1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1992, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <errno.h>
33 #include <stdint.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include "libc_private.h"
37
38 #if defined(I_AM_QSORT_R)
39 typedef int cmp_t(const void *, const void *, void *);
40 #elif defined(I_AM_QSORT_R_COMPAT)
41 typedef int cmp_t(void *, const void *, const void *);
42 #elif defined(I_AM_QSORT_S)
43 typedef int cmp_t(const void *, const void *, void *);
44 #else
45 typedef int cmp_t(const void *, const void *);
46 #endif
47 static inline char *med3(char *, char *, char *, cmp_t *, void *);
48
49 #define MIN(a, b) ((a) < (b) ? a : b)
50
51 /*
52 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
53 */
54
55 static inline void
swapfunc(char * a,char * b,size_t es)56 swapfunc(char *a, char *b, size_t es)
57 {
58 char t;
59
60 do {
61 t = *a;
62 *a++ = *b;
63 *b++ = t;
64 } while (--es > 0);
65 }
66
67 #define vecswap(a, b, n) \
68 if ((n) > 0) swapfunc(a, b, n)
69
70 #if defined(I_AM_QSORT_R)
71 #define CMP(t, x, y) (cmp((x), (y), (t)))
72 #elif defined(I_AM_QSORT_R_COMPAT)
73 #define CMP(t, x, y) (cmp((t), (x), (y)))
74 #elif defined(I_AM_QSORT_S)
75 #define CMP(t, x, y) (cmp((x), (y), (t)))
76 #else
77 #define CMP(t, x, y) (cmp((x), (y)))
78 #endif
79
80 static inline char *
med3(char * a,char * b,char * c,cmp_t * cmp,void * thunk __unused)81 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
82 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_R_COMPAT) && !defined(I_AM_QSORT_S)
83 __unused
84 #endif
85 )
86 {
87 return CMP(thunk, a, b) < 0 ?
88 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
89 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
90 }
91
92 /*
93 * The actual qsort() implementation is static to avoid preemptible calls when
94 * recursing. Also give them different names for improved debugging.
95 */
96 #if defined(I_AM_QSORT_R)
97 #define local_qsort local_qsort_r
98 #elif defined(I_AM_QSORT_R_COMPAT)
99 #define local_qsort local_qsort_r_compat
100 #elif defined(I_AM_QSORT_S)
101 #define local_qsort local_qsort_s
102 #endif
103 static void
local_qsort(void * a,size_t n,size_t es,cmp_t * cmp,void * thunk)104 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
105 {
106 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
107 size_t d1, d2;
108 int cmp_result;
109
110 /* if there are less than 2 elements, then sorting is not needed */
111 if (__predict_false(n < 2))
112 return;
113 loop:
114 if (n < 7) {
115 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
116 for (pl = pm;
117 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
118 pl -= es)
119 swapfunc(pl, pl - es, es);
120 return;
121 }
122 pm = (char *)a + (n / 2) * es;
123 if (n > 7) {
124 pl = a;
125 pn = (char *)a + (n - 1) * es;
126 if (n > 40) {
127 size_t d = (n / 8) * es;
128
129 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
130 pm = med3(pm - d, pm, pm + d, cmp, thunk);
131 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
132 }
133 pm = med3(pl, pm, pn, cmp, thunk);
134 }
135 swapfunc(a, pm, es);
136 pa = pb = (char *)a + es;
137
138 pc = pd = (char *)a + (n - 1) * es;
139 for (;;) {
140 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
141 if (cmp_result == 0) {
142 swapfunc(pa, pb, es);
143 pa += es;
144 }
145 pb += es;
146 }
147 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
148 if (cmp_result == 0) {
149 swapfunc(pc, pd, es);
150 pd -= es;
151 }
152 pc -= es;
153 }
154 if (pb > pc)
155 break;
156 swapfunc(pb, pc, es);
157 pb += es;
158 pc -= es;
159 }
160
161 pn = (char *)a + n * es;
162 d1 = MIN(pa - (char *)a, pb - pa);
163 vecswap(a, pb - d1, d1);
164 /*
165 * Cast es to preserve signedness of right-hand side of MIN()
166 * expression, to avoid sign ambiguity in the implied comparison. es
167 * is safely within [0, SSIZE_MAX].
168 */
169 d1 = MIN(pd - pc, pn - pd - (ssize_t)es);
170 vecswap(pb, pn - d1, d1);
171
172 d1 = pb - pa;
173 d2 = pd - pc;
174 if (d1 <= d2) {
175 /* Recurse on left partition, then iterate on right partition */
176 if (d1 > es) {
177 local_qsort(a, d1 / es, es, cmp, thunk);
178 }
179 if (d2 > es) {
180 /* Iterate rather than recurse to save stack space */
181 /* qsort(pn - d2, d2 / es, es, cmp); */
182 a = pn - d2;
183 n = d2 / es;
184 goto loop;
185 }
186 } else {
187 /* Recurse on right partition, then iterate on left partition */
188 if (d2 > es) {
189 local_qsort(pn - d2, d2 / es, es, cmp, thunk);
190 }
191 if (d1 > es) {
192 /* Iterate rather than recurse to save stack space */
193 /* qsort(a, d1 / es, es, cmp); */
194 n = d1 / es;
195 goto loop;
196 }
197 }
198 }
199
200 #if defined(I_AM_QSORT_R)
201 void
qsort_r(void * a,size_t n,size_t es,cmp_t * cmp,void * thunk)202 (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
203 {
204 local_qsort_r(a, n, es, cmp, thunk);
205 }
206 #elif defined(I_AM_QSORT_R_COMPAT)
207 void
__qsort_r_compat(void * a,size_t n,size_t es,void * thunk,cmp_t * cmp)208 __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
209 {
210 local_qsort_r_compat(a, n, es, cmp, thunk);
211 }
212 #elif defined(I_AM_QSORT_S)
213 errno_t
qsort_s(void * a,rsize_t n,rsize_t es,cmp_t * cmp,void * thunk)214 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
215 {
216 if (n > RSIZE_MAX) {
217 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
218 return (EINVAL);
219 } else if (es > RSIZE_MAX) {
220 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX",
221 EINVAL);
222 return (EINVAL);
223 } else if (n != 0) {
224 if (a == NULL) {
225 __throw_constraint_handler_s("qsort_s : a == NULL",
226 EINVAL);
227 return (EINVAL);
228 } else if (cmp == NULL) {
229 __throw_constraint_handler_s("qsort_s : cmp == NULL",
230 EINVAL);
231 return (EINVAL);
232 } else if (es <= 0) {
233 __throw_constraint_handler_s("qsort_s : es <= 0",
234 EINVAL);
235 return (EINVAL);
236 }
237 }
238
239 local_qsort_s(a, n, es, cmp, thunk);
240 return (0);
241 }
242 #else
243 void
qsort(void * a,size_t n,size_t es,cmp_t * cmp)244 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
245 {
246 local_qsort(a, n, es, cmp, NULL);
247 }
248 #endif
249