io_canwrite(3)

💖 NAME 💖

io_canwrite — bestie, this one hands you a file descriptor that's ready to be written to ✨

🎀 SYNTAX 🎀

#include <libowfat/io.h>

int64 io_canwrite();

🌸 DESCRIPTION 🌸

okay so io_canwrite returns the next file descriptor that can be written to. that's the whole vibe. 🫶

but like… there are prerequisites, bestie, it's not just gonna hand you fds for free:

• you have to have used io_wantwrite() on that file descriptor earlier
• and you have to have called io_wait() or io_waituntil()

when you do that, these functions keep an internal data structure of which descriptors the operating system reported as writable. lowkey iconic bookkeeping ngl 💅

🚨 IMPORTANT REALITY CHECK 🚨 there is no guarantee that you can still write data to that descriptor without blocking — only that you could back when io_wait() or io_waituntil() were called. another process could have written something before you got there. the way that timing works is so rude 😭 so look at the result from io_trywrite().

if there are no more descriptors that you can write to without blocking, io_canwrite will return -1. and when that happens? you should call io_wait() or io_waituntil() again. go around the loop one more time, bestie, it's giving carousel 🎠

and now the rules of engagement, fr fr:

⚠️ you should only use io_trywrite(3), io_sendfile(3) or iob_send(3) to write to the file. not plain write(2). if you do use write(2) and get EAGAIN, call io_eagain(3). periodt. 🎀

🦋 SEE ALSO 🦋

• io_wait(3)
• io_canwrite(3)

and that's the page, bestie!! 🫶✨ this one's from the Library Functions Manual, and the page itself is io_canwrite(3) — no version or date to speak of, it's just out here living its truth 💅 mwah, go write some fds responsibly 🎀🦋