Manual Pages for UNIX Operating System command usage for man copymsg

Kernel Functions for Drivers                          copymsg(9F)



NAME
     copymsg - copy a message

SYNOPSIS
     #include 



     mblk_t *copymsg(mblk_t *mp);


INTERFACE LEVEL
     Architecture independent level 1 (DDI/DKI).

PARAMETERS
     mp    Pointer to the message to be copied.


DESCRIPTION
     The copymsg() function forms a new message by allocating new
     message  blocks,  and  copying  the  contents of the message
     referred to by mp (using the copyb(9F) function). It returns
     a pointer to the new message.

RETURN VALUES
     If the copy is successful, copymsg() returns  a  pointer  to
     the new message. Otherwise, it returns a NULL pointer.

CONTEXT
     The copymsg() function can be called from  user,  interrupt,
     or kernel context.

EXAMPLES
     Example 1 : Using copymsg


     The routine lctouc() converts all the lowercase ASCII  char-
     acters  in  the message to uppercase. If the reference count
     is greater than one (line 8), then the  message  is  shared,
     and  must be copied before changing the contents of the data
     buffer. If the call to the copymsg()  function  fails  (line
     9), return NULL (line 10), otherwise, free the original mes-
     sage (line 11). If the reference count was equal to  1,  the
     message  can  be  modified.  For each character (line 16) in
     each message block (line 15), if it is a  lowercase  letter,
     convert  it  to  an uppercase letter (line 18). A pointer to
     the converted message is returned (line 21).



        1 mblk_t *lctouc(mp)
        2    mblk_t *mp;



SunOS 5.11          Last change: 16 Jan 2006                    1






Kernel Functions for Drivers                          copymsg(9F)



        3 {
        4    mblk_t *cmp;
        5    mblk_t *tmp;
        6    unsigned char *cp;
        7
        8    if (mp->b_datap->db_ref > 1) {
        9            if ((cmp = copymsg(mp)) == NULL)
       10                     return (NULL);
       11            freemsg(mp);
       12    } else {
       13            cmp = mp;
       14    }
       15    for (tmp = cmp; tmp; tmp = tmp->b_cont) {
       16            for (cp = tmp->b_rptr; cp < tmp->b_wptr; cp++) {
       17                    if ((*cp <= 'z') && (*cp >= 'a'))
       18                             *cp -= 0x20;
       19            }
       20    }
       21    return(cmp);
       22 }


SEE ALSO
     allocb(9F), copyb(9F), msgb(9S)


     Writing Device Drivers


     STREAMS Programming Guide

























SunOS 5.11          Last change: 16 Jan 2006                    2