/* Knuth step T5, the insert. */
static struct ts_entry *
tsearch_insert_k(const void *key,int kc,
struct ts_entry *p)
{
struct ts_entry *q = allocate_ts_entry(key);
if (!q) {
/* out of memory */
return NULL;
}
setlink(p,kc,q);
/* Non-NULL means inserted. */
return q;
}
/**
* copy a link, actually we recreate the link and only copy its stat() data.
*/
int copy_link(struct cow *cow)
{
int len;
char link[PATHLEN_MAX];
if ((len = readlink(cow->from_path, link, sizeof(link)-1)) == -1) {
syslog(LOG_WARNING, "readlink: %s", cow->from_path);
return (1);
}
if (symlink(cow->from_path, cow->to_path)) {
syslog(LOG_WARNING, "symlink: %s", link);
return (1);
}
return setlink(cow->to_path, cow->stat);
}
int
copy_link(FTSENT *p, int exists)
{
int len;
char link[MAXPATHLEN];
if ((len = readlink(p->fts_path, link, sizeof(link)-1)) == -1) {
warn("readlink: %s", p->fts_path);
return (1);
}
link[len] = '\0';
if (exists && unlink(to.p_path)) {
warn("unlink: %s", to.p_path);
return (1);
}
if (symlink(link, to.p_path)) {
warn("symlink: %s", link);
return (1);
}
return (pflag ? setlink(p->fts_statp) : 0);
}
static int
copy_link(FTSENT *p, int exists)
{
int len;
char linkname[PATH_MAX];
if ((len = readlink(p->fts_path, linkname, sizeof(linkname)-1)) == -1) {
warn("readlink: %s", p->fts_path);
return (1);
}
linkname[len] = '\0';
if (exists && unlink(to.p_path)) {
warn("unlink: %s", to.p_path);
return (1);
}
if (symlink(linkname, to.p_path)) {
warn("symlink: %s", linkname);
return (1);
}
return (setlink(p->fts_statp));
}
/* Returns deleted node parent unless the head changed.
Returns NULL if wanted node not found or the tree
is now empty or the head node changed.
Sets *did_delete if it found and deleted a node.
Sets *tree_empty if there are no more user nodes present.
*/
static struct ts_entry *
tdelete_inner(const void *key,
struct ts_entry *head,
int (*compar)(const void *, const void *),
int *tree_empty,
int *did_delete
)
{
struct ts_entry *p = 0;
struct ts_entry *pp = 0;
struct pkrecord * pkarray = 0;
int depth = head->llink - (struct ts_entry *)0;
unsigned k = 0;
/* Allocate extra, head is on the stack we create
here and the depth might increase. */
depth = depth + 4;
pkarray = calloc(sizeof(struct pkrecord),depth);
if(!pkarray) {
/* Malloc fails, we could abort... */
return NULL;
}
k = 0;
pkarray[k].pk=head;
pkarray[k].ak=1;
p = head->rlink;
while(p) {
int kc = 0;
k++;
kc = compar(key,p->keyptr);
pkarray[k].pk = p;
pkarray[k].ak = kc;
if(!kc) {
break;
}
p = getlink(p,kc);
}
if(!p) {
/* Node to delete never found. */
free(pkarray);
return NULL;
}
{
struct ts_entry *p = 0;
struct ts_entry *t = 0;
struct ts_entry *r = 0;
int pak = 0;
int ppak = 0;
p = pkarray[k].pk;
pak = pkarray[k].ak;
pp = pkarray[k-1].pk;
ppak = pkarray[k-1].ak;
/* Found a match. p to be deleted. */
t = p;
*did_delete = 1;
if(!t->rlink) {
if(k == 1 && !t->llink) {
*tree_empty = 1;
/* upper level will fix up head node. */
free(t);
free(pkarray);
return NULL;
}
/* t->llink might be NULL. */
setlink(pp,ppak,t->llink);
/* ASSERT: t->llink NULL or t->llink
has no children, balance zero and balance
of t->llink not changing. */
k--;
/* Step D4. */
free(t);
goto balance;
}
#ifdef IMPLEMENTD15
/* Step D1.5 */
if(!t->llink) {
setlink(pp,ppak,t->rlink);
/* we change the left link off ak */
k--;
/* Step D4. */
free(t);
goto balance;
}
#endif /* IMPLEMENTD15 */
/* Step D2 */
r = t->rlink;
if (!r->llink) {
/* We decrease the height of the right tree. */
r->llink = t->llink;
setlink(pp,ppak,r);
pkarray[k].pk = r;
pkarray[k].ak = 1;
/* The following essential line not mentioned
in Knuth AFAICT. */
r->balance = t->balance;
/* Step D4. */
free(t);
goto balance;
}
/* Step D3, we rearrange the tree
and pkarray so the balance step can work.
