]>
git.ipfire.org Git - thirdparty/systemd.git/blob - src/basic/io-util.c
1 /* SPDX-License-Identifier: LGPL-2.1+ */
11 #include "time-util.h"
13 int flush_fd(int fd
) {
14 struct pollfd pollfd
= {
20 /* Read from the specified file descriptor, until POLLIN is not set anymore, throwing away everything
21 * read. Note that some file descriptors (notable IP sockets) will trigger POLLIN even when no data can be read
22 * (due to IP packet checksum mismatches), hence this function is only safe to be non-blocking if the fd used
23 * was set to non-blocking too. */
30 r
= poll(&pollfd
, 1, 0);
40 l
= read(fd
, buf
, sizeof(buf
));
57 ssize_t
loop_read(int fd
, void *buf
, size_t nbytes
, bool do_poll
) {
64 /* If called with nbytes == 0, let's call read() at least
65 * once, to validate the operation */
67 if (nbytes
> (size_t) SSIZE_MAX
)
73 k
= read(fd
, p
, nbytes
);
78 if (errno
== EAGAIN
&& do_poll
) {
80 /* We knowingly ignore any return value here,
81 * and expect that any error/EOF is reported
84 (void) fd_wait_for_event(fd
, POLLIN
, USEC_INFINITY
);
88 return n
> 0 ? n
: -errno
;
94 assert((size_t) k
<= nbytes
);
104 int loop_read_exact(int fd
, void *buf
, size_t nbytes
, bool do_poll
) {
107 n
= loop_read(fd
, buf
, nbytes
, do_poll
);
110 if ((size_t) n
!= nbytes
)
116 int loop_write(int fd
, const void *buf
, size_t nbytes
, bool do_poll
) {
117 const uint8_t *p
= buf
;
122 if (_unlikely_(nbytes
> (size_t) SSIZE_MAX
))
128 k
= write(fd
, p
, nbytes
);
133 if (errno
== EAGAIN
&& do_poll
) {
134 /* We knowingly ignore any return value here,
135 * and expect that any error/EOF is reported
138 (void) fd_wait_for_event(fd
, POLLOUT
, USEC_INFINITY
);
145 if (_unlikely_(nbytes
> 0 && k
== 0)) /* Can't really happen */
148 assert((size_t) k
<= nbytes
);
152 } while (nbytes
> 0);
157 int pipe_eof(int fd
) {
158 struct pollfd pollfd
= {
160 .events
= POLLIN
|POLLHUP
,
165 r
= poll(&pollfd
, 1, 0);
172 return pollfd
.revents
& POLLHUP
;
175 int fd_wait_for_event(int fd
, int event
, usec_t t
) {
177 struct pollfd pollfd
= {
185 r
= ppoll(&pollfd
, 1, t
== USEC_INFINITY
? NULL
: timespec_store(&ts
, t
), NULL
);
191 return pollfd
.revents
;
194 static size_t nul_length(const uint8_t *p
, size_t sz
) {
209 ssize_t
sparse_write(int fd
, const void *p
, size_t sz
, size_t run_length
) {
210 const uint8_t *q
, *w
, *e
;
218 n
= nul_length(q
, e
- q
);
220 /* If there are more than the specified run length of
221 * NUL bytes, or if this is the beginning or the end
222 * of the buffer, then seek instead of write */
223 if ((n
> run_length
) ||
225 (n
> 0 && q
+ n
>= e
)) {
227 l
= write(fd
, w
, q
- w
);
234 if (lseek(fd
, n
, SEEK_CUR
) == (off_t
) -1)
246 l
= write(fd
, w
, q
- w
);
253 return q
- (const uint8_t*) p
;