diff options
| author | Paulo Alcantara <paulo@paulo.ac> | 2018-08-17 11:30:16 -0300 |
|---|---|---|
| committer | Stefan Metzmacher <metze@samba.org> | 2018-09-05 13:31:39 +0200 |
| commit | b53eb6f62f83126c28fc8b7d55831f74a589a158 (patch) | |
| tree | a0864f63c19ad2346ba84080b417535116a6c90f /lib | |
| parent | 1b01025bf8c86dd67f36994733f0866eecffb3e1 (diff) | |
| download | samba-b53eb6f62f83126c28fc8b7d55831f74a589a158.tar.gz | |
s3: util: Do not take over stderr when there is no log file
In case we don't have either a /var/log/samba directory, or pass a
non-existent log directory through '-l' option, all commands that are
daemonized with '-D' option hang when executed within a subshell.
An example on how to trigger that:
# rm -r /var/log/samba
# s=$(nmbd -D -s /etc/samba/smb.conf -l /foo123)
(never returns)
So, when the above command is executed within a subshell the following
happens:
(a) Parent shell creates a pipe, sets write side of it to fd 1
(stdout), call read() on read-side fd, forks off a new child process
and then executes nmbd in it.
(b) nmbd sets up initial logging to go through fd 1 (stdout) by
calling setup_logging(..., DEBUG_DEFAULT_STDOUT). 'state.fd' is now
set to 1.
(c) reopen_logs() is called by the first time which then calls
reopen_logs_internal()
(d) in reopen_logs_internal(), it attempts to create log.nmbd file in
/foo123 directory and fails because directory doesn't exist.
(e) Regardless whether the log file was created or not, it calls
dup2(state.fd, 2) which dups fd 1 into fd 2.
(f) At some point, fd 0 and 1 are closed and set to /dev/null
The problem with that is because parent shell in (a) is still blocked in
read() call and the new write side of the pipe is now fd 2 -- after
dup2() in (e) -- and remains unclosed.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=13578
Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Reviewed-by: Jim McDonough <jmcd@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Sat Aug 18 01:32:25 CEST 2018 on sn-devel-144
(cherry picked from commit 41aa55f49233ea7682cf14e5a7062617274434ce)
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/util/debug.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/lib/util/debug.c b/lib/util/debug.c index b58303e8c82..022e37b36c7 100644 --- a/lib/util/debug.c +++ b/lib/util/debug.c @@ -1069,8 +1069,11 @@ bool reopen_logs_internal(void) force_check_log_size(); (void)umask(oldumask); - /* Take over stderr to catch output into logs */ - if (state.fd > 0) { + /* + * If log file was opened or created successfully, take over stderr to + * catch output into logs. + */ + if (new_fd != -1) { if (dup2(state.fd, 2) == -1) { /* Close stderr too, if dup2 can't point it - at the logfile. There really isn't much |