src/cp-hash.c

   1 /* cp-hash.c  -- file copying (hash search routines)
   2    Copyright (C) 89, 90, 91, 1995-2001 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 #if HAVE_INTTYPES_H
  24 # include <inttypes.h>
  25 #endif
  26 #include <stdio.h>
  27 #include <sys/types.h>
  28 #include "system.h"
  29
  30 #include "same.h"
  31 #include "quote.h"
  32 #include "hash.h"
  33 #include "error.h"
  34 #include "cp-hash.h"
  35
  36 /* Use ST_DEV and ST_INO as the key, FILENAME as the value.
  37    These are used e.g., in copy.c to associate the destination path with
  38    the source device/inode pair so that if we encounter a matching dev/ino
  39    pair in the source tree we can arrange to create a hard link between
  40    the corresponding names in the destination tree.  */
  41 struct Src_to_dest
  42 {
  43   ino_t st_ino;
  44   dev_t st_dev;
  45   /* Destination path name (of non-directory or pre-existing directory)
  46      corresponding to the dev/ino of a copied file, or the destination path
  47      name corresponding to a dev/ino pair for a newly-created directory. */
  48   char const* name;
  49 };
  50
  51 /* This table maps source dev/ino to destination file name.
  52    We use it to preserve hard links when copying.  */
  53 static Hash_table *src_to_dest;
  54
  55 /* Initial size of the above hash table.  */
  56 #define INITIAL_TABLE_SIZE 103
  57
  58 static unsigned int
  59 src_to_dest_hash (void const *x, unsigned int table_size)
  60 {
  61   struct Src_to_dest const *p = x;
  62
  63   /* Ignoring the device number here should be fine.  */
  64   /* The cast to uintmax_t prevents negative remainders
  65      if st_ino is negative.  */
  66   return (uintmax_t) p->st_ino % table_size;
  67 }
  68
  69 /* Compare two Src_to_dest entries.
  70    Return true if their keys are judged `equal'.  */
  71 static bool
  72 src_to_dest_compare (void const *x, void const *y)
  73 {
  74   struct Src_to_dest const *a = x;
  75   struct Src_to_dest const *b = y;
  76   return SAME_INODE (*a, *b) ? true : false;
  77 }
  78
  79 static void
  80 src_to_dest_free (void *x)
  81 {
  82   struct Src_to_dest *a = x;
  83   free ((char *) (a->name));
  84   free (x);
  85 }
  86
  87 /* Add PATH to the list of files that we have created.
  88    Return 1 if we can't stat PATH, otherwise 0.  */
  89
  90 int
  91 remember_created (const char *path)
  92 {
  93   struct stat sb;
  94
  95   if (stat (path, &sb) < 0)
  96     {
  97       error (0, errno, "%s", quote (path));
  98       return 1;
  99     }
 100
 101   remember_copied (path, sb.st_ino, sb.st_dev);
 102   return 0;
 103 }
 104
 105 /* Add path NAME, copied from inode number INO and device number DEV,
 106    to the list of files we have copied.
 107    Return NULL if inserted, otherwise non-NULL. */
 108
 109 char *
 110 remember_copied (const char *name, ino_t ino, dev_t dev)
 111 {
 112   struct Src_to_dest *ent;
 113   struct Src_to_dest *ent_from_table;
 114
 115   ent = (struct Src_to_dest *) xmalloc (sizeof *ent);
 116   ent->name = xstrdup (name);
 117   ent->st_ino = ino;
 118   ent->st_dev = dev;
 119
 120   ent_from_table = hash_insert (src_to_dest, ent);
 121   if (ent_from_table == NULL)
 122     {
 123       /* Insertion failed due to lack of memory.  */
 124       xalloc_die ();
 125     }
 126
 127   /* Determine whether there was already an entry in the table
 128      with a matching key.  If so, free ENT (it wasn't inserted) and
 129      return the `name' from the table entry.  */
 130   if (ent_from_table != ent)
 131     {
 132       src_to_dest_free (ent);
 133       return (char *) ent_from_table->name;
 134     }
 135
 136   /* New key;  insertion succeeded.  */
 137   return NULL;
 138 }
 139
 140 /* Initialize the hash table.  */
 141 void
 142 hash_init (void)
 143 {
 144   src_to_dest = hash_initialize (INITIAL_TABLE_SIZE, NULL,
 145                                  src_to_dest_hash,
 146                                  src_to_dest_compare,
 147                                  src_to_dest_free);
 148   if (src_to_dest == NULL)
 149     xalloc_die ();
 150 }
 151
 152 /* Reset the hash structure in the global variable `htab' to
 153    contain no entries.  */
 154
 155 void
 156 forget_all (void)
 157 {
 158   hash_free (src_to_dest);
 159 }