1 /* 2 * Copyright (c) 2014, Linaro Limited 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright notice, 9 * this list of conditions and the following disclaimer. 10 * 11 * 2. Redistributions in binary form must reproduce the above copyright notice, 12 * this list of conditions and the following disclaimer in the documentation 13 * and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 19 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 21 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 24 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25 * POSSIBILITY OF SUCH DAMAGE. 26 */ 27 #include <stdlib.h> 28 #include <string.h> 29 #include <kernel/handle.h> 30 31 /* 32 * Define the initial capacity of the database. It should be a low number 33 * multiple of 2 since some databases a likely to only use a few handles. 34 * Since the algorithm is to doubles up when growing it shouldn't cause a 35 * noticable overhead on large databases. 36 */ 37 #define HANDLE_DB_INITIAL_MAX_PTRS 4 38 39 void handle_db_destroy(struct handle_db *db) 40 { 41 if (db) { 42 free(db->ptrs); 43 db->ptrs = NULL; 44 db->max_ptrs = 0; 45 } 46 } 47 48 int handle_get(struct handle_db *db, void *ptr) 49 { 50 size_t n; 51 void *p; 52 size_t new_max_ptrs; 53 54 if (!db || !ptr) 55 return -1; 56 57 /* Try to find an empty location */ 58 for (n = 0; n < db->max_ptrs; n++) { 59 if (!db->ptrs[n]) { 60 db->ptrs[n] = ptr; 61 return n; 62 } 63 } 64 65 /* No location available, grow the ptrs array */ 66 if (db->max_ptrs) 67 new_max_ptrs = db->max_ptrs * 2; 68 else 69 new_max_ptrs = HANDLE_DB_INITIAL_MAX_PTRS; 70 p = realloc(db->ptrs, new_max_ptrs * sizeof(void *)); 71 if (!p) 72 return -1; 73 db->ptrs = p; 74 memset(db->ptrs + db->max_ptrs, 0, 75 (new_max_ptrs - db->max_ptrs) * sizeof(void *)); 76 db->max_ptrs = new_max_ptrs; 77 78 /* Since n stopped at db->max_ptrs there is an empty location there */ 79 db->ptrs[n] = ptr; 80 return n; 81 } 82 83 void *handle_put(struct handle_db *db, int handle) 84 { 85 void *p; 86 87 if (!db || handle < 0 || (size_t)handle >= db->max_ptrs) 88 return NULL; 89 90 p = db->ptrs[handle]; 91 db->ptrs[handle] = NULL; 92 return p; 93 } 94 95 void *handle_lookup(struct handle_db *db, int handle) 96 { 97 if (!db || handle < 0 || (size_t)handle >= db->max_ptrs) 98 return NULL; 99 100 return db->ptrs[handle]; 101 } 102