--- /dev/null
+/* Map a dev_t device number to a small integer.
+
+ Copyright 2009-2010 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 <http://www.gnu.org/licenses/>. */
+
+/* written by Jim Meyering */
+
+#include <config.h>
+#include "dev-map.h"
+
+#include <stdio.h>
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct dev_map_ent
+{
+ dev_t dev;
+ uint32_t mapped_dev;
+};
+
+enum { INITIAL_DEV_MAP_TABLE_SIZE = 31 };
+
+static size_t
+dev_hash (void const *x, size_t table_size)
+{
+ struct dev_map_ent const *p = x;
+ return (uintmax_t) p->dev % table_size;
+}
+
+/* Compare two dev_map_ent structs on "dev".
+ Return true if they are the same. */
+static bool
+dev_compare (void const *x, void const *y)
+{
+ struct dev_map_ent const *a = x;
+ struct dev_map_ent const *b = y;
+ return a->dev == b->dev ? true : false;
+}
+
+/* Initialize state. */
+int
+dev_map_init (struct dev_map *dev_map)
+{
+ assert (dev_map != NULL);
+ dev_map->n_device = 0;
+ dev_map->dev_map = hash_initialize (INITIAL_DEV_MAP_TABLE_SIZE, NULL,
+ dev_hash, dev_compare, free);
+ return dev_map->dev_map ? 0 : -1;
+}
+
+void
+dev_map_free (struct dev_map *dev_map)
+{
+ hash_free (dev_map->dev_map);
+}
+
+/* Insert device number, DEV, into the map, DEV_MAP if it's not there already,
+ and return the nonnegative, mapped and usually smaller, number.
+ If DEV is already in DEV_MAP, return the existing mapped value.
+ Upon memory allocation failure, return -1. */
+int
+dev_map_insert (struct dev_map *dev_map, dev_t dev)
+{
+ /* Attempt to insert <DEV,n_device> in the map.
+ Possible outcomes:
+ - DEV was already there, with a different necessarily smaller value
+ - DEV was not there, (thus was just inserted)
+ - insert failed: out of memory
+ Return -1 on out of memory.
+ */
+
+ struct dev_map_ent *ent_from_table;
+ struct dev_map_ent *ent = malloc (sizeof *ent);
+ if (!ent)
+ return -1;
+
+ ent->dev = dev;
+ ent->mapped_dev = dev_map->n_device;
+
+ ent_from_table = hash_insert (dev_map->dev_map, ent);
+ if (ent_from_table == NULL)
+ {
+ /* Insertion failed due to lack of memory. */
+ return -1;
+ }
+
+ if (ent_from_table == ent)
+ {
+ /* Insertion succeeded: new device. */
+ return dev_map->n_device++;
+ }
+
+ /* That DEV value is already in the table, so ENT was not inserted.
+ Free it and return the already-associated value. */
+ free (ent);
+ return ent_from_table->mapped_dev;
+}
--- /dev/null
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include "hash.h"
+
+struct dev_map
+{
+ /* KEY,VAL pair, where KEY is the raw st_dev value
+ and VAL is the small number that maps to. */
+ struct hash_table *dev_map;
+ size_t n_device;
+};
+
+#undef _ATTRIBUTE_NONNULL_
+#if __GNUC__ == 3 && __GNUC_MINOR__ >= 3 || 3 < __GNUC__
+# define _ATTRIBUTE_NONNULL_(m) __attribute__ ((__nonnull__ (m)))
+#else
+# define _ATTRIBUTE_NONNULL_(m)
+#endif
+
+int dev_map_init (struct dev_map *) _ATTRIBUTE_NONNULL_ (1);
+void dev_map_free (struct dev_map *) _ATTRIBUTE_NONNULL_ (1);
+int dev_map_insert (struct dev_map *, dev_t) _ATTRIBUTE_NONNULL_ (1);
--- /dev/null
+/* Test the dev-map module.
+ Copyright (C) 2010 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 <http://www.gnu.org/licenses/>. */
+
+/* Written by Jim Meyering. */
+
+#include <config.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/* FIXME: once/if in gnulib, use #include "macros.h" in place of this */
+#define ASSERT(expr) \
+ do \
+ { \
+ if (!(expr)) \
+ { \
+ fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
+ fflush (stderr); \
+ abort (); \
+ } \
+ } \
+ while (0)
+
+#include "dev-map.h"
+
+/* Risky: this is also defined in di-set.c; they should match. */
+#define N_DEV_BITS_4 5
+
+int
+main ()
+{
+ /* set_program_name (argv[0]); placate overzealous "syntax-check" test. */
+ struct dev_map dev_map;
+ ASSERT (dev_map_init (&dev_map) == 0);
+
+ ASSERT (dev_map_insert (&dev_map, 42) == 0);
+ ASSERT (dev_map_insert (&dev_map, 42) == 0);
+ ASSERT (dev_map_insert (&dev_map, 398) == 1);
+ ASSERT (dev_map_insert (&dev_map, 398) == 1);
+
+ int32_t i;
+ for (i = 0; i < (1 << N_DEV_BITS_4); i++)
+ {
+ ASSERT (dev_map_insert (&dev_map, 10000+i) == 2+i);
+ }
+
+ dev_map_free (&dev_map);
+
+ return 0;
+}
projects / thirdparty / coreutils.git / commitdiff
