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1 /* $OpenBSD: imsg-buffer.c,v 1.13 2021/03/31 17:42:24 eric Exp $ */
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 */
19 #include "../config.h"
21 #include <sys/types.h>
22 #include <sys/socket.h>
23 #include <sys/uio.h>
25 #include <limits.h>
26 #include <errno.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <unistd.h>
31 #include "imsg.h"
33 static int ibuf_realloc(struct ibuf *, size_t);
34 static void ibuf_enqueue(struct msgbuf *, struct ibuf *);
35 static void ibuf_dequeue(struct msgbuf *, struct ibuf *);
37 struct ibuf *
38 ibuf_open(size_t len)
39 {
40 struct ibuf *buf;
42 if ((buf = calloc(1, sizeof(struct ibuf))) == NULL)
43 return (NULL);
44 if ((buf->buf = malloc(len)) == NULL) {
45 free(buf);
46 return (NULL);
47 }
48 buf->size = buf->max = len;
49 buf->fd = -1;
51 return (buf);
52 }
54 struct ibuf *
55 ibuf_dynamic(size_t len, size_t max)
56 {
57 struct ibuf *buf;
59 if (max < len)
60 return (NULL);
62 if ((buf = ibuf_open(len)) == NULL)
63 return (NULL);
65 if (max > 0)
66 buf->max = max;
68 return (buf);
69 }
71 static int
72 ibuf_realloc(struct ibuf *buf, size_t len)
73 {
74 unsigned char *b;
76 /* on static buffers max is eq size and so the following fails */
77 if (buf->wpos + len > buf->max) {
78 errno = ERANGE;
79 return (-1);
80 }
82 b = recallocarray(buf->buf, buf->size, buf->wpos + len, 1);
83 if (b == NULL)
84 return (-1);
85 buf->buf = b;
86 buf->size = buf->wpos + len;
88 return (0);
89 }
91 int
92 ibuf_add(struct ibuf *buf, const void *data, size_t len)
93 {
94 if (buf->wpos + len > buf->size)
95 if (ibuf_realloc(buf, len) == -1)
96 return (-1);
98 memcpy(buf->buf + buf->wpos, data, len);
99 buf->wpos += len;
100 return (0);
103 void *
104 ibuf_reserve(struct ibuf *buf, size_t len)
106 void *b;
108 if (buf->wpos + len > buf->size)
109 if (ibuf_realloc(buf, len) == -1)
110 return (NULL);
112 b = buf->buf + buf->wpos;
113 buf->wpos += len;
114 return (b);
117 void *
118 ibuf_seek(struct ibuf *buf, size_t pos, size_t len)
120 /* only allowed to seek in already written parts */
121 if (pos + len > buf->wpos)
122 return (NULL);
124 return (buf->buf + pos);
127 size_t
128 ibuf_size(struct ibuf *buf)
130 return (buf->wpos);
133 size_t
134 ibuf_left(struct ibuf *buf)
136 return (buf->max - buf->wpos);
139 void
140 ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)
142 ibuf_enqueue(msgbuf, buf);
145 int
146 ibuf_write(struct msgbuf *msgbuf)
148 struct iovec iov[IOV_MAX];
149 struct ibuf *buf;
150 unsigned int i = 0;
151 ssize_t n;
153 memset(&iov, 0, sizeof(iov));
154 TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
155 if (i >= IOV_MAX)
156 break;
157 iov[i].iov_base = buf->buf + buf->rpos;
158 iov[i].iov_len = buf->wpos - buf->rpos;
159 i++;
162 again:
163 if ((n = writev(msgbuf->fd, iov, i)) == -1) {
164 if (errno == EINTR)
165 goto again;
166 if (errno == ENOBUFS)
167 errno = EAGAIN;
168 return (-1);
171 if (n == 0) { /* connection closed */
172 errno = 0;
173 return (0);
176 msgbuf_drain(msgbuf, n);
178 return (1);
181 void
182 ibuf_free(struct ibuf *buf)
184 if (buf == NULL)
185 return;
186 freezero(buf->buf, buf->size);
187 free(buf);
190 void
191 msgbuf_init(struct msgbuf *msgbuf)
193 msgbuf->queued = 0;
194 msgbuf->fd = -1;
195 TAILQ_INIT(&msgbuf->bufs);
198 void
199 msgbuf_drain(struct msgbuf *msgbuf, size_t n)
201 struct ibuf *buf, *next;
203 for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
204 buf = next) {
205 next = TAILQ_NEXT(buf, entry);
206 if (buf->rpos + n >= buf->wpos) {
207 n -= buf->wpos - buf->rpos;
208 ibuf_dequeue(msgbuf, buf);
209 } else {
210 buf->rpos += n;
211 n = 0;
216 void
217 msgbuf_clear(struct msgbuf *msgbuf)
219 struct ibuf *buf;
221 while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
222 ibuf_dequeue(msgbuf, buf);
225 int
226 msgbuf_write(struct msgbuf *msgbuf)
228 struct iovec iov[IOV_MAX];
229 struct ibuf *buf, *buf0 = NULL;
230 unsigned int i = 0;
231 ssize_t n;
232 struct msghdr msg;
233 struct cmsghdr *cmsg;
234 union {
235 struct cmsghdr hdr;
236 char buf[CMSG_SPACE(sizeof(int))];
237 } cmsgbuf;
239 memset(&iov, 0, sizeof(iov));
240 memset(&msg, 0, sizeof(msg));
241 memset(&cmsgbuf, 0, sizeof(cmsgbuf));
242 TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
243 if (i >= IOV_MAX)
244 break;
245 if (i > 0 && buf->fd != -1)
246 break;
247 iov[i].iov_base = buf->buf + buf->rpos;
248 iov[i].iov_len = buf->wpos - buf->rpos;
249 i++;
250 if (buf->fd != -1)
251 buf0 = buf;
254 msg.msg_iov = iov;
255 msg.msg_iovlen = i;
257 if (buf0 != NULL) {
258 msg.msg_control = (caddr_t)&cmsgbuf.buf;
259 msg.msg_controllen = sizeof(cmsgbuf.buf);
260 cmsg = CMSG_FIRSTHDR(&msg);
261 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
262 cmsg->cmsg_level = SOL_SOCKET;
263 cmsg->cmsg_type = SCM_RIGHTS;
264 *(int *)CMSG_DATA(cmsg) = buf0->fd;
267 again:
268 if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
269 if (errno == EINTR)
270 goto again;
271 if (errno == ENOBUFS)
272 errno = EAGAIN;
273 return (-1);
276 if (n == 0) { /* connection closed */
277 errno = 0;
278 return (0);
281 /*
282 * assumption: fd got sent if sendmsg sent anything
283 * this works because fds are passed one at a time
284 */
285 if (buf0 != NULL) {
286 close(buf0->fd);
287 buf0->fd = -1;
290 msgbuf_drain(msgbuf, n);
292 return (1);
295 static void
296 ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)
298 TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
299 msgbuf->queued++;
302 static void
303 ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf)
305 TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
307 if (buf->fd != -1)
308 close(buf->fd);
310 msgbuf->queued--;
311 ibuf_free(buf);