database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-13 07:41:39 +03:00
Code Activity

Treat EPERM as a non-error case when checking to see if old postmaster

Browse Source 
is still alive.  This improves our odds of not getting fooled by an
unrelated process when checking a stale lock file.  Other checks already
in place, plus one newly added in checkDataDir(), ensure that we cannot
attempt to usurp the place of a postmaster belonging to a different userid,
so there is no need to error out.  Add comments indicating the importance
of these other checks.
This commit is contained in:
Tom Lane
2005-03-18 03:48:49 +00:00
parent d344505d1b
commit 7a969cad2e
2 changed files with 46 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
src/backend/utils/init/miscinit.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/init/miscinit.c,v 1.137 2004/12/31 22:01:40 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/utils/init/miscinit.c,v 1.138 2005/03/18 03:48:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -505,6 +505,9 @@ CreateLockFile(const char *filename, bool amPostmaster,
{
/*
* Try to create the lock file --- O_EXCL makes this atomic.
*
* Think not to make the file protection weaker than 0600. See
* comments below.
*/
fd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
if (fd >= 0)
@ -564,6 +567,21 @@ CreateLockFile(const char *filename, bool amPostmaster,
* then all but the immediate parent shell will be root-owned processes
* and so the kill test will fail with EPERM.
*
* We can treat the EPERM-error case as okay because that error implies
* that the existing process has a different userid than we do, which
* means it cannot be a competing postmaster. A postmaster cannot
* successfully attach to a data directory owned by a userid other
* than its own. (This is now checked directly in checkDataDir(),
* but has been true for a long time because of the restriction that
* the data directory isn't group- or world-accessible.) Also,
* since we create the lockfiles mode 600, we'd have failed above
* if the lockfile belonged to another userid --- which means that
* whatever process kill() is reporting about isn't the one that
* made the lockfile. (NOTE: this last consideration is the only
* one that keeps us from blowing away a Unix socket file belonging
* to an instance of Postgres being run by someone else, at least
* on machines where /tmp hasn't got a stickybit.)
*
* Windows hasn't got getppid(), but doesn't need it since it's not
* using real kill() either...
*
@ -577,11 +595,11 @@ CreateLockFile(const char *filename, bool amPostmaster,
)
{
if (kill(other_pid, 0) == 0 ||
(errno != ESRCH
(errno != ESRCH &&
#ifdef __BEOS__
&& errno != EINVAL
errno != EINVAL &&
#endif
))
errno != EPERM))
{
/* lockfile belongs to a live process */
ereport(FATAL,