[PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

When invoking gdbserver, if the COMM parameter does not include a colon (:) and
is not the name of an existing character device, then a local (unix) domain
socket will be created with that name and gdbserver will listen for connections
on that.

    gdb/doc/
    * gdb.texinfo (Server): Describe connection over a local domain socket.

    gdb/gdbserver/
    * NEWS: Mention new feature.
    * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
    * remote-utils.c (remote_prepare): Create a local socket if requested.
    * remote-utils.c (remote_open):  Don't attempt to open a file if it's a socket.
    * remote-utils.c (handle_accept_event): Display the name of the socket on connection.
---
 gdb/NEWS                     |   4 ++
 gdb/doc/gdb.texinfo          |  26 +++++--
 gdb/gdbserver/configure.ac   |   2 +-
 gdb/gdbserver/remote-utils.c | 164 ++++++++++++++++++++++++++++++-------------
 4 files changed, 141 insertions(+), 55 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 78d20713a8..95c5083d9b 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -15,6 +15,10 @@
   can be passed using the '[ADDRESS]:PORT' notation, or the regular
   'ADDRESS:PORT' method.
 
+* GDB and GDBserver now support local domain socket connections.  The
+  name of a local domain socket may be provided instead of the
+  [ADDRESS]:PORT notation.
+
 * DWARF index cache: GDB can now automatically save indices of DWARF
   symbols on disk to speed up further loading of the same binaries.
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index efd6dffb1e..44b319ebc7 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21075,9 +21075,13 @@ syntax is:
 target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
 @end smallexample
 
-@var{comm} is either a device name (to use a serial line), or a TCP
+@var{comm} is either an existing device name (to use a serial line), or a TCP
 hostname and portnumber, or @code{-} or @code{stdio} to use
 stdin/stdout of @code{gdbserver}.
+If @var{comm} is none of the above, then a local domain socket
+will be created with that name.
+@cindex local socket
+@cindex Unix domain socket
 For example, to debug Emacs with the argument
 @samp{foo.txt} and communicate with @value{GDBN} over the serial port
 @file{/dev/com1}:
@@ -21107,6 +21111,20 @@ conflicts with another service, @code{gdbserver} prints an error message
 and exits.}  You must use the same port number with the host @value{GDBN}
 @code{target remote} command.
 
+If the target and local machine are one and the same, then you can
+use local domain socket instead of a TCP connection:
+
+@smallexample
+target> gdbserver /tmp/local-socket emacs foo.txt
+@end smallexample
+
+A local domain socket called @file{/tmp/local-socket} will be created
+in the filesystem.
+If there is already a local domain socket with this name it will be removed.
+@smallexample
+(gdb) target remote /tmp/local-socket
+@end smallexample
+
 The @code{stdio} connection is useful when starting @code{gdbserver}
 with ssh:
 
@@ -21155,10 +21173,10 @@ In case more than one copy of @var{program} is running, or @var{program}
 has multiple threads, most versions of @code{pidof} support the
 @code{-s} option to only return the first process ID.
 
-@subsubsection TCP port allocation lifecycle of @code{gdbserver}
+@subsubsection Socket lifecycle of @code{gdbserver}
 
 This section applies only when @code{gdbserver} is run to listen on a TCP
-port.
+port or a unix domain socket.
 
 @code{gdbserver} normally terminates after all of its debugged processes have
 terminated in @kbd{target remote} mode.  On the other hand, for @kbd{target
@@ -21174,7 +21192,7 @@ Such reconnecting is useful for features like @ref{disconnected tracing}.  For
 completeness, at most one @value{GDBN} can be connected at a time.
 
 @cindex @option{--once}, @code{gdbserver} option
-By default, @code{gdbserver} keeps the listening TCP port open, so that
+By default, @code{gdbserver} keeps the listening socket open, so that
 subsequent connections are possible.  However, if you start @code{gdbserver}
 with the @option{--once} option, it will stop listening for any further
 connection attempts after connecting to the first @value{GDBN} session.  This
diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
index fa3ca53efd..de7e7d4103 100644
--- a/gdb/gdbserver/configure.ac
+++ b/gdb/gdbserver/configure.ac
@@ -98,7 +98,7 @@ ACX_CONFIGURE_DIR(["../../libiberty"], ["build-libiberty-gdbserver"])
 AC_CHECK_HEADERS(termios.h sys/reg.h string.h dnl
 		 proc_service.h sys/procfs.h linux/elf.h dnl
 		 fcntl.h signal.h sys/file.h dnl
-		 sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
+		 sys/ioctl.h netinet/in.h sys/socket.h sys/un.h netdb.h dnl
 		 netinet/tcp.h arpa/inet.h)
 AC_FUNC_FORK
 AC_CHECK_FUNCS(getauxval pread pwrite pread64 setns)
diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
index 9199a9c7ad..00e3340156 100644
--- a/gdb/gdbserver/remote-utils.c
+++ b/gdb/gdbserver/remote-utils.c
@@ -38,6 +38,9 @@
 #if HAVE_NETINET_IN_H
 #include <netinet/in.h>
 #endif
+#if HAVE_SYS_UN_H
+#include <sys/un.h>
+#endif
 #if HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
@@ -193,20 +196,35 @@ handle_accept_event (int err, gdb_client_data client_data)
      descriptor open for add_file_handler to wait for a new connection.  */
   delete_file_handler (listen_desc);
 
-  /* Convert IP address to string.  */
-  char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
-
-  int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
-		       orig_host, sizeof (orig_host),
-		       orig_port, sizeof (orig_port),
-		       NI_NUMERICHOST | NI_NUMERICSERV);
+  if (sockaddr.ss_family == AF_UNIX)
+    {
+      struct sockaddr_un su;
+      socklen_t len;
+      if (0 != getsockname (listen_desc, (struct sockaddr *) &su, &len))
+	{
+	  perror (_("Could not obtain remote address"));
+	}
 
-  if (r != 0)
-    fprintf (stderr, _("Could not obtain remote address: %s\n"),
-	     gai_strerror (r));
+      fprintf (stderr, _("Remote debugging on local socket bound to %s\n"),
+	       su.sun_path);
+    }
   else
-    fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
-	     orig_host, orig_port);
+    {
+      /* Convert IP address to string.  */
+      char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
+
+      int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
+			   orig_host, sizeof (orig_host),
+			   orig_port, sizeof (orig_port),
+			   NI_NUMERICHOST | NI_NUMERICSERV);
+
+      if (r != 0)
+	fprintf (stderr, _("Could not obtain remote address: %s\n"),
+		 gai_strerror (r));
+      else
+	fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
+		 orig_host, orig_port);
+    }
 
   enable_async_notification (remote_desc);
 
@@ -250,6 +268,9 @@ remote_prepare (const char *name)
   struct addrinfo hint;
   struct addrinfo *ainfo;
 
+  struct sockaddr *addr;
+  socklen_t addrlen;
+
   memset (&hint, 0, sizeof (hint));
   /* Assume no prefix will be passed, therefore we should use
      AF_UNSPEC.  */
@@ -260,10 +281,17 @@ remote_prepare (const char *name)
   parsed_connection_spec parsed
     = parse_connection_spec_without_prefix (name, &hint);
 
+  struct stat statbuf;
+  int stat_result = stat (name, &statbuf);
+
   if (parsed.port_str.empty ())
     {
-      cs.transport_is_reliable = 0;
-      return;
+      if (stat_result == 0
+	  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
+	{
+	  cs.transport_is_reliable = 0;
+	  return;
+	}
     }
 
 #ifdef USE_WIN32API
@@ -276,47 +304,82 @@ remote_prepare (const char *name)
     }
 #endif
 
-  int r = getaddrinfo (parsed.host_str.c_str (), parsed.port_str.c_str (),
-		       &hint, &ainfo);
+  struct sockaddr_un unix_addr;
 
-  if (r != 0)
-    error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
+#endif
 
-  scoped_free_addrinfo freeaddrinfo (ainfo);
+  if (parsed.port_str.empty ())
+    {
+      if (strlen (name) > UNIX_PATH_MAX - 1)
+	{
+	  error
+	    (_("%s is too long.  Socket names may be no longer than %s bytes."),
+	     name, pulongest (UNIX_PATH_MAX - 1));
+	  return;
+	}
+      listen_desc = socket (AF_UNIX,  SOCK_STREAM,  0);
+      if (listen_desc < 0)
+	perror_with_name ("Can't open socket");
+
+      memset (&unix_addr, 0, sizeof (unix_addr));
+      unix_addr.sun_family = AF_UNIX;
+      strncpy (unix_addr.sun_path, parsed.host_str.c_str(), UNIX_PATH_MAX - 1);
+      if (stat_result == 0
+	  && (S_IFSOCK & statbuf.st_mode))
+	unlink (name);
+
+      addr = (struct sockaddr *) &unix_addr;
+      addrlen = sizeof (unix_addr);
+    }
+  else
+    {
+      struct addrinfo *iter;
 
-  struct addrinfo *iter;
+      int r = getaddrinfo (parsed.host_str.c_str (),
+			   parsed.port_str.c_str (),
+			   &hint, &ainfo);
 
-  for (iter = ainfo; iter != NULL; iter = iter->ai_next)
-    {
-      listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
-					iter->ai_protocol);
+      if (r != 0)
+	error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
 
-      if (listen_desc >= 0)
-	break;
-    }
+      scoped_free_addrinfo freeaddrinfo (ainfo);
 
-  if (iter == NULL)
-    perror_with_name ("Can't open socket");
+      for (iter = ainfo; iter != NULL; iter = iter->ai_next)
+	{
+	  listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
+					    iter->ai_protocol);
 
-  /* Allow rapid reuse of this port. */
-  tmp = 1;
-  setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
-	      sizeof (tmp));
+	  if (listen_desc >= 0)
+	    break;
+	}
 
-  switch (iter->ai_family)
-    {
-    case AF_INET:
-      ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
-      break;
-    case AF_INET6:
-      ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
-      break;
-    default:
-      internal_error (__FILE__, __LINE__,
-		      _("Invalid 'ai_family' %d\n"), iter->ai_family);
+      if (iter == NULL)
+	perror_with_name ("Can't open socket");
+
+      /* Allow rapid reuse of this port. */
+      tmp = 1;
+      setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
+		  sizeof (tmp));
+
+      switch (iter->ai_family)
+	{
+	case AF_INET:
+	  ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
+	  break;
+	case AF_INET6:
+	  ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
+	  break;
+	default:
+	  internal_error (__FILE__, __LINE__,
+			  _("Invalid 'ai_family' %d\n"), iter->ai_family);
+	}
+      addr = iter->ai_addr;
+      addrlen = iter->ai_addrlen;
     }
 
-  if (bind (listen_desc, iter->ai_addr, iter->ai_addrlen) != 0)
+  if (bind (listen_desc, addr, addrlen) != 0)
     perror_with_name ("Can't bind address");
 
   if (listen (listen_desc, 1) != 0)
@@ -334,6 +397,9 @@ remote_open (const char *name)
   const char *port_str;
 
   port_str = strchr (name, ':');
+  struct stat statbuf;
+  int stat_result = stat (name, &statbuf);
+
 #ifdef USE_WIN32API
   if (port_str == NULL)
     error ("Only HOST:PORT is supported on this platform.");
@@ -353,12 +419,10 @@ remote_open (const char *name)
       add_file_handler (remote_desc, handle_serial_event, NULL);
     }
 #ifndef USE_WIN32API
-  else if (port_str == NULL)
+  else if (port_str == NULL && stat_result == 0
+	   && 0 == (S_IFSOCK & statbuf.st_mode))
     {
-      struct stat statbuf;
-
-      if (stat (name, &statbuf) == 0
-	  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
+      if (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode))
 	remote_desc = open (name, O_RDWR);
       else
 	{
-- 
2.11.0

Gdbserver can listen on local domain sockets.

[John Darrington]

This is the complement to commit c1168a2f66553cd4730931cf59e3be8378a1a03f
It allows gdbserver to use a local (unix) domain socket instead of a TCP
socket. 

It probably doesn't have much practical use, except that it makes automated
testing of gdb's remote target a little easier.

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Eli Zaretskii]

> From: John Darrington <john@darrington.wattle.id.au>
> Cc: John Darrington <john@darrington.wattle.id.au>
> Date: Tue,  9 Oct 2018 19:32:57 +0200
> 
> When invoking gdbserver, if the COMM parameter does not include a colon (:) and
> is not the name of an existing character device, then a local (unix) domain
> socket will be created with that name and gdbserver will listen for connections
> on that.
> 
>     gdb/doc/
>     * gdb.texinfo (Server): Describe connection over a local domain socket.
> 
>     gdb/gdbserver/
>     * NEWS: Mention new feature.
>     * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
>     * remote-utils.c (remote_prepare): Create a local socket if requested.
>     * remote-utils.c (remote_open):  Don't attempt to open a file if it's a socket.
>     * remote-utils.c (handle_accept_event): Display the name of the socket on connection.

