Add s6-notifyoncheck

2 files changed, 249 insertions, 0 deletions

diff --git a/src/supervision/deps-exe/s6-notifyoncheck b/src/supervision/deps-exe/s6-notifyoncheck
new file mode 100644
index 0000000..7a6675b
--- /dev/null
+++ b/src/supervision/deps-exe/s6-notifyoncheck
@@ -0,0 +1,5 @@
+${LIBS6}
+-lskarnet
+${SOCKET_LIB}
+${TAINNOW_LIB}
+${SPAWN_LIB}
diff --git a/src/supervision/s6-notifyoncheck.c b/src/supervision/s6-notifyoncheck.c
new file mode 100644
index 0000000..3d988de
--- /dev/null
+++ b/src/supervision/s6-notifyoncheck.c
@@ -0,0 +1,244 @@
+/* ISC license. */
+
+#include <stdint.h>
+#include <unistd.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <sys/wait.h>
+#include <skalibs/types.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/tai.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/selfpipe.h>
+#include <skalibs/iopause.h>
+#include <execline/config.h>
+#include <s6/s6-supervise.h>
+#include <s6/ftrigr.h>
+
+#define USAGE "s6-notifyoncheck [ -d ] [ -3 fd ] [ -s initialsleep ] [ -T globaltimeout ] [ -t localtimeout ] [ -w waitingtime ] [ -n tries ] [ -c \"checkprog...\" ] prog..."
+#define dieusage() strerr_dieusage(100, USAGE)
+
+
+static inline int read_uint (char const *file, unsigned int *fd)
+{
+  char buf[UINT_FMT + 1] ;
+  ssize_t r = openreadnclose_nb(file, buf, UINT_FMT) ;
+  if (r < 0) return -1 ;
+  buf[byte_chr(buf, r, '\n')] = 0 ;
+  return !!uint0_scan(buf, fd) ;
+}
+
+static inline int handle_signals (pid_t pid, int *w)
+{
+  int gotit = 0 ;
+  for (;;)
+  {
+    switch (selfpipe_read())
+    {
+      case -1 : strerr_diefu1sys(111, "selfpipe_read") ;
+      case 0 : return gotit ;
+      case SIGCHLD :
+      {
+        int wstat ;
+        if (wait_pid_nohang(pid, &wstat) == pid)
+        {
+          *w = wstat ;
+          gotit = 1 ;
+        }
+        break ;
+      }
+    }
+  }
+}
+
+static int handle_event (ftrigr_t *a, uint16_t id, pid_t pid)
+{
+  int r ;
+  char what ;
+  if (ftrigr_update(a) < 0) strerr_diefu1sys(111, "ftrigr_update") ;
+  r = ftrigr_check(a, id, &what) ;
+  if (r < 0) strerr_diefu1sys(111, "ftrigr_check") ;
+  if (r && what == 'd')
+  {
+    if (pid) kill(pid, SIGTERM) ;
+    return 1 ;
+  }
+  return 0 ;
+}
+
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  ftrigr_t a = FTRIGR_ZERO ;
+  iopause_fd x[2] = { { .events = IOPAUSE_READ }, { .events = IOPAUSE_READ } } ;
+  char const *childargv[4] = { EXECLINE_EXTBINPREFIX "execlineb", "-c", 0, 0 } ;
+  char const *checkprog = 0 ;
+  unsigned int fd ;
+  int df = 0 ;
+  int autodetect = 1 ;
+  tain_t globaldeadline, sleeptto, localtto, waittto ;
+  unsigned int tries = 7 ;
+  uint16_t id ;
+  PROG = "s6-notifyoncheck" ;
+
+  {
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    unsigned int initialsleep = 10, globaltimeout = 0, localtimeout = 0, waitingtime = 1000 ;
+    for (;;)
+    {
+      int opt = subgetopt_r(argc, argv, "d3:s:T:t:w:n:c:", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case 'd' : df = 1 ; break ;
+        case '3' : if (!uint0_scan(l.arg, &fd)) dieusage() ; autodetect = 0 ; break ;
+        case 's' : if (!uint0_scan(l.arg, &initialsleep)) dieusage() ; break ;
+        case 'T' : if (!uint0_scan(l.arg, &globaltimeout)) dieusage() ; break ;
+        case 't' : if (!uint0_scan(l.arg, &localtimeout)) dieusage() ; break ;
+        case 'w' : if (!uint0_scan(l.arg, &waitingtime)) dieusage() ; break ;
+        case 'n' : if (!uint0_scan(l.arg, &tries)) dieusage() ; break ;
+        case 'c' : checkprog = l.arg ; break ;
+        default : dieusage() ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+    if (!argc) dieusage() ;
+
+    if (!tain_from_millisecs(&sleeptto, initialsleep)) dieusage() ;
+    if (globaltimeout) tain_from_millisecs(&globaldeadline, globaltimeout) ;
+    else globaldeadline = tain_infinite_relative ;
+    if (localtimeout) tain_from_millisecs(&localtto, localtimeout) ;
+    else localtto = tain_infinite_relative ;
+    if (waitingtime) tain_from_millisecs(&waittto, waitingtime) ;
+    else waittto = tain_infinite_relative ;
+    if (!tries) tries = UINT_MAX ;
+  }
+
+  {
+    int r = s6_svc_ok(".") ;
+    if (r < 0) strerr_diefu1sys(111, "sanity-check current service directory") ;
+    if (!r) strerr_dief1x(100, "s6-supervise not running.") ;
+  }
+  if (checkprog) childargv[2] = checkprog ;
+  else
+  {
+    childargv[0] = "./data/check" ;
+    childargv[1] = 0 ;
+  }
+
+  if (autodetect)
+  {
+    int r = read_uint("notification-fd", &fd) ;
+    if (r < 0) strerr_diefu2sys(111, "read ", "./notification-fd") ;
+    if (!r) strerr_dief2x(100, "invalid ", "./notification-fd") ;
+  }
+  if (fcntl(fd, F_GETFD) < 0)
+    strerr_dief2sys(111, "notification-fd", " sanity check failed") ;
+
+  tain_now_g() ;
+  tain_add_g(&globaldeadline, &globaldeadline) ;
+
+
+ /*
+   Fork, let the parent exec into the daemon, keep working in the child.
