On 27.07.2017 08:22, Didier Kryn wrote:
At first glance at least, it means that file offsets are managed in the kernel or VFS
Of course they are. That's required for any sane multiprocessing implementation. And some files/devices don't even have the notion of a current position (IOW: not seekable at all). > but they can be bypassed by pwrite(). AFAIR pwrite()
doesn't change the "current" file offset; it simply ignores and bypasses it, which isn't exactly what your example does.
Yes, that's an separate syscall for direct access. Simple streams (eg. tty's, pipes, stream sockets, etc) usually don't support it.
Using unistd's read() and write() in C means you are dealing with low level issues; otherwise why would you bother with the complexity it introduces - not only you need to deal with buffering but also with retries when interrupted by signals.
Usually you wanna care about signals - they actually mean something. The ansi stream functions might or might not make it easier - depending on your actual usecase. If you care about performance, you likely don't wanna use them. --mtx _______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