Thanks.  The documentation parts are approved, but I think we should
say somewhere that this feature is only available on systems that
support Unix domain sockets.

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Pedro Alves]

On 10/09/2018 06:32 PM, John Darrington wrote:
> When invoking gdbserver, if the COMM parameter does not include a colon (:) and
> is not the name of an existing character device, then a local (unix) domain
> socket will be created with that name and gdbserver will listen for connections
> on that.

Is that "colon/no-colon" magic something that tools frequently do?
Off hand it doesn't seem like a good idea to me, because if you typo a
character device name or unix tcp host name, you end up creating a
unix socket.  I'd think an explicit option would be better.  E.g.,
reuse gdb's connection specs, i.e., a prefix, like:

 gdbserver unix:/tmp/some/path 

which can be extended just like gdb's:

 gdbserver tcp:host:port
 gdbserver tcp6:host:port

etc.

That would suggest extending parse_connection_spec to support "unix" specs.

> 
>     gdb/doc/
>     * gdb.texinfo (Server): Describe connection over a local domain socket.
> 
>     gdb/gdbserver/
>     * NEWS: Mention new feature.

NEWS is under gdb/, not gdb/gdbserver/.

>     * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
>     * remote-utils.c (remote_prepare): Create a local socket if requested.
>     * remote-utils.c (remote_open):  Don't attempt to open a file if it's a socket.
>     * remote-utils.c (handle_accept_event): Display the name of the socket on connection.

Don't repeat "* remote-utils.c" for the second and third functions.

Add "* configure: Regenerate.".


> ---
>  gdb/NEWS                     |   4 ++
>  gdb/doc/gdb.texinfo          |  26 +++++--
>  gdb/gdbserver/configure.ac   |   2 +-
>  gdb/gdbserver/remote-utils.c | 164 ++++++++++++++++++++++++++++++-------------
>  4 files changed, 141 insertions(+), 55 deletions(-)
> 
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 78d20713a8..95c5083d9b 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -15,6 +15,10 @@
>    can be passed using the '[ADDRESS]:PORT' notation, or the regular
>    'ADDRESS:PORT' method.
>  
> +* GDB and GDBserver now support local domain socket connections.  The
> +  name of a local domain socket may be provided instead of the
> +  [ADDRESS]:PORT notation.
> +
>  * DWARF index cache: GDB can now automatically save indices of DWARF
>    symbols on disk to speed up further loading of the same binaries.
>  
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index efd6dffb1e..44b319ebc7 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -21075,9 +21075,13 @@ syntax is:
>  target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
>  @end smallexample
>  
> -@var{comm} is either a device name (to use a serial line), or a TCP
> +@var{comm} is either an existing device name (to use a serial line), or a TCP
>  hostname and portnumber, or @code{-} or @code{stdio} to use
>  stdin/stdout of @code{gdbserver}.
> +If @var{comm} is none of the above, then a local domain socket
> +will be created with that name.
> +@cindex local socket
> +@cindex Unix domain socket
>  For example, to debug Emacs with the argument
>  @samp{foo.txt} and communicate with @value{GDBN} over the serial port
>  @file{/dev/com1}:
> @@ -21107,6 +21111,20 @@ conflicts with another service, @code{gdbserver} prints an error message
>  and exits.}  You must use the same port number with the host @value{GDBN}
>  @code{target remote} command.
>  
> +If the target and local machine are one and the same, then you can
> +use local domain socket instead of a TCP connection:
> +
> +@smallexample
> +target> gdbserver /tmp/local-socket emacs foo.txt
> +@end smallexample
> +
> +A local domain socket called @file{/tmp/local-socket} will be created
> +in the filesystem.
> +If there is already a local domain socket with this name it will be removed.
> +@smallexample
> +(gdb) target remote /tmp/local-socket
> +@end smallexample
> +
>  The @code{stdio} connection is useful when starting @code{gdbserver}
>  with ssh:
>  
> @@ -21155,10 +21173,10 @@ In case more than one copy of @var{program} is running, or @var{program}
>  has multiple threads, most versions of @code{pidof} support the
>  @code{-s} option to only return the first process ID.
>  
> -@subsubsection TCP port allocation lifecycle of @code{gdbserver}
> +@subsubsection Socket lifecycle of @code{gdbserver}
>  
>  This section applies only when @code{gdbserver} is run to listen on a TCP
> -port.
> +port or a unix domain socket.
>  
>  @code{gdbserver} normally terminates after all of its debugged processes have
>  terminated in @kbd{target remote} mode.  On the other hand, for @kbd{target
> @@ -21174,7 +21192,7 @@ Such reconnecting is useful for features like @ref{disconnected tracing}.  For
>  completeness, at most one @value{GDBN} can be connected at a time.
>  
>  @cindex @option{--once}, @code{gdbserver} option
> -By default, @code{gdbserver} keeps the listening TCP port open, so that
> +By default, @code{gdbserver} keeps the listening socket open, so that
>  subsequent connections are possible.  However, if you start @code{gdbserver}
>  with the @option{--once} option, it will stop listening for any further
>  connection attempts after connecting to the first @value{GDBN} session.  This
> diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
> index fa3ca53efd..de7e7d4103 100644
> --- a/gdb/gdbserver/configure.ac
> +++ b/gdb/gdbserver/configure.ac
> @@ -98,7 +98,7 @@ ACX_CONFIGURE_DIR(["../../libiberty"], ["build-libiberty-gdbserver"])
>  AC_CHECK_HEADERS(termios.h sys/reg.h string.h dnl
>  		 proc_service.h sys/procfs.h linux/elf.h dnl
>  		 fcntl.h signal.h sys/file.h dnl
> -		 sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
> +		 sys/ioctl.h netinet/in.h sys/socket.h sys/un.h netdb.h dnl
>  		 netinet/tcp.h arpa/inet.h)
>  AC_FUNC_FORK
>  AC_CHECK_FUNCS(getauxval pread pwrite pread64 setns)
> diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
> index 9199a9c7ad..00e3340156 100644
> --- a/gdb/gdbserver/remote-utils.c
> +++ b/gdb/gdbserver/remote-utils.c
> @@ -38,6 +38,9 @@
>  #if HAVE_NETINET_IN_H
>  #include <netinet/in.h>
>  #endif
> +#if HAVE_SYS_UN_H
> +#include <sys/un.h>
> +#endif
>  #if HAVE_SYS_SOCKET_H
>  #include <sys/socket.h>
>  #endif
> @@ -193,20 +196,35 @@ handle_accept_event (int err, gdb_client_data client_data)
>       descriptor open for add_file_handler to wait for a new connection.  */
>    delete_file_handler (listen_desc);
>  
> -  /* Convert IP address to string.  */
> -  char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
> -
> -  int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
> -		       orig_host, sizeof (orig_host),
> -		       orig_port, sizeof (orig_port),
> -		       NI_NUMERICHOST | NI_NUMERICSERV);
> +  if (sockaddr.ss_family == AF_UNIX)
> +    {
> +      struct sockaddr_un su;
> +      socklen_t len;
> +      if (0 != getsockname (listen_desc, (struct sockaddr *) &su, &len))

We don't use that "constant on lhs style".  Put the 0 != on the rhs.

> +	{
> +	  perror (_("Could not obtain remote address"));
> +	}

Remove unnecessary curly braces.

>  
> -  if (r != 0)
> -    fprintf (stderr, _("Could not obtain remote address: %s\n"),
> -	     gai_strerror (r));
> +      fprintf (stderr, _("Remote debugging on local socket bound to %s\n"),
> +	       su.sun_path);
> +    }
>    else
> -    fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
> -	     orig_host, orig_port);
> +    {
> +      /* Convert IP address to string.  */
> +      char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
> +
> +      int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
> +			   orig_host, sizeof (orig_host),
> +			   orig_port, sizeof (orig_port),
> +			   NI_NUMERICHOST | NI_NUMERICSERV);
> +
> +      if (r != 0)
> +	fprintf (stderr, _("Could not obtain remote address: %s\n"),
> +		 gai_strerror (r));
> +      else
> +	fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
> +		 orig_host, orig_port);
> +    }
>  
>    enable_async_notification (remote_desc);
>  
> @@ -250,6 +268,9 @@ remote_prepare (const char *name)
>    struct addrinfo hint;
>    struct addrinfo *ainfo;
>  
> +  struct sockaddr *addr;
> +  socklen_t addrlen;
> +
>    memset (&hint, 0, sizeof (hint));
>    /* Assume no prefix will be passed, therefore we should use
>       AF_UNSPEC.  */
> @@ -260,10 +281,17 @@ remote_prepare (const char *name)
>    parsed_connection_spec parsed
>      = parse_connection_spec_without_prefix (name, &hint);
>  
> +  struct stat statbuf;
> +  int stat_result = stat (name, &statbuf);
> +
>    if (parsed.port_str.empty ())
>      {
> -      cs.transport_is_reliable = 0;
> -      return;
> +      if (stat_result == 0
> +	  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
> +	{
> +	  cs.transport_is_reliable = 0;
> +	  return;
> +	}
>      }
>  
>  #ifdef USE_WIN32API
> @@ -276,47 +304,82 @@ remote_prepare (const char *name)
>      }
>  #endif
>  
> -  int r = getaddrinfo (parsed.host_str.c_str (), parsed.port_str.c_str (),
> -		       &hint, &ainfo);
> +  struct sockaddr_un unix_addr;
>  
> -  if (r != 0)
> -    error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
> +#ifndef UNIX_PATH_MAX
> +#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
> +#endif
>  
> -  scoped_free_addrinfo freeaddrinfo (ainfo);
> +  if (parsed.port_str.empty ())
> +    {
> +      if (strlen (name) > UNIX_PATH_MAX - 1)
> +	{
> +	  error
> +	    (_("%s is too long.  Socket names may be no longer than %s bytes."),
> +	     name, pulongest (UNIX_PATH_MAX - 1));
> +	  return;
> +	}
> +      listen_desc = socket (AF_UNIX,  SOCK_STREAM,  0);
> +      if (listen_desc < 0)
> +	perror_with_name ("Can't open socket");
> +
> +      memset (&unix_addr, 0, sizeof (unix_addr));
> +      unix_addr.sun_family = AF_UNIX;
> +      strncpy (unix_addr.sun_path, parsed.host_str.c_str(), UNIX_PATH_MAX - 1);
> +      if (stat_result == 0
> +	  && (S_IFSOCK & statbuf.st_mode))
> +	unlink (name);
> +
> +      addr = (struct sockaddr *) &unix_addr;
> +      addrlen = sizeof (unix_addr);
> +    }
> +  else
> +    {
> +      struct addrinfo *iter;
>  
> -  struct addrinfo *iter;
> +      int r = getaddrinfo (parsed.host_str.c_str (),
> +			   parsed.port_str.c_str (),
> +			   &hint, &ainfo);
>  
> -  for (iter = ainfo; iter != NULL; iter = iter->ai_next)
> -    {
> -      listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
> -					iter->ai_protocol);
> +      if (r != 0)
> +	error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
>  
> -      if (listen_desc >= 0)
> -	break;
> -    }
> +      scoped_free_addrinfo freeaddrinfo (ainfo);
>  
> -  if (iter == NULL)
> -    perror_with_name ("Can't open socket");
> +      for (iter = ainfo; iter != NULL; iter = iter->ai_next)
> +	{
> +	  listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
> +					    iter->ai_protocol);
>  
> -  /* Allow rapid reuse of this port. */
> -  tmp = 1;
> -  setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
> -	      sizeof (tmp));
> +	  if (listen_desc >= 0)
> +	    break;
> +	}
>  
> -  switch (iter->ai_family)
> -    {
> -    case AF_INET:
> -      ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
> -      break;
> -    case AF_INET6:
> -      ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
> -      break;
> -    default:
> -      internal_error (__FILE__, __LINE__,
> -		      _("Invalid 'ai_family' %d\n"), iter->ai_family);
> +      if (iter == NULL)
> +	perror_with_name ("Can't open socket");
> +
> +      /* Allow rapid reuse of this port. */
> +      tmp = 1;
> +      setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
> +		  sizeof (tmp));
> +
> +      switch (iter->ai_family)
> +	{
> +	case AF_INET:
> +	  ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
> +	  break;
> +	case AF_INET6:
> +	  ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
> +	  break;
> +	default:
> +	  internal_error (__FILE__, __LINE__,
> +			  _("Invalid 'ai_family' %d\n"), iter->ai_family);
> +	}
> +      addr = iter->ai_addr;
> +      addrlen = iter->ai_addrlen;
>      }
>  
> -  if (bind (listen_desc, iter->ai_addr, iter->ai_addrlen) != 0)
> +  if (bind (listen_desc, addr, addrlen) != 0)
>      perror_with_name ("Can't bind address");
>  
>    if (listen (listen_desc, 1) != 0)
> @@ -334,6 +397,9 @@ remote_open (const char *name)
>    const char *port_str;
>  
>    port_str = strchr (name, ':');
> +  struct stat statbuf;
> +  int stat_result = stat (name, &statbuf);
> +
>  #ifdef USE_WIN32API
>    if (port_str == NULL)
>      error ("Only HOST:PORT is supported on this platform.");
> @@ -353,12 +419,10 @@ remote_open (const char *name)
>        add_file_handler (remote_desc, handle_serial_event, NULL);
>      }
>  #ifndef USE_WIN32API
> -  else if (port_str == NULL)
> +  else if (port_str == NULL && stat_result == 0
> +	   && 0 == (S_IFSOCK & statbuf.st_mode))

Constant on rhs.

