sdgetv(S)                      6 January 1993                      sdgetv(S)


 Name

    sdgetv, sdwaitv - synchronizes shared data access

 Syntax


    cc  . . .  -lx


    #include  <sys/sd.h>

    int sdgetv(addr)
    char *addr;

    int sdwaitv(addr, vnum)
    char *addr;
    int vnum;


 Description

    sdgetv and sdwaitv may be used to synchronize cooperating processes that
    are using shared data segments.  The return value of both routines is the
    version number of the shared data segment attached to the process at
    address addr.  The version number of a segment changes whenever some pro-
    cess does an sdleave for that segment.

    sdgetv simply returns the version number of the indicated segment.

    sdwaitv forces the current process to sleep until the version number for
    the indicated segment is no longer equal to vnum.

 Return value

    Upon successful completion, both sdgetv and sdwaitv return a positive
    integer that is the current version number for the indicated shared data
    segment.  Otherwise, a value of -1 is returned, and errno is set to indi-
    cate the error.

 See also

    sdenter(S), sdget(S)

 Standards conformance

    sdgetv and sdwaitv are not part of any currently supported standard; they
    are an extension of AT&T System V provided by the Santa Cruz Operation.