| 1 | /* strncasecmp.c -- case insensitive string comparator
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| 2 | Copyright (C) 1998-1999, 2005-2007, 2009-2012 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 3, 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, see <http://www.gnu.org/licenses/>. */
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| 16 |
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| 17 | #include <config.h>
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| 18 |
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| 19 | /* Specification. */
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| 20 | #include <string.h>
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| 21 |
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| 22 | #include <ctype.h>
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| 23 | #include <limits.h>
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| 24 |
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| 25 | #define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
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| 26 |
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| 27 | /* Compare no more than N bytes of strings S1 and S2, ignoring case,
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| 28 | returning less than, equal to or greater than zero if S1 is
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| 29 | lexicographically less than, equal to or greater than S2.
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| 30 | Note: This function cannot work correctly in multibyte locales. */
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| 31 |
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| 32 | int
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| 33 | strncasecmp (const char *s1, const char *s2, size_t n)
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| 34 | {
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| 35 | register const unsigned char *p1 = (const unsigned char *) s1;
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| 36 | register const unsigned char *p2 = (const unsigned char *) s2;
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| 37 | unsigned char c1, c2;
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| 38 |
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| 39 | if (p1 == p2 || n == 0)
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| 40 | return 0;
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| 41 |
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| 42 | do
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| 43 | {
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| 44 | c1 = TOLOWER (*p1);
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| 45 | c2 = TOLOWER (*p2);
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| 46 |
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| 47 | if (--n == 0 || c1 == '\0')
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| 48 | break;
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| 49 |
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| 50 | ++p1;
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| 51 | ++p2;
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| 52 | }
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| 53 | while (c1 == c2);
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| 54 |
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| 55 | if (UCHAR_MAX <= INT_MAX)
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| 56 | return c1 - c2;
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| 57 | else
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| 58 | /* On machines where 'char' and 'int' are types of the same size, the
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| 59 | difference of two 'unsigned char' values - including the sign bit -
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| 60 | doesn't fit in an 'int'. */
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| 61 | return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
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| 62 | }
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