>      {
> -      struct stat statbuf;
> -
> -      if (stat (name, &statbuf) == 0
> -	  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
> +      if (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode))
>  	remote_desc = open (name, O_RDWR);
>        else
>  	{
> 

Thanks,
Pedro Alves

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

On Tue, Oct 09, 2018 at 07:02:14PM +0100, Pedro Alves wrote:
     On 10/09/2018 06:32 PM, John Darrington wrote:
     > When invoking gdbserver, if the COMM parameter does not include a colon (:) and
     > is not the name of an existing character device, then a local (unix) domain
     > socket will be created with that name and gdbserver will listen for connections
     > on that.
     
     Is that "colon/no-colon" magic something that tools frequently do?

Not exactly.  Tools with which I'm familiar with work as follows:

:1234           Creates a unix domain socket on the local host called 1234
localhost:1234  Listens on TCP port 1234

which is the way I think gdb ought to work, but this would be
inconsistent with it's current behaviour and cause confusion if somebody
used an old version of gdb with a new version of gdbserver or
vici-versa.

J'

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Pedro Alves]

On 10/09/2018 07:41 PM, John Darrington wrote:
> On Tue, Oct 09, 2018 at 07:02:14PM +0100, Pedro Alves wrote:
>      On 10/09/2018 06:32 PM, John Darrington wrote:
>      > When invoking gdbserver, if the COMM parameter does not include a colon (:) and
>      > is not the name of an existing character device, then a local (unix) domain
>      > socket will be created with that name and gdbserver will listen for connections
>      > on that.
>      
>      Is that "colon/no-colon" magic something that tools frequently do?
> 
> Not exactly.  Tools with which I'm familiar with work as follows:
> 
> :1234           Creates a unix domain socket on the local host called 1234
> localhost:1234  Listens on TCP port 1234
> 
> which is the way I think gdb ought to work, but this would be
> inconsistent with it's current behaviour and cause confusion if somebody
> used an old version of gdb with a new version of gdbserver or
> vici-versa.

In that example you didn't even pass a path to a unix domain socket.
You let the tool create it, I suppose.  It doesn't feel like
apples to apples.

In those tools you know, how would you pass the path to the local
socket then?

Thanks,
Pedro Alves

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

On Tue, Oct 09, 2018 at 07:53:55PM +0100, Pedro Alves wrote:
     On 10/09/2018 07:41 PM, John Darrington wrote:
     > On Tue, Oct 09, 2018 at 07:02:14PM +0100, Pedro Alves wrote:
     >      On 10/09/2018 06:32 PM, John Darrington wrote:
     >      > When invoking gdbserver, if the COMM parameter does not include a colon (:) and
     >      > is not the name of an existing character device, then a local (unix) domain
     >      > socket will be created with that name and gdbserver will listen for connections
     >      > on that.
     >      
     >      Is that "colon/no-colon" magic something that tools frequently do?
     > 
     > Not exactly.  Tools with which I'm familiar with work as follows:
     > 
     > :1234           Creates a unix domain socket on the local host called 1234
     > localhost:1234  Listens on TCP port 1234
     > 
     > which is the way I think gdb ought to work, but this would be
     > inconsistent with it's current behaviour and cause confusion if somebody
     > used an old version of gdb with a new version of gdbserver or
     > vici-versa.
     
     In that example you didn't even pass a path to a unix domain socket.
     You let the tool create it, I suppose.  It doesn't feel like
     apples to apples.
     
     In those tools you know, how would you pass the path to the local
     socket then?
     

If you give no path, it'll refer to a socket in the current working
directory.  An example with a path would be  :/tmp/this/socket

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Pedro Alves]

-- 
Thanks,
Pedro Alves
On 10/09/2018 08:00 PM, John Darrington wrote:
> On Tue, Oct 09, 2018 at 07:53:55PM +0100, Pedro Alves wrote:
>      On 10/09/2018 07:41 PM, John Darrington wrote:
>      > On Tue, Oct 09, 2018 at 07:02:14PM +0100, Pedro Alves wrote:
>      >      On 10/09/2018 06:32 PM, John Darrington wrote:
>      >      > When invoking gdbserver, if the COMM parameter does not include a colon (:) and
>      >      > is not the name of an existing character device, then a local (unix) domain
>      >      > socket will be created with that name and gdbserver will listen for connections
>      >      > on that.
>      >      
>      >      Is that "colon/no-colon" magic something that tools frequently do?
>      > 
>      > Not exactly.  Tools with which I'm familiar with work as follows:
>      > 
>      > :1234           Creates a unix domain socket on the local host called 1234
>      > localhost:1234  Listens on TCP port 1234
>      > 
>      > which is the way I think gdb ought to work, but this would be
>      > inconsistent with it's current behaviour and cause confusion if somebody
>      > used an old version of gdb with a new version of gdbserver or
>      > vici-versa.
>      
>      In that example you didn't even pass a path to a unix domain socket.
>      You let the tool create it, I suppose.  It doesn't feel like
>      apples to apples.
>      
>      In those tools you know, how would you pass the path to the local
>      socket then?
>      
> 
> If you give no path, it'll refer to a socket in the current working
> directory.  An example with a path would be  :/tmp/this/socket

Ah, I see now.

Still, yeah, I don't think we can change GDB like that.

Thanks,
Pedro Alves

[PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

[John Darrington]

gdb/doc:
* gdb.texinfo (Connecting)[Remote Connection Commands]:  Provide alternative
  unix::/tmp/xxx example.  Include @code{unix::@var{local-socket} in
  the list of remote and extended-remote syntaxes.
---
 gdb/doc/gdb.texinfo | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index b0dc3bf67c..1e97d692b6 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -20829,6 +20829,15 @@ 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.
+The above command is identical to the command:
+
+@smallexample
+target remote unix::/tmp/gdb-socket1
+@end smallexample
+@noindent
+
+See below for the explanation of this syntax.
+
 This feature is not available if the host system does not support
 Unix domain sockets.
 
@@ -20839,6 +20848,7 @@ Unix domain sockets.
 @itemx target remote @code{tcp4:@var{host}:@var{port}}
 @itemx target remote @code{tcp6:@var{host}:@var{port}}
 @itemx target remote @code{tcp6:@var{[host]}:@var{port}}
+@itemx target remote @code{unix::@var{local-socket}}
 @itemx target extended-remote @code{@var{host}:@var{port}}
 @itemx target extended-remote @code{@var{[host]}:@var{port}}
 @itemx target extended-remote @code{tcp:@var{host}:@var{port}}
@@ -20846,8 +20856,10 @@ Unix domain sockets.
 @itemx target extended-remote @code{tcp4:@var{host}:@var{port}}
 @itemx target extended-remote @code{tcp6:@var{host}:@var{port}}
 @itemx target extended-remote @code{tcp6:@var{[host]}:@var{port}}
+@itemx target extended-remote @code{unix::@var{local-socket}}
 @cindex @acronym{TCP} port, @code{target remote}
-Debug using a @acronym{TCP} connection to @var{port} on @var{host}.
+Debug using a @acronym{TCP} connection to @var{port} on @var{host}
+or using the Unix domain socket @var{local-socket} on the local machine.
 The @var{host} may be either a host name, a numeric @acronym{IPv4}
 address, or a numeric @acronym{IPv6} address (with or without the
 square brackets to separate the address from the port); @var{port}
@@ -20895,6 +20907,16 @@ target remote :1234
 @noindent
 
 Note that the colon is still required here.
+Alternatively you can use a Unix domain socket:
+
+@smallexample
+target remote unix::/tmp/gdb-socket1
+@end smallexample
+@noindent
+
+This has the advantage that it'll not fail if the port number is already
+in use.
+
 
 @item target remote @code{udp:@var{host}:@var{port}}
 @itemx target remote @code{udp:@var{[host]}:@var{port}}
-- 
2.11.0

[PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[John Darrington]

The documentation did not mention the possibility of invoking gdbserver
with the new connection forms such as tcp6:host:port.  This change fixes
that.

gdb/doc/

  * gdb.texinfo (Server): Tabulate the various permitted forms of the @var{comm}
   metasyntactical variable.  Include the unix:@var{host}:@var{socket} form as
   one of them.
---
 gdb/doc/gdb.texinfo | 60 +++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 44 insertions(+), 16 deletions(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 1e97d692b6..e3b62221cf 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21097,9 +21097,19 @@ syntax is:
 target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
 @end smallexample
 
-@var{comm} is either a device name (to use a serial line), or a TCP
-hostname and portnumber, or @code{-} or @code{stdio} to use
-stdin/stdout of @code{gdbserver}.
+@code{gdbserver} waits passively for the host @value{GDBN} to communicate
+with it.
+
+@var{comm} may take several forms:
+
+@table @code
+@item @code{@var{device}}
+A serial line device.
+
+@item @code{-}
+@itemx @code{stdio}
+To use the stdin/stdout of @code{gdbserver}.
+
 For example, to debug Emacs with the argument
 @samp{foo.txt} and communicate with @value{GDBN} over the serial port
 @file{/dev/com1}:
@@ -21108,8 +21118,27 @@ For example, to debug Emacs with the argument
 target> gdbserver /dev/com1 emacs foo.txt
 @end smallexample
 
-@code{gdbserver} waits passively for the host @value{GDBN} to communicate
-with it.
+The @code{stdio} connection is useful when starting @code{gdbserver}
+with ssh:
+
+@smallexample
+(gdb) target remote | ssh -T hostname gdbserver - hello
+@end smallexample
+
+The @samp{-T} option to ssh is provided because we don't need a remote pty,
+and we don't want escape-character handling.  Ssh does this by default when
+a command is provided, the flag is provided to make it explicit.
+You could elide it if you want to.
+
+Programs started with stdio-connected gdbserver have @file{/dev/null} for
+@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
+display through a pipe connected to gdbserver.
+Both @code{stdout} and @code{stderr} use the same pipe.
+
+@item @code{@var{host}:@var{port}}
+@itemx @code{tcp:@var{host}:@var{port}}
+@itemx @code{tcp4:@var{host}:@var{port}}
+To use a @acronym{TCP} @acronym{IPv4} socket connection on port number @var{port}.
 
 To use a TCP connection instead of a serial line:
 
@@ -21129,22 +21158,21 @@ conflicts with another service, @code{gdbserver} prints an error message
 and exits.}  You must use the same port number with the host @value{GDBN}
 @code{target remote} command.
 
-The @code{stdio} connection is useful when starting @code{gdbserver}
-with ssh:
+
+@item @code{tcp6:@var{host}:@var{port}}
+To use a @acronym{TCP} @acronym{IPv6} socket connection on port number @var{port}.
+
+@item @code{unix:@var{host}:@var{local-socket}}
+To use a Unix domain socket.  This will create a socket with the file
+system entry @var{local-socket} and listen on that.  For example:
 
 @smallexample
-(gdb) target remote | ssh -T hostname gdbserver - hello
+target> gdbserver unix:localhost:/tmp/gdb-socket0 emacs foo.txt
 @end smallexample
 
-The @samp{-T} option to ssh is provided because we don't need a remote pty,
-and we don't want escape-character handling.  Ssh does this by default when
-a command is provided, the flag is provided to make it explicit.
-You could elide it if you want to.
+@var{host} must either be the null string or the literal string @code{localhost}.
+@end table
 
-Programs started with stdio-connected gdbserver have @file{/dev/null} for
-@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
-display through a pipe connected to gdbserver.
-Both @code{stdout} and @code{stderr} use the same pipe.
 
