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