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 source tree.
   9  */
  10 #include "libbb.h"
  11
  12 typedef 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 */
  32 static 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  */
  38 char* 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 */
  59 void 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 */
  82 void 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