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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
c004493c LP |
2 | /*** |
3 | This file is part of systemd. | |
4 | ||
5 | Copyright 2010 Lennart Poettering | |
6 | ||
7 | systemd is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU Lesser General Public License as published by | |
9 | the Free Software Foundation; either version 2.1 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | systemd is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public License | |
18 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
19 | ***/ | |
20 | ||
11c3a366 TA |
21 | #include <errno.h> |
22 | #include <limits.h> | |
c004493c | 23 | #include <poll.h> |
11c3a366 TA |
24 | #include <stdio.h> |
25 | #include <time.h> | |
c004493c LP |
26 | #include <unistd.h> |
27 | ||
28 | #include "io-util.h" | |
11c3a366 | 29 | #include "time-util.h" |
c004493c LP |
30 | |
31 | int flush_fd(int fd) { | |
32 | struct pollfd pollfd = { | |
33 | .fd = fd, | |
34 | .events = POLLIN, | |
35 | }; | |
36 | ||
60d9771c LP |
37 | /* Read from the specified file descriptor, until POLLIN is not set anymore, throwing away everything |
38 | * read. Note that some file descriptors (notable IP sockets) will trigger POLLIN even when no data can be read | |
39 | * (due to IP packet checksum mismatches), hence this function is only safe to be non-blocking if the fd used | |
40 | * was set to non-blocking too. */ | |
41 | ||
c004493c LP |
42 | for (;;) { |
43 | char buf[LINE_MAX]; | |
44 | ssize_t l; | |
45 | int r; | |
46 | ||
47 | r = poll(&pollfd, 1, 0); | |
48 | if (r < 0) { | |
49 | if (errno == EINTR) | |
50 | continue; | |
51 | ||
52 | return -errno; | |
53 | ||
54 | } else if (r == 0) | |
55 | return 0; | |
56 | ||
57 | l = read(fd, buf, sizeof(buf)); | |
58 | if (l < 0) { | |
59 | ||
60 | if (errno == EINTR) | |
61 | continue; | |
62 | ||
63 | if (errno == EAGAIN) | |
64 | return 0; | |
65 | ||
66 | return -errno; | |
67 | } else if (l == 0) | |
68 | return 0; | |
69 | } | |
70 | } | |
71 | ||
72 | ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) { | |
73 | uint8_t *p = buf; | |
74 | ssize_t n = 0; | |
75 | ||
76 | assert(fd >= 0); | |
77 | assert(buf); | |
78 | ||
79 | /* If called with nbytes == 0, let's call read() at least | |
80 | * once, to validate the operation */ | |
81 | ||
82 | if (nbytes > (size_t) SSIZE_MAX) | |
83 | return -EINVAL; | |
84 | ||
85 | do { | |
86 | ssize_t k; | |
87 | ||
88 | k = read(fd, p, nbytes); | |
89 | if (k < 0) { | |
90 | if (errno == EINTR) | |
91 | continue; | |
92 | ||
93 | if (errno == EAGAIN && do_poll) { | |
94 | ||
95 | /* We knowingly ignore any return value here, | |
96 | * and expect that any error/EOF is reported | |
97 | * via read() */ | |
98 | ||
99 | (void) fd_wait_for_event(fd, POLLIN, USEC_INFINITY); | |
100 | continue; | |
101 | } | |
102 | ||
103 | return n > 0 ? n : -errno; | |
104 | } | |
105 | ||
106 | if (k == 0) | |
107 | return n; | |
108 | ||
109 | assert((size_t) k <= nbytes); | |
110 | ||
111 | p += k; | |
112 | nbytes -= k; | |
113 | n += k; | |
114 | } while (nbytes > 0); | |
115 | ||
116 | return n; | |
117 | } | |
118 | ||
119 | int loop_read_exact(int fd, void *buf, size_t nbytes, bool do_poll) { | |
120 | ssize_t n; | |
121 | ||
122 | n = loop_read(fd, buf, nbytes, do_poll); | |
123 | if (n < 0) | |
124 | return (int) n; | |
125 | if ((size_t) n != nbytes) | |
126 | return -EIO; | |
