Implement asynchronous GnuTLS connections

* doc/misc/emacs-gnutls.texi (Help For Developers): Mention
the nowait parameter.

* lisp/net/gnutls.el (open-gnutls-stream): Allow asynchronous
connections with the new nowait parameter.

* lisp/net/network-stream.el (network-stream-open-tls): Pass
on :nowait to open-gnutls-stream.

* lisp/url/url-http.el (url-http): Don't overwrite the
sentinel created by open-gnutls-stream.

* src/gnutls.c (Fgnutls_mark_process): New function.

* src/process.c (send_process): Don't write to GnuTLS sockets that
haven't been initialised yed.

* src/process.h: New slot gnutls_wait_p.

3 files changed, 17 insertions, 0 deletions

diff --git a/src/gnutls.c b/src/gnutls.c
index 01a5983d3b0..d11b11c7c54 100644
--- a/src/gnutls.c
+++ b/src/gnutls.c
@@ -686,6 +686,16 @@ emacs_gnutls_deinit (Lisp_Object proc)
   return Qt;
 }
 
+DEFUN ("gnutls-mark-process", Fgnutls_mark_process, Sgnutls_mark_process, 2, 2, 0,
+       doc: /* Mark this process as being a pre-init GnuTLS process.  */)
+  (Lisp_Object proc, Lisp_Object state)
+{
+  CHECK_PROCESS (proc);
+
+  XPROCESS (proc)->gnutls_wait_p = !NILP (state);
+  return Qnil;
+}
+
 DEFUN ("gnutls-get-initstage", Fgnutls_get_initstage, Sgnutls_get_initstage, 1, 1, 0,
        doc: /* Return the GnuTLS init stage of process PROC.
 See also `gnutls-boot'.  */)
@@ -1693,6 +1703,7 @@ syms_of_gnutls (void)
         make_number (GNUTLS_E_APPLICATION_ERROR_MIN));
 
   defsubr (&Sgnutls_get_initstage);
+  defsubr (&Sgnutls_mark_process);
   defsubr (&Sgnutls_errorp);
   defsubr (&Sgnutls_error_fatalp);
   defsubr (&Sgnutls_error_string);
diff --git a/src/process.c b/src/process.c
index 8cfa48db505..0fe45185361 100644
--- a/src/process.c
+++ b/src/process.c
@@ -5806,6 +5806,11 @@ send_process (Lisp_Object proc, const char *buf, ptrdiff_t len,
   if (p->outfd < 0)
     error ("Output file descriptor of %s is closed", SDATA (p->name));
 
+#ifdef HAVE_GNUTLS
+  if (p->gnutls_wait_p)
+    return;
+#endif
+
   coding = proc_encode_coding_system[p->outfd];
   Vlast_coding_system_used = CODING_ID_NAME (coding->id);
 
diff --git a/src/process.h b/src/process.h
index 990bbd55e3a..8bd555b83bd 100644
--- a/src/process.h
+++ b/src/process.h
@@ -192,6 +192,7 @@ struct Lisp_Process
     int gnutls_log_level;
     int gnutls_handshakes_tried;
     bool_bf gnutls_p : 1;
+    bool_bf gnutls_wait_p : 1;
 #endif
 };