libs/libc/string/lib_stpncpy.c: Correct the return poineter value for the case where the NUL terminator is transferred.

libs/libc/signal/sig_psignal.c

@@ -63,8 +63,8 @@
  *     the string pointed to by the message argument will be written,
  *     followed by a colon and a space.
  *
- *     Then the signal description string associated with signum or with the
- *     signal indicated by pinfo will be written, followed by a newline.
+ *     Then the signal description string associated with signum will be
+ *     written, followed by a newline.
  *
  * Returned Value
  *  None.  The errno value is never set in this implementation.
@@ -99,8 +99,8 @@ void psignal(int signum, FAR const char *message)
  *     the string pointed to by the message argument will be written,
  *     followed by a colon and a space.
  *
- *     Then the signal description string associated with signum or with the
- *     signal indicated by pinfo will be written, followed by a newline.
+ *     Then the signal description string associated with the signal
+ *     indicated by pinfo will be written, followed by a newline.
  *
  * Returned Value
  *  None.  Since no value is returned, an application wishing to check for
@@ -121,4 +121,4 @@ void psiginfo(FAR const siginfo_t *pinfo, FAR const char *message)
     }
 }
 
-#endif /* __KERNEL__ */
+#endif /* !__KERNEL__ */

libs/libc/string/lib_stpncpy.c

@@ -78,17 +78,24 @@ FAR char *strncpy(FAR char *dest, FAR const char *src, size_t n)
    * encountered.
    */
 
-  while ((dest != end) && (*dest++ = *src++) != '\0')
+  while ((dest != end) && (*dest = *src++) != '\0')
     {
+      /* Increment the 'dest' pointer only if it does not refer to the
+       * NUL terminator.
+       */
+
+      dest++;
     }
 
   /* Return the pointer to the NUL terminator (or to the end of the buffer
-   * + 1.
+   * + 1).
    */
 
   ret = dest;
 
-  /* Pad the remainder of the array pointer to 'dest' with NULs */
+  /* Pad the remainder of the array pointer to 'dest' with NULs.  This
+   * overwrites any previously copied NUL terminator.
+   */
 
   while (dest != end)
     {