qemu-option: move help handling to get_opt_name_value

Right now, help options are parsed normally and then checked
specially in opt_validate, but only if coming from
qemu_opts_parse_noisily.  has_help_option does the check on its own.

opt_validate() has two callers: qemu_opt_set(), which passes null and is
therefore unaffected, and opts_do_parse(), which is affected.

opts_do_parse() is called by qemu_opts_do_parse(), which passes null and
is therefore unaffected, and opts_parse().

opts_parse() is called by qemu_opts_parse() and qemu_opts_set_defaults(),
which pass null and are therefore unaffected, and
qemu_opts_parse_noisily().

Move the check from opt_validate to the parsing workhorse of QemuOpts,
get_opt_name_value.  This will come in handy in the next patch, which
will raise a warning for "-object memory-backend-ram,share" ("flag" option
with no =on/=off part) but not for "-object memory-backend-ram,help".

As a result:

- opts_parse and opts_do_parse do not return an error anymore
  when help is requested; qemu_opts_parse_noisily does not have
  to work around that anymore.

- various crazy ways to request help are not recognized anymore:
  - "help=..."
  - "nohelp" (sugar for "help=off")
  - "?=..."
  - "no?" (sugar for "?=off")

- "help" would be recognized as help request even if there is a (foolishly
  named) parameter "help".  No such parameters exist, though.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

util/qemu-option.c

@@ -496,8 +496,7 @@ static QemuOpt *opt_create(QemuOpts *opts, const char *name, char *value,
     return opt;
 }
 
-static bool opt_validate(QemuOpt *opt, bool *help_wanted,
+static bool opt_validate(QemuOpt *opt, Error **errp)
-                         Error **errp)
 {
     const QemuOptDesc *desc;
     const QemuOptsList *list = opt->opts->list;
@@ -505,9 +504,6 @@ static bool opt_validate(QemuOpt *opt, bool *help_wanted,
     desc = find_desc_by_name(list->desc, opt->name);
     if (!desc && !opts_accepts_any(list)) {
         error_setg(errp, QERR_INVALID_PARAMETER, opt->name);
-        if (help_wanted && is_help_option(opt->name)) {
-            *help_wanted = true;
-        }
         return false;
     }
 
@@ -524,7 +520,7 @@ bool qemu_opt_set(QemuOpts *opts, const char *name, const char *value,
 {
     QemuOpt *opt = opt_create(opts, name, g_strdup(value), false);
 
-    if (!opt_validate(opt, NULL, errp)) {
+    if (!opt_validate(opt, errp)) {
         qemu_opt_del(opt);
         return false;
     }
@@ -760,10 +756,12 @@ void qemu_opts_print(QemuOpts *opts, const char *separator)
 
 static const char *get_opt_name_value(const char *params,
                                       const char *firstname,
+                                      bool *help_wanted,
                                       char **name, char **value)
 {
     const char *p;
     size_t len;
+    bool is_help = false;
 
     len = strcspn(params, "=,");
     if (params[len] != '=') {
@@ -780,6 +778,7 @@ static const char *get_opt_name_value(const char *params,
                 *value = g_strdup("off");
             } else {
                 *value = g_strdup("on");
+                is_help = is_help_option(*name);
             }
         }
     } else {
@@ -791,6 +790,9 @@ static const char *get_opt_name_value(const char *params,
     }
 
     assert(!*p || *p == ',');
+    if (help_wanted && is_help) {
+        *help_wanted = true;
+    }
     if (*p == ',') {
         p++;
     }
@@ -806,7 +808,12 @@ static bool opts_do_parse(QemuOpts *opts, const char *params,
     QemuOpt *opt;
 
     for (p = params; *p;) {
-        p = get_opt_name_value(p, firstname, &option, &value);
+        p = get_opt_name_value(p, firstname, help_wanted, &option, &value);
+        if (help_wanted && *help_wanted) {
+            g_free(option);
+            g_free(value);
+            return false;
+        }
         firstname = NULL;
 
         if (!strcmp(option, "id")) {
@@ -817,7 +824,7 @@ static bool opts_do_parse(QemuOpts *opts, const char *params,
 
         opt = opt_create(opts, option, value, prepend);
         g_free(option);
-        if (!opt_validate(opt, help_wanted, errp)) {
+        if (!opt_validate(opt, errp)) {
             qemu_opt_del(opt);
             return false;
         }
@@ -832,7 +839,7 @@ static char *opts_parse_id(const char *params)
     char *name, *value;
 
     for (p = params; *p;) {
-        p = get_opt_name_value(p, NULL, &name, &value);
+        p = get_opt_name_value(p, NULL, NULL, &name, &value);
         if (!strcmp(name, "id")) {
             g_free(name);
             return value;
@@ -848,11 +855,10 @@ bool has_help_option(const char *params)
 {
     const char *p;
     char *name, *value;
-    bool ret;
+    bool ret = false;
 
     for (p = params; *p;) {
-        p = get_opt_name_value(p, NULL, &name, &value);
+        p = get_opt_name_value(p, NULL, &ret, &name, &value);
-        ret = is_help_option(name);
         g_free(name);
         g_free(value);
         if (ret) {
@@ -937,11 +943,13 @@ QemuOpts *qemu_opts_parse_noisily(QemuOptsList *list, const char *params,
     QemuOpts *opts;
     bool help_wanted = false;
 
-    opts = opts_parse(list, params, permit_abbrev, false, &help_wanted, &err);
+    opts = opts_parse(list, params, permit_abbrev, false,
-    if (err) {
+                      opts_accepts_any(list) ? NULL : &help_wanted,
+                      &err);
+    if (!opts) {
+        assert(!!err + !!help_wanted == 1);
         if (help_wanted) {
             qemu_opts_print_help(list, true);
-            error_free(err);
         } else {
             error_report_err(err);
         }