nshlib/nsh_builtin.c : Add support to run builtin dirrectly as command

  Add a new config: NSH_BUILTIN_AS_COMMAND.
  Provide a new implementation for nsh_builtin
  when CONFIG_NSH_BUILTIN_APPS_AS_COMMAND is enabled.

Signed-off-by: Chengdong Wang <wangchengdong@lixiang.com>

Author: wangchdo

nshlib/CMakeLists.txt

@@ -51,7 +51,9 @@ if(CONFIG_NSH_LIBRARY)
   list(APPEND CSRCS nsh_fsutils.c)
 
   if(CONFIG_NSH_BUILTIN_APPS)
-    list(APPEND CSRCS nsh_builtin.c)
+    if(NOT CONFIG_NSH_BUILTIN_AS_COMMAND)
+      list(APPEND CSRCS nsh_builtin.c)
+    endif()
   endif()
 
   if(CONFIG_NSH_FILE_APPS)

nshlib/Kconfig

@@ -242,6 +242,14 @@ config NSH_BUILTIN_APPS
 		more information).  This options requires support for builtin
 		applications (BUILTIN).
 
+config NSH_BUILTIN_AS_COMMAND
+	bool "Run builtin apps as command"
+	default n
+	depends on BUILTIN
+	---help---
+		Enable to run builtin application directly without creating
+		a separate thread.
+
 config NSH_FILE_APPS
 	bool "Enable execution of program files"
 	default n

nshlib/Makefile

@@ -36,8 +36,10 @@ endif
 CSRCS += nsh_fsutils.c
 
 ifeq ($(CONFIG_NSH_BUILTIN_APPS),y)
+ifneq ($(CONFIG_NSH_BUILTIN_AS_COMMAND),y)
 CSRCS += nsh_builtin.c
 endif
+endif
 
 ifeq ($(CONFIG_NSH_FILE_APPS),y)
 CSRCS += nsh_fileapps.c

nshlib/nsh_command.c

@@ -1213,10 +1213,14 @@ static int cmd_expr(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char **argv)
 
 int nsh_command(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char *argv[])
 {
-  const struct cmdmap_s *cmdmap;
-  const char            *cmd;
-  nsh_cmd_t              handler = cmd_unrecognized;
-  int                    ret;
+  const struct cmdmap_s  *cmdmap;
+  const char             *cmd;
+  nsh_cmd_t               handler = cmd_unrecognized;
+#ifdef CONFIG_NSH_BUILTIN_AS_COMMAND
+  const struct builtin_s *builtin;
+  int                     index;
+#endif
+  int                     ret;
 
   /* The form of argv is:
    *
@@ -1228,6 +1232,23 @@ int nsh_command(FAR struct nsh_vtbl_s *vtbl, int argc, FAR char *argv[])
 
   cmd = argv[0];
 
+#ifdef CONFIG_NSH_BUILTIN_AS_COMMAND
+  /* Check if the command is available in the builtin list */
+
+  index = builtin_isavail(cmd);
+
+  if (index > 0)
+    {
+      /* Get the builtin structure by index */
+
+      builtin = builtin_for_index(index);
+      if (builtin != NULL)
+        {
+          return (builtin->main)(argc, (FAR char **)argv);
+        }
+    }
+#endif
+
   /* See if the command is one that we understand */
 
   for (cmdmap = g_cmdmap; cmdmap->cmd; cmdmap++)

nshlib/nsh_parse.c

@@ -512,12 +512,12 @@ static int nsh_execute(FAR struct nsh_vtbl_s *vtbl,
    *
    * 1. Load a file from file system if possible.  An external command on a
    *    file system with the provided name (and on the defined PATH) takes
-   *    precendence over any other source of a command by that name.  This
+   *    precedence over any other source of a command by that name.  This
    *    allows the user to replace a built-in command with a command on a`
    *    file system
    *
    * 2. If not, run a built-in application of that name if possible.  A
-   *    built-in application will take precendence over any NSH command.
+   *    built-in application will take precedence over any NSH command.
    *
    * 3. If not, run an NSH command line command if possible.
    *
@@ -540,7 +540,7 @@ static int nsh_execute(FAR struct nsh_vtbl_s *vtbl,
    * Note the priority is not effected by nice-ness.
    */
 
-#ifdef CONFIG_NSH_BUILTIN_APPS
+#if defined(CONFIG_NSH_BUILTIN_APPS) && !defined(CONFIG_NSH_BUILTIN_AS_COMMAND)
   ret = nsh_builtin(vtbl, argv[0], argv, param);
   if (ret >= 0)
     {
@@ -637,7 +637,7 @@ static int nsh_execute(FAR struct nsh_vtbl_s *vtbl,
       sh_argv[3] = NULL;
 
       /* np.np_bg still there, try use nsh_builtin or nsh_fileapp to
-       * dispatch the backgroud by sh -c ""
+       * dispatch the background by sh -c ""
        */
 
       ret = nsh_execute(vtbl, 4, sh_argv, param);