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/* ISC license. */
#include <skalibs/sysdeps.h>
#if defined(SKALIBS_HASPRCTL) || defined(SKALIBS_HASPROCCTL) || defined(SKALIBS_HASKEVENT)
#include <skalibs/nonposix.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <errno.h>
#undef NEEDS_KEVENT
#if defined(SKALIBS_HASPRCTL)
# include <sys/prctl.h>
# define NEEDS_KEVENT 0
#elif defined(SKALIBS_HASPROCCTL)
# include <sys/procctl.h>
# define NEEDS_KEVENT 0
#elif defined (SKALIBS_HASKEVENT)
# include <sys/types.h>
# include <sys/event.h>
# include <sys/time.h>
# include <pthread.h>
# include <fcntl.h>
# include <limits.h>
# include <skalibs/keventbridge.h>
# define NEEDS_KEVENT 1
#endif
#include <skalibs/posixplz.h>
#include <skalibs/types.h>
#include <skalibs/prog.h>
#include <skalibs/gol.h>
#include <skalibs/bytestr.h>
#include <skalibs/strerr.h>
#include <skalibs/tai.h>
#include <skalibs/selfpipe.h>
#include <skalibs/iopause.h>
#include <skalibs/cspawn.h>
#include <skalibs/djbunix.h>
#define USAGE "s6-background-watch [ -t timeout ] [ -d notif ] pidfile prog..."
#define dieusage() strerr_dieusage(100, USAGE)
static int handle_signals_early (pid_t pid, char const *pidfile, char const *prog)
{
int sig ;
for (;;) switch (sig = selfpipe_read())
{
case -1 : strerr_diefu1sys(111, "read selfpipe") ;
case 0 : return 0 ;
case SIGCHLD :
{
int wstat ;
pid_t r = wait_pid_nohang(pid, &wstat) ;
if (r == -1) strerr_diefu1sys(111, "wait") ;
if (!r) break ;
if (WIFEXITED(wstat))
{
if (WEXITSTATUS(wstat))
{
char fmt[UINT_FMT] ;
fmt[uint_fmt(fmt, WEXITSTATUS(wstat))] = 0 ;
unlink_void(pidfile) ;
strerr_dief3x(wait_estatus(wstat), prog, " (parent) exited ", fmt) ;
}
else return 1 ;
}
else
{
char fmt[UINT_FMT] ;
fmt[uint_fmt(fmt, WTERMSIG(wstat))] = 0 ;
unlink_void(pidfile) ;
strerr_dief3x(wait_estatus(wstat), prog, " (parent) crashed with signal ", fmt) ;
}
break ;
}
default :
kill(pid, sig) ;
break ;
}
}
static inline int read_file (char const *file, char *buf, size_t n)
{
ssize_t r = openreadnclose_nb(file, buf, n) ;
if (r == -1)
{
if (errno != ENOENT) strerr_diefu2sys(111, "open ", file) ;
return 0 ;
}
buf[byte_chr(buf, r, '\n')] = 0 ;
return 1 ;
}
static inline pid_t get_pid_from_pidfile (char const *pidfile, char const *prog)
{ /* for now, assume the pidfile is there once the parent has exited */
pid_t pid ;
char buf[128] ;
if (!read_file(pidfile, buf, 128))
strerr_diefu4sys(104, prog, " (parent) exited but pidfile ", pidfile, " does not exist") ;
if (!pid0_scan(buf, &pid))
strerr_dief3x(104, "pidfile ", pidfile, " does not contain a valid pid") ;
return pid ;
}
static inline int handle_signals (pid_t pid, int iske, int *code)
{
int sig ;
for (;;) switch (sig = selfpipe_read())
{
case -1 : strerr_diefu1sys(111, "read selfpipe") ;
case 0 : return 0 ;
case SIGCHLD :
{
int wstat ;
pid_t r = wait_pid_nohang(pid, &wstat) ;
if (r == -1)
if (errno != ECHILD || !iske) strerr_diefu1sys(111, "wait") ;
else break ;
else if (!r) break ;
*code = wait_estatus(wstat) ;
return 1 ;
}
default :
kill(pid, sig) ;
break ;
}
}
enum rgola_e
{
GOLA_TIMEOUT,
GOLA_NOTIF,
GOLA_N
} ;
static gol_arg const rgola[GOLA_N] =
{
{ .so = 't', .lo = "timeout-ready", .i = GOLA_TIMEOUT },
{ .so = 'd', .lo = "notification-fd", .i = GOLA_NOTIF }