 @anchor{Attaching to a program}
 @subsubsection Attaching to a Running Program
-- 
2.11.0

[PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

When invoking gdbserver, if the COMM parameter takes the form "unix::/path/name"
then a local (unix) domain socket will be created with that name and gdbserver
will listen for connections on that.

    gdb/
    * NEWS: Mention new feature.

    gdb/gdbserver/
    * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
    * configure: Regenerate.
    * remote-utils.c (remote_prepare): Create a local socket if requested.
     (remote_open):  Don't attempt to open a file if it's a socket.
     (handle_accept_event): Display the name of the socket on connection.

   gdb/common/
   * netstuff.c (parse_connection_spec)[prefixes]: New member for local domain sockets.
---
 gdb/NEWS                     |   4 ++
 gdb/common/netstuff.c        |   9 +++
 gdb/gdbserver/configure.ac   |   2 +-
 gdb/gdbserver/remote-utils.c | 148 ++++++++++++++++++++++++++++++-------------
 4 files changed, 117 insertions(+), 46 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 126e61e282..23de349324 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -15,6 +15,10 @@
   can be passed using the '[ADDRESS]:PORT' notation, or the regular
   'ADDRESS:PORT' method.
 
+* GDB and GDBserver now support local domain socket connections.  The
+  name of a local domain socket may be provided instead of the
+  [ADDRESS]:PORT notation.
+
 * DWARF index cache: GDB can now automatically save indices of DWARF
   symbols on disk to speed up further loading of the same binaries.
 
diff --git a/gdb/common/netstuff.c b/gdb/common/netstuff.c
index c1c401ccb2..8da6aba24e 100644
--- a/gdb/common/netstuff.c
+++ b/gdb/common/netstuff.c
@@ -57,6 +57,8 @@ parse_connection_spec_without_prefix (std::string spec, struct addrinfo *hint)
 			  || std::count (spec.begin (),
 					 spec.end (), ':') > 1)));
 
+  bool is_unix = hint->ai_family == AF_UNIX;
+
   if (is_ipv6)
     {
       if (spec[0] == '[')
@@ -109,6 +111,12 @@ parse_connection_spec_without_prefix (std::string spec, struct addrinfo *hint)
   if (ret.host_str.empty ())
     ret.host_str = "localhost";
 
+  if (is_unix && ret.host_str != "localhost")
+    error (_("The host name must be empty or 'localhost' for a unix domain socket."));
+
+  if (is_unix && ret.port_str.empty ())
+    error (_("A path name must be specified for a unix domain socket."));
+
   return ret;
 }
 
@@ -138,6 +146,7 @@ parse_connection_spec (const char *spec, struct addrinfo *hint)
       { "tcp4:", AF_INET,   SOCK_STREAM },
       { "udp6:", AF_INET6,  SOCK_DGRAM },
       { "tcp6:", AF_INET6,  SOCK_STREAM },
+      { "unix:", AF_LOCAL,  SOCK_STREAM },
     };
 
   for (const host_prefix prefix : prefixes)
diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
index fa3ca53efd..de7e7d4103 100644
--- a/gdb/gdbserver/configure.ac
+++ b/gdb/gdbserver/configure.ac
@@ -98,7 +98,7 @@ ACX_CONFIGURE_DIR(["../../libiberty"], ["build-libiberty-gdbserver"])
 AC_CHECK_HEADERS(termios.h sys/reg.h string.h dnl
 		 proc_service.h sys/procfs.h linux/elf.h dnl
 		 fcntl.h signal.h sys/file.h dnl
-		 sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
+		 sys/ioctl.h netinet/in.h sys/socket.h sys/un.h netdb.h dnl
 		 netinet/tcp.h arpa/inet.h)
 AC_FUNC_FORK
 AC_CHECK_FUNCS(getauxval pread pwrite pread64 setns)
diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
index 9199a9c7ad..0eb53c2116 100644
--- a/gdb/gdbserver/remote-utils.c
+++ b/gdb/gdbserver/remote-utils.c
@@ -38,6 +38,9 @@
 #if HAVE_NETINET_IN_H
 #include <netinet/in.h>
 #endif
+#if HAVE_SYS_UN_H
+#include <sys/un.h>
+#endif
 #if HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
@@ -193,20 +196,33 @@ handle_accept_event (int err, gdb_client_data client_data)
      descriptor open for add_file_handler to wait for a new connection.  */
   delete_file_handler (listen_desc);
 
-  /* Convert IP address to string.  */
-  char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
-
-  int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
-		       orig_host, sizeof (orig_host),
-		       orig_port, sizeof (orig_port),
-		       NI_NUMERICHOST | NI_NUMERICSERV);
+  if (sockaddr.ss_family == AF_UNIX)
+    {
+      struct sockaddr_un su;
+      socklen_t len;
+      if (getsockname (listen_desc, (struct sockaddr *) &su, &len) != 0)
+	perror (_("Could not obtain remote address"));
 
-  if (r != 0)
-    fprintf (stderr, _("Could not obtain remote address: %s\n"),
-	     gai_strerror (r));
+      fprintf (stderr, _("Remote debugging on local socket bound to %s\n"),
+	       su.sun_path);
+    }
   else
-    fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
-	     orig_host, orig_port);
+    {
+      /* Convert IP address to string.  */
+      char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
+
+      int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
+			   orig_host, sizeof (orig_host),
+			   orig_port, sizeof (orig_port),
+			   NI_NUMERICHOST | NI_NUMERICSERV);
+
+      if (r != 0)
+	fprintf (stderr, _("Could not obtain remote address: %s\n"),
+		 gai_strerror (r));
+      else
+	fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
+		 orig_host, orig_port);
+    }
 
   enable_async_notification (remote_desc);
 
@@ -250,6 +266,9 @@ remote_prepare (const char *name)
   struct addrinfo hint;
   struct addrinfo *ainfo;
 
+  struct sockaddr *addr;
+  socklen_t addrlen;
+
   memset (&hint, 0, sizeof (hint));
   /* Assume no prefix will be passed, therefore we should use
      AF_UNSPEC.  */
@@ -258,7 +277,7 @@ remote_prepare (const char *name)
   hint.ai_protocol = IPPROTO_TCP;
 
   parsed_connection_spec parsed
-    = parse_connection_spec_without_prefix (name, &hint);
+    = parse_connection_spec (name, &hint);
 
   if (parsed.port_str.empty ())
     {
@@ -276,47 +295,86 @@ remote_prepare (const char *name)
     }
 #endif
 
-  int r = getaddrinfo (parsed.host_str.c_str (), parsed.port_str.c_str (),
-		       &hint, &ainfo);
+  struct sockaddr_un unix_addr;
 
-  if (r != 0)
-    error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
+#endif
 
-  scoped_free_addrinfo freeaddrinfo (ainfo);
+  if (hint.ai_family == AF_LOCAL)
+    {
+      const char *sock_name = parsed.port_str.c_str ();
+      if (parsed.port_str.length() > UNIX_PATH_MAX - 1)
+	{
+	  error
+	    (_("%s is too long.  Socket names may be no longer than %s bytes."),
+	     sock_name, pulongest (UNIX_PATH_MAX - 1));
+	  return;
+	}
+      listen_desc = socket (AF_UNIX,  SOCK_STREAM,  0);
+      if (listen_desc < 0)
+	perror_with_name ("Can't open socket");
 
-  struct addrinfo *iter;
+      memset (&unix_addr, 0, sizeof (unix_addr));
+      unix_addr.sun_family = AF_UNIX;
+      strncpy (unix_addr.sun_path, sock_name, UNIX_PATH_MAX - 1);
 
-  for (iter = ainfo; iter != NULL; iter = iter->ai_next)
-    {
-      listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
-					iter->ai_protocol);
+      struct stat statbuf;
+      int stat_result = stat (sock_name, &statbuf);
+      if (stat_result == 0
+	  && (S_IFSOCK & statbuf.st_mode))
+	unlink (sock_name);
 
-      if (listen_desc >= 0)
-	break;
+      addr = (struct sockaddr *) &unix_addr;
+      addrlen = sizeof (unix_addr);
     }
+  else
+    {
+      struct addrinfo *iter;
 
-  if (iter == NULL)
-    perror_with_name ("Can't open socket");
+      int r = getaddrinfo (parsed.host_str.c_str (),
+			   parsed.port_str.c_str (),
+			   &hint, &ainfo);
 
-  /* Allow rapid reuse of this port. */
-  tmp = 1;
-  setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
-	      sizeof (tmp));
+      if (r != 0)
+	error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
 
-  switch (iter->ai_family)
-    {
-    case AF_INET:
-      ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
-      break;
-    case AF_INET6:
-      ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
-      break;
-    default:
-      internal_error (__FILE__, __LINE__,
-		      _("Invalid 'ai_family' %d\n"), iter->ai_family);
+      scoped_free_addrinfo freeaddrinfo (ainfo);
+
+      for (iter = ainfo; iter != NULL; iter = iter->ai_next)
+	{
+	  listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
+					    iter->ai_protocol);
+
+	  if (listen_desc >= 0)
+	    break;
+	}
+
+      if (iter == NULL)
+	perror_with_name ("Can't open socket");
+
+      /* Allow rapid reuse of this port. */
+      tmp = 1;
+      setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
+		  sizeof (tmp));
+
+      switch (iter->ai_family)
+	{
+	case AF_INET:
+	  ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
+	  break;
+	case AF_INET6:
+	  ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
+	  break;
+	default:
+	  internal_error (__FILE__, __LINE__,
+			  _("Invalid 'ai_family' %d\n"), iter->ai_family);
+	}
+      addr = iter->ai_addr;
+      addrlen = iter->ai_addrlen;
     }
 
-  if (bind (listen_desc, iter->ai_addr, iter->ai_addrlen) != 0)
+  if (bind (listen_desc, addr, addrlen) != 0)
     perror_with_name ("Can't bind address");
 
   if (listen (listen_desc, 1) != 0)
@@ -354,11 +412,11 @@ remote_open (const char *name)
     }
 #ifndef USE_WIN32API
   else if (port_str == NULL)
-    {
+     {
       struct stat statbuf;
 
       if (stat (name, &statbuf) == 0
-	  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
+         && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
 	remote_desc = open (name, O_RDWR);
       else
 	{
-- 
2.11.0

[PATCH 4/4] GDB: Remote target can now accept the form unix::/path/to/socket.

[John Darrington]

Allow target remote to use the unix::/path/to/socket syntax as well as just
plain /path/to/socket

gdb/

  * ser-uds.c (uds_open): Use parse_connection_spec to deal with the
    comm form unix::/path/to/socket.

  * serial.c (serial_open): Consider the "unix:" prefix when deciding which
    interface to use.
---
 gdb/ser-uds.c | 18 ++++++++++++++++--
 gdb/serial.c  |  5 +++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/gdb/ser-uds.c b/gdb/ser-uds.c
index a98469f67b..acace258be 100644
--- a/gdb/ser-uds.c
+++ b/gdb/ser-uds.c
@@ -23,6 +23,8 @@
 
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <netdb.h>
+#include "netstuff.h"
 
 #ifndef UNIX_PATH_MAX
 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
@@ -33,9 +35,21 @@
 static int
 uds_open (struct serial *scb, const char *name)
 {
+  struct addrinfo hint;
+
+  memset (&hint, 0, sizeof (hint));
+  /* Assume no prefix will be passed, therefore we should use
+     AF_UNSPEC.  */
+  hint.ai_family = AF_UNSPEC;
+  hint.ai_socktype = SOCK_STREAM;
+
+  parsed_connection_spec parsed = parse_connection_spec (name, &hint);
+
+  const char *socket_name = parsed.port_str.empty() ? name : parsed.port_str.c_str ();
+
   struct sockaddr_un addr;
 
-  if (strlen (name) > UNIX_PATH_MAX - 1)
+  if (strlen (socket_name) > UNIX_PATH_MAX - 1)
     {
       warning
         (_("The socket name is too long.  It may be no longer than %s bytes."),
@@ -45,7 +59,7 @@ uds_open (struct serial *scb, const char *name)
 
   memset (&addr, 0, sizeof addr);
   addr.sun_family = AF_UNIX;
-  strncpy (addr.sun_path, name, UNIX_PATH_MAX - 1);
+  strncpy (addr.sun_path, socket_name, UNIX_PATH_MAX - 1);
 
   int sock = socket (AF_UNIX, SOCK_STREAM, 0);
 
diff --git a/gdb/serial.c b/gdb/serial.c
index 7f9362a3bf..f7c3e6e5ee 100644
--- a/gdb/serial.c
+++ b/gdb/serial.c
@@ -210,7 +210,7 @@ serial_open (const char *name)
   /* Check for a colon, suggesting an IP address/port pair.
      Do this *after* checking for all the interesting prefixes.  We
      don't want to constrain the syntax of what can follow them.  */
-  else if (strchr (name, ':'))
+  else if (!startswith (name, "unix:") && (strchr (name, ':')))
     ops = serial_interface_lookup ("tcp");
   else
     {
@@ -218,7 +218,8 @@ serial_open (const char *name)
       /* Check to see if name is a socket.  If it is, then treat it
          as such.  Otherwise assume that it's a character device.  */
       struct stat sb;
-      if (stat (name, &sb) == 0 && (sb.st_mode & S_IFMT) == S_IFSOCK)
+      if (startswith (name, "unix:") ||
+	  (stat (name, &sb) == 0 && (sb.st_mode & S_IFMT) == S_IFSOCK))
 	ops = serial_interface_lookup ("local");
       else
 #endif
-- 
2.11.0

Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[Eli Zaretskii]

> From: John Darrington <john@darrington.wattle.id.au>
> Cc: John Darrington <john@darrington.wattle.id.au>
> Date: Sat, 13 Oct 2018 19:58:00 +0200
> 
> The documentation did not mention the possibility of invoking gdbserver
> with the new connection forms such as tcp6:host:port.  This change fixes
> that.

Thanks.  Please see a few comments below.

> +@table @code
> +@item @code{@var{device}}
> +A serial line device.

Since your @table uses @code by default, there's no need to use @code
in each @item of the table.

> +@var{host} must either be the null string or the literal string @code{localhost}.

What is a "null string"?  Do you mean an empty string?

Thanks.

Re: [PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

[Eli Zaretskii]

> From: John Darrington <john@darrington.wattle.id.au>
> Cc: John Darrington <john@darrington.wattle.id.au>
> Date: Sat, 13 Oct 2018 19:57:59 +0200
> 
> gdb/doc:
> * gdb.texinfo (Connecting)[Remote Connection Commands]:  Provide alternative
>   unix::/tmp/xxx example.  Include @code{unix::@var{local-socket} in
>   the list of remote and extended-remote syntaxes.

OK.

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Eli Zaretskii]

> From: John Darrington <john@darrington.wattle.id.au>
> Cc: John Darrington <john@darrington.wattle.id.au>
> Date: Sat, 13 Oct 2018 19:57:58 +0200
> 
> When invoking gdbserver, if the COMM parameter takes the form "unix::/path/name"
> then a local (unix) domain socket will be created with that name and gdbserver
> will listen for connections on that.
> 
>     gdb/
>     * NEWS: Mention new feature.
> 
>     gdb/gdbserver/
>     * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
>     * configure: Regenerate.
>     * remote-utils.c (remote_prepare): Create a local socket if requested.
>      (remote_open):  Don't attempt to open a file if it's a socket.
>      (handle_accept_event): Display the name of the socket on connection.
> 
>    gdb/common/
>    * netstuff.c (parse_connection_spec)[prefixes]: New member for local domain sockets.

OK for the NEWS part.

Thanks.

Re: [PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

[Simon Tatham]

On 13/10/18 18:57, John Darrington wrote:
> +Alternatively you can use a Unix domain socket:
> +
> +@smallexample
> +target remote unix::/tmp/gdb-socket1
> +@end smallexample
> +@noindent
> +
> +This has the advantage that it'll not fail if the port number is already
> +in use.
> +

Hi,

I was pointed at this thread by a colleague, because last week I was 
also considering submitting a patch to allow gdb and gdbserver to talk 
to each other over Unix-domain sockets, and he pointed out that it was 
already in progress :-)

I'd like to suggest that this documentation change under-stresses what I 
see as the most important reason why this is a useful feature: security.

The gdbserver protocol is cleartext and unauthenticated. Running it on a 
TCP port means that anyone who can connect to that port – and depending 
on the network environment, that might be a lot of people – can request 
gdbserver to execute arbitrary code in the context of the process being 
debugged, without having to give a vestige of proof as to their right to 
ask for it. This is not really the kind of feature we like about network 
protocols in the modern world!

But Unix-domain sockets are access-controlled via the file permissions 
on the path leading to the socket file. If you use this new feature to 
make a Unix-domain socket inside a directory that only your user id has 
access to, then any process physically capable of connecting to the 
socket has already proved its right to run code under your user id. So 
this solves the whole issue, while keeping all the other conveniences of 
the socket-based gdbserver transport.

Also, current versions of OpenSSH support general forwarding of 
Unix-domain sockets over SSH connections. Using that, it should even be 
possible to use this system for genuinely _remote_ debugging (i.e. 
between different machines), without reintroducing the same security 
hazard, because the Unix socket at each end is access-controlled, and 
the network connection in between them is cryptographically protected.

Cheers,
Simon

Re: [PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

[John Darrington]

On Mon, Oct 15, 2018 at 10:31:01AM +0100, Simon Tatham wrote:
     Hi,
     
     I was pointed at this thread by a colleague, because last week I was also
     considering submitting a patch to allow gdb and gdbserver to talk to each
     other over Unix-domain sockets, and he pointed out that it was already in
     progress :-)
     
     I'd like to suggest that this documentation change under-stresses what I
     see as the most important reason why this is a useful feature: security.
     
     The gdbserver protocol is cleartext and unauthenticated. Running it on a
     TCP port means that anyone who can connect to that port ??? and depending
     on the network environment, that might be a lot of people ??? can request
     gdbserver to execute arbitrary code in the context of the process being
     debugged, without having to give a vestige of proof as to their right to
     ask for it. This is not really the kind of feature we like about network
     protocols in the modern world!
     
     But Unix-domain sockets are access-controlled via the file permissions on
     the path leading to the socket file. If you use this new feature to make
     a Unix-domain socket inside a directory that only your user id has access
     to, then any process physically capable of connecting to the socket has
     already proved its right to run code under your user id. So this solves
     the whole issue, while keeping all the other conveniences of the
     socket-based gdbserver transport.
     
     
     Cheers,
     Simon

This is a good point.  But really it belongs under the heading of the
risks associated with TCP/IP sockets - not the risk which is absent when
using Unix sockets.

The documentation already has this warning:

     _Warning:_ 'gdbserver' does not have any built-in security.  Do not
     run 'gdbserver' connected to any public network; a GDB connection
     to 'gdbserver' provides access to the target system with the same
     privileges as the user running 'gdbserver'.

... perhaps that could be expanded to discuss the relative merits of 
UDS vs. TCP/IP

J'

-- 
Avoid eavesdropping.  Send strong encrypted email.
PGP Public key ID: 1024D/2DE827B3 
fingerprint = 8797 A26D 0854 2EAB 0285  A290 8A67 719C 2DE8 27B3
See http://sks-keyservers.net or any PGP keyserver for public key.

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Sergio Durigan Junior]

On Saturday, October 13 2018, John Darrington wrote:

> When invoking gdbserver, if the COMM parameter takes the form "unix::/path/name"
> then a local (unix) domain socket will be created with that name and gdbserver
> will listen for connections on that.

Thanks for the patch.

>     gdb/
>     * NEWS: Mention new feature.
>
>     gdb/gdbserver/
>     * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
>     * configure: Regenerate.
>     * remote-utils.c (remote_prepare): Create a local socket if requested.
>      (remote_open):  Don't attempt to open a file if it's a socket.
>      (handle_accept_event): Display the name of the socket on connection.
>
>    gdb/common/
>    * netstuff.c (parse_connection_spec)[prefixes]: New member for local domain sockets.
> ---
>  gdb/NEWS                     |   4 ++
>  gdb/common/netstuff.c        |   9 +++
>  gdb/gdbserver/configure.ac   |   2 +-
>  gdb/gdbserver/remote-utils.c | 148 ++++++++++++++++++++++++++++++-------------
>  4 files changed, 117 insertions(+), 46 deletions(-)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 126e61e282..23de349324 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -15,6 +15,10 @@
>    can be passed using the '[ADDRESS]:PORT' notation, or the regular
>    'ADDRESS:PORT' method.
>  
> +* GDB and GDBserver now support local domain socket connections.  The
> +  name of a local domain socket may be provided instead of the
> +  [ADDRESS]:PORT notation.

Is it worth explicitly mentioning "UNIX domain socket"?

> +
>  * DWARF index cache: GDB can now automatically save indices of DWARF
>    symbols on disk to speed up further loading of the same binaries.
>  
> diff --git a/gdb/common/netstuff.c b/gdb/common/netstuff.c
> index c1c401ccb2..8da6aba24e 100644
> --- a/gdb/common/netstuff.c
> +++ b/gdb/common/netstuff.c
> @@ -57,6 +57,8 @@ parse_connection_spec_without_prefix (std::string spec, struct addrinfo *hint)
>  			  || std::count (spec.begin (),
>  					 spec.end (), ':') > 1)));
>  
> +  bool is_unix = hint->ai_family == AF_UNIX;

No need for a newline between the declarations of is_ipv6 and is_unix.

Here, and everywhere else, AF_UNIX may be undefined if building GDB on a
non-UNIX environment.  I'm afraid you may have to guard this code with
"HAVE_SYS_UN_H".

> +
>    if (is_ipv6)
>      {
>        if (spec[0] == '[')
> @@ -109,6 +111,12 @@ parse_connection_spec_without_prefix (std::string spec, struct addrinfo *hint)
>    if (ret.host_str.empty ())
>      ret.host_str = "localhost";
>  
> +  if (is_unix && ret.host_str != "localhost")
> +    error (_("The host name must be empty or 'localhost' for a unix domain socket."));

This line has more than 80 chars, so you will need to break it.

Also, IIRC the official name for the system is "UNIX" (all caps).

> +
> +  if (is_unix && ret.port_str.empty ())
> +    error (_("A path name must be specified for a unix domain socket."));

So "port_str" is actually a path name if we're dealing with a UNIX
socket?  What do you think about changing the name of the field to
"resource_str" or some such?

> +
>    return ret;
>  }
>  
> @@ -138,6 +146,7 @@ parse_connection_spec (const char *spec, struct addrinfo *hint)
>        { "tcp4:", AF_INET,   SOCK_STREAM },
>        { "udp6:", AF_INET6,  SOCK_DGRAM },
>        { "tcp6:", AF_INET6,  SOCK_STREAM },
> +      { "unix:", AF_LOCAL,  SOCK_STREAM },

The comment I made about AF_UNIX above also applies to AF_LOCAL.

>      };
>  
>    for (const host_prefix prefix : prefixes)
> diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
> index fa3ca53efd..de7e7d4103 100644
> --- a/gdb/gdbserver/configure.ac
> +++ b/gdb/gdbserver/configure.ac
> @@ -98,7 +98,7 @@ ACX_CONFIGURE_DIR(["../../libiberty"], ["build-libiberty-gdbserver"])
>  AC_CHECK_HEADERS(termios.h sys/reg.h string.h dnl
>  		 proc_service.h sys/procfs.h linux/elf.h dnl
>  		 fcntl.h signal.h sys/file.h dnl
> -		 sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
> +		 sys/ioctl.h netinet/in.h sys/socket.h sys/un.h netdb.h dnl
>  		 netinet/tcp.h arpa/inet.h)
>  AC_FUNC_FORK
>  AC_CHECK_FUNCS(getauxval pread pwrite pread64 setns)

The change for "gdb/gdbserver/configure" hasn't been included in the
patch.  Perhaps you forgot to regenerate it?

> diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
> index 9199a9c7ad..0eb53c2116 100644
> --- a/gdb/gdbserver/remote-utils.c
> +++ b/gdb/gdbserver/remote-utils.c
> @@ -38,6 +38,9 @@
>  #if HAVE_NETINET_IN_H
>  #include <netinet/in.h>
>  #endif
> +#if HAVE_SYS_UN_H
> +#include <sys/un.h>
> +#endif
>  #if HAVE_SYS_SOCKET_H
>  #include <sys/socket.h>
>  #endif
> @@ -193,20 +196,33 @@ handle_accept_event (int err, gdb_client_data client_data)
>       descriptor open for add_file_handler to wait for a new connection.  */
>    delete_file_handler (listen_desc);
>  
> -  /* Convert IP address to string.  */
> -  char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
> -
> -  int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
> -		       orig_host, sizeof (orig_host),
> -		       orig_port, sizeof (orig_port),
> -		       NI_NUMERICHOST | NI_NUMERICSERV);
> +  if (sockaddr.ss_family == AF_UNIX)
> +    {
> +      struct sockaddr_un su;
> +      socklen_t len;

Missing newline here.

According to getsockname(2), 'len' should contain the initial size of
the 'struct sockaddr' you're passing in the second argument.  Therefore,
you should declare 'len' as 'sizeof (su)'.

