Casting const pointer to non-const pointer when using struct iovec

Question

struct iovec is defined in <uio.h> by the following way:

/* Structure for scatter/gather I/O. */
struct iovec
 {
 void *iov_base; /* Pointer to data. */
 size_t iov_len; /* Length of data. */
 };

Now I do ugly casting from const void* to void*:

int send_frame_once( int fd, const struct iovec* iov, size_t iovlen );
int send_frame( int fd, const void* buffer, size_t len )
{
 struct iovec iov;
 iov.iov_base = (void*)buffer; /* const iov cast */
 iov.iov_len = len;
 return send_frame_once( fd, &iov, 1 );
}

Is that necessary kludge? Or should I remove const keyword from declaration of send_frame function. Like this:

int send_frame( int fd, void* buffer, size_t len )

Answer 1

I think you should keep it. const is not only meant for the compiler, but also for anybody reading your code. Even with the void* cast, you're still saying to readers "Trust me, I'm not touching your buffer!" and this is a valuable information that should not be discarded.

• Loki Astari: assuming send_frame does not alter the content of buffer in any way.
• Quentin Pradet: Indeed, this is what I am assuming here.
• SKi: Yep, buffer is not modified.