src/cp-hash.c

   1 /* cp-hash.c  -- file copying (hash search routines)
   2    Copyright (C) 89, 90, 91, 1995-2004 Free Software Foundation.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17
  18    Written by Torbjorn Granlund, Sweden (tege@sics.se).
  19    Rewritten to use lib/hash.c by Jim Meyering.  */
  20
  21 #include <config.h>
  22
  23 #include <stdio.h>
  24 #include <sys/types.h>
  25 #include "system.h"
  26
  27 #include "same.h"
  28 #include "quote.h"
  29 #include "hash.h"
  30 #include "error.h"
  31 #include "cp-hash.h"
  32
  33 /* Use ST_DEV and ST_INO as the key, FILENAME as the value.
  34    These are used e.g., in copy.c to associate the destination path with
  35    the source device/inode pair so that if we encounter a matching dev/ino
  36    pair in the source tree we can arrange to create a hard link between
  37    the corresponding names in the destination tree.  */
  38 struct Src_to_dest
  39 {
  40   ino_t st_ino;
  41   dev_t st_dev;
  42   /* Destination path name (of non-directory or pre-existing directory)
  43      corresponding to the dev/ino of a copied file, or the destination path
  44      name corresponding to a dev/ino pair for a newly-created directory. */
  45   char *name;
  46 };
  47
  48 /* This table maps source dev/ino to destination file name.
  49    We use it to preserve hard links when copying.  */
  50 static Hash_table *src_to_dest;
  51
  52 /* Initial size of the above hash table.  */
  53 #define INITIAL_TABLE_SIZE 103
  54
  55 static size_t
  56 src_to_dest_hash (void const *x, size_t table_size)
  57 {
  58   struct Src_to_dest const *p = x;
  59
  60   /* Ignoring the device number here should be fine.  */
  61   /* The cast to uintmax_t prevents negative remainders
  62      if st_ino is negative.  */
  63   return (uintmax_t) p->st_ino % table_size;
  64 }
  65
  66 /* Compare two Src_to_dest entries.
  67    Return true if their keys are judged `equal'.  */
  68 static bool
  69 src_to_dest_compare (void const *x, void const *y)
  70 {
  71   struct Src_to_dest const *a = x;
  72   struct Src_to_dest const *b = y;
  73   return SAME_INODE (*a, *b) ? true : false;
  74 }
  75
  76 static void
  77 src_to_dest_free (void *x)
  78 {
  79   struct Src_to_dest *a = x;
  80   free (a->name);
  81   free (x);
  82 }
  83
  84 /* Remove the entry matching INO/DEV from the table
  85    that maps source ino/dev to destination file name.  */
  86 extern void
  87 forget_created (ino_t ino, dev_t dev)
  88 {
  89   struct Src_to_dest probe;
  90   struct Src_to_dest *ent;
  91
  92   probe.st_ino = ino;
  93   probe.st_dev = dev;
  94   probe.name = NULL;
  95
  96   ent = hash_delete (src_to_dest, &probe);
  97   if (ent)
  98     src_to_dest_free (ent);
  99 }
 100
 101 /* Add PATH to the list of files that we have created.
 102    Return true if successful.  */
 103
 104 extern bool
 105 remember_created (const char *path)
 106 {
 107   struct stat sb;
 108
 109   if (stat (path, &sb) < 0)
 110     {
 111       error (0, errno, "%s", quote (path));
 112       return false;
 113     }
 114
 115   remember_copied (path, sb.st_ino, sb.st_dev);
 116   return true;
 117 }
 118
 119 /* If INO/DEV correspond to an already-copied source file, return the
 120    name of the corresponding destination file.  Otherwise, return NULL.  */
 121
 122 extern char *
 123 src_to_dest_lookup (ino_t ino, dev_t dev)
 124 {
 125   struct Src_to_dest ent;
 126   struct Src_to_dest const *e;
 127   ent.st_ino = ino;
 128   ent.st_dev = dev;
 129   e = hash_lookup (src_to_dest, &ent);
 130   return e ? e->name : NULL;
 131 }
 132
 133 /* Add path NAME, copied from inode number INO and device number DEV,
 134    to the list of files we have copied.
 135    Return NULL if inserted, otherwise non-NULL. */
 136
 137 extern char *
 138 remember_copied (const char *name, ino_t ino, dev_t dev)
 139 {
 140   struct Src_to_dest *ent;
 141   struct Src_to_dest *ent_from_table;
 142
 143   ent = xmalloc (sizeof *ent);
 144   ent->name = xstrdup (name);
 145   ent->st_ino = ino;
 146   ent->st_dev = dev;
 147
 148   ent_from_table = hash_insert (src_to_dest, ent);
 149   if (ent_from_table == NULL)
 150     {
 151       /* Insertion failed due to lack of memory.  */
 152       xalloc_die ();
 153     }
 154
 155   /* Determine whether there was already an entry in the table
 156      with a matching key.  If so, free ENT (it wasn't inserted) and
 157      return the `name' from the table entry.  */
 158   if (ent_from_table != ent)
 159     {
 160       src_to_dest_free (ent);
 161       return (char *) ent_from_table->name;
 162     }
 163
 164   /* New key;  insertion succeeded.  */
 165   return NULL;
 166 }
 167
 168 /* Initialize the hash table.  */
 169 extern void
 170 hash_init (void)
 171 {
 172   src_to_dest = hash_initialize (INITIAL_TABLE_SIZE, NULL,
 173                                  src_to_dest_hash,
 174                                  src_to_dest_compare,
 175                                  src_to_dest_free);
 176   if (src_to_dest == NULL)
 177     xalloc_die ();
 178 }
 179
 180 /* Reset the hash structure in the global variable `htab' to
 181    contain no entries.  */
 182
 183 extern void
 184 forget_all (void)
 185 {
 186   hash_free (src_to_dest);
 187 }