[PATCH v6] Implement backend program convention command for vhost-user-blk

[Micky Yun Chan <chanmickyyun@gmail.com>]

From: michan <michan@redhat.com>

This patch is to add standard commands defined in docs/interop/vhost-user.rst
For vhost-user-* program

Signed-off-by: Micky Yun Chan (michiboo) <chanmickyyun@gmail.com>
---
 contrib/vhost-user-blk/vhost-user-blk.c | 108 ++++++++++++++----------
 docs/interop/vhost-user.json            |  31 +++++++
 2 files changed, 95 insertions(+), 44 deletions(-)

diff --git a/contrib/vhost-user-blk/vhost-user-blk.c b/contrib/vhost-user-blk/vhost-user-blk.c
index ae61034656..6fd91c7e99 100644
--- a/contrib/vhost-user-blk/vhost-user-blk.c
+++ b/contrib/vhost-user-blk/vhost-user-blk.c
@@ -576,70 +576,90 @@ vub_new(char *blk_file)
     return vdev_blk;
 }
 
+static int opt_fdnum = -1;
+static char *opt_socket_path;
+static char *opt_blk_file;
+static gboolean opt_print_caps;
+static gboolean opt_read_only;
+
+static GOptionEntry entries[] = {
+    { "print-capabilities", 'c', 0, G_OPTION_ARG_NONE, &opt_print_caps,
+      "Print capabilities", NULL },
+    { "fd", 'f', 0, G_OPTION_ARG_INT, &opt_fdnum,
+      "Use inherited fd socket", "FDNUM" },
+    { "socket-path", 's', 0, G_OPTION_ARG_FILENAME, &opt_socket_path,
+      "Use UNIX socket path", "PATH" },
+    {"blk-file", 'b', 0, G_OPTION_ARG_FILENAME, &opt_blk_file,
+     "block device or file path", "PATH"},
+    { "read-only", 'r', 0, G_OPTION_ARG_NONE, &opt_read_only,
+      "Enable read-only", NULL }
+};
+
 int main(int argc, char **argv)
 {
-    int opt;
-    char *unix_socket = NULL;
-    char *blk_file = NULL;
-    bool enable_ro = false;
     int lsock = -1, csock = -1;
     VubDev *vdev_blk = NULL;
+    GError *error = NULL;
+    GOptionContext *context;
 
-    while ((opt = getopt(argc, argv, "b:rs:h")) != -1) {
-        switch (opt) {
-        case 'b':
-            blk_file = g_strdup(optarg);
-            break;
-        case 's':
-            unix_socket = g_strdup(optarg);
-            break;
-        case 'r':
-            enable_ro = true;
-            break;
-        case 'h':
-        default:
-            printf("Usage: %s [ -b block device or file, -s UNIX domain socket"
-                   " | -r Enable read-only ] | [ -h ]\n", argv[0]);
-            return 0;
+    context = g_option_context_new(NULL);
+    g_option_context_add_main_entries(context, entries, NULL);
+    if (!g_option_context_parse(context, &argc, &argv, &error)) {
+        g_printerr("Option parsing failed: %s\n", error->message);
+        exit(EXIT_FAILURE);
+    }
+    if (opt_print_caps) {
+        g_print("{\n");
+        g_print("  \"type\": \"block\",\n");
+        g_print("  \"features\": [\n");
+        g_print("    \"read-only\",\n");
+        g_print("    \"blk-file\"\n");
+        g_print("  ]\n");
+        g_print("}\n");
+        exit(EXIT_SUCCESS);
+    }
+
+    if (!opt_blk_file) {
+        g_print("%s\n", g_option_context_get_help(context, true, NULL));
+        exit(EXIT_FAILURE);
+    }
+
+    if (opt_socket_path) {
+        lsock = unix_sock_new(opt_socket_path);
+        if (lsock < 0) {
+            exit(EXIT_FAILURE);
         }
+    } else if (opt_fdnum < 0) {
+        g_print("%s\n", g_option_context_get_help(context, true, NULL));
+        exit(EXIT_FAILURE);
+    } else {
+        lsock = opt_fdnum;
     }
 
-    if (!unix_socket || !blk_file) {
-        printf("Usage: %s [ -b block device or file, -s UNIX domain socket"
-               " | -r Enable read-only ] | [ -h ]\n", argv[0]);
-        return -1;
-    }
-
-    lsock = unix_sock_new(unix_socket);
-    if (lsock < 0) {
-        goto err;
-    }
-
-    csock = accept(lsock, (void *)0, (void *)0);
+    csock = accept(lsock, NULL, NULL);
     if (csock < 0) {
-        fprintf(stderr, "Accept error %s\n", strerror(errno));
-        goto err;
+        g_printerr("Accept error %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
     }
 
-    vdev_blk = vub_new(blk_file);
+    vdev_blk = vub_new(opt_blk_file);
     if (!vdev_blk) {
-        goto err;
+        exit(EXIT_FAILURE);
     }
-    if (enable_ro) {
+    if (opt_read_only) {
         vdev_blk->enable_ro = true;
     }
 
     if (!vug_init(&vdev_blk->parent, VHOST_USER_BLK_MAX_QUEUES, csock,
                   vub_panic_cb, &vub_iface)) {
-        fprintf(stderr, "Failed to initialized libvhost-user-glib\n");
-        goto err;
+        g_printerr("Failed to initialize libvhost-user-glib\n");
+        exit(EXIT_FAILURE);
     }
 
     g_main_loop_run(vdev_blk->loop);
-
+    g_main_loop_unref(vdev_blk->loop);
+    g_option_context_free(context);
     vug_deinit(&vdev_blk->parent);
-
-err:
     vub_free(vdev_blk);
     if (csock >= 0) {
         close(csock);
@@ -647,8 +667,8 @@ err:
     if (lsock >= 0) {
         close(lsock);
     }
-    g_free(unix_socket);
-    g_free(blk_file);
+    g_free(opt_socket_path);
+    g_free(opt_blk_file);
 
     return 0;
 }
diff --git a/docs/interop/vhost-user.json b/docs/interop/vhost-user.json
index da6aaf51c8..d25c3a957f 100644
--- a/docs/interop/vhost-user.json
+++ b/docs/interop/vhost-user.json
@@ -54,6 +54,37 @@
   ]
 }
 
+##
+# @VHostUserBackendBlockFeature:
+#
+# List of vhost user "block" features.
+#
+# @read-only: The --read-only command line option is supported.
+# @blk-file: The --blk-file command line option is supported.
+#
+# Since: 4.0
+##
+{
+  'enum': 'VHostUserBackendBlockFeature',
+  'data': [ 'read-only', 'blk-file' ]
+}
+
+##
+# @VHostUserBackendCapabilitiesBlock:
+#
+# Capabilities reported by vhost user "block" backends
+#
+# @features: list of supported features.
+#
+# Since: 4.0
+##
+{
+  'struct': 'VHostUserBackendCapabilitiesBlock',
+  'data': {
+    'features': [ 'VHostUserBackendBlockFeature' ]
+  }
+}
+
 ##
 # @VHostUserBackendInputFeature:
 #
-- 
2.21.0