Problem - Kevin Tafuro

int spc_fd_isset(int fd, SPC_FD_SET *fdset) {
if (fd < 0 || fd >= fdset->fds_size) return 0;
return (fdset->fds_bits[fd / sizeof(long)] & (1 fds_bits) free(fdset->fds_bits);
}
int spc_fd_setsize(SPC_FD_SET *fdset) {
return fdset->fds_size;
}
Notice that we’ve added two additional functions, spc_fd_free( ) and spc_fd_
setsize( ). Because we are now dynamically allocating the array, there must be some
way to free it. The function spc_fd_free( ) will only free the inner contents of the
SPC_FD_SET object passed to it, leaving management of the SPC_FD_SET object up to
you—you may allocate these objects either statically or dynamically. The other function,
spc_fd_setsize( ), is a replacement for the FD_SETSIZE macro that is normally
used as the first argument to select( ), indicating the size of the FD_SET objects
passed as the next three arguments.
Finally, using the new code requires some minor changes to existing code that uses
the standard fd_set. Consider the following code example, where the variable
client_count is a global variable that represents the number of connected clients, and
the variable client_fds is a global variable that is an array of socket descriptors for
each connected client:
void main_server_loop(int server_fd) {
int i;
fd_set read_mask;
for (;;) {
FD_ZERO(&read_mask);
FD_SET(server_fd, &read_mask);
for (i = 0; i < client_count; i++) FD_SET(client_fds[i], &read_mask);
select(FD_SETSIZE, &read_mask, 0, 0, 0);
if (FD_ISSET(server_fd, &read_mask)) {
/* Do something with the server_fd such as call accept( ) */
}
for (i = 0; i < client_count; i++)
if (FD_ISSET(client_fds[i], &read_mask)) {
/* Read some data from the client's socket descriptor */
}
}
}
}
The equivalent code using the SPC_FD_SET data type and the functions that operate on
it would be:
void main_server_loop(int server_fd) {
int i;
114 | Chapter 3: Input Validation
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