Also, there's another 'len' declare in the scope above.  In order to
avoid -Wshadow warnings, I'd recommend you to choose another variable
name here.

Last, but not least, this code also needs to be guarded with #ifdef's.

> +      if (getsockname (listen_desc, (struct sockaddr *) &su, &len) != 0)
> +	perror (_("Could not obtain remote address"));
>  
> -  if (r != 0)
> -    fprintf (stderr, _("Could not obtain remote address: %s\n"),
> -	     gai_strerror (r));
> +      fprintf (stderr, _("Remote debugging on local socket bound to %s\n"),
> +	       su.sun_path);
> +    }
>    else
> -    fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
> -	     orig_host, orig_port);
> +    {
> +      /* Convert IP address to string.  */
> +      char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
> +
> +      int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
> +			   orig_host, sizeof (orig_host),
> +			   orig_port, sizeof (orig_port),
> +			   NI_NUMERICHOST | NI_NUMERICSERV);
> +
> +      if (r != 0)
> +	fprintf (stderr, _("Could not obtain remote address: %s\n"),
> +		 gai_strerror (r));
> +      else
> +	fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
> +		 orig_host, orig_port);
> +    }
>  
>    enable_async_notification (remote_desc);
>  
> @@ -250,6 +266,9 @@ remote_prepare (const char *name)
>    struct addrinfo hint;
>    struct addrinfo *ainfo;
>  
> +  struct sockaddr *addr;
> +  socklen_t addrlen;
> +
>    memset (&hint, 0, sizeof (hint));
>    /* Assume no prefix will be passed, therefore we should use
>       AF_UNSPEC.  */
> @@ -258,7 +277,7 @@ remote_prepare (const char *name)
>    hint.ai_protocol = IPPROTO_TCP;
>  
>    parsed_connection_spec parsed
> -    = parse_connection_spec_without_prefix (name, &hint);
> +    = parse_connection_spec (name, &hint);

There's a problem here: gdbserver doesn't work with UDP connections.
Actually, this is the only reason why there's a "_without_prefix"
variant of "parse_connection_spec": because, in this particular case, we
*don't* want to consider prefixes.  Because (so far) gdbserver deals
only with TCP sockets, and because IPv4 and IPv6 addresses are easily
distinguishable, we don't use any kind of prefix.

However, with your patch, we will probably need a prefix indeed (to
differentiate between serial tty devices and UNIX sockets, at least).
My suggestion is that you make a "parse_connection_spec_maybe_unix" or
some such, which takes into account *just* the UNIX prefix (and no
other).  After you extract the "unix:" prefix, you can pass the rest of
the string to "parse_connection_spec_without_prefix" (which would be
made "static" since it won't be used externally anymore).

>  
>    if (parsed.port_str.empty ())
>      {
> @@ -276,47 +295,86 @@ remote_prepare (const char *name)
>      }
>  #endif
>  
> -  int r = getaddrinfo (parsed.host_str.c_str (), parsed.port_str.c_str (),
> -		       &hint, &ainfo);
> +  struct sockaddr_un unix_addr;
>  
> -  if (r != 0)
> -    error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
> +#ifndef UNIX_PATH_MAX
> +#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
                               ^

Missing whitespace between function and parens.

> +#endif

Even though I don't quite like using "PATH_MAX"-like because of
reproducibility issues, I don't really know what else could be done here
to prevent that.

>  
> -  scoped_free_addrinfo freeaddrinfo (ainfo);
> +  if (hint.ai_family == AF_LOCAL)
> +    {
> +      const char *sock_name = parsed.port_str.c_str ();
> +      if (parsed.port_str.length() > UNIX_PATH_MAX - 1)
                                   ^
Missing whitespace between function and parens.

> +	{
> +	  error
> +	    (_("%s is too long.  Socket names may be no longer than %s bytes."),

s/bytes/characters/ (increases readability, IMHO)?

> +	     sock_name, pulongest (UNIX_PATH_MAX - 1));
> +	  return;
> +	}
> +      listen_desc = socket (AF_UNIX,  SOCK_STREAM,  0);
> +      if (listen_desc < 0)
> +	perror_with_name ("Can't open socket");
>  
> -  struct addrinfo *iter;
> +      memset (&unix_addr, 0, sizeof (unix_addr));
> +      unix_addr.sun_family = AF_UNIX;
> +      strncpy (unix_addr.sun_path, sock_name, UNIX_PATH_MAX - 1);
>  
> -  for (iter = ainfo; iter != NULL; iter = iter->ai_next)
> -    {
> -      listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
> -					iter->ai_protocol);
> +      struct stat statbuf;
> +      int stat_result = stat (sock_name, &statbuf);

Missing newline here.  No need for the "stat_result" variable; you can
just check its return value in the "if" below.

> +      if (stat_result == 0
> +	  && (S_IFSOCK & statbuf.st_mode))

Don't think you need to break the line.

You should use S_ISSOCK (statbuf.st_mode).

> +	unlink (sock_name);
>  
> -      if (listen_desc >= 0)
> -	break;
> +      addr = (struct sockaddr *) &unix_addr;
> +      addrlen = sizeof (unix_addr);
>      }
> +  else
> +    {
> +      struct addrinfo *iter;
>  
> -  if (iter == NULL)
> -    perror_with_name ("Can't open socket");
> +      int r = getaddrinfo (parsed.host_str.c_str (),
> +			   parsed.port_str.c_str (),
> +			   &hint, &ainfo);
>  
> -  /* Allow rapid reuse of this port. */
> -  tmp = 1;
> -  setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
> -	      sizeof (tmp));
> +      if (r != 0)
> +	error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
>  
> -  switch (iter->ai_family)
> -    {
> -    case AF_INET:
> -      ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
> -      break;
> -    case AF_INET6:
> -      ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
> -      break;
> -    default:
> -      internal_error (__FILE__, __LINE__,
> -		      _("Invalid 'ai_family' %d\n"), iter->ai_family);
> +      scoped_free_addrinfo freeaddrinfo (ainfo);
> +
> +      for (iter = ainfo; iter != NULL; iter = iter->ai_next)
> +	{
> +	  listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
> +					    iter->ai_protocol);
> +
> +	  if (listen_desc >= 0)
> +	    break;
> +	}
> +
> +      if (iter == NULL)
> +	perror_with_name ("Can't open socket");
> +
> +      /* Allow rapid reuse of this port. */
> +      tmp = 1;
> +      setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
> +		  sizeof (tmp));
> +
> +      switch (iter->ai_family)
> +	{
> +	case AF_INET:
> +	  ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
> +	  break;
> +	case AF_INET6:
> +	  ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
> +	  break;
> +	default:
> +	  internal_error (__FILE__, __LINE__,
> +			  _("Invalid 'ai_family' %d\n"), iter->ai_family);
> +	}
> +      addr = iter->ai_addr;
> +      addrlen = iter->ai_addrlen;
>      }
>  
> -  if (bind (listen_desc, iter->ai_addr, iter->ai_addrlen) != 0)
> +  if (bind (listen_desc, addr, addrlen) != 0)
>      perror_with_name ("Can't bind address");
>  
>    if (listen (listen_desc, 1) != 0)
> @@ -354,11 +412,11 @@ remote_open (const char *name)
>      }
>  #ifndef USE_WIN32API
>    else if (port_str == NULL)
> -    {
> +     {
>        struct stat statbuf;
>  
>        if (stat (name, &statbuf) == 0
> -	  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
> +         && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))

These two changes are unrelated and should go in a separate patch (they
can be pushed as obvious, BTW).

>  	remote_desc = open (name, O_RDWR);
>        else
>  	{
> -- 
> 2.11.0

Thanks,

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Re: [PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

[Sergio Durigan Junior]

On Saturday, October 13 2018, John Darrington wrote:

> gdb/doc:
> * gdb.texinfo (Connecting)[Remote Connection Commands]:  Provide alternative
>   unix::/tmp/xxx example.  Include @code{unix::@var{local-socket} in
                                                                   ^

Missing close-curly bracket.

>   the list of remote and extended-remote syntaxes.
> ---
>  gdb/doc/gdb.texinfo | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index b0dc3bf67c..1e97d692b6 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -20829,6 +20829,15 @@ 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.
> +The above command is identical to the command:
> +
> +@smallexample
> +target remote unix::/tmp/gdb-socket1
> +@end smallexample
> +@noindent
> +
> +See below for the explanation of this syntax.
> +
>  This feature is not available if the host system does not support
>  Unix domain sockets.
>  
> @@ -20839,6 +20848,7 @@ Unix domain sockets.
>  @itemx target remote @code{tcp4:@var{host}:@var{port}}
>  @itemx target remote @code{tcp6:@var{host}:@var{port}}
>  @itemx target remote @code{tcp6:@var{[host]}:@var{port}}
> +@itemx target remote @code{unix::@var{local-socket}}
>  @itemx target extended-remote @code{@var{host}:@var{port}}
>  @itemx target extended-remote @code{@var{[host]}:@var{port}}
>  @itemx target extended-remote @code{tcp:@var{host}:@var{port}}
> @@ -20846,8 +20856,10 @@ Unix domain sockets.
>  @itemx target extended-remote @code{tcp4:@var{host}:@var{port}}
>  @itemx target extended-remote @code{tcp6:@var{host}:@var{port}}
>  @itemx target extended-remote @code{tcp6:@var{[host]}:@var{port}}
> +@itemx target extended-remote @code{unix::@var{local-socket}}
>  @cindex @acronym{TCP} port, @code{target remote}
> -Debug using a @acronym{TCP} connection to @var{port} on @var{host}.
> +Debug using a @acronym{TCP} connection to @var{port} on @var{host}
> +or using the Unix domain socket @var{local-socket} on the local machine.
>  The @var{host} may be either a host name, a numeric @acronym{IPv4}
>  address, or a numeric @acronym{IPv6} address (with or without the
>  square brackets to separate the address from the port); @var{port}
> @@ -20895,6 +20907,16 @@ target remote :1234
>  @noindent
>  
>  Note that the colon is still required here.
> +Alternatively you can use a Unix domain socket:
> +
> +@smallexample
> +target remote unix::/tmp/gdb-socket1
> +@end smallexample
> +@noindent
> +
> +This has the advantage that it'll not fail if the port number is already
> +in use.
> +
>  
>  @item target remote @code{udp:@var{host}:@var{port}}
>  @itemx target remote @code{udp:@var{[host]}:@var{port}}
> -- 
> 2.11.0

-- 
Sergio
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Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[Sergio Durigan Junior]

On Saturday, October 13 2018, John Darrington wrote:

> The documentation did not mention the possibility of invoking gdbserver
> with the new connection forms such as tcp6:host:port.  This change fixes
> that.

Thanks for the patch.

As I mentioned while reviewing patch #1, there is a reason why gdbserver
doesn't accept prefixes (which means that there isn't a mistake in the
docs).  If you go with my suggestion and implement just the support for
the "unix:" prefix, then this patch will need to be changed because it
still won't be correct to mention the "tcp" prefixes.

