copyb(9r)copyb(9r)NAME
copyb - STREAMS: Copies a message block
SYNOPSIS
#include <sys/stream.h>
MBLKP copyb(
MBLKP message_block );
ARGUMENTS
Specifies a pointer to the message block from which copyb copies the data. The typedef MBLKP is an alternate name for typedef struct msgb
*.
DESCRIPTION
The copyb interface allocates a new message block and copies into it the data from the block pointed to by the message block (the mes-
sage_block argument). The new message block is at least as large as the message block being copied. The copyb interface uses the b_rptr and
b_wptr members of the msgb structure pointer to determine how many bytes to copy.
RETURN VALUES
Upon successful completion, the copyb interface returns a pointer to the newly allocated message block that contains the copied data. This
newly allocated message block is of type struct msgb *. The msgb data structure is defined in the /usr/sys/include/sys/stream.h file.
Otherwise, copyb returns a NULL pointer.
SEE ALSO
Kernel Interfaces: allocb(9r)
Programmer's Guide: STREAMS
copyb(9r)
Check Out this Related Man Page
copyb(9F) Kernel Functions for Drivers copyb(9F)NAME
copyb - copy a message block
SYNOPSIS
#include <sys/stream.h>
mblk_t *copyb(mblk_t *bp);
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
PARAMETERS
bp Pointer to the message block from which data is copied.
DESCRIPTION
copyb() allocates a new message block, and copies into it the data from the block that bp denotes. The new block will be at least as large
as the block being copied. copyb() uses the b_rptr and b_wptr members of bp to determine how many bytes to copy.
RETURN VALUES
If successful, copyb() returns a pointer to the newly allocated message block containing the copied data. Otherwise, it returns a NULL
pointer.
CONTEXT
copyb() can be called from user or interrupt context.
EXAMPLES
Example 1: : Using copyb
For each message in the list, test to see if the downstream queue is full with the canputnext(9F) function (line 21). If it is not full,
use copyb to copy a header message block, and dupmsg(9F) to duplicate the data to be retransmitted. If either operation fails, reschedule a
timeout at the next valid interval.
Update the new header block with the correct destination address (line 34), link the message to it (line 35), and send it downstream (line
36). At the end of the list, reschedule this routine.
1 struct retrans {
2 mblk_t *r_mp;
3 int r_address;
4 queue_t *r_outq;
5 struct retrans *r_next;
6 };
7
8 struct protoheader {
...
9 int h_address;
...
10 };
11
12 mblk_t *header;
13
14 void
15 retransmit(struct retrans *ret)
16 {
17 mblk_t *bp, *mp;
18 struct protoheader *php;
19
20 while (ret) {
21 if (!canputnext(ret->r_outq)) { /* no room */
22 ret = ret->r_next;
23 continue;
24 }
25 bp = copyb(header); /* copy header msg. block */
26 if (bp == NULL)
27 break;
28 mp = dupmsg(ret->r_mp); /* duplicate data */
29 if (mp == NULL) { /* if unsuccessful */
30 freeb(bp); /* free the block */
31 break;
32 }
33 php = (struct protoheader *)bp->b_rptr;
34 php->h_address = ret->r_address; /* new header */
35 bp->bp_cont = mp; /* link the message */
36 putnext(ret->r_outq, bp); /* send downstream */
37 ret = ret->r_next;
38 }
39 /* reschedule */
40 (void) timeout(retransmit, (caddr_t)ret, RETRANS_TIME);
41 }
SEE ALSO allocb(9F), canputnext(9F), dupmsg(9F)
Writing Device Drivers
STREAMS Programming Guide
SunOS 5.10 07 Nov 1996 copyb(9F)