src/lib/libutil/pidfile.c, branch releng/10.0

libutil: Use O_CLOEXEC for internal file descriptors from open().

2013-08-28T21:10:37+00:00

When pidptr was passed as NULL to pidfile_open(3), we were returning

2013-03-14T20:22:52+00:00

EAGAIN/EWOULDBLOCK when another daemon was running and had the pidfile open.
We should return EEXIST in that case, fix it.

Reported by:	Dirk Engling 
Reviewed by:	jhb, Dirk Engling 
MFC after:	1 week

Set the O_CLOEXEC flag when opening the pidfile to avoid leaking the

2012-02-20T13:59:24+00:00

file descriptor via exec(3).

Now that daemon(8) has been fixed to resolve the issue noted by trociny,
the consensus is that this change should be OK.

Using the O_CLOEXEC flag on open(2) caused the pidfile lock to be lost

2012-02-06T14:11:24+00:00

when the child process execs daemon's target program thanks to flock(2)
semantics. So, we apparently have to leak the open pidfile's file
descriptor to keep the lock for the pidfile(3) functions to work properly.

Test case demonstrated by trociny:

ref8-amd64:/home/trociny% uname -r
8.2-STABLE
ref8-amd64:/home/trociny% daemon -p /tmp/sleep.pid sleep 10
ref8-amd64:/home/trociny% daemon -p /tmp/sleep.pid sleep 10
daemon: process already running, pid: 19799

kopusha:~% uname -r
10.0-CURRENT
kopusha:~% daemon -p /tmp/sleep.pid sleep 10
kopusha:~% daemon -p /tmp/sleep.pid sleep 10
kopusha:~%

Move struct pidfh definition into pidfile.c, and leave a forward declaration

2012-01-12T22:49:36+00:00

for pidfh in libutil.h in its place.
This allows us to hide the contents of the pidfh structure, and also
allowed removal of the "#ifdef _SYS_PARAM_H" guard from around the
pidfile_* function prototypes.

Suggested by pjd.

jilles pointed out that O_CLOEXEC could be used in the open(2) flags

2012-01-11T16:35:26+00:00

rather than using fcntl(2) later, and in addition to saving a system
call, removes a possible race with fork/exec from threads or signal
handlers.

Constify arguments.

2012-01-11T00:31:04+00:00

Style fixes courtesy of pjd.

2012-01-10T21:47:58+00:00

Add pidfile_fileno() to obtain the file descriptor for an open

2012-01-10T19:53:25+00:00

pidfile.

Set the FD_CLOEXEC flag on the open pidfile file descriptor.

2012-01-10T18:43:27+00:00

Discussed with: pjd, des