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 int swap_cnt;
110
111 /* if there are less than 2 elements, then sorting is not needed */
112 if (__predict_false(n < 2))
113 return;
114 loop:
115 swap_cnt = 0;
116 if (n < 7) {
117 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
118 for (pl = pm;
119 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
120 pl -= es)
121 swapfunc(pl, pl - es, es);
122 return;
123 }
124 pm = (char *)a + (n / 2) * es;
125 if (n > 7) {
126 pl = a;
127 pn = (char *)a + (n - 1) * es;
128 if (n > 40) {
129 size_t d = (n / 8) * es;
130
131 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
132 pm = med3(pm - d, pm, pm + d, cmp, thunk);
133 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
134 }
135 pm = med3(pl, pm, pn, cmp, thunk);
136 }
137 swapfunc(a, pm, es);
138 pa = pb = (char *)a + es;
139
140 pc = pd = (char *)a + (n - 1) * es;
141 for (;;) {
142 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
143 if (cmp_result == 0) {
144 swap_cnt = 1;
145 swapfunc(pa, pb, es);
146 pa += es;
147 }
148 pb += es;
149 }
150 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
151 if (cmp_result == 0) {
152 swap_cnt = 1;
153 swapfunc(pc, pd, es);
154 pd -= es;
155 }
156 pc -= es;
157 }
158 if (pb > pc)
159 break;
160 swapfunc(pb, pc, es);
161 swap_cnt = 1;
162 pb += es;
163 pc -= es;
164 }
165 if (swap_cnt == 0) { /* Switch to insertion sort */
166 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
167 for (pl = pm;
168 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
169 pl -= es)
170 swapfunc(pl, pl - es, es);
171 return;
172 }
173
174 pn = (char *)a + n * es;
175 d1 = MIN(pa - (char *)a, pb - pa);
176 vecswap(a, pb - d1, d1);
177 /*
178 * Cast es to preserve signedness of right-hand side of MIN()
179 * expression, to avoid sign ambiguity in the implied comparison. es
180 * is safely within [0, SSIZE_MAX].
181 */
182 d1 = MIN(pd - pc, pn - pd - (ssize_t)es);
183 vecswap(pb, pn - d1, d1);
184
185 d1 = pb - pa;
186 d2 = pd - pc;
187 if (d1 <= d2) {
188 /* Recurse on left partition, then iterate on right partition */
189 if (d1 > es) {
190 local_qsort(a, d1 / es, es, cmp, thunk);
191 }
192 if (d2 > es) {
193 /* Iterate rather than recurse to save stack space */
194 /* qsort(pn - d2, d2 / es, es, cmp); */
195 a = pn - d2;
196 n = d2 / es;
197 goto loop;
198 }
199 } else {
200 /* Recurse on right partition, then iterate on left partition */
201 if (d2 > es) {
202 local_qsort(pn - d2, d2 / es, es, cmp, thunk);
203 }
204 if (d1 > es) {
205 /* Iterate rather than recurse to save stack space */
206 /* qsort(a, d1 / es, es, cmp); */
207 n = d1 / es;
208 goto loop;
209 }
210 }
211 }
212
213 #if defined(I_AM_QSORT_R)
214 void
215 (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
216 {
217 local_qsort_r(a, n, es, cmp, thunk);
218 }
219 #elif defined(I_AM_QSORT_R_COMPAT)
220 void
__qsort_r_compat(void * a,size_t n,size_t es,void * thunk,cmp_t * cmp)221 __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
222 {
223 local_qsort_r_compat(a, n, es, cmp, thunk);
224 }
225 #elif defined(I_AM_QSORT_S)
226 errno_t
qsort_s(void * a,rsize_t n,rsize_t es,cmp_t * cmp,void * thunk)227 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
228 {
229 if (n > RSIZE_MAX) {
230 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
231 return (EINVAL);
232 } else if (es > RSIZE_MAX) {
233 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX",
234 EINVAL);
235 return (EINVAL);
236 } else if (n != 0) {
237 if (a == NULL) {
238 __throw_constraint_handler_s("qsort_s : a == NULL",
239 EINVAL);
240 return (EINVAL);
241 } else if (cmp == NULL) {
242 __throw_constraint_handler_s("qsort_s : cmp == NULL",
243 EINVAL);
244 return (EINVAL);
245 } else if (es <= 0) {
246 __throw_constraint_handler_s("qsort_s : es <= 0",
247 EINVAL);
248 return (EINVAL);
249 }
250 }
251
252 local_qsort_s(a, n, es, cmp, thunk);
253 return (0);
254 }
255 #else
256 void
qsort(void * a,size_t n,size_t es,cmp_t * cmp)257 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
258 {
259 local_qsort(a, n, es, cmp, NULL);
260 }
261 #endif
262