Allow remote debugging over a Unix local domain socket.

Extend the "target remote" and "target extended-remote" commands
such that if the filename provided is a Unix local domain (AF_UNIX)
socket, then it'll be treated as such, instead of trying to open
it as if it were a character device.

gdb/ChangeLog:
	* NEWS: Mention changed commands.
	* ser-uds.c: New file.
	* configure.ac (SER_HARDWIRE): Add ser-uds.o.
	* configure: Regenerate.
	* Makefile.in: Add new file.
	* serial.c (serial_open): Check if filename is a socket
	  and lookup the appropriate interface accordingly.

gdb/doc/ChangeLog:
	* gdb.texinfo (Remote Connection Commands): Describe
	  the changes to target remote and target extended-remote
	  relating to Unix domain sockets.

1 files changed, 118 insertions, 0 deletions

diff --git a/gdb/ser-uds.c b/gdb/ser-uds.c
new file mode 100644
index 0000000..a98469f
--- /dev/null
+++ b/gdb/ser-uds.c
@@ -0,0 +1,118 @@
+/* Serial interface for local domain connections on Un*x like systems.
+
+   Copyright (C) 1992-2018 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "serial.h"
+#include "ser-base.h"
+
+#include <sys/socket.h>
+#include <sys/un.h>
+
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
+#endif
+
+/* Open an AF_UNIX socket.  */
+
+static int
+uds_open (struct serial *scb, const char *name)
+{
+  struct sockaddr_un addr;
+
+  if (strlen (name) > UNIX_PATH_MAX - 1)
+    {
+      warning
+        (_("The socket name is too long.  It may be no longer than %s bytes."),
+         pulongest (UNIX_PATH_MAX - 1L));
+      return -1;
+    }
+
+  memset (&addr, 0, sizeof addr);
+  addr.sun_family = AF_UNIX;
+  strncpy (addr.sun_path, name, UNIX_PATH_MAX - 1);
+
+  int sock = socket (AF_UNIX, SOCK_STREAM, 0);
+
+  if (connect (sock, (struct sockaddr *) &addr,
+	       sizeof (struct sockaddr_un)) < 0)
+    {
+      close (sock);
+      scb->fd = -1;
+      return -1;
+    }
+
+  scb->fd = sock;
+
+  return 0;
+}
+
+static void
+uds_close (struct serial *scb)
+{
+  if (scb->fd == -1)
+    return;
+
+  close (scb->fd);
+  scb->fd = -1;
+}
+
+static int
+uds_read_prim (struct serial *scb, size_t count)
+{
+  return recv (scb->fd, scb->buf, count, 0);
+}
+
+static int
+uds_write_prim (struct serial *scb, const void *buf, size_t count)
+{
+  return send (scb->fd, buf, count, 0);
+}
+
+/* The local socket ops.  */
+
+static const struct serial_ops uds_ops =
+{
+  "local",
+  uds_open,
+  uds_close,
+  NULL,
+  ser_base_readchar,
+  ser_base_write,
+  ser_base_flush_output,
+  ser_base_flush_input,
+  ser_base_send_break,
+  ser_base_raw,
+  ser_base_get_tty_state,
+  ser_base_copy_tty_state,
+  ser_base_set_tty_state,
+  ser_base_print_tty_state,
+  ser_base_setbaudrate,
+  ser_base_setstopbits,
+  ser_base_setparity,
+  ser_base_drain_output,
+  ser_base_async,
+  uds_read_prim,
+  uds_write_prim
+};
+
+void
+_initialize_ser_socket (void)
+{
+  serial_add_interface (&uds_ops);
+}