busybox/libbb/inode_hash.c

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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) many different people.
* If you wrote this, please acknowledge your work.
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
typedef struct ino_dev_hash_bucket_struct {
ino_t ino;
dev_t dev;
/*
* Above fields can be 64-bit, while pointer may be 32-bit.
* Putting "next" field here may reduce size of this struct:
*/
struct ino_dev_hash_bucket_struct *next;
/*
* Reportedly, on cramfs a file and a dir can have same ino.
* Need to also remember "file/dir" bit:
*/
char isdir; /* bool */
char name[1];
} ino_dev_hashtable_bucket_t;
#define HASH_SIZE 311u /* Should be prime */
#define hash_inode(i) ((unsigned)(i) % HASH_SIZE)
/* array of [HASH_SIZE] elements */
static ino_dev_hashtable_bucket_t **ino_dev_hashtable;
/*
* Return name if statbuf->st_ino && statbuf->st_dev are recorded in
* ino_dev_hashtable, else return NULL
*/
char* FAST_FUNC is_in_ino_dev_hashtable(const struct stat *statbuf)
{
ino_dev_hashtable_bucket_t *bucket;
if (!ino_dev_hashtable)
return NULL;
bucket = ino_dev_hashtable[hash_inode(statbuf->st_ino)];
while (bucket != NULL) {
if ((bucket->ino == statbuf->st_ino)
&& (bucket->dev == statbuf->st_dev)
&& (bucket->isdir == !!S_ISDIR(statbuf->st_mode))
) {
return bucket->name;
}
bucket = bucket->next;
}
return NULL;
}
/* Add statbuf to statbuf hash table */
void FAST_FUNC add_to_ino_dev_hashtable(const struct stat *statbuf, const char *name)
{
int i;
ino_dev_hashtable_bucket_t *bucket;
if (!name)
name = "";
bucket = xmalloc(sizeof(ino_dev_hashtable_bucket_t) + strlen(name));
bucket->ino = statbuf->st_ino;
bucket->dev = statbuf->st_dev;
bucket->isdir = !!S_ISDIR(statbuf->st_mode);
strcpy(bucket->name, name);
if (!ino_dev_hashtable)
ino_dev_hashtable = xzalloc(HASH_SIZE * sizeof(*ino_dev_hashtable));
i = hash_inode(statbuf->st_ino);
bucket->next = ino_dev_hashtable[i];
ino_dev_hashtable[i] = bucket;
}
#if ENABLE_DU || ENABLE_FEATURE_CLEAN_UP
/* Clear statbuf hash table */
void FAST_FUNC reset_ino_dev_hashtable(void)
{
int i;
ino_dev_hashtable_bucket_t *bucket, *next;
if (!ino_dev_hashtable)
return;
for (i = 0; i < HASH_SIZE; i++) {
bucket = ino_dev_hashtable[i];
while (bucket != NULL) {
next = bucket->next;
free(bucket);
bucket = next;
}
}
free(ino_dev_hashtable);
ino_dev_hashtable = NULL;
}
#endif