1 files changed, 116 insertions, 0 deletions
diff --git a/src/sysdeps/tryancilautoclose.c b/src/sysdeps/tryancilautoclose.c
new file mode 100644
index 0000000..7b4a563
--- /dev/null
+++ b/src/sysdeps/tryancilautoclose.c
@@ -0,0 +1,116 @@
+/* ISC license. */
+
+#undef _POSIX_C_SOURCE
+#undef _XOPEN_SOURCE
+
+#ifndef _XPG4_2
+# define _XPG4_2
+#endif
+
+#include <sys/types.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#if defined(__FreeBSD__)
+# include <sys/param.h>
+#endif
+
+typedef struct ancilbuf_s ancilbuf_t, *ancilbuf_t_ref ;
+struct ancilbuf_s
+{
+  struct cmsghdr h ;
+  int fd ;
+} ;
+
+static int ancil_send_fd (int sock, int fd)
+{
+  struct msghdr msghdr ;
+  struct iovec nothing_ptr ;
+  ancilbuf_t buf ;
+  struct cmsghdr *cmsg ;
+  char nothing = '!' ;
+  
+  nothing_ptr.iov_base = &nothing ;
+  nothing_ptr.iov_len = 1 ;
+  msghdr.msg_name = 0 ;
+  msghdr.msg_namelen = 0 ;
+  msghdr.msg_iov = &nothing_ptr ;
+  msghdr.msg_iovlen = 1 ;
+  msghdr.msg_flags = 0 ;
+  msghdr.msg_control = &buf ;
+  msghdr.msg_controllen = sizeof(ancilbuf_t) ;
+  cmsg = CMSG_FIRSTHDR(&msghdr) ;
+  cmsg->cmsg_len = msghdr.msg_controllen ;
+  cmsg->cmsg_level = SOL_SOCKET ;
+  cmsg->cmsg_type = SCM_RIGHTS ;
+  *((int *)CMSG_DATA(cmsg)) = fd ;
+  return (sendmsg(sock, &msghdr, 0) >= 0) ;
+}
+
+static int ancil_recv_fd (int sock)
+{
+  struct msghdr msghdr ;
+  struct iovec nothing_ptr ;
+  ancilbuf_t buf ;
+  struct cmsghdr *cmsg ;
+  char nothing ;
+
+  nothing_ptr.iov_base = &nothing ;
+  nothing_ptr.iov_len = 1 ;
+  msghdr.msg_name = 0 ;
+  msghdr.msg_namelen = 0 ;
+  msghdr.msg_iov = &nothing_ptr ;
+  msghdr.msg_iovlen = 1 ;
+  msghdr.msg_flags = 0 ;
+  msghdr.msg_control = &buf ;
+  msghdr.msg_controllen = sizeof(ancilbuf_t) ;
+  cmsg = CMSG_FIRSTHDR(&msghdr) ;
+  cmsg->cmsg_len = msghdr.msg_controllen ;
+  cmsg->cmsg_level = SOL_SOCKET ;
+  cmsg->cmsg_type = SCM_RIGHTS ;
+  *((int *)CMSG_DATA(cmsg)) = -1 ;
+  if (recvmsg(sock, &msghdr, 0) < 0) return -1 ;
+  return *((int *)CMSG_DATA(cmsg)) ;
+}
+
+static int client (int sock)
+{
+  int p ;
+  char c ;
+  if (read(sock, &c, 1) < 1) return 111 ;
+  if (c != 'b') return 111 ;
+  p = ancil_recv_fd(sock) ;
+  if (p < 0) return 111 ;
+  if (read(sock, &c, 1) < 1) return 111 ;
+  if (c != 'a') return 111 ;
+  if (read(p, &c, 1) < 1) return 111 ;
+  if (c != 'K') return 111 ;
+  if (read(p, &c, 1) < 1) return 111 ;
+  return c ;
+}
+
+static void server (int sock)
+{
+  int p[2] ;
+  char c = 1 ;
+  if (pipe(p) < 0) return ;
+  if (write(sock, "b", 1) < 1) return ;
+  if (!ancil_send_fd(sock, p[0])) return ;
+  if (write(sock, "a", 1) < 1) return ;
+  if (write(p[1], "K", 1) < 1) return ;
+  if ((close(p[0]) < 0) && (errno == EBADF)) c = 0 ;
+  write(p[1], &c, 1) ;
+}
+
+int main (void)
+{
+  int fd[2] ;
+  if (socketpair(AF_UNIX, SOCK_STREAM, 0, fd) < 0) return 111 ;
+  switch (fork())
+  {
+    case -1 : return 111 ;
+    case 0 : close(fd[0]) ; server(fd[1]) ; return 0 ;
+    default : close(fd[1]) ; return client(fd[0]) ;
+  }
+}