libbb/inode_hash.c

   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 tarball for details.
   9  */
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include "libbb.h"
  15
  16 typedef struct ino_dev_hash_bucket_struct {
  17         struct ino_dev_hash_bucket_struct *next;
  18         ino_t ino;
  19         dev_t dev;
  20         char name[1];
  21 } ino_dev_hashtable_bucket_t;
  22
  23 #define HASH_SIZE       311             /* Should be prime */
  24 #define hash_inode(i)   ((i) % HASH_SIZE)
  25
  26 /* array of [HASH_SIZE] elements */
  27 static ino_dev_hashtable_bucket_t **ino_dev_hashtable;
  28
  29 /*
  30  * Return name if statbuf->st_ino && statbuf->st_dev are recorded in
  31  * ino_dev_hashtable, else return NULL
  32  */
  33 char *is_in_ino_dev_hashtable(const struct stat *statbuf)
  34 {
  35         ino_dev_hashtable_bucket_t *bucket;
  36
  37         if (!ino_dev_hashtable)
  38                 return NULL;
  39
  40         bucket = ino_dev_hashtable[hash_inode(statbuf->st_ino)];
  41         while (bucket != NULL) {
  42                 if ((bucket->ino == statbuf->st_ino)
  43                  && (bucket->dev == statbuf->st_dev)
  44                 ) {
  45                         return bucket->name;
  46                 }
  47                 bucket = bucket->next;
  48         }
  49         return NULL;
  50 }
  51
  52 /* Add statbuf to statbuf hash table */
  53 void add_to_ino_dev_hashtable(const struct stat *statbuf, const char *name)
  54 {
  55         int i;
  56         ino_dev_hashtable_bucket_t *bucket;
  57
  58         i = hash_inode(statbuf->st_ino);
  59         if (!name)
  60                 name = "";
  61         bucket = xmalloc(sizeof(ino_dev_hashtable_bucket_t) + strlen(name));
  62         bucket->ino = statbuf->st_ino;
  63         bucket->dev = statbuf->st_dev;
  64         strcpy(bucket->name, name);
  65
  66         if (!ino_dev_hashtable)
  67                 ino_dev_hashtable = xzalloc(HASH_SIZE * sizeof(*ino_dev_hashtable));
  68
  69         bucket->next = ino_dev_hashtable[i];
  70         ino_dev_hashtable[i] = bucket;
  71 }
  72
  73 #if ENABLE_FEATURE_CLEAN_UP
  74 /* Clear statbuf hash table */
  75 void reset_ino_dev_hashtable(void)
  76 {
  77         int i;
  78         ino_dev_hashtable_bucket_t *bucket;
  79
  80         for (i = 0; ino_dev_hashtable && i < HASH_SIZE; i++) {
  81                 while (ino_dev_hashtable[i] != NULL) {
  82                         bucket = ino_dev_hashtable[i]->next;
  83                         free(ino_dev_hashtable[i]);
  84                         ino_dev_hashtable[i] = bucket;
  85                 }
  86         }
  87         free(ino_dev_hashtable);
  88         ino_dev_hashtable = NULL;
  89 }
  90 #else
  91 void reset_ino_dev_hashtable(void);
  92 #endif