sdget(2)                  SYSTEM CALLS                   sdget(2)



NAME
     sdget, sdfree - attaches and detaches a shared data segment.

SYNOPSIS
     cc [flag ...] file ... -lx
     #include <sys/sd.h>

     char *sdget(char *path, in flags, /* long size, int mode */;

     int sdfree(char *addr);

DESCRIPTION
     sdget attaches a shared data segment to the  data  space  of
     the  current  process.  The actions performed are controlled
     by the value of flags.  flags values are constructed by  OR-
     ing  flags  from the following list:  Attach the segment for
     reading only.  Attach the segment for both reading and writ-
     ing.   If the segment named by path exists and is not in use
     (active), this flag will have the same effect as creating  a
     segment  from  scratch.   Otherwise,  the segment is created
     according to the values of size and mode.   Read  and  write
     access to the segment is granted to other processes based on
     the permissions passed in mode, and functions  the  same  as
     those for regular files.  Execute permission is meaningless.
     The segment is initialized to contain all  zeroes.   If  the
     segment is created because of this call, the segment will be
     made so that more than one process can  be  between  sdenter
     and sdleave calls.  sdfree detaches the current process from
     the shared data segment that is attached  at  the  specified
     address.  If the current process has done sdenter but not an
     sdleave for the specified  segment,  sdleave  will  be  done
     before  detaching  the  segment.   When  no  process remains
     attached to the segment, the contents of that segment disap-
     pear,  and  no  process  can  attach  to the segment without
     creating it by using the SD_CREAT flag in sdget.   errno  is
     set  to  EEXIST  if  a process tries to create a shared data
     segment that exists and is in use.  errno is set to  ENOTNAM
     if  a process attempts an sdget on a file that exists but is
     not a shared data type.

DIAGNOSTICS
     On successful completion, the address at which  the  segment
     was  attached  is  returned.  Otherwise, -1 is returned, and
     errno is set to indicate the error.  errno is set to  EINVAL
     if a process does an sdget on a shared data segment to which
     it is already attached.  errno is set to EEXIST if a process
     tries  to  create a shared data segment that exists an is in
     use.  errno is set to ENOTNAM if a process attempts an sdget
     on  a  file  that exists but is not a shared data type.  The
     mode parameter must be included on the  first  call  of  the
     sdget function.




            Last change: XENIX Compatibility Package            1

sdget(2)                  SYSTEM CALLS                   sdget(2)



SEE ALSO
     sdenter(2), sdgetv(2).





















































            Last change: XENIX Compatibility Package            2