write(9e) - osol9

1write(9E)                     Driver Entry Points                    write(9E)
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NAME

6       write - write data to a device
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SYNOPSIS

9       #include <sys/types.h>
10       #include <sys/errno.h>
11       #include <sys/open.h>
12       #include <sys/cred.h>
13       #include <sys/ddi.h>
14       #include <sys/sunddi.h>
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18       int prefixwrite(dev_t dev, struct uio *uio_p, cred_t *cred_p);
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INTERFACE LEVEL

22       Architecture  independent  level  1  (DDI/DKI).  This  entry  point  is
23       optional.
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PARAMETERS

26       dev        Device number.
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29       uio_p      Pointer to the  uio(9S) structure that describes  where  the
30                  data is to be stored in user space.
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33       cred_p     Pointer to the  user credential structure for the I/O trans‐
34                  action.
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DESCRIPTION

38       Used for character or raw data I/O,  the  driver   write()  routine  is
39       called  indirectly  through   cb_ops(9S)  by the  write(2) system call.
40       The  write() routine supervises the data transfer from user space to  a
41       device described by the  uio(9S) structure.
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44       The  write() routine should check the validity of the minor number com‐
45       ponent of  dev and the user credentials pointed to by cred_p, if perti‐
46       nent.
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RETURN VALUES

49       The   write()  routine  should return 0 for success, or the appropriate
50       error number.
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EXAMPLES

53       The following is an example of a write() routine  using  physio(9F)  to
54       perform writes to a seekable device:
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56         static int
57         xxwrite(dev_t dev, struct uio *uiop, cred_t *credp)
58         {
59               int instance;
60               xx_t     xx;
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62               instance = getminor(dev);
63               xx = ddi_get_soft_state(xxstate, instance);
64               if (xx == NULL)
65                      return (ENXIO);
66               return (physio(xxstrategy, NULL, dev, B_WRITE,
67                      xxmin, uiop));
68         }
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