virt-admin: Tweak command parsing logic so that aliases point to new commands

Change the logic in a way, so that VSH_CMD_FLAG_ALIAS behaves similarly to
how VSH_OT_ALIAS for command options, i.e. there is no need for code duplication
for the alias and the aliased command structures. Along with that change,
switch any existing VSH_CMD_FLAG_ALIAS occurrences to this new format. Also,
since this patch introduces a new command structure element, adjust the
virsh-self-test test to make sure we won't ever miss to specify the '.alias'
member for an aliased command because doing that would lead to an internal
error.
Signed-off-by: NErik Skultety <eskultet@redhat.com>

tools/virsh-nodedev.c

@@ -986,10 +986,8 @@ const vshCmdDef nodedevCmds[] = {
      .flags = 0
     },
     {.name = "nodedev-dettach",
-     .handler = cmdNodeDeviceDetach,
-     .opts = opts_node_device_detach,
-     .info = info_node_device_detach,
-     .flags = VSH_CMD_FLAG_ALIAS
+     .flags = VSH_CMD_FLAG_ALIAS,
+     .alias = "nodedev-detach"
     },
     {.name = "nodedev-dumpxml",
      .handler = cmdNodeDeviceDumpXML,

tools/vsh.c

@@ -330,6 +330,13 @@ vshCmddefCheckInternals(const vshCmdDef *cmd)
     size_t i;
     const char *help = NULL;
 
+    /* in order to perform the validation resolve the alias first */
+    if (cmd->flags & VSH_CMD_FLAG_ALIAS) {
+        if (!cmd->alias)
+            return -1;
+        cmd = vshCmddefSearch(cmd->alias);
+    }
+
     /* Each command has to provide a non-empty help string. */
     if (!(help = vshCmddefGetInfo(cmd, "help")) || !*help)
         return -1;
@@ -1407,6 +1414,13 @@ vshCommandParse(vshControl *ctl, vshCommandParser *parser)
                     vshError(ctl, _("unknown command: '%s'"), tkdata);
                     goto syntaxError;   /* ... or ignore this command only? */
                 }
+
+                /* aliases need to be resolved to the actual commands */
+                if (cmd->flags & VSH_CMD_FLAG_ALIAS) {
+                    VIR_FREE(tkdata);
+                    tkdata = vshStrdup(ctl, cmd->alias);
+                    cmd = vshCmddefSearch(tkdata);
+                }
                 if (vshCmddefOptParse(cmd, &opts_need_arg,
                                       &opts_required) < 0) {
                     vshError(ctl,
@@ -2568,7 +2582,8 @@ vshReadlineCommandGenerator(const char *text, int state)
 
         if (cmds[cmd_list_index].name) {
             while ((name = cmds[cmd_list_index].name)) {
-                cmd_list_index++;
+                if (cmds[cmd_list_index++].flags & VSH_CMD_FLAG_ALIAS)
+                    continue;
 
                 if (STREQLEN(name, text, len))
                     return vshStrdup(NULL, name);
@@ -2706,8 +2721,10 @@ vshReadlineParse(const char *text, int state)
             if (!cmd) {
                 if (!(cmd = vshCmddefSearch(tkdata)))
                     goto error;
-                cmd_exists = true;
+                if (cmd->flags & VSH_CMD_FLAG_ALIAS)
+                    cmd = vshCmddefSearch(cmd->alias);
 
+                cmd_exists = true;
                 if (vshCmddefOptParse(cmd, &const_opts_need_arg,
                                       &const_opts_required) < 0)
                     goto error;
@@ -3351,9 +3368,6 @@ cmdSelfTest(vshControl *ctl, const vshCmd *cmd ATTRIBUTE_UNUSED)
 
     for (grp = cmdGroups; grp->name; grp++) {
         for (def = grp->commands; def->name; def++) {
-            if (def->flags & VSH_CMD_FLAG_ALIAS)
-                continue;
-
             if (vshCmddefCheckInternals(def) < 0)
                 return false;
         }

tools/vsh.h

@@ -179,6 +179,7 @@ struct _vshCmdDef {
     const vshCmdOptDef *opts;   /* definition of command options */
     const vshCmdInfo *info;     /* details about command */
     unsigned int flags;         /* bitwise OR of VSH_CMD_FLAG */
+    const char *alias;          /* name of the aliased command */
 };
 
 /*
@@ -445,7 +446,8 @@ bool cmdSelfTest(vshControl *ctl, const vshCmd *cmd);
         .handler = cmdSelfTest,                         \
         .opts = NULL,                                   \
         .info = info_selftest,                          \
-        .flags = VSH_CMD_FLAG_NOCONNECT | VSH_CMD_FLAG_ALIAS    \
+        .flags = VSH_CMD_FLAG_NOCONNECT | VSH_CMD_FLAG_ALIAS,    \
+        .alias = "self-test"                            \
     }