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daemon: add supervision_enabled var

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explicitly name a bunch of boolean checks that enable
supervison mode and improve comments

Reviewed by:	kevans
Pull Request:	https://github.com/freebsd/freebsd-src/pull/669
This commit is contained in:
Ihor Antonov 2023-03-01 21:00:42 -06:00 committed by Kyle Evans
parent 259ed21d21
commit 203df05b69
1 changed files with 25 additions and 10 deletions
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35
usr.sbin/daemon/daemon.c
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@ -47,6 +47,7 @@ __FBSDID("$FreeBSD$");
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
@ -141,6 +142,7 @@ usage(int exitcode)
int
main(int argc, char *argv[])
{
bool supervision_enabled = false;
char *p = NULL;
const char *pidfile = NULL;
const char *logtag = "daemon";
@ -275,18 +277,31 @@ main(int argc, char *argv[])
}
/* Write out parent pidfile if needed. */
pidfile_write(ppfh);
/*
* If the pidfile or restart option is specified the daemon
* executes the command in a forked process and wait on child
* exit to remove the pidfile or restart the command. Normally
* we don't want the monitoring daemon to be terminated
* leaving the running process and the stale pidfile, so we
* catch SIGTERM and forward it to the children expecting to
* get SIGCHLD eventually. We also must fork() to obtain a
* readable pipe with the child for writing to a log file
* and syslog.
* Supervision mode is enabled if one of the following options are used:
* --child-pidfile -p
* --supervisor-pidfile -P
* --restart -r / --restart-delay -R
* --syslog -S
* --syslog-facility -l
* --syslog-priority -s
* --syslog-tag -T
*
* In supervision mode daemon executes the command in a forked process
* and observes the child by waiting for SIGCHILD. In supervision mode
* daemon must never exit before the child, this is necessary to prevent
* orphaning the child and leaving a stale pid file.
* To achieve this daemon catches SIGTERM and
* forwards it to the child, expecting to get SIGCHLD eventually.
*/
if (pidfile || ppidfile || restart || outfd != -1 || dosyslog) {
supervision_enabled = pidfile != NULL ||
ppidfile != NULL ||
restart != 0 ||
outfd != -1 ||
dosyslog != 0;
if (supervision_enabled) {
struct sigaction act_term = { 0 };
struct sigaction act_chld = { 0 };
struct sigaction act_hup = { 0 };