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ctdb-daemon: Check PID in ctdb_remove_pidfile(), not unreliable flag

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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 <sbose@redhat.com> for the idea.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
This commit is contained in:
Martin Schwenke 2014-06-30 17:22:14 +10:00 committed by Amitay Isaacs
parent c7b3be97d9
commit e454e5ac9c
2 changed files with 2 additions and 9 deletions
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8
ctdb/common/ctdb_fork.c
View File

@ -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;

3
ctdb/server/ctdb_daemon.c
View File

@ -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));