1 files changed, 69 insertions, 0 deletions
diff --git a/src/misc/s6-linux-init-logouthookd.c b/src/misc/s6-linux-init-logouthookd.c
new file mode 100644
index 0000000..cc542ba
--- /dev/null
+++ b/src/misc/s6-linux-init-logouthookd.c
@@ -0,0 +1,69 @@
+/* ISC license. */
+
+#include <skalibs/sysdeps.h>
+
+#ifndef SKALIBS_HASSOPEERCRED
+#error "The SO_PEERCRED option to getsockopt() is required."
+#endif
+
+#include <skalibs/nonposix.h>
+
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <errno.h>
+#include <utmpx.h>
+
+#include <skalibs/allreadwrite.h>
+#include <skalibs/strerr2.h>
+
+#ifndef UT_NAMESIZE
+#define UT_NAMESIZE 32
+#endif
+
+#ifndef UT_HOSTSIZE
+#define UT_HOSTSIZE 256
+#endif
+
+int main (void)
+{
+  struct utmpx *utx ;
+  struct ucred client ;
+  socklen_t len = sizeof(client) ;
+  ssize_t r ;
+  char c ;
+
+  close(1) ;
+  if (getsockopt(0, SOL_SOCKET, SO_PEERCRED, &client, &len) == -1)
+    strerr_diefu1sys(111, "getsockopt") ;
+
+ /* Only take connections from root. */
+  if (client.uid) return 1 ;
+
+ /* Wait for the client to die. */
+  r = fd_read(0, &c, 1) ;
+  if (r < 0) strerr_diefu1sys(111, "read from stdin") ;
+  if (r) strerr_dief1x(2, "client attempted to write") ;
+
+ /* Clean up utmpx record for the client's pid, then exit. */
+  for (;;)
+  {
+    errno = 0 ;
+    utx = getutxent() ;
+    if (!utx) break ;
+    if (utx->ut_pid == client.pid) goto gotit ;
+  }
+  if (errno) strerr_diefu1sys(111, "getutxent") ;
+  return 0 ;
+
+ gotit:
+  utx->ut_type = DEAD_PROCESS ;
+  memset(utx->ut_user, 0, UT_NAMESIZE) ;
+  memset(utx->ut_host, 0, UT_HOSTSIZE) ;
+  utx->ut_tv.tv_sec = 0 ;
+  utx->ut_tv.tv_usec = 0 ;
+  setutxent() ;
+  if (!pututxline(utx)) strerr_diefu1sys(111, "pututxline") ;
+  return 0 ;
+}