]>
git.ipfire.org Git - thirdparty/systemd.git/blob - src/basic/io-util.c
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
= {
36 /* Read from the specified file descriptor, until POLLIN is not set anymore, throwing away everything
37 * read. Note that some file descriptors (notable IP sockets) will trigger POLLIN even when no data can be read
38 * (due to IP packet checksum mismatches), hence this function is only safe to be non-blocking if the fd used
39 * was set to non-blocking too. */
46 r
= poll(&pollfd
, 1, 0);
56 l
= read(fd
, buf
, sizeof(buf
));
71 ssize_t
loop_read(int fd
, void *buf
, size_t nbytes
, bool do_poll
) {
78 /* If called with nbytes == 0, let's call read() at least
79 * once, to validate the operation */
81 if (nbytes
> (size_t) SSIZE_MAX
)
87 k
= read(fd
, p
, nbytes
);
92 if (errno
== EAGAIN
&& do_poll
) {
94 /* We knowingly ignore any return value here,
95 * and expect that any error/EOF is reported
98 (void) fd_wait_for_event(fd
, POLLIN
, USEC_INFINITY
);
102 return n
> 0 ? n
: -errno
;
108 assert((size_t) k
<= nbytes
);
113 } while (nbytes
> 0);
118 int loop_read_exact(int fd
, void *buf
, size_t nbytes
, bool do_poll
) {
121 n
= loop_read(fd
, buf
, nbytes
, do_poll
);
124 if ((size_t) n
!= nbytes
)
130 int loop_write(int fd
, const void *buf
, size_t nbytes
, bool do_poll
) {
131 const uint8_t *p
= buf
;
136 if (nbytes
> (size_t) SSIZE_MAX
)
142 k
= write(fd
, p
, nbytes
);
147 if (errno
== EAGAIN
&& do_poll
) {
148 /* We knowingly ignore any return value here,
149 * and expect that any error/EOF is reported
152 (void) fd_wait_for_event(fd
, POLLOUT
, USEC_INFINITY
);
159 if (_unlikely_(nbytes
> 0 && k
== 0)) /* Can't really happen */
162 assert((size_t) k
<= nbytes
);
166 } while (nbytes
> 0);
171 int pipe_eof(int fd
) {
172 struct pollfd pollfd
= {
174 .events
= POLLIN
|POLLHUP
,
179 r
= poll(&pollfd
, 1, 0);
186 return pollfd
.revents
& POLLHUP
;
189 int fd_wait_for_event(int fd
, int event
, usec_t t
) {
191 struct pollfd pollfd
= {
199 r
= ppoll(&pollfd
, 1, t
== USEC_INFINITY
? NULL
: timespec_store(&ts
, t
), NULL
);
206 return pollfd
.revents
;
209 static size_t nul_length(const uint8_t *p
, size_t sz
) {
224 ssize_t
sparse_write(int fd
, const void *p
, size_t sz
, size_t run_length
) {
225 const uint8_t *q
, *w
, *e
;
233 n
= nul_length(q
, e
- q
);
235 /* If there are more than the specified run length of
236 * NUL bytes, or if this is the beginning or the end
237 * of the buffer, then seek instead of write */
238 if ((n
> run_length
) ||
240 (n
> 0 && q
+ n
>= e
)) {
242 l
= write(fd
, w
, q
- w
);
249 if (lseek(fd
, n
, SEEK_CUR
) == (off_t
) -1)
261 l
= write(fd
, w
, q
- w
);
268 return q
- (const uint8_t*) p
;