NAME
       strnlen - determine the length of a fixed-size string
SYNOPSIS
       #define _GNU_SOURCE
       #include <string.h>
       size_t strnlen(const char *s, size_t maxlen);
DESCRIPTION
       The  strnlen()  function returns the number of characters in the string
       pointed to by s, not including the terminating '\0' character,  but  at
       most  maxlen.   In doing this, strnlen() looks only at the first maxlen
       characters at s and never beyond s+maxlen.
RETURN VALUE
       The strnlen() function returns strlen(s), if that is less than  maxlen,
       or  maxlen  if  there  is  no  '\0'  character  among  the first maxlen
       characters pointed to by s.
CONFORMING TO
       This function is a GNU extension.
SEE ALSO
       strlen(3), feature_test_macros(7)
COLOPHON
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       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.