autoassign tty number

When no tty number is specified in the command line,
let the tty service to provide choose one available
tty and provide this one.

The documentation is updated wrt this modification and
I did a little fix to generate the date of the documentation.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

configure.ac

@@ -19,6 +19,7 @@ AS_AC_EXPAND(LIBEXECDIR, $libexecdir)
 AS_AC_EXPAND(SYSCONFDIR, $sysconfdir)
 AS_AC_EXPAND(LOCALSTATEDIR, $localstatedir)
 AS_AC_EXPAND(LXCPATH, "${localstatedir}/lib/lxc")
+AS_AC_EXPAND(LXC_GENERATE_DATE, "$(date)")
 
 AC_CHECK_HEADERS([linux/netlink.h linux/genetlink.h], [], AC_MSG_ERROR([netlink headers not found]),
 [#include <linux/types.h>

doc/lxc-console.sgml.in

@@ -45,7 +45,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
   <refsynopsisdiv>
     <cmdsynopsis>
       <command>lxc-console <replaceable>-n name</replaceable>
-	<replaceable>-t ttynum</replaceable>
+	<optional>-t ttynum</optional>
       </command>
     </cmdsynopsis>
   </refsynopsisdiv>
@@ -56,7 +56,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
     <para>
       If the tty service has been configured and is available for the
       container specified as parameter, this command will launch a
-      console allowing to log to the container.
+      console allowing to log on the container.
     </para>
 
     <para>
@@ -91,11 +91,12 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 
       <varlistentry>
 	<term>
-	  <option>-t <replaceable>ttynum</replaceable></option>
+	  <option>-t <optional>ttynum</optional></option>
 	</term>
 	<listitem>
 	  <para>
-	    Specify the tty number to connect.
+	    Specify the tty number to connect, if not specified a tty
+	    number will be automatically choosen by the container.
 	  </para>
 	</listitem>
       </varlistentry>

src/lxc/console.c

@@ -45,30 +45,34 @@ extern int lxc_console(const char *name, int ttynum, int *fd)
 	sock = lxc_af_unix_connect(addr.sun_path);
 	if (sock < 0) {
 		ERROR("failed to connect to the tty service");
-		goto out_err;
+		goto out;
 	}
 
 	ret = lxc_af_unix_send_credential(sock, &ttynum, sizeof(ttynum));
 	if (ret < 0) {
 		SYSERROR("failed to send credentials");
-		goto out_err;
+		goto out_close;
 	}
 
-	ret = lxc_af_unix_recv_fd(sock, fd, NULL, 0);
+	ret = lxc_af_unix_recv_fd(sock, fd, &ttynum, sizeof(ttynum));
 	if (ret < 0) {
 		ERROR("failed to connect to the tty");
-		goto out_err;
+		goto out_close;
 	}
 
+	INFO("tty %d allocated", ttynum);
+
 	if (!ret) {
-		ERROR("tty%d denied by '%s'", ttynum, name);
+		ERROR("console denied by '%s'", name);
 		ret = -LXC_ERROR_TTY_DENIED;
-		goto out_err;
+		goto out_close;
 	}
 
 	ret = 0;
 
-out_err:
-	close(sock);
+out:
 	return ret;
+out_close:
+	close(sock);
+	goto out;
 }

src/lxc/lxc.h

@@ -120,6 +120,8 @@ extern int lxc_monitor_close(int fd);
 /*
  * Show the console of the container.
  * @name : the name of container
+ * @tty  : the tty number
+ * @fd   : a pointer to a tty file descriptor
  * Returns 0 on sucess, < 0 otherwise
  */
 extern int lxc_console(const char *name, int ttynum, int *fd);

src/lxc/lxc_console.c

@@ -47,7 +47,7 @@ void usage(char *cmd)
 {
 	fprintf(stderr, "%s <command>\n", basename(cmd));
 	fprintf(stderr, "\t -n <name>   : name of the container\n");
-	fprintf(stderr, "\t -t <tty#>   : tty number\n");
+	fprintf(stderr, "\t [-t <tty#>] : tty number\n");
 	_exit(1);
 }
 
@@ -55,9 +55,9 @@ int main(int argc, char *argv[])
 {
 	char *name = NULL;
 	int opt;
-	int ttynum = 0;
 	int nbargs = 0;
 	int master = -1;
+	int ttynum = -1;
 	int wait4q = 0;
 	int err = LXC_ERROR_INTERNAL;
 	struct termios tios, oldtios;
@@ -67,6 +67,7 @@ int main(int argc, char *argv[])
 		case 'n':
 			name = optarg;
 			break;
+
 		case 't':
 			ttynum = atoi(optarg);
 			break;
@@ -75,7 +76,7 @@ int main(int argc, char *argv[])
 		nbargs++;
 	}
 
-	if (!name || !ttynum)
+	if (!name)
 		usage(argv[0]);
 
 	/* Get current termios */

src/lxc/start.c

@@ -197,31 +197,41 @@ static int ttyservice_handler(int fd, void *data,
 	if (lxc_af_unix_rcv_credential(conn, &ttynum, sizeof(ttynum)))
 		goto out_close;
 
-	if (ttynum <= 0 || ttynum > tty_info->nbtty)
+	if (ttynum > 0) {
+		if (ttynum > tty_info->nbtty)
+			goto out_close;
+
+		if (tty_info->pty_info[ttynum - 1].busy)
+			goto out_close;
+
+		goto out_send;
+	}
+
+	/* fixup index tty1 => [0] */
+	for (ttynum = 1;
+	     ttynum <= tty_info->nbtty && tty_info->pty_info[ttynum - 1].busy;
+	     ttynum++);
+
+	/* we didn't find any available slot for tty */
+	if (ttynum > tty_info->nbtty)
 		goto out_close;
 
-	/* fixup index array (eg. tty1 is index 0) */
-	ttynum--;
-
-	if (tty_info->pty_info[ttynum].busy)
-		goto out_close;
-
-	if (lxc_af_unix_send_fd(conn, tty_info->pty_info[ttynum].master, 
-				NULL, 0) < 0) {
+out_send:
+	if (lxc_af_unix_send_fd(conn, tty_info->pty_info[ttynum - 1].master,
+				&ttynum, sizeof(ttynum)) < 0) {
 		ERROR("failed to send tty to client");
 		goto out_close;
 	}
 
-	if (lxc_mainloop_add_handler(descr, conn, 
+	if (lxc_mainloop_add_handler(descr, conn,
 				     ttyclient_handler, tty_info)) {
 		ERROR("failed to add tty client handler");
 		goto out_close;
 	}
 
-	tty_info->pty_info[ttynum].busy = conn;
+	tty_info->pty_info[ttynum - 1].busy = conn;
 
 	ret = 0;
-
 out:
 	return ret;
 out_close: