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Sourcecode: qemu version File versions

sbuf.c

/*
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#include <slirp.h>

static void sbappendsb(struct sbuf *sb, struct mbuf *m);

/* Done as a macro in socket.h */
/* int
 * sbspace(struct sockbuff *sb)
 * {
 *    return SB_DATALEN - sb->sb_cc;
 * }
 */

void
sbfree(sb)
      struct sbuf *sb;
{
      free(sb->sb_data);
}

void
sbdrop(sb, num)
      struct sbuf *sb;
      int num;
{
      /*
       * We can only drop how much we have
       * This should never succeed
       */
      if(num > sb->sb_cc)
            num = sb->sb_cc;
      sb->sb_cc -= num;
      sb->sb_rptr += num;
      if(sb->sb_rptr >= sb->sb_data + sb->sb_datalen)
            sb->sb_rptr -= sb->sb_datalen;

}

void
sbreserve(sb, size)
      struct sbuf *sb;
      int size;
{
      if (sb->sb_data) {
            /* Already alloced, realloc if necessary */
            if (sb->sb_datalen != size) {
                  sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)realloc(sb->sb_data, size);
                  sb->sb_cc = 0;
                  if (sb->sb_wptr)
                     sb->sb_datalen = size;
                  else
                     sb->sb_datalen = 0;
            }
      } else {
            sb->sb_wptr = sb->sb_rptr = sb->sb_data = (char *)malloc(size);
            sb->sb_cc = 0;
            if (sb->sb_wptr)
               sb->sb_datalen = size;
            else
               sb->sb_datalen = 0;
      }
}

/*
 * Try and write() to the socket, whatever doesn't get written
 * append to the buffer... for a host with a fast net connection,
 * this prevents an unnecessary copy of the data
 * (the socket is non-blocking, so we won't hang)
 */
void
sbappend(so, m)
      struct socket *so;
      struct mbuf *m;
{
      int ret = 0;

      DEBUG_CALL("sbappend");
      DEBUG_ARG("so = %lx", (long)so);
      DEBUG_ARG("m = %lx", (long)m);
      DEBUG_ARG("m->m_len = %d", m->m_len);

      /* Shouldn't happen, but...  e.g. foreign host closes connection */
      if (m->m_len <= 0) {
            m_free(m);
            return;
      }

      /*
       * If there is urgent data, call sosendoob
       * if not all was sent, sowrite will take care of the rest
       * (The rest of this function is just an optimisation)
       */
      if (so->so_urgc) {
            sbappendsb(&so->so_rcv, m);
            m_free(m);
            sosendoob(so);
            return;
      }

      /*
       * We only write if there's nothing in the buffer,
       * ottherwise it'll arrive out of order, and hence corrupt
       */
      if (!so->so_rcv.sb_cc)
         ret = send(so->s, m->m_data, m->m_len, 0);

      if (ret <= 0) {
            /*
             * Nothing was written
             * It's possible that the socket has closed, but
             * we don't need to check because if it has closed,
             * it will be detected in the normal way by soread()
             */
            sbappendsb(&so->so_rcv, m);
      } else if (ret != m->m_len) {
            /*
             * Something was written, but not everything..
             * sbappendsb the rest
             */
            m->m_len -= ret;
            m->m_data += ret;
            sbappendsb(&so->so_rcv, m);
      } /* else */
      /* Whatever happened, we free the mbuf */
      m_free(m);
}

/*
 * Copy the data from m into sb
 * The caller is responsible to make sure there's enough room
 */
static void
sbappendsb(struct sbuf *sb, struct mbuf *m)
{
      int len, n,  nn;

      len = m->m_len;

      if (sb->sb_wptr < sb->sb_rptr) {
            n = sb->sb_rptr - sb->sb_wptr;
            if (n > len) n = len;
            memcpy(sb->sb_wptr, m->m_data, n);
      } else {
            /* Do the right edge first */
            n = sb->sb_data + sb->sb_datalen - sb->sb_wptr;
            if (n > len) n = len;
            memcpy(sb->sb_wptr, m->m_data, n);
            len -= n;
            if (len) {
                  /* Now the left edge */
                  nn = sb->sb_rptr - sb->sb_data;
                  if (nn > len) nn = len;
                  memcpy(sb->sb_data,m->m_data+n,nn);
                  n += nn;
            }
      }

      sb->sb_cc += n;
      sb->sb_wptr += n;
      if (sb->sb_wptr >= sb->sb_data + sb->sb_datalen)
            sb->sb_wptr -= sb->sb_datalen;
}

/*
 * Copy data from sbuf to a normal, straight buffer
 * Don't update the sbuf rptr, this will be
 * done in sbdrop when the data is acked
 */
void
sbcopy(sb, off, len, to)
      struct sbuf *sb;
      int off;
      int len;
      char *to;
{
      char *from;

      from = sb->sb_rptr + off;
      if (from >= sb->sb_data + sb->sb_datalen)
            from -= sb->sb_datalen;

      if (from < sb->sb_wptr) {
            if (len > sb->sb_cc) len = sb->sb_cc;
            memcpy(to,from,len);
      } else {
            /* re-use off */
            off = (sb->sb_data + sb->sb_datalen) - from;
            if (off > len) off = len;
            memcpy(to,from,off);
            len -= off;
            if (len)
               memcpy(to+off,sb->sb_data,len);
      }
}

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