NAME

sdgetv - synchronizes shared data access.

SYNOPSIS

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

int sdgetv(addr)
int sdwaitv(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 process 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.

DIAGNOSTICS

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 indicate the error.

SEE ALSO

sdenter(2), sdget(2).