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/*
Authors:
Jan Cholasta <jcholast@redhat.com>
Copyright (C) 2012 Red Hat
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; either version 3 of the License, or
(at your option) any later version.
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, see <http://www.gnu.org/licenses/>.
*/
#include "util/atomic_io.h"
/* based on code from libssh <http://www.libssh.org> */
ssize_t sss_atomic_io_s(int fd, void *buf, size_t n, bool do_read)
{
char *b = buf;
size_t pos = 0;
ssize_t res;
struct pollfd pfd;
pfd.fd = fd;
pfd.events = do_read ? POLLIN : POLLOUT;
while (n > pos) {
if (do_read) {
res = read(fd, b + pos, n - pos);
} else {
res = write(fd, b + pos, n - pos);
}
switch (res) {
case -1:
if (errno == EINTR) {
continue;
}
if (errno == EAGAIN || errno == EWOULDBLOCK) {
(void) poll(&pfd, 1, -1);
continue;
}
return -1;
case 0:
/* read returns 0 on end-of-file */
errno = do_read ? 0 : EPIPE;
return pos;
default:
pos += (size_t) res;
}
}
return pos;
}
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