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MGETHDR(9r)
NAME
  MGETHDR - Network: Allocates an mbuf structure and initializes it to
  contain a packet header and internal data

SYNOPSIS
  #include <sys/mbuf.h>


  MGETHDR(
	  struct mbuf *mbuf_p,
	  int how,
	  int type );

ARGUMENTS
  mbuf_p
      Specifies a pointer to the mbuf structure for which you want to
      allocate memory.

  how Specifies how you want MGETHDR() to allocate the memory.	You can pass
      one of the following constants defined in <mbuf.h>:

      M_WAIT  Allocates memory from the virtual memory subsystem if there is
	      not enough memory in the preallocated pool. This constant
	      signifies that the internal interface that allocates the memory
	      can block.

      M_DONTWAIT
	      Does not allocate memory from the virtual memory subsystem if
	      there is not enough memory in the preallocated pool. This
	      constant signifies that the internal interface that allocates
	      the memory cannot block.

  type
      Specifies the type of memory buffer. The <mbuf.h> file defines the
      possible memory buffer constants that you can pass. The MGETHDR()
      routine uses this value to initialize the mh_type member of the mbuf
      structure.

DESCRIPTION
  The MGETHDR() routine calls an internal interface that allocates memory to
  accommodate the specified mbuf structure pointer. If MGETHDR() successfully
  allocates the memory, it initializes the following members to contain
  internal data:

    ·  mh_next

    ·  mh_type

    ·  mh_data

    ·  mh_flags

  Unlike the MGET() routine, MGETHDR() initializes the mh_flags member to
  specify that a packet header is included.

  If MGETHDR() cannot successfully allocate the memory, it calls an internal
  interface to retry allocating the memory.

RETURN VALUES
  None

FILES
  <mbuf.h>

SEE ALSO
  Routines: MGET(9r), MCLGET(9r), MCLGET2(9r)

  Data Structures: mbuf(9s)

Index for Section 9

Alphabetical listing for M

Top of page