1 /* $OpenBSD: imsg-buffer.c,v 1.12 2019/01/20 02:50:03 bcook Exp $ */
2
3 /*
4 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <sys/types.h>
20 #include <sys/socket.h>
21 #include <sys/uio.h>
22
23 #include <limits.h>
24 #include <errno.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28
29 #include "compat.h"
30 #include "imsg.h"
31
32 static int ibuf_realloc(struct ibuf *, size_t);
33 static void ibuf_enqueue(struct msgbuf *, struct ibuf *);
34 static void ibuf_dequeue(struct msgbuf *, struct ibuf *);
35
36 struct ibuf *
ibuf_open(size_t len)37 ibuf_open(size_t len)
38 {
39 struct ibuf *buf;
40
41 if ((buf = calloc(1, sizeof(struct ibuf))) == NULL)
42 return (NULL);
43 if ((buf->buf = malloc(len)) == NULL) {
44 free(buf);
45 return (NULL);
46 }
47 buf->size = buf->max = len;
48 buf->fd = -1;
49
50 return (buf);
51 }
52
53 struct ibuf *
ibuf_dynamic(size_t len,size_t max)54 ibuf_dynamic(size_t len, size_t max)
55 {
56 struct ibuf *buf;
57
58 if (max < len)
59 return (NULL);
60
61 if ((buf = ibuf_open(len)) == NULL)
62 return (NULL);
63
64 if (max > 0)
65 buf->max = max;
66
67 return (buf);
68 }
69
70 static int
ibuf_realloc(struct ibuf * buf,size_t len)71 ibuf_realloc(struct ibuf *buf, size_t len)
72 {
73 unsigned char *b;
74
75 /* on static buffers max is eq size and so the following fails */
76 if (buf->wpos + len > buf->max) {
77 errno = ERANGE;
78 return (-1);
79 }
80
81 b = recallocarray(buf->buf, buf->size, buf->wpos + len, 1);
82 if (b == NULL)
83 return (-1);
84 buf->buf = b;
85 buf->size = buf->wpos + len;
86
87 return (0);
88 }
89
90 int
ibuf_add(struct ibuf * buf,const void * data,size_t len)91 ibuf_add(struct ibuf *buf, const void *data, size_t len)
92 {
93 if (buf->wpos + len > buf->size)
94 if (ibuf_realloc(buf, len) == -1)
95 return (-1);
96
97 memcpy(buf->buf + buf->wpos, data, len);
98 buf->wpos += len;
99 return (0);
100 }
101
102 void *
ibuf_reserve(struct ibuf * buf,size_t len)103 ibuf_reserve(struct ibuf *buf, size_t len)
104 {
105 void *b;
106
107 if (buf->wpos + len > buf->size)
108 if (ibuf_realloc(buf, len) == -1)
109 return (NULL);
110
111 b = buf->buf + buf->wpos;
112 buf->wpos += len;
113 return (b);
114 }
115
116 void *
ibuf_seek(struct ibuf * buf,size_t pos,size_t len)117 ibuf_seek(struct ibuf *buf, size_t pos, size_t len)
118 {
119 /* only allowed to seek in already written parts */
120 if (pos + len > buf->wpos)
121 return (NULL);
122
123 return (buf->buf + pos);
124 }
125
126 size_t
ibuf_size(struct ibuf * buf)127 ibuf_size(struct ibuf *buf)
128 {
129 return (buf->wpos);
130 }
131
132 size_t
ibuf_left(struct ibuf * buf)133 ibuf_left(struct ibuf *buf)
134 {
135 return (buf->max - buf->wpos);
136 }
137
138 void
ibuf_close(struct msgbuf * msgbuf,struct ibuf * buf)139 ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)
140 {
141 ibuf_enqueue(msgbuf, buf);
142 }
143
144 int
ibuf_write(struct msgbuf * msgbuf)145 ibuf_write(struct msgbuf *msgbuf)
146 {
147 struct iovec iov[IOV_MAX];
148 struct ibuf *buf;
149 unsigned int i = 0;
150 ssize_t n;
151
152 memset(&iov, 0, sizeof(iov));
153 TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
154 if (i >= IOV_MAX)
155 break;
156 iov[i].iov_base = buf->buf + buf->rpos;
157 iov[i].iov_len = buf->wpos - buf->rpos;
158 i++;
159 }
160
161 again:
162 if ((n = writev(msgbuf->fd, iov, i)) == -1) {
163 if (errno == EINTR)
