1 files changed, 145 insertions, 0 deletions
diff --git a/src/supervision/s6-notify-fd-from-socket.c b/src/supervision/s6-notify-fd-from-socket.c
new file mode 100644
index 0000000..b5a6233
--- /dev/null
+++ b/src/supervision/s6-notify-fd-from-socket.c
@@ -0,0 +1,145 @@
+/* ISC license. */
+
+#include <skalibs/nonposix.h>
+
+#include <sys/types.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+#include <skalibs/posixplz.h>
+#include <skalibs/uint64.h>
+#include <skalibs/types.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/envexec.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/tai.h>
+#include <skalibs/iopause.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/socket.h>
+
+#define USAGE "s6-notify-fd-from-socket [ -f ] [ -3 fd ] [ -t timeout ] prog..."
+#define dieusage() strerr_dieusage(100, USAGE)
+
+enum golb_e
+{
+  GOLB_SINGLEFORK = 0x01,
+} ;
+
+enum gola_e
+{
+  GOLA_NOTIF,
+  GOLA_TIMEOUT,
+  GOLA_N
+} ;
+
+static void bindit (int sock, char *name)
+{
+  struct sockaddr_un addr = { .sun_family = AF_UNIX, .sun_path = "" } ;
+  socklen_t addrlen = sizeof(struct sockaddr_un) ;
+  if (bind(sock, (struct sockaddr *)&addr, sizeof(sa_family_t)) == -1) /* autobind */
+    strerr_diefu1sys(111, "bind") ;
+  if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) == -1)
+    strerr_diefu1sys(111, "getsockname") ;
+  if (addr.sun_path[0])
+    strerr_diefu1x(111, "autobind to an abstract socket") ;
+  memcpy(name, addr.sun_path + 1, 5) ;
+  name[5] = 0 ;
+}
+
+static inline int run_child (int sock, int fd, unsigned int timeout)
+{
+  char buf[8192] ;
+  iopause_fd x = { .fd = fd, .events = IOPAUSE_READ } ;
+  int found = 0 ;
+  tain deadline = TAIN_INFINITE_RELATIVE ;
+  tain_now_g() ;
+  if (timeout) tain_from_millisecs(&deadline, timeout) ;
+  tain_add_g(&deadline, &deadline) ;
+  while (!found)
+  {
+    int r = iopause_g(&x, 1, &deadline) ;
+    if (r == -1) strerr_diefu1sys(111, "iopause") ;
+    if (!r) strerr_dief1x(99, "timed out waiting for notification") ;
+    r = sanitize_read(fd_recv(sock, buf, 8191, 0)) ;
+    if (r == -1)
+    {
+      if (errno == EPIPE) _exit(0) ;
+      else strerr_diefu1sys(111, "recv") ;
+    }
+    if (r)
+    {
+      buf[r++] = 0 ;
+      if (!strncmp(buf, "READY=1\n", 8) || strstr(buf, "\nREADY=1\n"))
+        found = 1 ;
+    }
+  }
+  fd_write(fd, "\n", 1) ;
+  _exit(0) ;
+}
+
+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 == -1) return -1 ;
+  buf[byte_chr(buf, r, '\n')] = 0 ;
+  return !!uint0_scan(buf, fd) ;
+}
+
+int main (int argc, char const *const *argv)
+{
+  static gol_bool const rgolb[] =
+  {
+    { .so = 'f', .lo = "no-doublefork", .clear = 0, .set = GOLB_SINGLEFORK },
+    { .so = 0, .lo = "doublefork", .clear = GOLB_SINGLEFORK, .set = 0 },
+  } ;
+  static gol_arg const rgola[] =
+  {
+    { .so = '3', .lo = "notification-fd", .i = GOLA_NOTIF },
+    { .so = 't', .lo = "timeout", .i = GOLA_TIMEOUT },
+  } ;
+  unsigned int fd = 0 ;
+  unsigned int timeout = 0 ;
+  uint64_t wgolb = 0 ;
+  char const *wgola[GOLA_N] = { 0 } ;
+  pid_t pid ;
+  int sock ;
+  unsigned int golc ;
+  char modif[21] = "NOTIFY_SOCKET=@XXXXX" ;
+  PROG = "s6-notify-fd-from-socket" ;
+
+  golc = GOL_main(argc, argv, rgolb, rgola, &wgolb, wgola) ;
+  argc -= golc ; argv += golc ;
+  if (!argc) dieusage() ;
+
+  if (wgola[GOLA_TIMEOUT] && !uint0_scan(wgola[GOLA_TIMEOUT], &timeout))
+    strerr_dief2x(100, "timeout", " must be an unsigned integer") ;
+  if (wgola[GOLA_NOTIF])
+  {
+    if (!uint0_scan(wgola[GOLA_NOTIF], &fd))
+      strerr_dief2x(100, "notification-fd", " must be an unsigned integer") ;
+  }
+  else
+  {
+    int r = read_uint("notification-fd", &fd) ;
+    if (r == -1) strerr_diefu2sys(111, "read ", "./notification-fd") ;
+    if (!r) strerr_dief2x(100, "invalid ", "./notification-fd") ;
+  }
+  if (fcntl(fd, F_GETFD) == -1)
+    strerr_dief2sys(111, "notification-fd", " sanity check failed") ;
+
+  sock = ipc_datagram_nbcoe() ;
+  if (sock == -1) strerr_diefu1sys(111, "create socket") ;
+  bindit(sock, modif + 15) ;
+
+  pid = wgolb & GOLB_SINGLEFORK ? fork() : doublefork() ;
+  if (pid == -1) strerr_diefu1sys(111, wgolb & GOLB_SINGLEFORK ? "fork" : "doublefork") ;
+  if (!pid) run_child(sock, fd, timeout) ;
+  fd_close(sock) ;
+  fd_close(fd) ;
+  xmexec_n(argv, modif, 21, 1) ;
+}