> gdb/doc/
>
>   * gdb.texinfo (Server): Tabulate the various permitted forms of the @var{comm}
>    metasyntactical variable.  Include the unix:@var{host}:@var{socket} form as
>    one of them.
> ---
>  gdb/doc/gdb.texinfo | 60 +++++++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 44 insertions(+), 16 deletions(-)
>
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 1e97d692b6..e3b62221cf 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -21097,9 +21097,19 @@ syntax is:
>  target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
>  @end smallexample
>  
> -@var{comm} is either a device name (to use a serial line), or a TCP
> -hostname and portnumber, or @code{-} or @code{stdio} to use
> -stdin/stdout of @code{gdbserver}.
> +@code{gdbserver} waits passively for the host @value{GDBN} to communicate
> +with it.
> +
> +@var{comm} may take several forms:
> +
> +@table @code
> +@item @code{@var{device}}
> +A serial line device.
> +
> +@item @code{-}
> +@itemx @code{stdio}
> +To use the stdin/stdout of @code{gdbserver}.
> +
>  For example, to debug Emacs with the argument
>  @samp{foo.txt} and communicate with @value{GDBN} over the serial port
>  @file{/dev/com1}:
> @@ -21108,8 +21118,27 @@ For example, to debug Emacs with the argument
>  target> gdbserver /dev/com1 emacs foo.txt
>  @end smallexample
>  
> -@code{gdbserver} waits passively for the host @value{GDBN} to communicate
> -with it.
> +The @code{stdio} connection is useful when starting @code{gdbserver}
> +with ssh:
> +
> +@smallexample
> +(gdb) target remote | ssh -T hostname gdbserver - hello
> +@end smallexample
> +
> +The @samp{-T} option to ssh is provided because we don't need a remote pty,
> +and we don't want escape-character handling.  Ssh does this by default when
> +a command is provided, the flag is provided to make it explicit.
> +You could elide it if you want to.
> +
> +Programs started with stdio-connected gdbserver have @file{/dev/null} for
> +@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
> +display through a pipe connected to gdbserver.
> +Both @code{stdout} and @code{stderr} use the same pipe.
> +
> +@item @code{@var{host}:@var{port}}
> +@itemx @code{tcp:@var{host}:@var{port}}
> +@itemx @code{tcp4:@var{host}:@var{port}}
> +To use a @acronym{TCP} @acronym{IPv4} socket connection on port number @var{port}.
>  
>  To use a TCP connection instead of a serial line:
>  
> @@ -21129,22 +21158,21 @@ conflicts with another service, @code{gdbserver} prints an error message
>  and exits.}  You must use the same port number with the host @value{GDBN}
>  @code{target remote} command.
>  
> -The @code{stdio} connection is useful when starting @code{gdbserver}
> -with ssh:
> +
> +@item @code{tcp6:@var{host}:@var{port}}
> +To use a @acronym{TCP} @acronym{IPv6} socket connection on port number @var{port}.
> +
> +@item @code{unix:@var{host}:@var{local-socket}}
> +To use a Unix domain socket.  This will create a socket with the file
> +system entry @var{local-socket} and listen on that.  For example:
>  
>  @smallexample
> -(gdb) target remote | ssh -T hostname gdbserver - hello
> +target> gdbserver unix:localhost:/tmp/gdb-socket0 emacs foo.txt
>  @end smallexample
>  
> -The @samp{-T} option to ssh is provided because we don't need a remote pty,
> -and we don't want escape-character handling.  Ssh does this by default when
> -a command is provided, the flag is provided to make it explicit.
> -You could elide it if you want to.
> +@var{host} must either be the null string or the literal string @code{localhost}.
> +@end table
>  
> -Programs started with stdio-connected gdbserver have @file{/dev/null} for
> -@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
> -display through a pipe connected to gdbserver.
> -Both @code{stdout} and @code{stderr} use the same pipe.
>  
>  @anchor{Attaching to a program}
>  @subsubsection Attaching to a Running Program
> -- 
> 2.11.0

-- 
Sergio
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Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[John Darrington]

On Thu, Oct 18, 2018 at 04:27:24PM -0400, Sergio Durigan Junior wrote:
     On Saturday, October 13 2018, John Darrington wrote:
     
     > The documentation did not mention the possibility of invoking gdbserver
     > with the new connection forms such as tcp6:host:port.  This change fixes
     > that.
     
     Thanks for the patch.
     
     As I mentioned while reviewing patch #1, there is a reason why gdbserver
     doesn't accept prefixes (which means that there isn't a mistake in the
     docs).  If you go with my suggestion and implement just the support for
     the "unix:" prefix, then this patch will need to be changed because it
     still won't be correct to mention the "tcp" prefixes.
     
Thanks for the reviews.

How about instead, we just add a test to print an error/warning if
someone tries to start gdbserver with a udp prefix?

J'

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Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

On Thu, Oct 18, 2018 at 04:18:48PM -0400, Sergio Durigan Junior wrote:

     > +  bool is_unix = hint->ai_family == AF_UNIX;
     
     No need for a newline between the declarations of is_ipv6 and is_unix.
     
     Here, and everywhere else, AF_UNIX may be undefined if building GDB on a
     non-UNIX environment.  I'm afraid you may have to guard this code with
     "HAVE_SYS_UN_H".
     

This is true.  But a quick experiment showed me that there are quite a
few other places in gdb which has this problem.

I can prepare a separate patch to fix those.

J'

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Sergio Durigan Junior]

On Friday, October 19 2018, John Darrington wrote:

> On Thu, Oct 18, 2018 at 04:18:48PM -0400, Sergio Durigan Junior wrote:
>
>      > +  bool is_unix = hint->ai_family == AF_UNIX;
>      
>      No need for a newline between the declarations of is_ipv6 and is_unix.
>      
>      Here, and everywhere else, AF_UNIX may be undefined if building GDB on a
>      non-UNIX environment.  I'm afraid you may have to guard this code with
>      "HAVE_SYS_UN_H".
>      
>
> This is true.  But a quick experiment showed me that there are quite a
> few other places in gdb which has this problem.

Which places?  There are some files that are not compiled on certain
systems, so it's fine to have system-dependent code without the guards.
I don't use proprietary OSes, so the way I test here is to compile GDB
using a mingw compiler.  If it passes, then I assume things are OK.
Your patch, for example, broke the compilation (because of
AF_UNIX/AF_LOCAL).

Cheers,

-- 
Sergio
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Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[Sergio Durigan Junior]

On Friday, October 19 2018, John Darrington wrote:

> On Thu, Oct 18, 2018 at 04:27:24PM -0400, Sergio Durigan Junior wrote:
>      On Saturday, October 13 2018, John Darrington wrote:
>      
>      > The documentation did not mention the possibility of invoking gdbserver
>      > with the new connection forms such as tcp6:host:port.  This change fixes
>      > that.
>      
>      Thanks for the patch.
>      
>      As I mentioned while reviewing patch #1, there is a reason why gdbserver
>      doesn't accept prefixes (which means that there isn't a mistake in the
>      docs).  If you go with my suggestion and implement just the support for
>      the "unix:" prefix, then this patch will need to be changed because it
>      still won't be correct to mention the "tcp" prefixes.
>      
> Thanks for the reviews.
>
> How about instead, we just add a test to print an error/warning if
> someone tries to start gdbserver with a udp prefix?

Hm, I thought about that while writing the email, but at the time it
didn't seem like a good option.  However, thinking about it again, I
think it would be mostly fine.  I guess it's OK to support the
"tcp{,6}:" prefixes.

The check needs to implemented on gdbserver/remote-utils.c:remote_open,
and gdbserver needs to error out if "hint.ai_protocol == IPPROTO_UDP".
And "parse_connection_spec_without_prefix" could be merged with
"parse_connection_spec".

Aside from the documentation, you'd also probably have to update the
tests (both the selftests and the regular ones).

Thanks,

-- 
Sergio
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Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[John Darrington]

On Fri, Oct 19, 2018 at 04:45:14PM -0400, Sergio Durigan Junior wrote:

     The check needs to implemented on gdbserver/remote-utils.c:remote_open,
     and gdbserver needs to error out if "hint.ai_protocol == IPPROTO_UDP".
     And "parse_connection_spec_without_prefix" could be merged with
     "parse_connection_spec".
     
A quick test shows that this is not necessary.  Any attempt to start
gdbserver with udp: will never get to remote_open because remote_prepare
will fail when it gets to listen:
 
  "Can't listen on socket: Operation no supported."

(listen is for connection orientated protocols only).


J'



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Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[Sergio Durigan Junior]

On Sunday, October 21 2018, John Darrington wrote:

> On Fri, Oct 19, 2018 at 04:45:14PM -0400, Sergio Durigan Junior wrote:
>
>      The check needs to implemented on gdbserver/remote-utils.c:remote_open,
>      and gdbserver needs to error out if "hint.ai_protocol == IPPROTO_UDP".
>      And "parse_connection_spec_without_prefix" could be merged with
>      "parse_connection_spec".
>      
> A quick test shows that this is not necessary.  Any attempt to start
> gdbserver with udp: will never get to remote_open because remote_prepare
> will fail when it gets to listen:
>  
>   "Can't listen on socket: Operation no supported."
>
> (listen is for connection orientated protocols only).

Yes, but this error message is not entirely clear.  We should show a
more user-friendly message, and the best way to do that is to do an
early check for the UDP protocol.

Thanks,

-- 
Sergio
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Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[John Darrington]

On Fri, Oct 19, 2018 at 04:45:14PM -0400, Sergio Durigan Junior wrote:

     Aside from the documentation, you'd also probably have to update the
     tests (both the selftests and the regular ones).
     

When I run "make check" I get  a large number of failures, and I'm told
that this is normal.   How do I run just the tests which you think need
to be adjusted?

J'

Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

[Sergio Durigan Junior]

On Tuesday, October 23 2018, John Darrington wrote:

> On Fri, Oct 19, 2018 at 04:45:14PM -0400, Sergio Durigan Junior wrote:
>
>      Aside from the documentation, you'd also probably have to update the
>      tests (both the selftests and the regular ones).
>      
>
> When I run "make check" I get  a large number of failures, and I'm told
> that this is normal.   How do I run just the tests which you think need
> to be adjusted?

You can take a look at the tests I touched when implementing IPv6:

commit c7ab0aef11d91b637bf091aa9176b8dc4aadee46
Author: Sergio Durigan Junior <sergiodj@redhat.com>
Date:   Fri May 18 01:29:24 2018 -0400

    Implement IPv6 support for GDB/gdbserver


Specifically gdb.server/server-connect.exp.  Offhand I'm not sure if any
other test needs to be adjusted; probably not.  I'd advise taking a look
under the gdb.server/ directory just to double check.

Thanks,

-- 
Sergio
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Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Simon Marchi]

On 2018-10-19 3:43 p.m., Sergio Durigan Junior wrote:
> On Friday, October 19 2018, John Darrington wrote:
> 
>> On Thu, Oct 18, 2018 at 04:18:48PM -0400, Sergio Durigan Junior wrote:
>>
>>      > +  bool is_unix = hint->ai_family == AF_UNIX;
>>      
>>      No need for a newline between the declarations of is_ipv6 and is_unix.
>>      
>>      Here, and everywhere else, AF_UNIX may be undefined if building GDB on a
>>      non-UNIX environment.  I'm afraid you may have to guard this code with
>>      "HAVE_SYS_UN_H".
>>      
>>
>> This is true.  But a quick experiment showed me that there are quite a
>> few other places in gdb which has this problem.
> 
> Which places?  There are some files that are not compiled on certain
> systems, so it's fine to have system-dependent code without the guards.
> I don't use proprietary OSes, so the way I test here is to compile GDB
> using a mingw compiler.  If it passes, then I assume things are OK.
> Your patch, for example, broke the compilation (because of
> AF_UNIX/AF_LOCAL).
> 
> Cheers,
> 

I just tried compiling with mingw and stumbled on this:

  CXX    common/netstuff.o
/home/simark/src/binutils-gdb/gdb/common/netstuff.c: In function ‘parsed_connection_spec parse_connection_spec(const char*, addrinfo*)’:
/home/simark/src/binutils-gdb/gdb/common/netstuff.c:148:18: error: ‘AF_LOCAL’ was not declared in this scope
       { "unix:", AF_LOCAL,  SOCK_STREAM },
                  ^~~~~~~~

What is the status on this?

Simon

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

Mea Culpa.

I missed that one.  I'll try to get a mingw environment set up and 
check in a fix.

J'


On Sun, Oct 28, 2018 at 12:20:28PM -0400, Simon Marchi wrote:
     On 2018-10-19 3:43 p.m., Sergio Durigan Junior wrote:
     > On Friday, October 19 2018, John Darrington wrote:
     > 
     >> On Thu, Oct 18, 2018 at 04:18:48PM -0400, Sergio Durigan Junior wrote:
     >>
     >>      > +  bool is_unix = hint->ai_family == AF_UNIX;
     >>      
     >>      No need for a newline between the declarations of is_ipv6 and is_unix.
     >>      
     >>      Here, and everywhere else, AF_UNIX may be undefined if building GDB on a
     >>      non-UNIX environment.  I'm afraid you may have to guard this code with
     >>      "HAVE_SYS_UN_H".
     >>      
     >>
     >> This is true.  But a quick experiment showed me that there are quite a
     >> few other places in gdb which has this problem.
     > 
     > Which places?  There are some files that are not compiled on certain
     > systems, so it's fine to have system-dependent code without the guards.
     > I don't use proprietary OSes, so the way I test here is to compile GDB
     > using a mingw compiler.  If it passes, then I assume things are OK.
     > Your patch, for example, broke the compilation (because of
     > AF_UNIX/AF_LOCAL).
     > 
     > Cheers,
     > 
     
     I just tried compiling with mingw and stumbled on this:
     
       CXX    common/netstuff.o
     /home/simark/src/binutils-gdb/gdb/common/netstuff.c: In function ???parsed_connection_spec parse_connection_spec(const char*, addrinfo*)???:
     /home/simark/src/binutils-gdb/gdb/common/netstuff.c:148:18: error: ???AF_LOCAL??? was not declared in this scope
            { "unix:", AF_LOCAL,  SOCK_STREAM },
                       ^~~~~~~~
     
     What is the status on this?
     
