mdw@git.distorted.org.uk Git - fwd/blob - chan.c

   1 /* -*-c-*-
   2  *
   3  * Channel management
   4  *
   5  * (c) 1999 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the `fwd' port forwarder.
  11  *
  12  * `fwd' is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * `fwd' is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with `fwd'; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 #include "fwd.h"
  28
  29 #ifdef CHAN_DEBUG
  30 #  define D(x) x
  31 #else
  32 #  define D(x)
  33 #endif
  34
  35 /*----- Main code ---------------------------------------------------------*/
  36
  37 /* --- @writechan@ --- *
  38  *
  39  * Arguments:   @int fd@ = file descriptor to write to
  40  *              @unsigned mode@ = what the descriptor is ready for
  41  *              @void *vp@ = pointer to channel block
  42  *
  43  * Returns:     ---
  44  *
  45  * Use:         Writes to a channel.
  46  */
  47
  48 static void writechan(int fd, unsigned mode, void *vp)
  49 {
  50   chan *c = vp;
  51   int w;
  52   unsigned base = c->base;
  53   unsigned len = c->len;
  54
  55   /* --- Write data from my buffer --- */
  56
  57   if (len) {
  58
  59     /* --- Do the write --- */
  60
  61     D( printf("writechan %d: base = %u, len = %u; ", fd, base, len); )
  62     if (base + len <= CHAN_BUFSZ) {
  63       D( printf("%u:%u", base, len); )
  64       w = write(fd, c->buf + base, len);
  65     } else {
  66       struct iovec iov[2];
  67       iov[0].iov_base = c->buf + base;
  68       iov[0].iov_len = CHAN_BUFSZ - base;
  69       iov[1].iov_base = c->buf;
  70       iov[1].iov_len = len - iov[0].iov_len;
  71       D( printf("%u:%u, %u:%u",
  72                 base, CHAN_BUFSZ - base,
  73                 0, len + base - CHAN_BUFSZ); )
  74       w = writev(fd, iov, 2);
  75     }
  76     D( printf("; returned %d\n", w); )
  77
  78     /* --- Sift through the results --- */
  79
  80     if (w < 0) {
  81       if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
  82         return;
  83       c->err = errno;
  84       goto close;
  85     } else if (w == 0)
  86       goto close;
  87     else if (c->len == CHAN_BUFSZ && !(c->f & CHANF_CLOSE))
  88       sel_addfile(&c->r);
  89     c->len -= w;
  90     c->base += w;
  91   }
  92   if (c->len == 0)
  93     sel_rmfile(&c->w);
  94
  95   /* --- Close the output end if necessary --- */
  96
  97   if (c->len == 0) {
  98     c->base = 0;
  99     if (c->f & CHANF_CLOSE)
 100       c->func(c->p);
 101   }
 102   return;
 103
 104   /* --- Force a close if an error occurred --- */
 105
 106 close:
 107   chan_close(c);
 108   c->func(c->p);
 109 }
 110
 111 /* --- @readchan@ --- *
 112  *
 113  * Arguments:   @int fd@ = file descriptor to read from
 114  *              @unsigned mode@ = what the descriptor is ready for
 115  *              @void *vp@ = pointer to channel block
 116  *
 117  * Returns:     ---
 118  *
 119  * Use:         Reads from a channel.
