qsort_r_compat.c revision 823abb63145c7a7db2b766cf7bb816cbdac1de66 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdlib.h>
18#include "qsort_r_compat.h"
19
20/*
21 * Note: This code is only used on the host, and is primarily here for
22 * Mac OS compatibility. Apparently, glibc and Apple's libc disagree on
23 * the parameter order for qsort_r.
24 */
25
26#if HAVE_BSD_QSORT_R
27
28/*
29 * BSD qsort_r parameter order is as we have defined here.
30 */
31
32void qsort_r_compat(void* base, size_t nel, size_t width, void* thunk,
33        int (*compar)(void*, const void* , const void*)) {
34    qsort_r(base, nel, width, thunk, compar);
35}
36
37#elif HAVE_GNU_QSORT_R
38
39/*
40 * GNU qsort_r parameter order places the thunk parameter last.
41 */
42
43struct compar_data {
44    void* thunk;
45    int (*compar)(void*, const void* , const void*);
46};
47
48static int compar_wrapper(const void* a, const void* b, void* data) {
49    struct compar_data* compar_data = (struct compar_data*)data;
50    return compar_data->compar(compar_data->thunk, a, b);
51}
52
53void qsort_r_compat(void* base, size_t nel, size_t width, void* thunk,
54        int (*compar)(void*, const void* , const void*)) {
55    struct compar_data compar_data;
56    compar_data.thunk = thunk;
57    compar_data.compar = compar;
58    qsort_r(base, nel, width, compar_wrapper, &compar_data);
59}
60
61#else
62
63/*
64 * Emulate qsort_r using thread local storage to access the thunk data.
65 */
66
67#include <cutils/threads.h>
68
69static thread_store_t compar_data_key = THREAD_STORE_INITIALIZER;
70
71struct compar_data {
72    void* thunk;
73    int (*compar)(void*, const void* , const void*);
74};
75
76static int compar_wrapper(const void* a, const void* b) {
77    struct compar_data* compar_data = (struct compar_data*)thread_store_get(&compar_data_key);
78    return compar_data->compar(compar_data->thunk, a, b);
79}
80
81void qsort_r_compat(void* base, size_t nel, size_t width, void* thunk,
82        int (*compar)(void*, const void* , const void*)) {
83    struct compar_data compar_data;
84    compar_data.thunk = thunk;
85    compar_data.compar = compar;
86    thread_store_set(&compar_data_key, &compar_data, NULL);
87    qsort(base, nel, width, compar_wrapper);
88}
89
90#endif
91