Determine the size of a pipe without calling read()

Question

I need a function called SizeOfPipe() which should return the size of a pipe - I only want to know how much data is in the pipe and not actually read data off t

Answer 1

Depending on your unix implementation ioctl/FIONREAD might do the trick

err = ioctl(pipedesc, FIONREAD, &bytesAvailable);

Unless this returns the error code for "invalid argument" (or any other error) bytesAvailable contains the amount of data available for unblocking read operations at that time.