 120  */
 121
 122 static void readchan(int fd, unsigned mode, void *vp)
 123 {
 124   chan *c = vp;
 125   int r;
 126   unsigned base = c->base;
 127   unsigned len = c->len;
 128
 129   /* --- Do the read --- */
 130
 131   D( printf("readchan %d: base = %u, len = %u; ", fd, base, len); )
 132   if (base == 0) {
 133     D( printf("%u:%u", len, CHAN_BUFSZ - len); )
 134     r = read(fd, c->buf + len, CHAN_BUFSZ - len);
 135   } else if (base + len >= CHAN_BUFSZ) {
 136     D( printf("%u:%u", base + len - CHAN_BUFSZ, CHAN_BUFSZ - len); )
 137     r = read(fd, c->buf + base + len - CHAN_BUFSZ, CHAN_BUFSZ - len);
 138   } else {
 139     struct iovec iov[2];
 140     iov[0].iov_base = c->buf + base + len;
 141     iov[0].iov_len = CHAN_BUFSZ - base - len;
 142     iov[1].iov_base = c->buf;
 143     iov[1].iov_len = base;
 144     D( printf("%u:%u, %u:%u",
 145               base + len, CHAN_BUFSZ - base - len,
 146               0, base); )
 147     r = readv(fd, iov, 2);
 148   }
 149   D( printf("; returned %d\n", r); )
 150
 151   /* --- Sift through the results --- */
 152
 153   if (r < 0) {
 154     if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
 155       return;
 156     c->err = errno;
 157     goto close;
 158   } else if (r == 0)
 159     goto close;
 160   else if (c->len == 0 && (c->f & CHANF_READY)) {
 161     sel_addfile(&c->w);
 162     sel_force(&c->w);
 163   }
 164   c->len += r;
 165   if (c->len == CHAN_BUFSZ)
 166     sel_rmfile(&c->r);
 167   return;
 168
 169   /* --- Close the read end of the channel --- */
 170
 171 close:
 172   c->f |= CHANF_CLOSE;
 173   if (!c->len && (c->f & CHANF_READY)) {
 174     sel_addfile(&c->w);
 175     sel_force(&c->w);
 176   }
 177   sel_rmfile(&c->r);
 178 }
 179
 180 /* --- @chan_close@ --- *
 181  *
 182  * Arguments:   @chan *c@ = pointer to channel
 183  *
 184  * Returns:     ---
 185  *
 186  * Use:         Closes down a channel prematurely.
 187  */
 188
 189 void chan_close(chan *c)
 190 {
 191   if (!(c->f & CHANF_CLOSE) && c->len != CHAN_BUFSZ)
 192     sel_rmfile(&c->r);
 193   if ((c->f & CHANF_READY) && c->len != 0)
 194     sel_rmfile(&c->w);
 195 }
 196
 197 /* --- @chan_dest@ --- *
 198  *
 199  * Arguments:   @chan *c@ = pointer to channel
 200  *              @int fd@ = destination file descriptor for channel
 201  *
 202  * Returns:     ---
 203  *
 204  * Use:         Sets the channel's destination so it knows where to put
 205  *              data.
 206  */
 207
 208 void chan_dest(chan *c, int fd)
 209 {
 210   if (c->f & CHANF_READY)
 211     return;
 212   sel_initfile(sel, &c->w, fd, SEL_WRITE, writechan, c);
 213   if (c->len || (c->f & CHANF_CLOSE)) {
 214     sel_addfile(&c->w);
 215     sel_force(&c->w);
 216   }
 217   c->f |= CHANF_READY;
 218 }
 219
 220 /* --- @chan_open@ --- *
 221  *
 222  * Arguments:   @chan *c@ = pointer to channel to open
 223  *              @int from, to@ = source and destination file descriptors
 224  *              @void (*func)(void *p)@ = function to call on closure
 225  *              @void *p@ = argument to pass to function
 226  *
 227  * Returns:     ---
 228  *
 229  * Use:         Opens a channel.  Data is copied from the source to the
 230  *              destination.  The @to@ argument may be @-1@ if the file
 231  *              descriptor isn't known yet.
 232  */
 233
 234 void chan_open(chan *c, int from, int to,
 235                void (*func)(void */*p*/), void *p)
 236 {
 237   c->func = func;
 238   c->p = p;
 239
 240   c->base = 0;
 241   c->len = 0;
 242   c->f = 0;
 243
 244   sel_initfile(sel, &c->r, from, SEL_READ, readchan, c);
 245   sel_addfile(&c->r);
 246
 247   if (to != -1)
 248     chan_dest(c, to);
 249 }
 250
 251 /*----- That's all, folks -------------------------------------------------*/