Added new dbus interface to query console info

obmc-console recipe configure consoles by setting the socket-id
field in the console server config file. obmc-console server use this
socket id to build a abract socket name and register new service
"xyz.openbmc_project.Console.Access". The leaf of the object path will
be socket-id configured. It also exposes the unix abstract socket name
through SocketName property. The socket name is sent as a byte stream as
abstract socket contains null character at the start.

*** For example if recipe configured socket-id as "console0" the
*** following object is exported through dbus interface

    # Tree for "console0" console.
    $ busctl tree xyz.openbmc_project.Console.console0
    `-/xyz
      `-/xyz/openbmc_project
        `-/xyz/openbmc_project/console
          `-/xyz/openbmc_project/console/console0

    # Get SocketName property for console0 object
    $ busctl get-property xyz.openbmc_project.Console.console0 /xyz/openbmc_project/console/console0 xyz.openbmc_project.Console.Access SocketName
    ay 22 0 111 98 109 99 45 99 111 110 115 111 108 101 46 99 111 110 115 111 108 101 48

    # Tree for "hypervisor" console
    $ busctl tree xyz.openbmc_project.Console.hypervisor
    `-/xyz
      `-/xyz/openbmc_project
        `-/xyz/openbmc_project/console
          `-/xyz/openbmc_project/console/hypervisor

    # Get SocketName property for hypervisor object
    $ busctl get-property xyz.openbmc_project.Console.hypervisor /xyz/openbmc_project/console/hypervisor xyz.openbmc_project.Console.Access SocketName
    ay 24 0 111 98 109 99 45 99 111 110 115 111 108 101 46 104 121 112 101 114 118 105 115 111 114

    # Note that this is an example of two consoles one is 'console0' and
    # second is 'hypervisor'. I have formated the output to easy viewing.
    # We also have one extra service for console that is coming from the
    # service exist today to get/set the tty device baud rate.
    $ busctl call  xyz.openbmc_project.ObjectMapper \
        /xyz/openbmc_project/object_mapper xyz.openbmc_project.ObjectMapper \
        GetSubTree sias /xyz/openbmc_project/console 0 1 \
        xyz.openbmc_project.Console.Access
    a{sa{sas}}
    2
    "/xyz/openbmc_project/console/console0" \
        1
        "xyz.openbmc_project.Console.console0"
           4 "org.freedesktop.DBus.Introspectable"
             "org.freedesktop.DBus.Peer"
             "org.freedesktop.DBus.Properties"
             "xyz.openbmc_project.Console.Access"
    "/xyz/openbmc_project/console/hypervisor"
        2
        "xyz.openbmc_project.Console.hypervisor"
           4 "org.freedesktop.DBus.Introspectable"
             "org.freedesktop.DBus.Peer"
             "org.freedesktop.DBus.Properties"
             "xyz.openbmc_project.Console.Access"
        "xyz.openbmc_project.console"
          4 "org.freedesktop.DBus.Introspectable"
            "org.freedesktop.DBus.Peer"
            "org.freedesktop.DBus.Properties"
            "xyz.openbmc_project.Console.Access"

Tested:
    Tested on the rainer system with busctl command and integration
    with bmcweb

Related commits:
    1) phosphor-dbus-interface: https://gerrit.openbmc.org/c/openbmc/phosphor-dbus-interfaces/+/61486
    2) obmc-console: https://gerrit.openbmc.org/c/openbmc/obmc-console/+/62496
    3) bmcweb: https://gerrit.openbmc.org/c/openbmc/bmcweb/+/62525

Change-Id: Ifb70ce5585c3937f3abd904ffbae51ca67f58724
Signed-off-by: Ninad Palsule <ninadpalsule@us.ibm.com>
diff --git a/console-server.c b/console-server.c
index d06cc32..f52c719 100644
--- a/console-server.c
+++ b/console-server.c
@@ -34,6 +34,7 @@
 
 #include <sys/types.h>
 #include <sys/time.h>
+#include <sys/socket.h>
 #include <poll.h>
 
 #include "console-server.h"
@@ -302,6 +303,30 @@
 	return write_buf_to_fd(console->tty_fd, data, len);
 }
 
+/* Read console if from config and prepare a socket name */
+static int set_socket_info(struct console *console, struct config *config)
+{
+	ssize_t len;
+
+	console->console_id = config_get_value(config, "socket-id");
+	if (!console->console_id) {
+		warnx("Error: The socket-id is not set in the config file");
+		return EXIT_FAILURE;
+	}
+
+	/* Get the socket name/path */
+	len = console_socket_path(console->socket_name, console->console_id);
+	if (len < 0) {
+		warn("Failed to set socket path: %s", strerror(errno));
+		return EXIT_FAILURE;
+	}
+
+	/* Socket name is not a null terminated string hence save the length */
+	console->socket_name_len = len;
+
+	return 0;
+}
+
 static void handlers_init(struct console *console, struct config *config)
 {
 	/* NOLINTBEGIN(bugprone-reserved-identifier,cert-dcl37-c,cert-dcl51-cpp) */
@@ -732,6 +757,10 @@
 		return EXIT_FAILURE;
 	}
 
+	if (set_socket_info(console, config)) {
+		return EXIT_FAILURE;
+	}
+
 	console->tty_kname = config_tty_kname;
 
 	console->console_id = config_get_value(config, "socket-id");