Implement chunked write to the cmdfd.

This is needed so big input like a paste of several megabyte does not clog our
I/O.
This commit is contained in:
Christoph Lohmann 2015-07-10 14:15:39 +02:00
parent f8c6e7d041
commit 261ea4b7e0

53
st.c
View file

@ -1478,8 +1478,57 @@ ttyread(void)
void
ttywrite(const char *s, size_t n)
{
if (xwrite(cmdfd, s, n) == -1)
die("write error on tty: %s\n", strerror(errno));
fd_set wfd;
struct timespec tv;
ssize_t r;
/*
* Remember that we are using a pty, which might be a modem line.
* Writing too much will clog the line. That's why we are doing this
* dance.
* FIXME: Migrate the world to Plan 9.
*/
while (n > 0) {
FD_ZERO(&wfd);
FD_SET(cmdfd, &wfd);
tv.tv_sec = 0;
tv.tv_nsec = 0;
/* Check if we can write. */
if (pselect(cmdfd+1, NULL, &wfd, NULL, &tv, NULL) < 0) {
if (errno == EINTR)
continue;
die("select failed: %s\n", strerror(errno));
}
if(!FD_ISSET(cmdfd, &wfd)) {
/* No, then free some buffer space. */
ttyread();
} else {
/*
* Only write 256 bytes at maximum. This seems to be a
* reasonable value for a serial line. Bigger values
* might clog the I/O.
*/
r = write(cmdfd, s, (n < 256)? n : 256);
if (r < 0) {
die("write error on tty: %s\n",
strerror(errno));
}
if (r < n) {
/*
* We weren't able to write out everything.
* This means the buffer is getting full
* again. Empty it.
*/
ttyread();
n -= r;
s += r;
} else {
/* All bytes have been written. */
break;
}
}
}
}
void