[PATCH] Use a shell command as a socket for gdbserver

Gabriel Corona
2015-05-02T22:40:21Z

This brings feature parity with gdb in this regard.

This can be used to do gdbserver over unix socket (without redirecting
the inferior stdio to /dev/null):

$ gdbserver '|socat STDIO UNIX-LISTEN:foo.sock' ./foo

and in gdb:

(gdb) target remote |socat STDIO UNIX:foo.sock

Altneratively, we can initiate a connection to a remote server:

$ gdbserver '|socat STDIO TCP:gdb.example.com:9000' ./foo

gdb/gdbserver/ChangeLog:

* remote-utils.c: add support for using a shell command stdio as COMM
* remote.c: add documentation about this feature
---
gdb/gdbserver/remote-utils.c | 63 ++++++++++++++++++++++++++++++++++++++++++++
gdb/gdbserver/server.c | 3 ++-
2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
index 1de86be..6d88968 100644
--- a/gdb/gdbserver/remote-utils.c
+++ b/gdb/gdbserver/remote-utils.c
@@ -58,6 +58,8 @@
#endif
#include <sys/stat.h>

+#include "gdb_wait.h"
+
#if USE_WIN32API
#include <winsock2.h>
#endif
@@ -239,6 +241,14 @@ remote_prepare (char *name)
return;
}

+#ifndef USE_WIN32API
+ if (name[0] == '|')
+ {
+ transport_is_reliable = 1;
+ return;
+ }
+#endif
+
port_str = strchr (name, ':');
if (port_str == NULL)
{
@@ -280,6 +290,48 @@ remote_prepare (char *name)
transport_is_reliable = 1;
}

+#ifndef USE_WIN32API
+static int open_shell_command(char* command)
+{
+ int sockets[2];
+ int res;
+ pid_t child, pid;
+
+ res = socketpair(AF_LOCAL, SOCK_STREAM, 0, sockets);
+ if (res < 0)
+ error ("Could not get socketpair.");
+ child = fork();
+ if (child < 0)
+ {
+ error ("Could not fork.");
+ }
+ else if (child == 0)
+ {
+ if (close (sockets[0]) < 0)
+ exit (1);
+ if (dup2 (sockets[1], 0) < 0 || dup2 (sockets[1], 1) < 0)
+ exit (1);
+ res = fork ();
+ if (res < 0)
+ exit (1);
+ if (res != 0)
+ exit (0);
+ execl ("/bin/sh", "sh", "-c", command, NULL);
+ exit (1);
+ }
+ else
+ {
+ signal (SIGPIPE, SIG_IGN);
+ while ((pid = waitpid (child, NULL, 0)) < 0 && errno == EINTR);
+ if (pid < 0)
+ error ("Could not wait for child.");
+ close (sockets[1]);
+ return sockets[0];
+ }
+ return -1;
+}
+#endif
+
/* Open a connection to a remote debugger.
NAME is the filename used for communication. */

@@ -288,6 +340,17 @@ remote_open (char *name)
{
char *port_str;

+#ifndef USE_WIN32API
+ if (name[0] == '|')
+ {
+ fprintf (stderr, "Remote debugging using shell command\n");
+ remote_desc = open_shell_command (name + 1);
+ enable_async_notification (remote_desc);
+ add_file_handler (remote_desc, handle_serial_event, NULL);
+ return;
+ }
+#endif
+
port_str = strchr (name, ':');
#ifdef USE_WIN32API
if (port_str == NULL)
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index d2e20d9..9ed4049 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -3036,7 +3036,8 @@ gdbserver_usage (FILE *stream)
"\tgdbserver [OPTIONS] --attach COMM PID\n"
"\tgdbserver [OPTIONS] --multi COMM\n"
"\n"
- "COMM may either be a tty device (for serial debugging),\n"
+ "COMM may be a tty device (for serial debugging),\n"
+ "'|some shell command' to use stdin/stdout of a given shell command,\n"
"HOST:PORT to listen for a TCP connection, or '-' or 'stdio' to use \n"
"stdin/stdout of gdbserver.\n"
"PROG is the executable program. ARGS are arguments passed to inferior.\n"
--
2.1.4