[PATCH] Allow remote debugging over a local domain socket

John Darrington
2018-08-31T10:18:27Z

Extend the "target remote" and "target extended-remote" commands
such that if the filename provided is a unix 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:
* gdb/NEWS: Mention changed commands.
* gdb/configure.ac (SER_HARDWIRE): Add ser-socket.o
* gdb/doc/gdb.texinfo (Remote Connection Commands): Describe
changed commands.
* gdb/ser-socket.c: New file.
* gdb/ser-socket.h: New file.
* gdb/Makefile.in: Add new files.
* gdb/serial.c (serial_open): Check if filename is a socket
and lookup the appropriate interface accordingly.
---
gdb/Makefile.in | 2 +
gdb/NEWS | 5 ++
gdb/configure.ac | 2 +-
gdb/doc/gdb.texinfo | 19 +++++++-
gdb/ser-socket.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++++
gdb/ser-socket.h | 31 ++++++++++++
gdb/serial.c | 10 +++-
7 files changed, 198 insertions(+), 3 deletions(-)
create mode 100644 gdb/ser-socket.c
create mode 100644 gdb/ser-socket.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index f448d1ee19..cb98f987da 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1355,6 +1355,7 @@ HFILES_NO_SRCDIR = \
sentinel-frame.h \
ser-base.h \
ser-event.h \
+ ser-socket.h \
ser-tcp.h \
ser-unix.h \
serial.h \
@@ -2324,6 +2325,7 @@ ALLDEPFILES = \
ser-go32.c \
ser-mingw.c \
ser-pipe.c \
+ ser-socket.c \
ser-tcp.c \
sh-nbsd-nat.c \
sh-nbsd-tdep.c \
diff --git a/gdb/NEWS b/gdb/NEWS
index c46056525a..c7436e0ced 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -40,6 +40,11 @@ maint show dwarf unwinders

* Changed commands

+target remote FILENAME
+target extended-remote FILENAME
+ If FILENAME is a unix domain socket gdb will attempt to connect
+ to this socket instead of opening FILENAME as a character device.
+
thread apply [all | COUNT | -COUNT] [FLAG]... COMMAND
The 'thread apply' command accepts new FLAG arguments.
FLAG arguments allow to control what output to produce and how to handle
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 13bc5f9a8f..f6735858d7 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1870,7 +1870,7 @@ lose

dnl Figure out which of the many generic ser-*.c files the _host_ supports.
-SER_HARDWIRE="ser-base.o ser-unix.o ser-pipe.o ser-tcp.o"
+SER_HARDWIRE="ser-base.o ser-unix.o ser-pipe.o ser-socket.o ser-tcp.o"
case ${host} in
*go32* ) SER_HARDWIRE=ser-go32.o ;;
*djgpp* ) SER_HARDWIRE=ser-go32.o ;;
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index e4ecd57a9e..5ae53e0582 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -20703,7 +20703,8 @@ programs.

@subsection Remote Connection Commands
@cindex remote connection commands
-@value{GDBN} can communicate with the target over a serial line, or
+@value{GDBN} can communicate with the target over a serial line, a
+local socket, or
over an @acronym{IP} network using @acronym{TCP} or @acronym{UDP}. In
each case, @value{GDBN} uses the same protocol for debugging your
program; only the medium carrying the debugging packets varies. The
@@ -20728,6 +20729,22 @@ If you're using a serial line, you may want to give @value{GDBN} the
(@pxref{Remote Configuration, set serial baud}) before the
@code{target} command.