step D2 is insufficient so not done. */
k = rearrange_tree_so_p_llink_null(pkarray,k,
head,r,
p,pak,pp,ppak);
goto balance;
}
/* Now use pkarray decide if rebalancing
needed and, if needed, to rebalance.
k here matches l-1 in Knuth. */
balance:
{
unsigned k2 = k;
/* We do not want a test in the for() itself. */
for( ; 1 ; k2--) {
struct ts_entry *pk = 0;
int ak = 0;
int bk = 0;
if (k2 == 0) {
/* decreased in height */
head->llink--;
goto cleanup;
}
pk = pkarray[k2].pk;
if (!pk) {
/* Nothing here to work with. Move up. */
continue;
}
ak = pkarray[k2].ak;
bk = pk->balance;
if(bk == ak) {
pk->balance = 0;
continue;
}
if(bk == 0) {
pk->balance = -ak;
goto cleanup;
}
/* ASSERT: bk == -ak. We
will use bk == adel here (just below). */
/* Rebalancing required. Here we use (1) and (2)
in 6.2.3 to adjust the nodes */
{
/* Rebalance. We use s for what
is called A in Knuth Case 1, Case 2
page 461. r For what is called B.
So the link movement logic looks similar
to the tsearch insert case.*/
struct ts_entry *r = 0;
struct ts_entry *s = 0;
struct ts_entry *pa = 0;
int pak = 0;
int adel = -ak;
s = pk;
r = getlink(s,adel);
pa = pkarray[k2-1].pk;
pak = pkarray[k2-1].ak;
if(r->balance == adel) {
/* case 1. */
setlink(s,adel,getlink(r,-adel));
setlink(r,-adel,s);
/* A10 in tsearch. */
setlink(pa,pak,r);
s->balance = 0;
r->balance = 0;
continue;
} else if (r->balance == -adel) {
/* case 2 */
/* x plays the role of p in step A9 */
struct ts_entry*x = getlink(r,-adel);
setlink(r,-adel,getlink(x,adel));
setlink(x,adel,r);
setlink(s,adel,getlink(x,-adel));
setlink(x,-adel,s);
/* A10 in tsearch. */
setlink(pa,pak,x);
if(x->balance == adel) {
s->balance = -adel;
r->balance = 0;
} else if (x->balance == 0) {
s->balance = 0;
r->balance = 0;
} else if (x->balance == -adel) {
s->balance = 0;
r->balance = adel;
}
x->balance = 0;
continue;
} else {
/* r->balance == 0 case 3
we do a single rotation and
we are done. */
setlink(s,adel,getlink(r,-adel));
setlink(r,-adel,s);
setlink(pa,pak,r);
r->balance = -adel;
/*s->balance = r->balance = 0; */
goto cleanup;
}
}
}
}
cleanup:
free(pkarray);
#ifdef DW_CHECK_CONSISTENCY
dwarf_check_balance(head,1);
#endif
return pp;
}
static unsigned
rearrange_tree_so_p_llink_null( struct pkrecord * pkarray,
unsigned k,
struct ts_entry *head,
struct ts_entry *r,
struct ts_entry *p,
UNUSEDARG int pak,
struct ts_entry *pp,
int ppak)
{
struct ts_entry *s = 0;
unsigned k2 = 0; /* indexing pkarray */
int pbalance = p->balance;
/* Step D3 */
/* Since we are going to modify the tree by
movement of a node down the tree a ways,
we need to build pkarray with the (not yet
found) new next node, in pkarray[k], not
p.
The deletion will be of p, but by then
p will be moved in the tree so it has a null left link.
P's possibly-non-null right link
*/
k2 = k;
k2++;
r = p->rlink;
pkarray[k2].pk = r;
pkarray[k2].ak = -1;
s = r->llink;
/* Move down and left to get a null llink. */
while (s->llink) {
k2++;
r = s;
s = r->llink;
pkarray[k2].pk = r;
pkarray[k2].ak = -1;
}
/* Now we move S up in place (in the tree)
of the node P we will delete.
and p replaces s.
