1 files changed, 86 insertions, 0 deletions
diff --git a/src/daemontools-extras/s6-notifywhenup.c b/src/daemontools-extras/s6-notifywhenup.c
new file mode 100644
index 0000000..a4be329
--- /dev/null
+++ b/src/daemontools-extras/s6-notifywhenup.c
@@ -0,0 +1,86 @@
+/* ISC license. */
+
+#include <unistd.h>
+#include <errno.h>
+#include <skalibs/uint.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/tai.h>
+#include <skalibs/iopause.h>
+#include <skalibs/djbunix.h>
+#include <s6/ftrigw.h>
+
+#define USAGE "s6-notifywhenup [ -d fd ] [ -e fifodir ] [ -f ] [ -t timeout ] prog..."
+#define dieusage() strerr_dieusage(100, USAGE)
+
+static int run_child (int fd, char const *fifodir, unsigned int timeout)
+{
+  char dummy[4096] ;
+  iopause_fd x = { .fd = fd, .events = IOPAUSE_READ } ;
+  tain_t deadline ;
+  int haswritten = 0 ;
+  register int r = 0 ;
+  if (!tain_now_g()) strerr_diefu1sys(111, "tain_now") ;
+  tain_from_millisecs(&deadline, timeout) ;
+  tain_add_g(&deadline, &deadline) ;
+  while (!r)
+  {
+    register int r = iopause_g(&x, 1, &deadline) ;
+    if (r < 0) strerr_diefu1sys(111, "iopause") ;
+    if (!r) return 99 ;
+    while (r > 0)
+    {
+      r = sanitize_read(fd_read(fd, dummy, 4096)) ;
+      if (r > 0) haswritten = 1 ;
+    }
+  }
+  if (errno != EPIPE) strerr_diefu1sys(111, "read from parent") ;
+  if (haswritten) ftrigw_notify(fifodir, 'U') ;
+  return 0 ;
+}
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  unsigned int fd = 1 ;
+  char const *fifodir = "event" ;
+  int df = 1 ;
+  unsigned int timeout = 0 ;
+  PROG = "s6-notifywhenup" ;
+  {
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    for (;;)
+    {
+      register int opt = subgetopt_r(argc, argv, "d:e:ft:", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case 'd' : if (!uint0_scan(l.arg, &fd)) dieusage() ; break ;
+        case 'e' : fifodir = l.arg ; break ;
+        case 'f' : df = 0 ; break ;
+        case 't' : if (!uint0_scan(l.arg, &timeout)) dieusage() ; break ;
+        default : dieusage() ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+  }
+  if (!argc) dieusage() ;
+
+  {
+    int p[2] ;
+    pid_t pid ;
+    if (pipe(p) < 0) strerr_diefu1sys(111, "pipe") ;
+    pid = df ? doublefork() : fork() ;
+    if (pid < 0) strerr_diefu1sys(111, df ? "doublefork" : "fork") ;
+    else if (pid)
+    {
+      PROG = "s6-notifywhenup (child)" ;
+      fd_close(p[1]) ;
+      return run_child(p[0], fifodir, timeout) ;
+    }
+    fd_close(p[0]) ;
+    if (fd_move((int)fd, p[1]) < 0) strerr_diefu1sys(111, "fd_move") ;
+  }
+  pathexec_run(argv[0], argv, envp) ;
+  strerr_dieexec(111, argv[1]) ;
+}