osf1 man page for esballoc

esballoc(9r)															      esballoc(9r)

NAME
       esballoc - STREAMS: Allocates a message block with a shared buffer

SYNOPSIS
       #include <sys/stream.h>

       mblk_t * esballoc(
	       unsigned char *base,
	       int size,
	       int pri,
	       frtn_t *free_rtnp );

ARGUMENTS
       Specifies  the  address of the user-supplied data buffer.  Specifies the number of bytes in the data buffer.  Specifies the priority of the
       allocation request (to be used by the allocb interface, which esballoc calls).  Specifies the free interface (routine) data structure.

DESCRIPTION
       The esballoc interface creates a STREAMS message and attaches a user-supplied data buffer in place of a STREAMS data buffer.  The interface
       calls allocb to obtain a message and data block header. The user-supplied data buffer, pointed to by the base argument, is used as the data
       buffer for the message.

       The free_rtn structure is referenced by the dp_freep member of the datab structure.  When the freeb interface is called to  free  the  mes-
       sage, the driver's message free interface (referenced through the free_rtn structure) is called, with arguments, to free the data buffer.

       The free_rtn structure is defined as follows:

       /* Free return structure for esballoc */ typedef struct free_rtn {
	 void	 (*free_func)(char *, char *); /* Interface to free buffer */
	 char *  free_arg;		       /* Parameter to free_func */ } frtn_t;

       Instead	of  requiring  a specific number of arguments, the free_arg member is of type char *. This way, the driver can pass a pointer to a
       structure if more than one argument is needed.

NOTES
       The free_func interface must be defined in kernel space and should be declared void. It has no user context and must not sleep.

RETURN VALUES
       Upon successful completion, the esballoc interface returns a pointer to the newly allocated message block. This message block  is  of  type
       struct msgb *. The msgb data structure is defined in the /usr/sys/include/sys/stream.h file.

       On failure, esballoc returns a NULL pointer.

SEE ALSO
       Kernel Interfaces: allocb(9r), freeb(9r)

       Programmer's Guide: STREAMS

																      esballoc(9r)