errstr, rerrstr, werrstr – description of last system call error|
When a system call fails it returns –1 and records a null terminated
string describing the error in a per–process buffer. Errstr swaps
the contents of that buffer with the contents of the array err.
Errstr will write at most nerr bytes into err; if the per–process
error string does not fit, it is silently truncated at a UTF
character boundary. The returned string is NUL–terminated. Usually
errstr will be called with an empty string, but the exchange property
provides a mechanism for libraries to set the return value for
the next call to errstr.
Errstr always returns 0.|