     Simon

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Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Simon Marchi]

On 2018-10-28 14:10, John Darrington wrote:
> Mea Culpa.
> 
> I missed that one.  I'll try to get a mingw environment set up and
> check in a fix.

Ok.  If you are on Linux, it shouldn't be too hard.  For example, I use 
these packages (on two different machines):

https://aur.archlinux.org/packages/mingw-w64-gcc/
https://packages.ubuntu.com/en/bionic/gcc-mingw-w64

and configure with --host=x86_64-w64-mingw32.  I think that's all.

Simon

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

On Sun, Oct 28, 2018 at 02:51:50PM -0400, Simon Marchi wrote:
     On 2018-10-28 14:10, John Darrington wrote:
     > Mea Culpa.
     > 
     > I missed that one.  I'll try to get a mingw environment set up and
     > check in a fix.
     
     Ok.  If you are on Linux, it shouldn't be too hard.  For example, I use
     these packages (on two different machines):
     
     https://aur.archlinux.org/packages/mingw-w64-gcc/
     https://packages.ubuntu.com/en/bionic/gcc-mingw-w64
     
     and configure with --host=x86_64-w64-mingw32.  I think that's all.
     
For some reason, when I try to crossbuild in this way, there are many
failures (unrelated to this issue).

However I've checked in a fix for this issue, and tested it by building
natively with a hacked set of standard include headers.

J'

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Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Rainer Orth]

Hi John,

> However I've checked in a fix for this issue, and tested it by building
> natively with a hacked set of standard include headers.

you always need to post patches here, if only for reference.

Besides, we're currently very inconsistent here (haven't checked which
part of that is due to your code): most places use AF_UNIX, only two use
AF_LOCAL instead (common/netstuff.c, gdbserver/remote-utils.c), and your
configure check only checks for AF_LOCAL.  I believe we should
canonicalize for one of the two and allow for systems that define only
one or the other.

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Rainer Orth]

Hi John,

>> However I've checked in a fix for this issue, and tested it by building
>> natively with a hacked set of standard include headers.
>
> you always need to post patches here, if only for reference.

I also noticed that your ChangeLog entry had a couple of formatting
issues.  I've fixed them with my last commit.

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Simon Marchi]

On 2018-10-29 5:11 a.m., Rainer Orth wrote:
> Hi John,
> 
>> However I've checked in a fix for this issue, and tested it by building
>> natively with a hacked set of standard include headers.
> 
> you always need to post patches here, if only for reference.

Not only should you post here the patches you push as obvious, but I don't
think that this:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=98a17ece013cb94cd602496b9efb92b8816b3953

falls under the obvious rule:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gdb/MAINTAINERS;h=d5154d394206861ef5471b4984a4762589c34fc4;hb=HEAD#l82

I can't judge whether the patch is right or not with a quick glance, but it
certainly is complex enough to warrant a discussion (as Rainer's reply below
shows).

Additionally, it seems like the initial 4-patch series was pushed without
explicit approval from a maintainer (at least I can't find any).  Next time,
please wait to have an approval before pushing.  If you are not sure whether
a reply constitutes an a approval, it's better to ask the maintainer to
clarify.

> Besides, we're currently very inconsistent here (haven't checked which
> part of that is due to your code): most places use AF_UNIX, only two use
> AF_LOCAL instead (common/netstuff.c, gdbserver/remote-utils.c), and your
> configure check only checks for AF_LOCAL.  I believe we should
> canonicalize for one of the two and allow for systems that define only
> one or the other.

mingw defines AF_UNIX, so I would tend to go towards that route.  Any of you
knows what happens at runtime when you try to bind a AF_UNIX socket on mingw/Windows?

Simon

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

On Mon, Oct 29, 2018 at 03:51:55PM +0000, Simon Marchi wrote:
     On 2018-10-29 5:11 a.m., Rainer Orth wrote:
     > Hi John,
     > 
     >> However I've checked in a fix for this issue, and tested it by building
     >> natively with a hacked set of standard include headers.
     > 
     > you always need to post patches here, if only for reference.
     
Doesn't that make the gdb-cvs list completely redundant?

     Not only should you post here the patches you push as obvious, but I don't
     think that this:
     
     https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=98a17ece013cb94cd602496b9efb92b8816b3953
     
     falls under the obvious rule:

But a number of people had complained that their build was broken, and
this was a fix for that.   I judged that in consideration of those
people fixding their problem was more important than strict observance 
of protocol.
     
     I can't judge whether the patch is right or not with a quick glance, but it
     certainly is complex enough to warrant a discussion (as Rainer's reply below
     shows).

     
     Additionally, it seems like the initial 4-patch series was pushed without
     explicit approval from a maintainer (at least I can't find any).  Next time,
     please wait to have an approval before pushing.  If you are not sure whether
     a reply constitutes an a approval, it's better to ask the maintainer to
     clarify.

All of those patches were certainly discussed.   In the past, when I've
followed up a person who has commented on a patch, but been vague about
approval, I have had either a piqued response; or no response at all.

If you think it necesary however I can revert anything you think hasn't
had enough discussion.

     
     > Besides, we're currently very inconsistent here (haven't checked which
     > part of that is due to your code): most places use AF_UNIX, only two use
     > AF_LOCAL instead (common/netstuff.c, gdbserver/remote-utils.c), and your
     > configure check only checks for AF_LOCAL.  I believe we should
     > canonicalize for one of the two and allow for systems that define only
     > one or the other.
     
     mingw defines AF_UNIX, so I would tend to go towards that route.  Any of you
     knows what happens at runtime when you try to bind a AF_UNIX socket on mingw/Windows?
     
AS I understand it, it depends upon which version of windows.
Apparently recent versions have local ssockets, but older ones do not.

See https://blogs.msdn.microsoft.com/commandline/2017/12/19/af_unix-comes-to-windows/

J'

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Sergio Durigan Junior]

On Monday, October 29 2018, John Darrington wrote:

> On Mon, Oct 29, 2018 at 03:51:55PM +0000, Simon Marchi wrote:
>      On 2018-10-29 5:11 a.m., Rainer Orth wrote:
>      > Hi John,
>      > 
>      >> However I've checked in a fix for this issue, and tested it by building
>      >> natively with a hacked set of standard include headers.
>      > 
>      > you always need to post patches here, if only for reference.
>      
> Doesn't that make the gdb-cvs list completely redundant?
>
>      Not only should you post here the patches you push as obvious, but I don't
>      think that this:
>      
>      https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=98a17ece013cb94cd602496b9efb92b8816b3953
>      
>      falls under the obvious rule:
>
> But a number of people had complained that their build was broken, and
> this was a fix for that.   I judged that in consideration of those
> people fixding their problem was more important than strict observance 
> of protocol.
>      
>      I can't judge whether the patch is right or not with a quick glance, but it
>      certainly is complex enough to warrant a discussion (as Rainer's reply below
>      shows).
>
>      
>      Additionally, it seems like the initial 4-patch series was pushed without
>      explicit approval from a maintainer (at least I can't find any).  Next time,
>      please wait to have an approval before pushing.  If you are not sure whether
>      a reply constitutes an a approval, it's better to ask the maintainer to
>      clarify.
>
> All of those patches were certainly discussed.   In the past, when I've
> followed up a person who has commented on a patch, but been vague about
> approval, I have had either a piqued response; or no response at all.

We were certainly discussing the patches, but they were not approved by
anyone.  It's also worth mentioning that I raised various points that
were not addressed (even though we discussed them).  It is still a
requirement that the patches need to be approved by at least one
maintainer before it is pushed to the repository.

> If you think it necesary however I can revert anything you think hasn't
> had enough discussion.

Yes, please.  The patch series is not ready to be pushed yet; there are
a bunch of points I raised that were not addressed (and are now causing
the failures).  I am not a global maintainer, but it is my opinion that
the patch series should be reverted for now.  We can continue discussing
and fixing things with it here in the list.

Thanks,

-- 
Sergio
GPG key ID: 237A 54B1 0287 28BF 00EF  31F4 D0EB 7628 65FC 5E36
Please send encrypted e-mail if possible
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Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[John Darrington]

On Mon, Oct 29, 2018 at 12:42:43PM -0400, Sergio Durigan Junior wrote:

     > If you think it necesary however I can revert anything you think hasn't
     > had enough discussion.
     
     Yes, please.  The patch series is not ready to be pushed yet; there are
     a bunch of points I raised that were not addressed (and are now causing
     the failures).  I am not a global maintainer, but it is my opinion that
     the patch series should be reverted for now.  We can continue discussing
     and fixing things with it here in the list.
     
Done.

Start discussing.

J'

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Simon Marchi]

On 2018-10-29 12:42 p.m., Sergio Durigan Junior wrote:
> On Monday, October 29 2018, John Darrington wrote:
> 
>> On Mon, Oct 29, 2018 at 03:51:55PM +0000, Simon Marchi wrote:
>>      On 2018-10-29 5:11 a.m., Rainer Orth wrote:
>>      > Hi John,
>>      > 
>>      >> However I've checked in a fix for this issue, and tested it by building
>>      >> natively with a hacked set of standard include headers.
>>      > 
>>      > you always need to post patches here, if only for reference.
>>      
>> Doesn't that make the gdb-cvs list completely redundant?

Perhaps, I don't know.  Personally, I am not subscribed to gdb-cvs.  And generally,
when posting on gdb-patches, you'll mention that the patch was pushed as "obvious",
which the commit message won't necessarily contain.

It's also sometimes necessary to discuss a patch that was initially committed as
obvious.  The post on gdb-patches would be the place for that.

>>      Not only should you post here the patches you push as obvious, but I don't
>>      think that this:
>>      
>>      https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=98a17ece013cb94cd602496b9efb92b8816b3953
>>      
>>      falls under the obvious rule:
>>
>> But a number of people had complained that their build was broken, and
>> this was a fix for that.   I judged that in consideration of those
>> people fixding their problem was more important than strict observance 
>> of protocol.

Let me reassure you, I completely understand that the intention was good.  I don't
want you to feel bad in any way for trying to fix things up!  Next time, post the
patch to the mailing list for review.  If the patch title contains "Fix build for...",
it is likely that it will be reviewed quite quickly.

>>      
>>      I can't judge whether the patch is right or not with a quick glance, but it
>>      certainly is complex enough to warrant a discussion (as Rainer's reply below
>>      shows).
>>
>>      
>>      Additionally, it seems like the initial 4-patch series was pushed without
>>      explicit approval from a maintainer (at least I can't find any).  Next time,
>>      please wait to have an approval before pushing.  If you are not sure whether
>>      a reply constitutes an a approval, it's better to ask the maintainer to
>>      clarify.
>>
>> All of those patches were certainly discussed.   In the past, when I've
>> followed up a person who has commented on a patch, but been vague about
>> approval, I have had either a piqued response; or no response at all.
> 
> We were certainly discussing the patches, but they were not approved by
> anyone.  It's also worth mentioning that I raised various points that
> were not addressed (even though we discussed them).  It is still a
> requirement that the patches need to be approved by at least one
> maintainer before it is pushed to the repository.

Yep.

>> If you think it necesary however I can revert anything you think hasn't
>> had enough discussion.
> 
> Yes, please.  The patch series is not ready to be pushed yet; there are
> a bunch of points I raised that were not addressed (and are now causing
> the failures).  I am not a global maintainer, but it is my opinion that
> the patch series should be reverted for now.  We can continue discussing
> and fixing things with it here in the list.

I have reverted the initial series as well as the fixup.  Sergio has mentioned on IRC
that it causes some test failures on the buildbot that cause the test time very long.
So this needs more testing before we push it again.

Simon

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

[Simon Marchi]

On 2018-10-29 1:34 p.m., John Darrington wrote:
> On Mon, Oct 29, 2018 at 12:42:43PM -0400, Sergio Durigan Junior wrote:
> 
>      > If you think it necesary however I can revert anything you think hasn't
>      > had enough discussion.
>      
>      Yes, please.  The patch series is not ready to be pushed yet; there are
>      a bunch of points I raised that were not addressed (and are now causing
>      the failures).  I am not a global maintainer, but it is my opinion that
>      the patch series should be reverted for now.  We can continue discussing
>      and fixing things with it here in the list.
>      
> Done.
> 
> Start discussing.

Well, there are these two loose ends.

https://sourceware.org/ml/gdb-patches/2018-10/msg00438.html
https://sourceware.org/ml/gdb-patches/2018-10/msg00465.html

Also, please check why this series made the buildbot go crazy in
the native-extended-gdbserver configuration:

  https://gdb-build.sergiodj.net/builders/Fedora-x86_64-native-extended-gdbserver-m64/builds/11314

It was suggested on IRC that the scoped_free_addrinfo in remote-utils.c is
at a wrong place, causing something to be used after free.

Simon