Add perror()

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@5061 7fd9a85b-ad96-42d3-883c-3090e2eb8679

apps/ChangeLog.txt

@@ -289,5 +289,5 @@
 	  threds to no more than 3 of each priority.  Bad things happen
 	  when the existing logic tried to created several hundred test
 	  treads!
-
-
+	* apps/nshlib/nsh.h:  Both CONFIG_LIBC_STRERROR and CONFIG_NSH_STRERROR
+	  must be defined to use strerror() with NSH.

apps/nshlib/Kconfig

@@ -148,9 +148,12 @@ config NSH_FILEIOSIZE
 config NSH_STRERROR
 	bool "Use strerror()"
 	default n
+	depends on LIBC_STRERROR
 	---help---
 		strerror(errno) makes more readable output but strerror() is
 		very large and will not be used unless this setting is 'y'
+		This setting depends upon the strerror() having been enabled
+		with LIBC_STRERROR.
 
 config NSH_LINELEN
 	int "Max command line length"

apps/nshlib/README.txt

@@ -915,7 +915,9 @@ NSH-Specific Configuration Settings
 
   * CONFIG_NSH_STRERROR
       strerror(errno) makes more readable output but strerror() is
-      very large and will not be used unless this setting is 'y'
+      very large and will not be used unless this setting is 'y'.
+      This setting depends upon the strerror() having been enabled
+      with CONFIG_LIBC_STRERROR.
 
   * CONFIG_NSH_LINELEN
       The maximum length of one command line and of one output line.

apps/nshlib/nsh.h

@@ -238,9 +238,14 @@
 #define NSH_MAX_ARGUMENTS 6
 
 /* strerror() produces much nicer output but is, however, quite large and
- * will only be used if CONFIG_NSH_STRERROR is defined.
+ * will only be used if CONFIG_NSH_STRERROR is defined.  Note that the strerror
+ * interface must also have been enabled with CONFIG_LIBC_STRERROR.
  */
 
+#ifndef CONFIG_LIBC_STRERROR
+#  undef CONFIG_NSH_STRERROR
+#endif
+
 #ifdef CONFIG_NSH_STRERROR
 #  define NSH_ERRNO         strerror(errno)
 #  define NSH_ERRNO_OF(err) strerror(err)