compat/imsg-buffer.c

   1 /*      $OpenBSD: imsg-buffer.c,v 1.11 2017/12/14 09:27:44 kettenis 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 "got_compat.h"
  30
  31 static int      ibuf_realloc(struct ibuf *, size_t);
  32 static void     ibuf_enqueue(struct msgbuf *, struct ibuf *);
  33 static void     ibuf_dequeue(struct msgbuf *, struct ibuf *);
  34
  35 struct ibuf *
  36 ibuf_open(size_t len)
  37 {
  38         struct ibuf     *buf;
  39
  40         if ((buf = calloc(1, sizeof(struct ibuf))) == NULL)
  41                 return (NULL);
  42         if ((buf->buf = malloc(len)) == NULL) {
  43                 free(buf);
  44                 return (NULL);
  45         }
  46         buf->size = buf->max = len;
  47         buf->fd = -1;
  48
  49         return (buf);
  50 }
  51
  52 struct ibuf *
  53 ibuf_dynamic(size_t len, size_t max)
  54 {
  55         struct ibuf     *buf;
  56
  57         if (max < len)
  58                 return (NULL);
  59
  60         if ((buf = ibuf_open(len)) == NULL)
  61                 return (NULL);
  62
  63         if (max > 0)
  64                 buf->max = max;
  65
  66         return (buf);
  67 }
  68
  69 static int
  70 ibuf_realloc(struct ibuf *buf, size_t len)
  71 {
  72         u_char  *b;
  73
  74         /* on static buffers max is eq size and so the following fails */
  75         if (buf->wpos + len > buf->max) {
  76                 errno = ERANGE;
  77                 return (-1);
  78         }
  79
  80         b = recallocarray(buf->buf, buf->size, buf->wpos + len, 1);
  81         if (b == NULL)
  82                 return (-1);
  83         buf->buf = b;
  84         buf->size = buf->wpos + len;
  85
  86         return (0);
  87 }
  88
  89 int
  90 ibuf_add(struct ibuf *buf, const void *data, size_t len)
  91 {
  92         if (buf->wpos + len > buf->size)
  93                 if (ibuf_realloc(buf, len) == -1)
  94                         return (-1);
  95
  96         memcpy(buf->buf + buf->wpos, data, len);
  97         buf->wpos += len;
  98         return (0);
  99 }
 100
 101 void *
 102 ibuf_reserve(struct ibuf *buf, size_t len)
 103 {
 104         void    *b;
 105
 106         if (buf->wpos + len > buf->size)
 107                 if (ibuf_realloc(buf, len) == -1)
 108                         return (NULL);
 109
 110         b = buf->buf + buf->wpos;
 111         buf->wpos += len;
 112         return (b);
 113 }
 114
 115 void *
 116 ibuf_seek(struct ibuf *buf, size_t pos, size_t len)
 117 {
 118         /* only allowed to seek in already written parts */
 119         if (pos + len > buf->wpos)
 120                 return (NULL);
 121
 122         return (buf->buf + pos);
 123 }
 124
 125 size_t
 126 ibuf_size(struct ibuf *buf)
 127 {
 128         return (buf->wpos);
 129 }
 130
 131 size_t
 132 ibuf_left(struct ibuf *buf)
 133 {
 134         return (buf->max - buf->wpos);
 135 }
 136
 137 void
 138 ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)
 139 {
 140         ibuf_enqueue(msgbuf, buf);
 141 }
 142
 143 int
 144 ibuf_write(struct msgbuf *msgbuf)
 145 {
 146         struct iovec     iov[IOV_MAX];
 147         struct ibuf     *buf;
 148         unsigned int     i = 0;
 149         ssize_t n;
 150
 151         memset(&iov, 0, sizeof(iov));
 152         TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
 153                 if (i >= IOV_MAX)
 154                         break;
 155                 iov[i].iov_base = buf->buf + buf->rpos;
 156                 iov[i].iov_len = buf->wpos - buf->rpos;
 157                 i++;
 158         }
 159
 160 again:
 161         if ((n = writev(msgbuf->fd, iov, i)) == -1) {
 162                 if (errno == EINTR)
 163                         goto again;
 164                 if (errno == ENOBUFS)
 165                         errno = EAGAIN;
 166                 return (-1);
 167         }
 168
 169         if (n == 0) {                   /* connection closed */
 170                 errno = 0;
 171                 return (0);
 172         }
 173
 174         msgbuf_drain(msgbuf, n);
