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 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37
38 #include <errno.h>
39 #include <stdint.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include "libc_private.h"
43
44 #if defined(I_AM_QSORT_R)
45 typedef int cmp_t(const void *, const void *, void *);
46 #elif defined(I_AM_QSORT_R_COMPAT)
47 typedef int cmp_t(void *, const void *, const void *);
48 #elif defined(I_AM_QSORT_S)
49 typedef int cmp_t(const void *, const void *, void *);
50 #else
51 typedef int cmp_t(const void *, const void *);
52 #endif
53 static inline char *med3(char *, char *, char *, cmp_t *, void *);
54
55 #define MIN(a, b) ((a) < (b) ? a : b)
56
57 /*
58 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
59 */
60
61 static inline void
swapfunc(char * a,char * b,size_t es)62 swapfunc(char *a, char *b, size_t es)
63 {
64 char t;
65
66 do {
67 t = *a;
68 *a++ = *b;
69 *b++ = t;
70 } while (--es > 0);
71 }
72
73 #define vecswap(a, b, n) \
74 if ((n) > 0) swapfunc(a, b, n)
75
76 #if defined(I_AM_QSORT_R)
77 #define CMP(t, x, y) (cmp((x), (y), (t)))
78 #elif defined(I_AM_QSORT_R_COMPAT)
79 #define CMP(t, x, y) (cmp((t), (x), (y)))
80 #elif defined(I_AM_QSORT_S)
81 #define CMP(t, x, y) (cmp((x), (y), (t)))
82 #else
83 #define CMP(t, x, y) (cmp((x), (y)))
84 #endif
85
86 static inline char *
med3(char * a,char * b,char * c,cmp_t * cmp,void * thunk __unused)87 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
88 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_R_COMPAT) && !defined(I_AM_QSORT_S)
89 __unused
90 #endif
91 )
92 {
93 return CMP(thunk, a, b) < 0 ?
94 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
95 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
96 }
97
98 /*
99 * The actual qsort() implementation is static to avoid preemptible calls when
100 * recursing. Also give them different names for improved debugging.
101 */
102 #if defined(I_AM_QSORT_R)
103 #define local_qsort local_qsort_r
104 #elif defined(I_AM_QSORT_R_COMPAT)
105 #define local_qsort local_qsort_r_compat
106 #elif defined(I_AM_QSORT_S)
107 #define local_qsort local_qsort_s
108 #endif
109 static void
local_qsort(void * a,size_t n,size_t es,cmp_t * cmp,void * thunk)110 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
111 {
112 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
113 size_t d1, d2;
114 int cmp_result;
115 int swap_cnt;
116
117 /* if there are less than 2 elements, then sorting is not needed */
118 if (__predict_false(n < 2))
119 return;
120 loop:
121 swap_cnt = 0;
122 if (n < 7) {
123 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
124 for (pl = pm;
125 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
126 pl -= es)
127 swapfunc(pl, pl - es, es);
128 return;
129 }
130 pm = (char *)a + (n / 2) * es;
131 if (n > 7) {
132 pl = a;
133 pn = (char *)a + (n - 1) * es;
134 if (n > 40) {
135 size_t d = (n / 8) * es;
136
137 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
138 pm = med3(pm - d, pm, pm + d, cmp, thunk);
139 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
140 }
141 pm = med3(pl, pm, pn, cmp, thunk);
142 }
143 swapfunc(a, pm, es);
144 pa = pb = (char *)a + es;
145
146 pc = pd = (char *)a + (n - 1) * es;
147 for (;;) {
148 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
149 if (cmp_result == 0) {
150 swap_cnt = 1;
151 swapfunc(pa, pb, es);
152 pa += es;
153 }
154 pb += es;
155 }
156 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
157 if (cmp_result == 0) {
158 swap_cnt = 1;
159 swapfunc(pc, pd, es);
160 pd -= es;
161 }
162 pc -= es;
163 }
164 if (pb > pc)
165 break;
166 swapfunc(pb, pc, es);
167 swap_cnt = 1;
168 pb += es;
169 pc -= es;
170 }
171 if (swap_cnt == 0) { /* Switch to insertion sort */
172 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
173 for (pl = pm;
174 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
175 pl -= es)
176 swapfunc(pl, pl - es, es);
177 return;
178 }
179
180 pn = (char *)a + n * es;
181 d1 = MIN(pa - (char *)a, pb - pa);
182 vecswap(a, pb - d1, d1);
183 /*
184 * Cast es to preserve signedness of right-hand side of MIN()
185 * expression, to avoid sign ambiguity in the implied comparison. es
186 * is safely within [0, SSIZE_MAX].
187 */
188 d1 = MIN(pd - pc, pn - pd - (ssize_t)es);
189 vecswap(pb, pn - d1, d1);
190
191 d1 = pb - pa;
192 d2 = pd - pc;
193 if (d1 <= d2) {
194 /* Recurse on left partition, then iterate on right partition */
195 if (d1 > es) {
196 local_qsort(a, d1 / es, es, cmp, thunk);
197 }
198 if (d2 > es) {
199 /* Iterate rather than recurse to save stack space */
200 /* qsort(pn - d2, d2 / es, es, cmp); */
201 a = pn - d2;
202 n = d2 / es;
203 goto loop;
204 }
205 } else {
206 /* Recurse on right partition, then iterate on left partition */
207 if (d2 > es) {
208 local_qsort(pn - d2, d2 / es, es, cmp, thunk);
209 }
210 if (d1 > es) {
211 /* Iterate rather than recurse to save stack space */
212 /* qsort(a, d1 / es, es, cmp); */
213 n = d1 / es;
214 goto loop;
215 }
216 }
217 }
218
219 #if defined(I_AM_QSORT_R)
220 void
221 (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
222 {
223 local_qsort_r(a, n, es, cmp, thunk);
224 }
225 #elif defined(I_AM_QSORT_R_COMPAT)
226 void
__qsort_r_compat(void * a,size_t n,size_t es,void * thunk,cmp_t * cmp)227 __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
228 {
229 local_qsort_r_compat(a, n, es, cmp, thunk);
230 }
231 #elif defined(I_AM_QSORT_S)
232 errno_t
qsort_s(void * a,rsize_t n,rsize_t es,cmp_t * cmp,void * thunk)233 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
234 {
235 if (n > RSIZE_MAX) {
236 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
237 return (EINVAL);
238 } else if (es > RSIZE_MAX) {
239 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX",
240 EINVAL);
241 return (EINVAL);
242 } else if (n != 0) {
243 if (a == NULL) {
244 __throw_constraint_handler_s("qsort_s : a == NULL",
245 EINVAL);
246 return (EINVAL);
247 } else if (cmp == NULL) {
248 __throw_constraint_handler_s("qsort_s : cmp == NULL",
249 EINVAL);
250 return (EINVAL);
251 } else if (es <= 0) {
252 __throw_constraint_handler_s("qsort_s : es <= 0",
253 EINVAL);
254 return (EINVAL);
255 }
256 }
257
258 local_qsort_s(a, n, es, cmp, thunk);
259 return (0);
260 }
261 #else
262 void
qsort(void * a,size_t n,size_t es,cmp_t * cmp)263 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
264 {
265 local_qsort(a, n, es, cmp, NULL);
266 }
267 #endif
268