[v2,1/2] Use a shell command as a socket for gdbserver
Commit Message
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 | 71 ++++++++++++++++++++++++++++++++++++++++++++
gdb/gdbserver/server.c | 3 +-
2 files changed, 73 insertions(+), 1 deletion(-)
Comments
On 04 May 2015 23:54, Gabriel Corona wrote:
> +static int
> +open_shell_command (char *command)
const ?
> +{
> + int sockets[2];
> + pid_t child, grandchild, res;
> + int status;
> +
> + if (socketpair (AF_LOCAL, SOCK_STREAM, 0, sockets) < 0)
> + perror_with_name ("Can't get socketpair");
> + child = fork ();
prefer a blank line above the fork assignment
> + if (dup2 (sockets[1], 0) < 0 || dup2 (sockets[1], 1) < 0)
> + perror_with_name ("Can't dup socket to stdio");
use STDIN_FILENO & STDOUT_FILENO instead of 0 & 1
> + if (close (sockets[1]) < 0)
> + perror_with_name ("Can't close original socket");
dup2 has an edge case where if the fd is the same as an existing one, it won't
create a new one. i think before you close, you need to compare it to
STDIN_FILENO & STDOUT_FILENO and only close it if it doesn't match.
> + /* Double fork in order to inherit the grandchild. The process
> + is expected to exit when the other end of the socketpair is
> + closed.
> + */
prefer a blank line above this comment to space the code out. also, GNU style
says:
- use two spaces after periods
- cuddle the trailing */ rather than putting it on a new line by itself
> + else
> + {
> + close (sockets[1]);
check return value ?
> + signal (SIGPIPE, SIG_IGN);
> + while ((res = waitpid (child, &status, 0)) < 0 && errno == EINTR);
> + if (res < 0)
> + perror_with_name ("Can't wait child process");
phrasing is awkward ... maybe insert "on" or "for the" in there ?
> + }
> + return -1;
> +}
i think GNU style says you should have a blank line above this last return
-mike
@@ -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 +290,56 @@ remote_prepare (char *name)
transport_is_reliable = 1;
}
+#ifndef USE_WIN32API
+static int
+open_shell_command (char *command)
+{
+ int sockets[2];
+ pid_t child, grandchild, res;
+ int status;
+
+ if (socketpair (AF_LOCAL, SOCK_STREAM, 0, sockets) < 0)
+ perror_with_name ("Can't get socketpair");
+ child = fork ();
+ if (child < 0)
+ {
+ perror_with_name ("Can't fork");
+ }
+ else if (child == 0)
+ {
+ if (close (sockets[0]) < 0)
+ perror_with_name ("Can't close socket");
+ if (dup2 (sockets[1], 0) < 0 || dup2 (sockets[1], 1) < 0)
+ perror_with_name ("Can't dup socket to stdio");
+ if (close (sockets[1]) < 0)
+ perror_with_name ("Can't close original socket");
+ /* Double fork in order to inherit the grandchild. The process
+ is expected to exit when the other end of the socketpair is
+ closed.
+ */
+ grandchild = fork ();
+ if (grandchild < 0)
+ perror_with_name ("Can't double fork command process");
+ if (grandchild != 0)
+ exit (0);
+ execl ("/bin/sh", "sh", "-c", command, NULL);
+ perror_with_name ("Can't exec command");
+ }
+ else
+ {
+ close (sockets[1]);
+ signal (SIGPIPE, SIG_IGN);
+ while ((res = waitpid (child, &status, 0)) < 0 && errno == EINTR);
+ if (res < 0)
+ perror_with_name ("Can't wait child process");
+ if (!WIFEXITED (status) || WEXITSTATUS (status))
+ perror_with_name ("Child process did not terminate correctly");
+ return sockets[0];
+ }
+ return -1;
+}
+#endif
+
/* Open a connection to a remote debugger.
NAME is the filename used for communication. */
@@ -288,6 +348,17 @@ 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)
@@ -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"