imsg-buffer.c

   1 /*      $OpenBSD$       */
   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/param.h>
  20 #include <sys/queue.h>
  21 #include <sys/socket.h>
  22 #include <sys/uio.h>
  23
  24 #include <errno.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28
  29 #include "imsg.h"
  30
  31 int     buf_realloc(struct buf *, size_t);
  32 void    buf_enqueue(struct msgbuf *, struct buf *);
  33 void    buf_dequeue(struct msgbuf *, struct buf *);
  34
  35 struct buf *
  36 buf_open(size_t len)
  37 {
  38         struct buf      *buf;
  39
  40         if ((buf = calloc(1, sizeof(struct buf))) == 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 buf *
  53 buf_dynamic(size_t len, size_t max)
  54 {
  55         struct buf      *buf;
  56
  57         if (max < len)
  58                 return (NULL);
  59
  60         if ((buf = buf_open(len)) == NULL)
  61                 return (NULL);
  62
  63         if (max > 0)
  64                 buf->max = max;
  65
  66         return (buf);
  67 }
  68
  69 int
  70 buf_realloc(struct buf *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 = ENOMEM;
  77                 return (-1);
  78         }
  79
  80         b = realloc(buf->buf, buf->wpos + len);
  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 buf_add(struct buf *buf, const void *data, size_t len)
  91 {
  92         if (buf->wpos + len > buf->size)
  93                 if (buf_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 buf_reserve(struct buf *buf, size_t len)
 103 {
 104         void    *b;
 105
 106         if (buf->wpos + len > buf->size)
 107                 if (buf_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 buf_seek(struct buf *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 buf_size(struct buf *buf)
 127 {
 128         return (buf->wpos);
 129 }
 130
 131 size_t
 132 buf_left(struct buf *buf)
 133 {
 134         return (buf->max - buf->wpos);
 135 }
 136
 137 void
 138 buf_close(struct msgbuf *msgbuf, struct buf *buf)
 139 {
 140         buf_enqueue(msgbuf, buf);
 141 }
 142
 143 int
 144 buf_write(struct msgbuf *msgbuf)
 145 {
 146         struct iovec     iov[IOV_MAX];
 147         struct buf      *buf;
 148         unsigned int     i = 0;
 149         ssize_t n;
 150
 151         bzero(&iov, 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         if ((n = writev(msgbuf->fd, iov, i)) == -1) {
 161                 if (errno == EAGAIN || errno == ENOBUFS ||
 162                     errno == EINTR)     /* try later */
 163                         return (0);
 164                 else
 165                         return (-1);
 166         }
 167
 168         if (n == 0) {                   /* connection closed */
 169                 errno = 0;
 170                 return (-2);
 171         }
 172
 173         msgbuf_drain(msgbuf, n);
 174
 175         return (0);
 176 }
 177
 178 void
 179 buf_free(struct buf *buf)
 180 {
 181         free(buf->buf);
 182         free(buf);
 183 }
 184
 185 void
 186 msgbuf_init(struct msgbuf *msgbuf)
 187 {
 188         msgbuf->queued = 0;
 189         msgbuf->fd = -1;
 190         TAILQ_INIT(&msgbuf->bufs);
 191 }
 192
 193 void
 194 msgbuf_drain(struct msgbuf *msgbuf, size_t n)
 195 {
 196         struct buf      *buf, *next;
 197
 198         for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
 199             buf = next) {
 200                 next = TAILQ_NEXT(buf, entry);
 201                 if (buf->rpos + n >= buf->wpos) {
 202                         n -= buf->wpos - buf->rpos;
 203                         buf_dequeue(msgbuf, buf);
 204                 } else {
 205                         buf->rpos += n;
 206                         n = 0;
 207                 }
 208         }
 209 }
 210
 211 void
 212 msgbuf_clear(struct msgbuf *msgbuf)
 213 {
 214         struct buf      *buf;
 215
 216         while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
 217                 buf_dequeue(msgbuf, buf);
 218 }
 219
 220 int
 221 msgbuf_write(struct msgbuf *msgbuf)
 222 {
 223         struct iovec     iov[IOV_MAX];
 224         struct buf      *buf;
 225         unsigned int     i = 0;
 226         ssize_t          n;
 227         struct msghdr    msg;
 228         struct cmsghdr  *cmsg;
 229         union {
 230                 struct cmsghdr  hdr;
 231                 char            buf[CMSG_SPACE(sizeof(int))];
 232         } cmsgbuf;
 233
 234         bzero(&iov, sizeof(iov));
 235         bzero(&msg, sizeof(msg));
 236         TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
 237                 if (i >= IOV_MAX)
 238                         break;
 239                 iov[i].iov_base = buf->buf + buf->rpos;
 240                 iov[i].iov_len = buf->wpos - buf->rpos;
 241                 i++;
 242                 if (buf->fd != -1)
 243                         break;
 244         }
 245
 246         msg.msg_iov = iov;
 247         msg.msg_iovlen = i;
 248
 249         if (buf != NULL && buf->fd != -1) {
 250                 msg.msg_control = (caddr_t)&cmsgbuf.buf;
 251                 msg.msg_controllen = sizeof(cmsgbuf.buf);
 252                 cmsg = CMSG_FIRSTHDR(&msg);
 253                 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
 254                 cmsg->cmsg_level = SOL_SOCKET;
 255                 cmsg->cmsg_type = SCM_RIGHTS;
 256                 *(int *)CMSG_DATA(cmsg) = buf->fd;
 257         }
 258
 259         if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
 260                 if (errno == EAGAIN || errno == ENOBUFS ||
 261                     errno == EINTR)     /* try later */
 262                         return (0);
 263                 else
 264                         return (-1);
 265         }
 266
 267         if (n == 0) {                   /* connection closed */
 268                 errno = 0;
 269                 return (-2);
 270         }
 271
 272         /*
 273          * assumption: fd got sent if sendmsg sent anything
 274          * this works because fds are passed one at a time
 275          */
 276         if (buf != NULL && buf->fd != -1) {
 277                 close(buf->fd);
 278                 buf->fd = -1;
 279         }
 280
 281         msgbuf_drain(msgbuf, n);
 282
 283         return (0);
 284 }
 285
 286 void
 287 buf_enqueue(struct msgbuf *msgbuf, struct buf *buf)
 288 {
 289         TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
 290         msgbuf->queued++;
 291 }
 292
 293 void
 294 buf_dequeue(struct msgbuf *msgbuf, struct buf *buf)
 295 {
 296         TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
 297
 298         if (buf->fd != -1)
 299                 close(buf->fd);
 300
 301         msgbuf->queued--;
 302         buf_free(buf);
 303 }