127 | ||
128 | return 0; | |
129 | } | |
130 | ||
131 | int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) { | |
132 | const uint8_t *p = buf; | |
133 | ||
134 | assert(fd >= 0); | |
135 | assert(buf); | |
136 | ||
137 | if (nbytes > (size_t) SSIZE_MAX) | |
138 | return -EINVAL; | |
139 | ||
140 | do { | |
141 | ssize_t k; | |
142 | ||
143 | k = write(fd, p, nbytes); | |
144 | if (k < 0) { | |
145 | if (errno == EINTR) | |
146 | continue; | |
147 | ||
148 | if (errno == EAGAIN && do_poll) { | |
149 | /* We knowingly ignore any return value here, | |
150 | * and expect that any error/EOF is reported | |
151 | * via write() */ | |
152 | ||
153 | (void) fd_wait_for_event(fd, POLLOUT, USEC_INFINITY); | |
154 | continue; | |
155 | } | |
156 | ||
157 | return -errno; | |
158 | } | |
159 | ||
160 | if (_unlikely_(nbytes > 0 && k == 0)) /* Can't really happen */ | |
161 | return -EIO; | |
162 | ||
163 | assert((size_t) k <= nbytes); | |
164 | ||
165 | p += k; | |
166 | nbytes -= k; | |
167 | } while (nbytes > 0); | |
168 | ||
169 | return 0; | |
170 | } | |
171 | ||
172 | int pipe_eof(int fd) { | |
173 | struct pollfd pollfd = { | |
174 | .fd = fd, | |
175 | .events = POLLIN|POLLHUP, | |
176 | }; | |
177 | ||
178 | int r; | |
179 | ||
180 | r = poll(&pollfd, 1, 0); | |
181 | if (r < 0) | |
182 | return -errno; | |
183 | ||
184 | if (r == 0) | |
185 | return 0; | |
186 | ||
187 | return pollfd.revents & POLLHUP; | |
188 | } | |
189 | ||
190 | int fd_wait_for_event(int fd, int event, usec_t t) { | |
191 | ||
192 | struct pollfd pollfd = { | |
193 | .fd = fd, | |
194 | .events = event, | |
195 | }; | |
196 | ||
197 | struct timespec ts; | |
198 | int r; | |
199 | ||
200 | r = ppoll(&pollfd, 1, t == USEC_INFINITY ? NULL : timespec_store(&ts, t), NULL); | |
201 | if (r < 0) | |
202 | return -errno; | |
203 | ||
204 | if (r == 0) | |
205 | return 0; | |
206 | ||
207 | return pollfd.revents; | |
208 | } | |
209 | ||
210 | static size_t nul_length(const uint8_t *p, size_t sz) { | |
211 | size_t n = 0; | |
212 | ||
213 | while (sz > 0) { | |
214 | if (*p != 0) | |
215 | break; | |
216 | ||
217 | n++; | |
218 | p++; | |
219 | sz--; | |
220 | } | |
221 | ||
222 | return n; | |
223 | } | |
224 | ||
225 | ssize_t sparse_write(int fd, const void *p, size_t sz, size_t run_length) { | |
226 | const uint8_t *q, *w, *e; | |
227 | ssize_t l; | |
228 | ||
229 | q = w = p; | |
230 | e = q + sz; | |
231 | while (q < e) { | |
232 | size_t n; | |
233 | ||
234 | n = nul_length(q, e - q); | |
235 | ||
236 | /* If there are more than the specified run length of | |
237 | * NUL bytes, or if this is the beginning or the end | |
238 | * of the buffer, then seek instead of write */ | |
239 | if ((n > run_length) || | |
240 | (n > 0 && q == p) || | |
241 | (n > 0 && q + n >= e)) { | |
242 | if (q > w) { | |
243 | l = write(fd, w, q - w); | |
244 | if (l < 0) | |
245 | return -errno; | |
246 | if (l != q -w) | |
247 | return -EIO; | |
248 | } | |
249 | ||
250 | if (lseek(fd, n, SEEK_CUR) == (off_t) -1) | |
251 | return -errno; | |
252 | ||
253 | q += n; | |
254 | w = q; | |
255 | } else if (n > 0) | |
256 | q += n; | |
257 | else | |
313cefa1 | 258 | q++; |
c004493c LP |
259 | } |
260 | ||
261 | if (q > w) { | |
262 | l = write(fd, w, q - w); | |
263 | if (l < 0) | |
264 | return -errno; | |
265 | if (l != q - w) | |
266 | return -EIO; | |
267 | } | |
268 | ||
269 | return q - (const uint8_t*) p; | |
270 | } |