2 This file is part of systemd.
4 Copyright 2010 Lennart Poettering
6 systemd is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
11 systemd is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with systemd; If not, see <http://www.gnu.org/licenses/>.
28 #include "time-util.h"
30 int flush_fd(int fd) {
31 struct pollfd pollfd = {
41 r = poll(&pollfd, 1, 0);
51 l = read(fd, buf, sizeof(buf));
66 ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
73 /* If called with nbytes == 0, let's call read() at least
74 * once, to validate the operation */
76 if (nbytes > (size_t) SSIZE_MAX)
82 k = read(fd, p, nbytes);
87 if (errno == EAGAIN && do_poll) {
89 /* We knowingly ignore any return value here,
90 * and expect that any error/EOF is reported
93 (void) fd_wait_for_event(fd, POLLIN, USEC_INFINITY);
97 return n > 0 ? n : -errno;
103 assert((size_t) k <= nbytes);
108 } while (nbytes > 0);
113 int loop_read_exact(int fd, void *buf, size_t nbytes, bool do_poll) {
116 n = loop_read(fd, buf, nbytes, do_poll);
119 if ((size_t) n != nbytes)
125 int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
126 const uint8_t *p = buf;
131 if (nbytes > (size_t) SSIZE_MAX)
137 k = write(fd, p, nbytes);
142 if (errno == EAGAIN && do_poll) {
143 /* We knowingly ignore any return value here,
144 * and expect that any error/EOF is reported
147 (void) fd_wait_for_event(fd, POLLOUT, USEC_INFINITY);
154 if (_unlikely_(nbytes > 0 && k == 0)) /* Can't really happen */
157 assert((size_t) k <= nbytes);
161 } while (nbytes > 0);
166 int pipe_eof(int fd) {
167 struct pollfd pollfd = {
169 .events = POLLIN|POLLHUP,
174 r = poll(&pollfd, 1, 0);
181 return pollfd.revents & POLLHUP;
184 int fd_wait_for_event(int fd, int event, usec_t t) {
186 struct pollfd pollfd = {
194 r = ppoll(&pollfd, 1, t == USEC_INFINITY ? NULL : timespec_store(&ts, t), NULL);
201 return pollfd.revents;
204 static size_t nul_length(const uint8_t *p, size_t sz) {
219 ssize_t sparse_write(int fd, const void *p, size_t sz, size_t run_length) {
220 const uint8_t *q, *w, *e;
228 n = nul_length(q, e - q);
230 /* If there are more than the specified run length of
231 * NUL bytes, or if this is the beginning or the end
232 * of the buffer, then seek instead of write */
233 if ((n > run_length) ||
235 (n > 0 && q + n >= e)) {
237 l = write(fd, w, q - w);
244 if (lseek(fd, n, SEEK_CUR) == (off_t) -1)
256 l = write(fd, w, q - w);
263 return q - (const uint8_t*) p;