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/* cp-hash.c -- file copying (hash search routines)
Copyright (C) 1989, 1990, 1991, 1995 Free Software Foundation.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Written by Torbjorn Granlund, Sweden (tege@sics.se). */
#include <config.h>
#include <stdio.h>
#include "cp.h"
char *hash_insert ();
char *hash_insert2 ();
struct htab *htab;
char new_file;
/* Add PATH to the list of files that we have created.
Return 0 if successful, 1 if not. */
int
remember_created (path)
char *path;
{
struct stat sb;
if (stat (path, &sb) < 0)
{
error (0, errno, "%s", path);
return 1;
}
hash_insert (sb.st_ino, sb.st_dev, &new_file);
return 0;
}
/* Add path NODE, copied from inode number INO and device number DEV,
to the list of files we have copied.
Return NULL if inserted, otherwise non-NULL. */
char *
remember_copied (node, ino, dev)
char *node;
ino_t ino;
dev_t dev;
{
return hash_insert (ino, dev, node);
}
/* Allocate space for the hash structures, and set the global
variable `htab' to point to it. The initial hash module is specified in
MODULUS, and the number of entries are specified in ENTRY_TAB_SIZE. (The
hash structure will be rebuilt when ENTRY_TAB_SIZE entries have been
inserted, and MODULUS and ENTRY_TAB_SIZE in the global `htab' will be
doubled.) */
void
hash_init (modulus, entry_tab_size)
unsigned modulus;
unsigned entry_tab_size;
{
struct htab *htab_r;
htab_r = (struct htab *)
xmalloc (sizeof (struct htab) + sizeof (struct entry *) * modulus);
htab_r->entry_tab = (struct entry *)
xmalloc (sizeof (struct entry) * entry_tab_size);
htab_r->modulus = modulus;
htab_r->entry_tab_size = entry_tab_size;
htab = htab_r;
forget_all ();
}
/* Reset the hash structure in the global variable `htab' to
contain no entries. */
void
forget_all ()
{
int i;
struct entry **p;
htab->first_free_entry = 0;
p = htab->hash;
for (i = htab->modulus; i > 0; i--)
*p++ = NULL;
}
/* Insert path NODE, copied from inode number INO and device number DEV,
into the hash structure in the global variable `htab', if an entry with
the same inode and device was not found already.
Return NULL if inserted, otherwise non-NULL. */
char *
hash_insert (ino, dev, node)
ino_t ino;
dev_t dev;
char *node;
{
struct htab *htab_r = htab;
if (htab_r->first_free_entry >= htab_r->entry_tab_size)
{
int i;
struct entry *ep;
unsigned modulus;
unsigned entry_tab_size;
/* Increase the number of hash entries, and re-hash the data.
The method of shrinking and increasing is made to compactify
the heap. If twice as much data would be allocated
straightforwardly, we would never re-use a byte of memory. */
/* Let htab shrink. Keep only the header, not the pointer vector. */
htab_r = (struct htab *)
xrealloc ((char *) htab_r, sizeof (struct htab));
modulus = 2 * htab_r->modulus;
entry_tab_size = 2 * htab_r->entry_tab_size;
/* Increase the number of possible entries. */
htab_r->entry_tab = (struct entry *)
xrealloc ((char *) htab_r->entry_tab,
sizeof (struct entry) * entry_tab_size);
/* Increase the size of htab again. */
htab_r = (struct htab *)
xrealloc ((char *) htab_r,
sizeof (struct htab) + sizeof (struct entry *) * modulus);
htab_r->modulus = modulus;
htab_r->entry_tab_size = entry_tab_size;
htab = htab_r;
i = htab_r->first_free_entry;
/* Make the increased hash table empty. The entries are still
available in htab->entry_tab. */
forget_all ();
/* Go through the entries and install them in the pointer vector
htab->hash. The items are actually inserted in htab->entry_tab at
the position where they already are. The htab->coll_link need
however be updated. Could be made a little more efficient. */
for (ep = htab_r->entry_tab; i > 0; i--)
{
hash_insert2 (htab_r, ep->ino, ep->dev, ep->node);
ep++;
}
}
return hash_insert2 (htab_r, ino, dev, node);
}
/* Insert path NODE, copied from inode number INO and device number DEV,
into the hash structure HTAB, if not already present.
Return NULL if inserted, otherwise non-NULL. */
char *
hash_insert2 (htab, ino, dev, node)
struct htab *htab;
ino_t ino;
dev_t dev;
char *node;
{
struct entry **hp, *ep2, *ep;
hp = &htab->hash[ino % htab->modulus];
ep2 = *hp;
/* Collision? */
if (ep2 != NULL)
{
ep = ep2;
/* Search for an entry with the same data. */
do
{
if (ep->ino == ino && ep->dev == dev)
return ep->node; /* Found an entry with the same data. */
ep = ep->coll_link;
}
while (ep != NULL);
/* Did not find it. */
}
ep = *hp = &htab->entry_tab[htab->first_free_entry++];
ep->ino = ino;
ep->dev = dev;
ep->node = node;
ep->coll_link = ep2; /* ep2 is NULL if not collision. */
return NULL;
}
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