Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ndb.h>

/* replace a in t with b, the line structure in b is lost, c'est la vie */
Ndbtuple*
ndbsubstitute(Ndbtuple *t, Ndbtuple *a, Ndbtuple *b)
{
        Ndbtuple *nt;

        if(a == b){
                ndbsetmalloctag(t, getcallerpc(&t));
                return t;
        }
        if(b == nil){
                t = ndbdiscard(t, a);
                ndbsetmalloctag(t, getcallerpc(&t));
                return t;
        }

        /* all pointers to a become pointers to b */
        for(nt = t; nt != nil; nt = nt->entry){
                if(nt->line == a)
                        nt->line = b;
                if(nt->entry == a)
                        nt->entry = b;
        }

        /* end of b chain points to a's successors */
        for(nt = b; nt->entry; nt = nt->entry)
                nt->line = nt->entry;
        nt->line = a->line;
        nt->entry = a->entry;

        a->entry = nil;
        ndbfree(a);

        if(a == t){
                ndbsetmalloctag(b, getcallerpc(&t));
                return b;
        }else{
                ndbsetmalloctag(t, getcallerpc(&t));
                return t;
        }
}