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 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 * 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 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 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 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 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