LXR busybox/libbb/inode

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Utility routines.
   4 *
   5 * Copyright (C) many different people.
   6 * If you wrote this, please acknowledge your work.
   7 *
   8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9 */
  10#include "libbb.h"
  11
  12typedef struct ino_dev_hash_bucket_struct {
  13        ino_t ino;
  14        dev_t dev;
  15        /*
  16         * Above fields can be 64-bit, while pointer may be 32-bit.
  17         * Putting "next" field here may reduce size of this struct:
  18         */
  19        struct ino_dev_hash_bucket_struct *next;
  20        /*
  21         * Reportedly, on cramfs a file and a dir can have same ino.
  22         * Need to also remember "file/dir" bit:
  23         */
  24        char isdir; /* bool */
  25        char name[1];
  26} ino_dev_hashtable_bucket_t;
  27
  28#define HASH_SIZE      311u   /* Should be prime */
  29#define hash_inode(i)  ((unsigned)(i) % HASH_SIZE)
  30
  31/* array of [HASH_SIZE] elements */
  32static ino_dev_hashtable_bucket_t **ino_dev_hashtable;
  33
  34/*
  35 * Return name if statbuf->st_ino && statbuf->st_dev are recorded in
  36 * ino_dev_hashtable, else return NULL
  37 */
  38char* FAST_FUNC is_in_ino_dev_hashtable(const struct stat *statbuf)
  39{
  40        ino_dev_hashtable_bucket_t *bucket;
  41
  42        if (!ino_dev_hashtable)
  43                return NULL;
  44
  45        bucket = ino_dev_hashtable[hash_inode(statbuf->st_ino)];
  46        while (bucket != NULL) {
  47                if ((bucket->ino == statbuf->st_ino)
  48                 && (bucket->dev == statbuf->st_dev)
  49                 && (bucket->isdir == !!S_ISDIR(statbuf->st_mode))
  50                ) {
  51                        return bucket->name;
  52                }
  53                bucket = bucket->next;
  54        }
  55        return NULL;
  56}
  57
  58/* Add statbuf to statbuf hash table */
  59void FAST_FUNC add_to_ino_dev_hashtable(const struct stat *statbuf, const char *name)
  60{
  61        int i;
  62        ino_dev_hashtable_bucket_t *bucket;
  63
  64        if (!name)
  65                name = "";
  66        bucket = xmalloc(sizeof(ino_dev_hashtable_bucket_t) + strlen(name));
  67        bucket->ino = statbuf->st_ino;
  68        bucket->dev = statbuf->st_dev;
  69        bucket->isdir = !!S_ISDIR(statbuf->st_mode);
  70        strcpy(bucket->name, name);
  71
  72        if (!ino_dev_hashtable)
  73                ino_dev_hashtable = xzalloc(HASH_SIZE * sizeof(*ino_dev_hashtable));
  74
  75        i = hash_inode(statbuf->st_ino);
  76        bucket->next = ino_dev_hashtable[i];
  77        ino_dev_hashtable[i] = bucket;
  78}
  79
  80#if ENABLE_FEATURE_CLEAN_UP
  81/* Clear statbuf hash table */
  82void FAST_FUNC reset_ino_dev_hashtable(void)
  83{
  84        int i;
  85        ino_dev_hashtable_bucket_t *bucket, *next;
  86
  87        if (!ino_dev_hashtable)
  88                return;
  89
  90        for (i = 0; i < HASH_SIZE; i++) {
  91                bucket = ino_dev_hashtable[i];
  92
  93                while (bucket != NULL) {
  94                        next = bucket->next;
  95                        free(bucket);
  96                        bucket = next;
  97                }
  98        }
  99        free(ino_dev_hashtable);
 100        ino_dev_hashtable = NULL;
 101}
 102#endif
 103