source: MondoRescue/branches/3.3/mindi-busybox/libbb/inode_hash.c@ 3770

/* 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