+
+@item target remote @var{local-socket}
+@itemx target extended-remote @var{local-socket}
+@cindex local socket, @code{target remote}
+Use @var{local-socket} to communicate with the target. For example,
+to use a local socket bound to the file system entry @file{/tmp/gdb-socket0}:
+
+@smallexample
+target remote /tmp/gdb-socket0
+@end smallexample
+
+Note that this command has the same form as the command to connect
+to a serial line. @value{GDBN} will automatically determine which
+kind of file you have specified and will make the appropriate kind
+of connection.
+
@item target remote @code{@var{host}:@var{port}}
@itemx target remote @code{@var{[host]}:@var{port}}
@itemx target remote @code{tcp:@var{host}:@var{port}}
diff --git a/gdb/ser-socket.c b/gdb/ser-socket.c
new file mode 100644
index 0000000000..54d14f36ad
--- /dev/null
+++ b/gdb/ser-socket.c
@@ -0,0 +1,132 @@
+/* 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 "ser-socket.h"
+
+#include <sys/socket.h>
+#include <sys/un.h>
+
+
+/* Open a AF_UNIX socket. */
+int
+socket_open (struct serial *scb, const char *name)
+{
+ struct sockaddr_un addr;
+
+ memset (&addr, 0, sizeof addr);
+ addr.sun_family = AF_UNIX;
+#ifndef UNIX_MAX_PATH
+# define UNIX_MAX_PATH 108
+#endif
+ strncpy (addr.sun_path, name, UNIX_MAX_PATH - 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;
+}
+
+void
+socket_close (struct serial *scb)
+{
+ if (scb->fd == -1)
+ return;
+
+ close (scb->fd);
+ scb->fd = -1;
+}
+
+int
+socket_read_prim (struct serial *scb, size_t count)
+{
+ /* Need to cast to silence -Wpointer-sign on MinGW, as Winsock's
+ 'recv' takes 'char *' as second argument, while 'scb->buf' is
+ 'unsigned char *'. */
+ return recv (scb->fd, (char *) scb->buf, count, 0);
+}
+
+int
+socket_write_prim (struct serial *scb, const void *buf, size_t count)
+{
+ /* On Windows, the second parameter to send is a "const char *"; on
+ UNIX systems it is generally "const void *". The cast to "const
+ char *" is OK everywhere, since in C++ any data pointer type can
+ be implicitly converted to "const void *". */
+ return send (scb->fd, (const char *) buf, count, 0);
+}
+
+int
+ser_socket_send_break (struct serial *scb)
+{
+ /* Send telnet IAC and BREAK characters. */
+ return (serial_write (scb, "\377\363", 2));
+}
+
+#ifndef USE_WIN32API
+
+/* The SOCKET ops. */
+
+static const struct serial_ops socket_ops =
+{
+ "socket",
+ socket_open,
+ socket_close,
+ NULL,
+ ser_base_readchar,
+ ser_base_write,
+ ser_base_flush_output,
+ ser_base_flush_input,
+ ser_socket_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,
+ socket_read_prim,
+ socket_write_prim
+};
+
+#endif /* USE_WIN32API */
+
+void
+_initialize_ser_socket (void)
+{
+#ifdef USE_WIN32API
+ /* Do nothing; Windoze does not have local domain sockets. */
+#else
+ serial_add_interface (&socket_ops);
+#endif /* USE_WIN32API */
+}
diff --git a/gdb/ser-socket.h b/gdb/ser-socket.h
new file mode 100644
index 0000000000..58509302d6
--- /dev/null
+++ b/gdb/ser-socket.h
@@ -0,0 +1,31 @@
+/* Serial interface for raw TCP connections on Un*x like systems.
+
+ Copyright (C) 2006-2018 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/>. */
+
+#ifndef SER_SOCKET_H
+#define SER_SOCKET_H
+
+struct serial;
+
+extern int socket_open (struct serial *scb, const char *name);
+extern void socket_close (struct serial *scb);
+extern int socket_read_prim (struct serial *scb, size_t count);
+extern int socket_write_prim (struct serial *scb, const void *buf, size_t count);
+extern int ser_socket_send_break (struct serial *scb);
+
+#endif
diff --git a/gdb/serial.c b/gdb/serial.c
index fb2b212918..13b1af3873 100644
--- a/gdb/serial.c
+++ b/gdb/serial.c
@@ -213,7 +213,15 @@ serial_open (const char *name)
else if (strchr (name, ':'))
ops = serial_interface_lookup ("tcp");
else
- ops = serial_interface_lookup ("hardwire");
+ {
+ /* Check to see if name is a socket. If it is, then treat is
+ as such. Otherwise assume that it's a character device. */
+ struct stat sb;
+ if (0 == stat (name, &sb) && ((sb.st_mode & S_IFMT) == S_IFSOCK))
+ ops = serial_interface_lookup ("socket");
+ else
+ ops = serial_interface_lookup ("hardware");
+ }

if (!ops)
return NULL;
--
2.11.0