From e454e5ac9c8ed77409d9fa4463b2b29985e67e10 Mon Sep 17 00:00:00 2001 From: Martin Schwenke Date: Mon, 30 Jun 2014 17:22:14 +1000 Subject: [PATCH] ctdb-daemon: Check PID in ctdb_remove_pidfile(), not unreliable flag If something unexpectedly uses fork() then an exiting child will remove the PID file while the main daemon is still running. The real test is whether the current process has the PID of the main CTDB daemon, which is the process that calls setsid(). This could be done using getpgrp() instead. At the moment the eventscript handler harmlessly calls setpgid() - harmless because the atexit() handlers are cleared upon exec(). However, it is possible that process groups will be used more in future so it is probably better to rely on the session ID. Thanks to Sumit Bose for the idea. Signed-off-by: Martin Schwenke Reviewed-by: Amitay Isaacs --- ctdb/common/ctdb_fork.c | 8 -------- ctdb/server/ctdb_daemon.c | 3 ++- 2 files changed, 2 insertions(+), 9 deletions(-) diff --git a/ctdb/common/ctdb_fork.c b/ctdb/common/ctdb_fork.c index aa9bcf01bc4..d7eef76c78d 100644 --- a/ctdb/common/ctdb_fork.c +++ b/ctdb/common/ctdb_fork.c @@ -23,11 +23,8 @@ #include "../include/ctdb_private.h" #include "../common/rb_tree.h" -static bool is_child = false; - void ctdb_set_child_info(TALLOC_CTX *mem_ctx, const char *child_name_fmt, ...) { - is_child = true; if (child_name_fmt != NULL) { va_list ap; char *t; @@ -40,11 +37,6 @@ void ctdb_set_child_info(TALLOC_CTX *mem_ctx, const char *child_name_fmt, ...) } } -bool ctdb_is_child_process(void) -{ - return is_child; -} - void ctdb_track_child(struct ctdb_context *ctdb, pid_t pid) { char *process; diff --git a/ctdb/server/ctdb_daemon.c b/ctdb/server/ctdb_daemon.c index eb42e18886c..448e7dcc98e 100644 --- a/ctdb/server/ctdb_daemon.c +++ b/ctdb/server/ctdb_daemon.c @@ -1109,7 +1109,8 @@ static void ctdb_tevent_trace(enum tevent_trace_point tp, static void ctdb_remove_pidfile(void) { - if (ctdbd_pidfile != NULL && !ctdb_is_child_process()) { + /* Only the main ctdbd's PID matches the SID */ + if (ctdbd_pidfile != NULL && getsid(0) == getpid()) { if (unlink(ctdbd_pidfile) == 0) { DEBUG(DEBUG_NOTICE, ("Removed PID file %s\n", ctdbd_pidfile)); -- 2.11.4.GIT