Make xephyr usage resumable.

1 files changed, 26 insertions, 13 deletions

diff --git a/rainbow/rainbow/inject.py b/rainbow/rainbow/inject.py
index f5195e4..7dd1d32 100644
--- a/rainbow/rainbow/inject.py
+++ b/rainbow/rainbow/inject.py
@@ -2,7 +2,7 @@ import os
 from os import R_OK, W_OK, X_OK, fork, symlink, unlink, O_CREAT, O_EXCL, chown, chmod
 from os import setgroups, setgid, setuid, chdir, umask, execvpe, waitpid, WEXITSTATUS
 from os import getpid, getuid, _exit, rename, readlink
-from os.path import join, basename, realpath, lexists
+from os.path import join, basename, realpath, lexists, exists
 from subprocess import check_call, Popen, PIPE
 from stat import S_IFDIR
 from tempfile import mkdtemp, mkstemp
@@ -232,19 +232,32 @@ def configure_xephyr(_, spool, owner_gid, uid, env, safe_fds):
     # XXX: MUST CHECK RETURN VALUES on subprocesses!!!!!
     # XXX: I shouldn't be running these subprocesses as uid 0.
     # XXX: Must get env, fds right!!!!
-    cookie = Popen(["mcookie"], stdout=PIPE).communicate()[0]
-    symlink(cookie, join(spool, 'uid_to_xephyr_cookie', str(uid)))
-    display = reserve_elt(join(spool, 'xephyr_display_pool'), 100, 10000, 2, 'displays')
-    symlink(str(display), join(spool, 'uid_to_xephyr_display', str(uid)))
-
-    fd, name = mkstemp(prefix='tmp', dir=join(spool, 'uid_to_xephyr_auth'))
-    os.close(fd)
-    Popen(["xauth", "-f", name], stdin=PIPE).communicate("add :%d . %s\n" % (display, cookie))
-    auth_path = join(spool, 'uid_to_xephyr_auth', str(uid))
-    rename(name, auth_path)
-    chmod(auth_path, 0640)
-    chown(auth_path, 0, owner_gid)
+    cookie_path = join(spool, 'uid_to_xephyr_cookie', str(uid))
+    if lexists(cookie_path):
+        cookie = readlink(cookie_path)
+    else:
+        cookie = Popen(["mcookie"], stdout=PIPE).communicate()[0]
+        symlink(cookie, join(spool, 'uid_to_xephyr_cookie', str(uid)))
 
+    display_path = join(spool, 'uid_to_xephyr_display', str(uid))
+    if lexists(display_path):
+        display = int(readlink(display_path))
+    else:
+        display = reserve_elt(join(spool, 'xephyr_display_pool'), 100, 10000, 2, 'displays')
+        symlink(str(display), display_path)
+
+    auth_path = join(spool, 'uid_to_xephyr_auth', str(uid))
+    if not exists(auth_path):
+        fd, name = mkstemp(prefix='tmp', dir=join(spool, 'uid_to_xephyr_auth'))
+        os.close(fd)
+        Popen(["xauth", "-f", name], stdin=PIPE).communicate("add :%d . %s\n" % (display, cookie))
+        rename(name, auth_path)
+        chmod(auth_path, 0640)
+        chown(auth_path, 0, owner_gid)
+
+    # NB: Current versions of Xephyr will exit if the display we specified is
+    # already in use. This permits us to run Xephyr unconditionally even when
+    # we're resuming an old uid. <MS>
     Popen(["Xephyr", "-screen", "800x600x24", "-auth", auth_path, "-reset", "-terminate", ":%d" % display])
 
     newenv = {'DISPLAY' : ':%d' % display, 'XAUTHORITY' : auth_path}