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Diffstat (limited to 'src/cp-hash.c')
| -rw-r--r-- | src/cp-hash.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/src/cp-hash.c b/src/cp-hash.c new file mode 100644 index 0000000..10ab2cd --- /dev/null +++ b/src/cp-hash.c @@ -0,0 +1,164 @@ +/* cp-hash.c -- file copying (hash search routines) + Copyright (C) 1989-2020 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. + + Written by Torbjorn Granlund, Sweden (tege@sics.se). + Rewritten to use lib/hash.c by Jim Meyering. */ + +#include <config.h> + +#include <sys/types.h> +#include "system.h" + +#include "hash.h" +#include "cp-hash.h" + +/* Use ST_DEV and ST_INO as the key, FILENAME as the value. + These are used e.g., in copy.c to associate the destination name with + the source device/inode pair so that if we encounter a matching dev/ino + pair in the source tree we can arrange to create a hard link between + the corresponding names in the destination tree. */ +struct Src_to_dest +{ + ino_t st_ino; + dev_t st_dev; + /* Destination file name (of non-directory or pre-existing directory) + corresponding to the dev/ino of a copied file, or the destination file + name corresponding to a dev/ino pair for a newly-created directory. */ + char *name; +}; + +/* This table maps source dev/ino to destination file name. + We use it to preserve hard links when copying. */ +static Hash_table *src_to_dest; + +/* Initial size of the above hash table. */ +#define INITIAL_TABLE_SIZE 103 + +static size_t +src_to_dest_hash (void const *x, size_t table_size) +{ + struct Src_to_dest const *p = x; + + /* Ignoring the device number here should be fine. */ + /* The cast to uintmax_t prevents negative remainders + if st_ino is negative. */ + return (uintmax_t) p->st_ino % table_size; +} + +/* Compare two Src_to_dest entries. + Return true if their keys are judged 'equal'. */ +static bool +src_to_dest_compare (void const *x, void const *y) +{ + struct Src_to_dest const *a = x; + struct Src_to_dest const *b = y; + return SAME_INODE (*a, *b) ? true : false; +} + +static void +src_to_dest_free (void *x) +{ + struct Src_to_dest *a = x; + free (a->name); + free (x); +} + +/* Remove the entry matching INO/DEV from the table + that maps source ino/dev to destination file name. */ +extern void +forget_created (ino_t ino, dev_t dev) +{ + struct Src_to_dest probe; + struct Src_to_dest *ent; + + probe.st_ino = ino; + probe.st_dev = dev; + probe.name = NULL; + + ent = hash_delete (src_to_dest, &probe); + if (ent) + src_to_dest_free (ent); +} + +/* If INO/DEV correspond to an already-copied source file, return the + name of the corresponding destination file. Otherwise, return NULL. */ + +extern char * +src_to_dest_lookup (ino_t ino, dev_t dev) +{ + struct Src_to_dest ent; + struct Src_to_dest const *e; + ent.st_ino = ino; + ent.st_dev = dev; + e = hash_lookup (src_to_dest, &ent); + return e ? e->name : NULL; +} + +/* Add file NAME, copied from inode number INO and device number DEV, + to the list of files we have copied. + Return NULL if inserted, otherwise non-NULL. */ + +extern char * +remember_copied (const char *name, ino_t ino, dev_t dev) +{ + struct Src_to_dest *ent; + struct Src_to_dest *ent_from_table; + + ent = xmalloc (sizeof *ent); + ent->name = xstrdup (name); + ent->st_ino = ino; + ent->st_dev = dev; + + ent_from_table = hash_insert (src_to_dest, ent); + if (ent_from_table == NULL) + { + /* Insertion failed due to lack of memory. */ + xalloc_die (); + } + + /* Determine whether there was already an entry in the table + with a matching key. If so, free ENT (it wasn't inserted) and + return the 'name' from the table entry. */ + if (ent_from_table != ent) + { + src_to_dest_free (ent); + return (char *) ent_from_table->name; + } + + /* New key; insertion succeeded. */ + return NULL; +} + +/* Initialize the hash table. */ +extern void +hash_init (void) +{ + src_to_dest = hash_initialize (INITIAL_TABLE_SIZE, NULL, + src_to_dest_hash, + src_to_dest_compare, + src_to_dest_free); + if (src_to_dest == NULL) + xalloc_die (); +} + +/* Reset the hash structure in the global variable 'htab' to + contain no entries. */ + +extern void +forget_all (void) +{ + hash_free (src_to_dest); +} |