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/* cp-hash.c -- file copying (hash search routines)
Copyright (C) 1989-2016 Free Software Foundation, Inc.
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 3 of the License, 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, see <http://www.gnu.org/licenses/>.
Written by Torbjorn Granlund, Sweden (tege@sics.se).
Rewritten to use lib/hash.c by Jim Meyering. */
#include <config.h>
#include <sys/types.h>
#include "system.h"
#include "hash.h"
#include "cp-hash.h"
/* Use ST_DEV and ST_INO as the key, FILENAME as the value.
These are used e.g., in copy.c to associate the destination name with
the source device/inode pair so that if we encounter a matching dev/ino
pair in the source tree we can arrange to create a hard link between
the corresponding names in the destination tree. */
struct Src_to_dest
{
ino_t st_ino;
dev_t st_dev;
/* Destination file name (of non-directory or pre-existing directory)
corresponding to the dev/ino of a copied file, or the destination file
name corresponding to a dev/ino pair for a newly-created directory. */
char *name;
};
/* This table maps source dev/ino to destination file name.
We use it to preserve hard links when copying. */
static Hash_table *src_to_dest;
/* Initial size of the above hash table. */
#define INITIAL_TABLE_SIZE 103
static size_t
src_to_dest_hash (void const *x, size_t table_size)
{
struct Src_to_dest const *p = x;
/* Ignoring the device number here should be fine. */
/* The cast to uintmax_t prevents negative remainders
if st_ino is negative. */
return (uintmax_t) p->st_ino % table_size;
}
/* Compare two Src_to_dest entries.
Return true if their keys are judged 'equal'. */
static bool
src_to_dest_compare (void const *x, void const *y)
{
struct Src_to_dest const *a = x;
struct Src_to_dest const *b = y;
return SAME_INODE (*a, *b) ? true : false;
}
static void
src_to_dest_free (void *x)
{
struct Src_to_dest *a = x;
free (a->name);
free (x);
}
/* Remove the entry matching INO/DEV from the table
that maps source ino/dev to destination file name. */
extern void
forget_created (ino_t ino, dev_t dev)
{
struct Src_to_dest probe;
struct Src_to_dest *ent;
probe.st_ino = ino;
probe.st_dev = dev;
probe.name = NULL;
ent = hash_delete (src_to_dest, &probe);
if (ent)
src_to_dest_free (ent);
}
/* If INO/DEV correspond to an already-copied source file, return the
name of the corresponding destination file. Otherwise, return NULL. */
extern char *
src_to_dest_lookup (ino_t ino, dev_t dev)
{
struct Src_to_dest ent;
struct Src_to_dest const *e;
ent.st_ino = ino;
ent.st_dev = dev;
e = hash_lookup (src_to_dest, &ent);
return e ? e->name : NULL;
}
/* Add file NAME, copied from inode number INO and device number DEV,
to the list of files we have copied.
Return NULL if inserted, otherwise non-NULL. */
extern char *
remember_copied (const char *name, ino_t ino, dev_t dev)
{
struct Src_to_dest *ent;
struct Src_to_dest *ent_from_table;
ent = xmalloc (sizeof *ent);
ent->name = xstrdup (name);
ent->st_ino = ino;
ent->st_dev = dev;
ent_from_table = hash_insert (src_to_dest, ent);
if (ent_from_table == NULL)
{
/* Insertion failed due to lack of memory. */
xalloc_die ();
}
/* Determine whether there was already an entry in the table
with a matching key. If so, free ENT (it wasn't inserted) and
return the 'name' from the table entry. */
if (ent_from_table != ent)
{
src_to_dest_free (ent);
return (char *) ent_from_table->name;
}
/* New key; insertion succeeded. */
return NULL;
}
/* Initialize the hash table. */
extern void
hash_init (void)
{
src_to_dest = hash_initialize (INITIAL_TABLE_SIZE, NULL,
src_to_dest_hash,
src_to_dest_compare,
src_to_dest_free);
if (src_to_dest == NULL)
xalloc_die ();
}
/* Reset the hash structure in the global variable 'htab' to
contain no entries. */
extern void
forget_all (void)
{
hash_free (src_to_dest);
}
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