xl: Add "xl domname" command, a clone of "xm domname".

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>

tools/libxl/xl_cmdimpl.c

@@ -1240,6 +1240,9 @@ void help(char *command)
     } else if (!strcmp(command, "domid")) {
         printf("Usage: xl domid <DomainName>\n\n");
         printf("Convert a domain name to domain id.\n");
+    } else if (!strcmp(command, "domname")) {
+        printf("Usage: xl domname <DomainId>\n\n");
+        printf("Convert a domain id to domain name.\n");
     }
 }
 
@@ -2997,3 +3000,43 @@ int main_domid(int argc, char **argv)
 
     exit(0);
 }
+
+int main_domname(int argc, char **argv)
+{
+    int opt;
+    char *domname = NULL;
+    char *endptr = NULL;
+
+    while ((opt = getopt(argc, argv, "h")) != -1) {
+        switch (opt) {
+        case 'h':
+            help("domname");
+            exit(0);
+        default:
+            fprintf(stderr, "option `%c' not supported.\n", opt);
+            break;
+        }
+    }
+
+    if (!argv[optind]) {
+        fprintf(stderr, "Must specify a domain id.\n\n");
+        help("domname");
+        exit(1);
+    }
+    domid = strtol(argv[optind], &endptr, 10);
+    if (domid == 0 && !strcmp(endptr, argv[optind])) {
+        /*no digits at all*/
+        fprintf(stderr, "Invalid domain id.\n\n");
+        exit(1);
+    }
+
+    domname = libxl_domid_to_name(&ctx, domid);
+    if (!domname) {
+        fprintf(stderr, "Can't get domain name of domain id '%d', maybe this domain does not exist.\n", domid);
+        exit(1);
+    }
+
+    printf("%s\n", domname);
+
+    exit(0);
+}

tools/libxl/xl_cmdimpl.h

@@ -36,5 +36,6 @@ int main_vcpuset(int argc, char **argv);
 int main_memset(int argc, char **argv);
 int main_sched_credit(int argc, char **argv);
 int main_domid(int argc, char **argv);
+int main_domname(int argc, char **argv);
 
 void help(char *command);

tools/libxl/xl_cmdtable.c

@@ -37,6 +37,7 @@ struct cmd_spec cmd_table[] = {
     { "info", &main_info, "get information about Xen host" },
     { "sched-credit", &main_sched_credit, "get/set credit scheduler parameters" },
     { "domid", &main_domid, "convert a domain name to domain id"},
+    { "domname", &main_domname, "convert a domain id to domain name"},
 };
 
 int cmdtable_len = sizeof(cmd_table)/sizeof(struct cmd_spec);