libs/libc/builtin/: builtint_isavail() should not set the errno variable because this functions may be used by internal OS logic for which setting the rrno variable would be inappropriate.

TODO

@@ -286,6 +286,7 @@ o Task/Scheduler (sched/)
                  open() used within the OS.  There are places under libs/ and
                  boards/ that have not been converted.  I also note cases
                  where fopen() is called under libs/libc/netdb/.
+               2019-09-11:  built_isavail() no longer sets the errno varaible.
 
   Status:      Open
   Priority:    Low.  Things are working OK the way they are.  But the design

binfmt/builtin.c

@@ -123,11 +123,9 @@ static int builtin_loadbinary(struct binary_s *binp)
   index = builtin_isavail(filename);
   if (index < 0)
     {
-      int errval = get_errno();
       berr("ERROR: %s is not a builtin application\n", filename);
       close(fd);
-      return -errval;
-
+      return index;
     }
 
   /* Return the load information.  NOTE: that there is no way to configure

include/nuttx/lib/builtin.h

@@ -131,9 +131,9 @@ EXTERN const int g_builtin_count;
  *
  * Input Parameters:
  *   builtins - The list of built-in functions.  Each entry is a name-value
- *              pair that maps a builtin function name to its user-space
+ *              pair that maps a built-in function name to its user-space
  *              entry point address.
- *   count    - The number of name-value pairs in the builtin list.
+ *   count    - The number of name-value pairs in the built-in list.
  *
  * Returned Value:
  *   None
@@ -149,15 +149,18 @@ void builtin_setlist(FAR const struct builtin_s *builtins, int count);
  * Name: builtin_isavail
  *
  * Description:
- *   Checks for availability of application registered during compile time.
+ *   Checks for availability of an application named 'appname' registered
+ *   during compile time and, if available, returns the index into the table
+ *   of built-in applications.
  *
  * Input Parameters:
  *   filename - Name of the linked-in binary to be started.
  *
  * Returned Value:
- *   This is an end-user function, so it follows the normal convention:
- *   Returns index of builtin application. If it is not found then it
- *   returns -1 (ERROR) and sets errno appropriately.
+ *   This is an internal function, used by by the NuttX binfmt logic and
+ *   by the application built-in logic.  It returns a non-negative index to
+ *   the application entry in the table of built-in applications on success
+ *   or a negated errno value in the event of a failure.
  *
  ****************************************************************************/
 
@@ -185,9 +188,10 @@ FAR const char *builtin_getname(int index);
  * Name: builtin_for_index
  *
  * Description:
- *   Returns the builtin_s structure for the selected builtin.
- *   If support for builtin functions is enabled in the NuttX configuration,
- *   then this function must be provided by the application code.
+ *   Returns the builtin_s structure for the selected built-in.
+ *   If support for built-in functions is enabled in the NuttX
+ *   configuration, then this function must be provided by the application
+ *   code.
  *
  * Input Parameters:
  *   index, from 0 and on...

libs/libc/builtin/lib_builtin_forindex.c

@@ -49,6 +49,25 @@
  * Public Functions
  ****************************************************************************/
 
+/****************************************************************************
+ * Name: builtin_for_index
+ *
+ * Description:
+ *   Returns the builtin_s structure for the selected built-in.
+ *   If support for built-in functions is enabled in the NuttX
+ *   configuration, then this function must be provided by the application
+ *   code.
+ *
+ * Input Parameters:
+ *   index, from 0 and on...
+ *
+ * Returned Value:
+ *   Returns valid pointer pointing to the builtin_s structure if index is
+ *   valid.
+ *   Otherwise, NULL is returned.
+ *
+ ****************************************************************************/
+
 FAR const struct builtin_s *builtin_for_index(int index)
 {
   if (index < g_builtin_count)

libs/libc/builtin/lib_builtin_getname.c

@@ -58,8 +58,15 @@
  * Name: builtin_getname
  *
  * Description:
- *   Return the name of the application at index in the table of builtin
- *   applications.
+ *   Returns pointer the a name of the application at 'index' in the table
+ *   of built-in applications.
+ *
+ * Input Parameters:
+ *   index - From 0 and on ...
+ *
+ * Returned Value:
+ *   Returns valid pointer pointing to the app name if index is valid.
+ *   Otherwise NULL is returned.
  *
  ****************************************************************************/
 

libs/libc/builtin/lib_builtin_isavail.c

@@ -8,7 +8,7 @@
  *
  * With subsequent updates, modifications, and general maintenance by:
  *
- *   Copyright (C) 2012-2013 Gregory Nutt.  All rights reserved.
+ *   Copyright (C) 2012-2013, 2019 Gregory Nutt.  All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -62,8 +62,18 @@
  * Name: builtin_isavail
  *
  * Description:
- *   Return the index into the table of applications for the application with
- *   the name 'appname'.
+ *   Checks for availability of an application named 'appname' registered
+ *   during compile time and, if available, returns the index into the table
+ *   of built-in applications.
+ *
+ * Input Parameters:
+ *   filename - Name of the linked-in binary to be started.
+ *
+ * Returned Value:
+ *   This is an internal function, used by by the NuttX binfmt logic and
+ *   by the application built-in logic.  It returns a non-negative index to
+ *   the application entry in the table of built-in applications on success
+ *   or a negated errno value in the event of a failure.
  *
  ****************************************************************************/
 
@@ -72,16 +82,15 @@ int builtin_isavail(FAR const char *appname)
   FAR const char *name;
   int i;
 
-  for (i = 0; (name = builtin_getname(i)); i++)
+  for (i = 0; (name = builtin_getname(i)) != NULL; i++)
     {
-      if (!strncmp(name, appname, NAME_MAX))
+      if (strncmp(name, appname, NAME_MAX) == 0)
         {
           return i;
         }
     }
 
-  set_errno(ENOENT);
-  return ERROR;
+  return -ENOENT;
 }
 
 #endif /* HAVE_BUILTIN_CONTEXT */

libs/libc/builtin/lib_builtin_setlist.c

@@ -78,9 +78,9 @@ int g_builtin_count;
  *
  * Input Parameters:
  *   builtins - The list of built-in functions.  Each entry is a name-value
- *              pair that maps a builtin function name to its user-space
+ *              pair that maps a built-in function name to its user-space
  *              entry point address.
- *   count    - The number of name-value pairs in the builtin list.
+ *   count    - The number of name-value pairs in the built-in list.
  *
  * Returned Value:
  *   None