cosmopolitan/dsp/tty/write.c

62 lines
2.9 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "dsp/tty/tty.h"
#include "libc/calls/calls.h"
#include "libc/calls/termios.h"
#include "libc/errno.h"
#include "libc/sock/sock.h"
#include "libc/sysv/consts/poll.h"
#include "libc/sysv/consts/termios.h"
/* TODO(jart): DELETE */
/**
* Sends data to teletypewriter the pain-free way.
*
* This function blocks forever until the full amount is transmitted,
* regardless of whether or not the character device is in non-blocking
* mode, regardless of whether or not it's interrupted by a signal. It
* can still be escaped by longjmp'ing out of a signal handler.
*
* @return 0 on success, or -1 w/ errno
*/
ssize_t ttywrite(int fd, const void *data, size_t size) {
char *p;
ssize_t rc;
size_t wrote, n;
p = data;
n = size;
do {
TryAgain:
if ((rc = write(fd, p, n)) != -1) {
wrote = rc;
p += wrote;
n -= wrote;
} else if (errno == EINTR) {
goto TryAgain;
} else if (errno == EAGAIN) {
poll((struct pollfd[]){{fd, POLLOUT}}, 1, -1);
} else {
return -1;
}
} while (n);
return 0;
}