} ;
int main (int argc, char const *const *argv)
{
iopause_fd x[1 + NEEDS_KEVENT] = { { .events = IOPAUSE_READ } } ;
tain tto = TAIN_INFINITE_RELATIVE ;
tain deadline ;
unsigned int notif = 0 ;
pid_t pid ;
char const *wgola[GOLA_N] = { 0 } ;
unsigned int golc ;
PROG = "s6-background-watch" ;
golc = gol_main(argc, argv, 0, 0, rgola, GOLA_N, 0, wgola) ;
argc -= golc ; argv += golc ;
if (argc < 2) dieusage() ;
if (wgola[GOLA_TIMEOUT])
{
unsigned int t ;
if (!uint0_scan(wgola[GOLA_TIMEOUT], &t)) dieusage() ;
if (!tain_from_millisecs(&tto, t)) dieusage() ;
}
if (wgola[GOLA_NOTIF])
{
if (!uint0_scan(wgola[GOLA_NOTIF], ¬if)) dieusage() ;
if (notif < 3) strerr_dief2x(100, "notification-fd", " cannot be 0, 1 or 2") ;
if (fcntl(notif, F_GETFD) == -1) strerr_diefu2sys(111, "check ", "notification-fd") ;
if (coe(notif) == -1) strerr_diefu1sys(111, "coe notification-fd") ;
}
{
sigset_t full ;
sigfillset(&full) ;
if (selfpipe_init() == -1)
strerr_diefu1sys(111, "init selfpipe") ;
if (!selfpipe_trapset(&full))
strerr_diefu1sys(111, "trap all signals") ;
x[0].fd = selfpipe_fd() ;
}
#if defined(SKALIBS_HASPRCTL)
if (prctl(PR_SET_CHILD_SUBREAPER, 1) == -1)
strerr_diefu1sys(111, "prctl with PR_SET_CHILD_SUBREAPER") ;
#elif defined(SKALIBS_HASPROCCTL)
if (procctl(P_PID, 0, PROC_REAP_ACQUIRE, 0) == -1)
strerr_diefu1sys(111, "procctl with PROC_REAP_ACQUIRE") ;
#endif
pid = cspawn(argv[1], argv + 1, (char const *const *)environ, CSPAWN_FLAGS_SELFPIPE_FINISH, 0, 0) ;
if (!pid) strerr_diefu2sys(errno == ENOEXEC ? 126 : 127, "spawn ", argv[1]) ;
tain_now_set_stopwatch_g() ;
tain_add_g(&deadline, &tto) ;
for (;;)
{
int r = iopause_g(x, 1, &deadline) ;
if (r == -1) strerr_diefu1sys(111, "iopause") ;
if (!r)
{
strerr_warnw2x(argv[1], " (parent) did not exit before timeout-ready, killing it") ;
kill(pid, SIGKILL) ;
}
else if (handle_signals_early(pid, argv[0], argv[1])) break ;
}
pid = get_pid_from_pidfile(argv[0], argv[1]) ;
if (kill(pid, 0) == -1) strerr_diefu1sys(111, "check daemon with a null signal") ;
#if NEEDS_KEVENT
keventbridge kb = KEVENTBRIDGE_ZERO ;
struct kevent ke ;
x[1].events = IOPAUSE_READ ;
x[1].fd = keventbridge_start(&kb) ;
if (x[1].fd == -1) strerr_diefu1sys(111, "keventbridge_start") ;
EV_SET(&ke, pid, EVFILT_PROC, EV_ADD | EV_ONESHOT, NOTE_EXIT, 0, 0) ;
if (keventbridge_write(&kb, &ke, 1) == -1) strerr_diefu1sys(111, "keventbridge_write") ;
#endif
if (notif)
{
write(notif, "\n", 1) ;
close(notif) ;
}
for (;;)
{
int r = iopause_g(x, 1 + NEEDS_KEVENT, 0) ;
if (r == -1) strerr_diefu1sys(111, "iopause") ;
if (x[0].revents & IOPAUSE_READ)
{
int code = 0 ;
if (handle_signals(pid, NEEDS_KEVENT, &code)) _exit(code) ;
}
#if NEEDS_KEVENT
else if (x[1].revents & IOPAUSE_READ)
{
int r = keventbridge_read(&kb, &ke) ;
if (r == -1) strerr_diefu1sys(111, "keventbridge_read") ;
else if (r && (pid_t)ke.ident == pid && ke.filter == EVFILT_PROC && ke.fflags & NOTE_EXIT)
_exit(wait_estatus(ke.data)) ;
}
#endif
}
}
#else
#include <skalibs/prog.h>
#include <skalibs/strerr.h>
int main (int argc, char const *const *argv)
{
PROG = "s6-background-watch" ;
strerr_dief1x(112, "system does not meet the requirements to watch auto-backgrounding daemons") ;
}
#endif
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