qemu-option: simplify search for end of key

Use strcspn to find an equal or comma value, and pass the result directly
to get_opt_name to avoid another strchr.

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

util/qemu-option.c

@@ -38,27 +38,19 @@
 #include "qemu/help_option.h"
 
 /*
- * Extracts the name of an option from the parameter string (p points at the
+ * Extracts the name of an option from the parameter string (@p points at the
  * first byte of the option name)
  *
- * The option name is delimited by delim (usually , or =) or the string end
- * and is copied into option. The caller is responsible for free'ing option
- * when no longer required.
+ * The option name is @len characters long and is copied into @option. The
+ * caller is responsible for free'ing @option when no longer required.
  *
  * The return value is the position of the delimiter/zero byte after the option
- * name in p.
+ * name in @p.
  */
-static const char *get_opt_name(const char *p, char **option, char delim)
+static const char *get_opt_name(const char *p, char **option, size_t len)
 {
-    char *offset = strchr(p, delim);
-
-    if (offset) {
-        *option = g_strndup(p, offset - p);
-        return offset;
-    } else {
-        *option = g_strdup(p);
-        return p + strlen(p);
-    }
+    *option = g_strndup(p, len);
+    return p + len;
 }
 
 /*
@@ -766,12 +758,11 @@ static const char *get_opt_name_value(const char *params,
                                       const char *firstname,
                                       char **name, char **value)
 {
-    const char *p, *pe, *pc;
-
-    pe = strchr(params, '=');
-    pc = strchr(params, ',');
+    const char *p;
+    size_t len;
 
-    if (!pe || (pc && pc < pe)) {
+    len = strcspn(params, "=,");
+    if (params[len] != '=') {
         /* found "foo,more" */
         if (firstname) {
             /* implicitly named first option */
@@ -779,7 +770,7 @@ static const char *get_opt_name_value(const char *params,
             p = get_opt_value(params, value);
         } else {
             /* option without value, must be a flag */
-            p = get_opt_name(params, name, ',');
+            p = get_opt_name(params, name, len);
             if (strncmp(*name, "no", 2) == 0) {
                 memmove(*name, *name + 2, strlen(*name + 2) + 1);
                 *value = g_strdup("off");
@@ -789,7 +780,7 @@ static const char *get_opt_name_value(const char *params,
         }
     } else {
         /* found "foo=bar,more" */
-        p = get_opt_name(params, name, '=');
+        p = get_opt_name(params, name, len);
         assert(*p == '=');
         p++;
         p = get_opt_value(p, value);