mbchain, mb_init, mb_initm, mb_done, mb_detach, mb_fixhdr, mb_reserve, mb_put_uint8, mb_put_uint16be,

       This manual page was written by Boris Popov <bp@FreeBSD.org>.

Debian                                          February 20, 2001                                     MBCHAIN(9)

       These  functions  are used to compose mbuf chains from various data types.  The mbchain structure is used
       as a working context and should be initialized with a call to either mb_init() or mb_initm().  It has the
       following fields:

       mb_top    (structmbuf*) A pointer to the top of constructed mbuf chain.

       mb_cur    (structmbuf*) A pointer to the currently filled mbuf.

       mb_mleft  (int) Number of bytes left in the current mbuf.

       mb_count  (int) Total number of bytes placed in the mbuf chain.

       mb_copy   (mb_copy_t*) User-defined function to perform a copy into mbuf; useful  if  any  unusual  data
                 conversion is necessary.

       mb_udata  (void*) User-supplied data which can be used in the mb_copy function.

       mb_done() function disposes an mbuf chain pointed to by mbp->mb_top field and sets the field to NULL.

       mb_detach() function returns the value of mbp->mb_top field and sets its value to NULL.

       mb_fixhdr() recalculates the length of an mbuf chain and updates the m_pkthdr.len field of the first mbuf
       in the chain.  It returns the calculated length.

       mb_reserve() ensures that the object of the length specified by the size argument will fit in the current
       mbuf  (mbuf  allocation  is  performed  if  necessary), and advances all pointers as if the real data was
       placed.  Returned value will point to the beginning of the reserved space.  Note that  the  size  of  the
       object should not exceed MLEN bytes.

       All  mb_put_*() functions perform an actual copy of the data into mbuf chain.  Functions which have le or
       be suffixes will perform conversion to the little- or big-endian data formats.

       mb_put_mem() function copies size bytes of data specified by the source argument to an mbuf  chain.   The
       type argument specifies the method used to perform a copy, and can be one of the following:

       MB_MSYSTEM  Use bcopy() function.

       MB_MUSER    Use copyin(9) function.

       MB_MINLINE  Use an “inline” loop which does not call any function.

       MB_MZERO    Do not copy any data, but just fill the destination with zero bytes.

       MB_MCUSTOM  Call function specified by the mbp->mb_copy field.

       struct mbchain *mbp;
       struct mbuf *m;

       mb_init(mbp);
       mb_put_uint8(mbp, 33);
       mb_put_uint16le(mbp, length);
       m = m_copym(mbp->mb_top, 0, M_COPYALL, M_WAIT);
       send(m);
       mb_done(mbp);

       mbchain,  mb_init,  mb_initm,  mb_done,  mb_detach, mb_fixhdr, mb_reserve, mb_put_uint8, mb_put_uint16be,
       mb_put_uint16le,   mb_put_uint32be,   mb_put_uint32le,   mb_put_int64be,   mb_put_int64le,    mb_put_mem,
       mb_put_mbuf, mb_put_uio — set of functions to build an mbuf chain from various data types

       All int functions except mb_fixhdr() return zero if successful and an error code otherwise.

       Note:  after  failure  of  any  function,  an  mbuf chain is left in the broken state, and only mb_done()
       function can safely be called to destroy it.

mbuf(9), mdchain(9)

optionsLIBMCHAINkldloadlibmchain#include<sys/param.h>#include<sys/uio.h>#include<sys/mchain.h>intmb_init(structmbchain*mbp);

       voidmb_initm(structmbchain*mbp, structmbuf*m);

       voidmb_done(structmbchain*mbp);

       structmbuf*mb_detach(structmbchain*mbp);

       intmb_fixhdr(structmbchain*mbp);

       caddr_tmb_reserve(structmbchain*mbp, intsize);

       intmb_put_uint8(structmbchain*mbp, uint8_tx);

       intmb_put_uint16be(structmbchain*mbp, uint16_tx);

       intmb_put_uint16le(structmbchain*mbp, uint16_tx);

       intmb_put_uint32be(structmbchain*mbp, uint32_tx);

       intmb_put_uint32le(structmbchain*mbp, uint32_tx);

       intmb_put_int64be(structmbchain*mbp, int64_tx);

       intmb_put_int64le(structmbchain*mbp, int64_tx);

       intmb_put_mem(structmbchain*mbp, c_caddr_tsource, intsize, inttype);

       intmb_put_mbuf(structmbchain*mbp, structmbuf*m);

       intmb_put_uio(structmbchain*mbp, structuio*uiop, intsize);