-DESCRIPTION
-
- Returns the maximum errno value for which a corresponding symbolic
- name or message is available. Note that in the case where
- we use the sys_errlist supplied by the system, it is possible for
- there to be more symbolic names than messages, or vice versa.
- In fact, the manual page for perror(3C) explicitly warns that one
- should check the size of the table (sys_nerr) before indexing it,
- since new error codes may be added to the system before they are
- added to the table. Thus sys_nerr might be smaller than value
- implied by the largest errno value defined in <errno.h>.
-
- We return the maximum value that can be used to obtain a meaningful
- symbolic name or message.