 175
 176         return (1);
 177 }
 178
 179 void
 180 ibuf_free(struct ibuf *buf)
 181 {
 182         if (buf == NULL)
 183                 return;
 184         freezero(buf->buf, buf->size);
 185         free(buf);
 186 }
 187
 188 void
 189 msgbuf_init(struct msgbuf *msgbuf)
 190 {
 191         msgbuf->queued = 0;
 192         msgbuf->fd = -1;
 193         TAILQ_INIT(&msgbuf->bufs);
 194 }
 195
 196 void
 197 msgbuf_drain(struct msgbuf *msgbuf, size_t n)
 198 {
 199         struct ibuf     *buf, *next;
 200
 201         for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
 202             buf = next) {
 203                 next = TAILQ_NEXT(buf, entry);
 204                 if (buf->rpos + n >= buf->wpos) {
 205                         n -= buf->wpos - buf->rpos;
 206                         ibuf_dequeue(msgbuf, buf);
 207                 } else {
 208                         buf->rpos += n;
 209                         n = 0;
 210                 }
 211         }
 212 }
 213
 214 void
 215 msgbuf_clear(struct msgbuf *msgbuf)
 216 {
 217         struct ibuf     *buf;
 218
 219         while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
 220                 ibuf_dequeue(msgbuf, buf);
 221 }
 222
 223 int
 224 msgbuf_write(struct msgbuf *msgbuf)
 225 {
 226         struct iovec     iov[IOV_MAX];
 227         struct ibuf     *buf;
 228         unsigned int     i = 0;
 229         ssize_t          n;
 230         struct msghdr    msg;
 231         struct cmsghdr  *cmsg;
 232         union {
 233                 struct cmsghdr  hdr;
 234                 char            buf[CMSG_SPACE(sizeof(int))];
 235         } cmsgbuf;
 236
 237         memset(&iov, 0, sizeof(iov));
 238         memset(&msg, 0, sizeof(msg));
 239         memset(&cmsgbuf, 0, sizeof(cmsgbuf));
 240         TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
 241                 if (i >= IOV_MAX)
 242                         break;
 243                 iov[i].iov_base = buf->buf + buf->rpos;
 244                 iov[i].iov_len = buf->wpos - buf->rpos;
 245                 i++;
 246                 if (buf->fd != -1)
 247                         break;
 248         }
 249
 250         msg.msg_iov = iov;
 251         msg.msg_iovlen = i;
 252
 253         if (buf != NULL && buf->fd != -1) {
 254                 msg.msg_control = (caddr_t)&cmsgbuf.buf;
 255                 msg.msg_controllen = sizeof(cmsgbuf.buf);
 256                 cmsg = CMSG_FIRSTHDR(&msg);
 257                 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
 258                 cmsg->cmsg_level = SOL_SOCKET;
 259                 cmsg->cmsg_type = SCM_RIGHTS;
 260                 *(int *)CMSG_DATA(cmsg) = buf->fd;
 261         }
 262
 263 again:
 264         if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
 265                 if (errno == EINTR)
 266                         goto again;
 267                 if (errno == ENOBUFS)
 268                         errno = EAGAIN;
 269                 return (-1);
 270         }
 271
 272         if (n == 0) {                   /* connection closed */
 273                 errno = 0;
 274                 return (0);
 275         }
 276
 277         /*
 278          * assumption: fd got sent if sendmsg sent anything
 279          * this works because fds are passed one at a time
 280          */
 281         if (buf != NULL && buf->fd != -1) {
 282                 close(buf->fd);
 283                 buf->fd = -1;
 284         }
 285
 286         msgbuf_drain(msgbuf, n);
 287
 288         return (1);
 289 }
 290
 291 static void
 292 ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)
 293 {
 294         TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
 295         msgbuf->queued++;
 296 }
 297
 298 static void
 299 ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf)
 300 {
 301         TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
 302
 303         if (buf->fd != -1)
 304                 close(buf->fd);
 305
 306         msgbuf->queued--;
 307         ibuf_free(buf);
 308 }