+
+   We want the child to die if the parent dies, because no need to keep
+  polling a dead service. And another child will be spawned next time the
+  service is relaunched by s6-supervise.
+   We could keep a pipe from the parent to the child, for death
+  notification, but that's an additional fd forever open in the parent,
+  which is not good (we need to be 100% transparent).
+   So we're using ftrigr to listen to a 'd' event in the servicedir's
+  fifodir. It's much heavier, but temporary - it doesn't use permanent
+  resources in the daemon - and we're polling anyway, so the user
+  doesn't care about being 100% lightweight.
+ */
+
+  if (!ftrigr_startf_g(&a, &globaldeadline))
+    strerr_diefu1sys(111, "ftrigr_startf") ;
+  id = ftrigr_subscribe_g(&a, "event", "d", 0, &globaldeadline) ;
+  if (!id) strerr_diefu1sys(111, "ftrigr_subscribe to event fifodir") ;
+  switch (df ? doublefork() : fork())
+  {
+    case -1: strerr_diefu1sys(111, df ? "doublefork" : "fork") ;
+    case 0 : break ;
+    default:
+    {
+      close((int)fd) ;
+      xpathexec_run(argv[0], argv, envp) ;
+    }
+  }
+
+  x[0].fd = selfpipe_init() ;
+  if (x[0].fd < 0) strerr_diefu1sys(111, "selfpipe_init") ;
+  if (selfpipe_trap(SIGCHLD) < 0) strerr_diefu1sys(111, "trap SIGCHLD") ;
+  x[1].fd = ftrigr_fd(&a) ;
+
+
+ /* Loop around a sleep and a ./data/check invocation */
+
+  while (tries == UINT_MAX || tries--)
+  {
+    tain_t deadline = globaldeadline ;
+    tain_t localdeadline ;
+    pid_t pid ;
+
+    tain_add_g(&localdeadline, &sleeptto) ;
+    sleeptto = waittto ;
+    if (tain_less(&localdeadline, &deadline)) deadline = localdeadline ;
+    for (;;)
+    {
+      int r = iopause_g(x+1, 1, &deadline) ;
+      if (r < 0) strerr_diefu1sys(111, "iopause") ;
+      if (!r)
+      {
+        if (!tain_future(&globaldeadline)) return 3 ;
+        else break ;
+      }
+      if (handle_event(&a, id, 0)) return 2 ;
+    }
+
+    pid = child_spawn0(childargv[0], childargv, envp) ;
+    if (!pid)
+    {
+      strerr_warnwu2sys("spawn ", childargv[0]) ;
+      continue ;
+    }
+    deadline = globaldeadline ;
+    tain_add_g(&localdeadline, &localtto) ;
+    if (tain_less(&localdeadline, &deadline)) deadline = localdeadline ;
+    for (;;)
+    {
+      int r = iopause_g(x, 2, &deadline) ;
+      if (r < 0) strerr_diefu1sys(111, "iopause") ;
+      if (!r)
+      {
+        if (!tain_future(&globaldeadline))
+        {
+          kill(pid, SIGTERM) ;
+          return 3 ;
+        }
+        else break ;
+      }
+      if (x[0].revents & IOPAUSE_READ)
+      {
+        int wstat ;
+        if (handle_signals(pid, &wstat))
+        {
+          if (WIFEXITED(wstat) && !WEXITSTATUS(wstat))
+          {
+            write((int)fd, "\n", 1) ;
+            return 0 ;
+          }
+          else break ;
+        }
+      }
+      if (x[1].revents & IOPAUSE_READ && handle_event(&a, id, pid)) return 2 ;
+    }
+  }
+
+  return 1 ;
+}