Finally winding up with a newly shaped balanced tree.
*/
{
struct ts_entry *tmp = 0;
int sbalance = s->balance;
s->llink = p->llink;
r->llink = p;
p->llink = 0;
tmp = p->rlink;
p->rlink = s->rlink;
s->rlink = tmp;
setlink(pp,ppak,s);
s->balance = pbalance;
p->balance = sbalance;
/* Now the tree is rearranged and still in balance. */
/* Replace the previous k position entry with S.
We trace the right link off of the moved S node. */
pkarray[k].pk = s;
pkarray[k].ak = 1;
r->llink = p->rlink;
/* Now p is out of the tree and we start
the rebalance at r. pkarray Index k2. */
}
/* Step D4 */
free(p);
return k2;
}
/* Algorithm A of Knuth 6.2.3, balanced tree.
key is pointer to a user data area containing the key
and possibly more.
We could recurse on this routine, but instead we
iterate (like Knuth does, but using for(;;) instead
of go-to.
*/
static struct ts_entry *
tsearch_inner( const void *key, struct ts_entry* head,
int (*compar)(const void *, const void *),
int*inserted,
struct ts_entry **nullme,
int * comparres)
{
/* t points to parent of p */
struct ts_entry *t = head;
/* p moves down tree, p starts as root. */
struct ts_entry *p = head->rlink;
/* s points where rebalancing may be needed. */
struct ts_entry *s = p;
struct ts_entry *r = 0;
struct ts_entry *q = 0;
int a = 0;
int kc = 0;
for(;;) {
/* A2. */
kc = compar(key,p->keyptr);
if(kc) {
/* A3 and A4 handled here. */
q = getlink(p,kc);
if(!q) {
/* Does step A5. */
q = tsearch_inner_do_insert(key,kc,inserted,p);
if (!q) {
/* Out of memory. */
return q;
}
break; /* to A5. */
}
if(q->balance) {
t = p;
s = q;
}
p = q;
continue;
}
/* K = KEY(P) in Knuth. */
/* kc == 0, we found the entry we search for. */
return p;
}
/* A5: work already done. */
/* A6: */
{
/* Balance factors on nodes betwen S and Q need to be
changed from zero to +-1 */
int kc2 = compar(key,s->keyptr);
if (kc2 < 0) {
a = -1;
} else {
a = 1;
}
r = p = getlink(s,a);
while (p != q) {
int kc3 = compar(key,p->keyptr);
if(kc3 < 0) {
p->balance = -1;
p = p->llink;
} else if (kc3 > 0) {
p->balance = 1;
p = p->rlink;
} else {
/* ASSERT: p == q */
break;
}
}
}
/* A7: */
{
if(! s->balance) {
/* Tree has grown higher. */
s->balance = a;
/* Counting in pointers, not integers. Ugh. */
head->llink = head->llink + 1;
return q;
}
if(s->balance == -a) {
/* Tree is more balanced */
s->balance = 0;
return q;
}
if (s->balance == a) {
/* Rebalance. */
if(r->balance == a) {
/* single rotation, step A8. */
p = r;
setlink(s,a,getlink(r,-a));
setlink(r,-a,s);
s->balance = 0;
r->balance = 0;
} else if (r->balance == -a) {
/* double rotation, step A9. */
p = getlink(r,-a);
setlink(r,-a,getlink(p,a));
setlink(p,a,r);
setlink(s,a,getlink(p,-a));
setlink(p,-a,s);
if(p->balance == a) {
s->balance = -a;
r->balance = 0;
} else if (p->balance == 0) {
s->balance = 0;
r->balance = 0;
} else if (p->balance == -a) {
s->balance = 0;
r->balance = a;
}
p->balance = 0;
} else {
fprintf(stderr,"Impossible balanced tree situation!\n");
/* Impossible. Cannot be here. */
exit(1);
}
} else {
fprintf(stderr,"Impossible balanced tree situation!!\n");
/* Impossible. Cannot be here. */
exit(1);
}
}
/* A10: */
if (s == t->rlink) {
t->rlink = p;
} else {
t->llink = p;
}
#ifdef DW_CHECK_CONSISTENCY
dwarf_check_balance(head,1);
#endif
return q;
}