164 goto again;
165 if (errno == ENOBUFS)
166 errno = EAGAIN;
167 return (-1);
168 }
169
170 if (n == 0) { /* connection closed */
171 errno = 0;
172 return (0);
173 }
174
175 msgbuf_drain(msgbuf, n);
176
177 return (1);
178 }
179
180 void
ibuf_free(struct ibuf * buf)181 ibuf_free(struct ibuf *buf)
182 {
183 if (buf == NULL)
184 return;
185 freezero(buf->buf, buf->size);
186 free(buf);
187 }
188
189 void
msgbuf_init(struct msgbuf * msgbuf)190 msgbuf_init(struct msgbuf *msgbuf)
191 {
192 msgbuf->queued = 0;
193 msgbuf->fd = -1;
194 TAILQ_INIT(&msgbuf->bufs);
195 }
196
197 void
msgbuf_drain(struct msgbuf * msgbuf,size_t n)198 msgbuf_drain(struct msgbuf *msgbuf, size_t n)
199 {
200 struct ibuf *buf, *next;
201
202 for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
203 buf = next) {
204 next = TAILQ_NEXT(buf, entry);
205 if (buf->rpos + n >= buf->wpos) {
206 n -= buf->wpos - buf->rpos;
207 ibuf_dequeue(msgbuf, buf);
208 } else {
209 buf->rpos += n;
210 n = 0;
211 }
212 }
213 }
214
215 void
msgbuf_clear(struct msgbuf * msgbuf)216 msgbuf_clear(struct msgbuf *msgbuf)
217 {
218 struct ibuf *buf;
219
220 while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
221 ibuf_dequeue(msgbuf, buf);
222 }
223
224 int
msgbuf_write(struct msgbuf * msgbuf)225 msgbuf_write(struct msgbuf *msgbuf)
226 {
227 struct iovec iov[IOV_MAX];
228 struct ibuf *buf;
229 unsigned int i = 0;
230 ssize_t n;
231 struct msghdr msg;
232 struct cmsghdr *cmsg;
233 union {
234 struct cmsghdr hdr;
235 char buf[CMSG_SPACE(sizeof(int))];
236 } cmsgbuf;
237
238 memset(&iov, 0, sizeof(iov));
239 memset(&msg, 0, sizeof(msg));
240 memset(&cmsgbuf, 0, sizeof(cmsgbuf));
241 TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
242 if (i >= IOV_MAX)
243 break;
244 iov[i].iov_base = buf->buf + buf->rpos;
245 iov[i].iov_len = buf->wpos - buf->rpos;
246 i++;
247 if (buf->fd != -1)
248 break;
249 }
250
251 msg.msg_iov = iov;
252 msg.msg_iovlen = i;
253
254 if (buf != NULL && buf->fd != -1) {
255 msg.msg_control = (caddr_t)&cmsgbuf.buf;
256 msg.msg_controllen = CMSG_SPACE(sizeof(int));
257 cmsg = CMSG_FIRSTHDR(&msg);
258 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
259 cmsg->cmsg_level = SOL_SOCKET;
260 cmsg->cmsg_type = SCM_RIGHTS;
261 *(int *)CMSG_DATA(cmsg) = buf->fd;
262 }
263
264 again:
265 if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
266 if (errno == EINTR)
267 goto again;
268 if (errno == ENOBUFS)
269 errno = EAGAIN;
270 return (-1);
271 }
272
273 if (n == 0) { /* connection closed */
274 errno = 0;
275 return (0);
276 }
277
278 /*
279 * assumption: fd got sent if sendmsg sent anything
280 * this works because fds are passed one at a time
281 */
282 if (buf != NULL && buf->fd != -1) {
283 close(buf->fd);
284 buf->fd = -1;
285 }
286
287 msgbuf_drain(msgbuf, n);
288
289 return (1);
290 }
291
292 static void
ibuf_enqueue(struct msgbuf * msgbuf,struct ibuf * buf)293 ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)
294 {
295 TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
296 msgbuf->queued++;
297 }
298
299 static void
ibuf_dequeue(struct msgbuf * msgbuf,struct ibuf * buf)300 ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf)
301 {
302 TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
303
304 if (buf->fd != -1)
305 close(buf->fd);
306
307 msgbuf->queued--;
308 ibuf_free(buf);
309 }
310