This warning appears when compiling with a modern Clang compiler:
send.c:1442:32: warning: the value of the size argument in 'strncat' is too large, might lead to a buffer overflow [-Wstrncat-size]
strncat(nbuf, pattern, sizeof(nbuf) - strlen(nbuf));
^~~~~~~~~~~~~~~~~~~~~~~~~~~
send.c:1442:32: note: change the argument to be the free space in the destination buffer minus the terminating null byte
strncat(nbuf, pattern, sizeof(nbuf) - strlen(nbuf));
^~~~~~~~~~~~~~~~~~~~~~~~~~~
sizeof(nbuf) - strlen(nbuf) - 1
This warning appears when compiling with a modern Clang compiler: