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annotate lib/memcoll.c @ 4120:77d7a6d46166

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(memcoll): Fall back on a simple algorithm using memcmp if strcoll doesn't work.
author Paul Eggert <eggert@cs.ucla.edu>
date Tue, 31 Dec 2002 22:11:34 +0000
parents f16f0fbf6ce2
children df44e79ce676
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1 /* Locale-specific memory comparison.
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2 Copyright (C) 1999, 2002 Free Software Foundation, Inc.
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3
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4 This program is free software; you can redistribute it and/or modify
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5 it under the terms of the GNU General Public License as published by
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6 the Free Software Foundation; either version 2, or (at your option)
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7 any later version.
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8
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9 This program is distributed in the hope that it will be useful,
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10 but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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12 GNU General Public License for more details.
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13
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14 You should have received a copy of the GNU General Public License
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15 along with this program; if not, write to the Free Software Foundation,
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16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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17
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18 /* Contributed by Paul Eggert <eggert@twinsun.com>. */
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19
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20 #if HAVE_CONFIG_H
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21 # include <config.h>
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22 #endif
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23
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24 #include <errno.h>
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25 #ifndef errno
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26 extern int errno;
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27 #endif
bd719c800d4b Include errno.h, and declare errno if not defined.
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28
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0bdf7a169706 Include sys/types.h. From Werner Almesberger.
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29 #include <sys/types.h>
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30
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31 #if HAVE_STRING_H
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32 # include <string.h>
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33 #endif
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34
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35 /* Compare S1 (with length S1LEN) and S2 (with length S2LEN) according
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36 to the LC_COLLATE locale. S1 and S2 do not overlap, and are not
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37 adjacent. Perhaps temporarily modify the bytes after S1 and S2,
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38 but restore their original contents before returning. Set errno to an
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39 error number if there is an error, and to zero otherwise. */
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40 int
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41 memcoll (char *s1, size_t s1len, char *s2, size_t s2len)
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42 {
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43 int diff;
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44
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45 #if HAVE_STRCOLL
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46
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47 char n1 = s1[s1len];
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48 char n2 = s2[s2len];
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49
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50 s1[s1len++] = '\0';
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51 s2[s2len++] = '\0';
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52
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53 while (! (errno = 0, (diff = strcoll (s1, s2)) || errno))
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54 {
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55 /* strcoll found no difference, but perhaps it was fooled by NUL
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56 characters in the data. Work around this problem by advancing
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57 past the NUL chars. */
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58 size_t size1 = strlen (s1) + 1;
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59 size_t size2 = strlen (s2) + 1;
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60 s1 += size1;
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61 s2 += size2;
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62 s1len -= size1;
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63 s2len -= size2;
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64
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65 if (s1len == 0)
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66 {
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67 if (s2len != 0)
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68 diff = -1;
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69 break;
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70 }
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71 else if (s2len == 0)
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72 {
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73 diff = 1;
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74 break;
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75 }
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76 }
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77
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78 s1[s1len - 1] = n1;
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79 s2[s2len - 1] = n2;
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80
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81 #else
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82
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83 diff = memcmp (s1, s2, s1len < s2len ? s1len : s2len);
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84 if (! diff)
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85 diff = s1len < s2len ? -1 : s1len != s2len;
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86
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87 #endif
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88
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89 return diff;
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90 }