deletions
diff --git a/bin/rainbow-gc b/bin/rainbow-gc
new file mode 100755
index 0000000..82a5cd7
--- /dev/null
+++ b/bin/rainbow-gc
@@ -0,0 +1,101 @@
+#!/usr/bin/env python
+
+import sys
+
+from subprocess import call, check_call, CalledProcessError
+from os import listdir, unlink
+from os.path import join, isdir, islink, exists
+from optparse import OptionParser
+from glob import glob
+
+from rainbow.util import trace, make_reporter
+
+def active_uid(uid):
+    cmd = ['/usr/bin/pgrep', '-U', uid]
+    ret = call(cmd, stdout=open('/dev/null'))
+    if ret in (0, 1):
+        return ret == 0
+    raise CalledProcessError(ret, cmd)
+
+def sticky_uid(spool, uid):
+    return exists(join(spool, "sticky_uids", uid))
+
+def gc_uid(log, spool, uid):
+    """This function conservatively attempts to garbage-collect stale uid
+    reservations.
+    """
+
+    # XXX: D-Bus caches passwd-db data!
+    # XXX: D-Bus uses a fixed 1k passwd buffer - be careful with long paths &
+    #      comments
+
+    reservation = join(spool, 'uid_pool', uid)
+    assert not isdir(reservation) and not islink(reservation)
+
+    # XXX: We perform several execv()'s as root based on strings derived from
+    # this 'uid' parameter, which originates as a file-name in a user-writable
+    # directory. Better ideas for input validation would be welcome.
+    uid_num = int(uid)
+    assert uid_num >= 1000 and uid_num <= 65534  # XXX: magic numbers from util/spool.py
+
+    if active_uid(uid) or sticky_uid(spool, uid):
+        log(1, "skipped uid %s", uid)
+        return
+
+    for table in ('uid_to_instance_dir', 'uid_to_home_dir', 'uid_to_gid', 'uid_to_xephyr_auth', 'uid_to_xephyr_cookie', 'uid_to_xephyr_display'):
+        row = join(spool, table, uid)
+        # NB: it is important that rm -rf doesn't follow links. <MS>
+        cmd = ['/bin/rm', '-r', '-f', row]
+        log(2, "%s", ' '.join(cmd))
+        check_call(cmd)
+
+    for row in glob(join(spool, 'gid_to_members', '*', uid)):
+        # NB: it is important that rm -rf doesn't follow links. <MS>
+        cmd = ['/bin/rm', '-r', '-f', row]
+        log(2, "%s", ' '.join(cmd))
+        check_call(cmd)
+
+    # So long as we unlink the reservation last, we run no risk of seeing inconsistency
+    unlink(reservation)
+    log(1, "cleaned uid %s", uid)
+
+def gc_spool(log, spool):
+    ret = 0
+    uspool = join(spool, 'uid_pool')
+    if exists(uspool) and isdir(uspool):
+        for maybe_uid in listdir(uspool):
+            try: gc_uid(log, spool, maybe_uid)
+            except KeyboardInterrupt:
+                raise
+            except:
+                trace()
+                ret = 1
+    else:
+        log(1, "Skipping spool %s", spool)
+        ret = 1
+    return ret
+
+def main():
+    sys.excepthook = trace
+
+    parser = OptionParser(version='0.1')
+    parser.add_option('-v', '--verbose', default=0, action='count',
+                      help='Verbosity. Repeat for more verbose output.')
+    parser.add_option('-q', '--quiet', default=False, action='store_true',
+                      help='Quiet. Disable all output.')
+    parser.add_option('-s', '--spool', default="/var/spool/rainbow/2",
+                      help='Location of the rainbow spool.')
+
+    opts, _ = parser.parse_args()
+
+    report = make_reporter(opts.verbose, opts.quiet, sys.stdout)
+
+    def check_spool(opts):
+        assert exists(opts.spool) and isdir(opts.spool)
+        return opts.spool
+
+    spool = check_spool(opts)
+    return gc_spool(report, spool)
+
+if __name__ == "__main__":
+    exit(main())