| 1 | /* strncasecmp.c -- case insensitive string comparator |
| 2 | Copyright (C) 1998-1999, 2005-2007, 2009-2010 Free Software Foundation, Inc. |
| 3 | |
| 4 | This program is free software; you can redistribute it and/or modify |
| 5 | it under the terms of the GNU Lesser General Public License as published by |
| 6 | the Free Software Foundation; either version 2, or (at your option) |
| 7 | any later version. |
| 8 | |
| 9 | This program is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | GNU Lesser General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Lesser General Public License |
| 15 | along with this program; if not, write to the Free Software Foundation, |
| 16 | Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ |
| 17 | |
| 18 | #include <config.h> |
| 19 | |
| 20 | /* Specification. */ |
| 21 | #include <string.h> |
| 22 | |
| 23 | #include <ctype.h> |
| 24 | #include <limits.h> |
| 25 | |
| 26 | #define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch)) |
| 27 | |
| 28 | /* Compare no more than N bytes of strings S1 and S2, ignoring case, |
| 29 | returning less than, equal to or greater than zero if S1 is |
| 30 | lexicographically less than, equal to or greater than S2. |
| 31 | Note: This function cannot work correctly in multibyte locales. */ |
| 32 | |
| 33 | int |
| 34 | strncasecmp (const char *s1, const char *s2, size_t n) |
| 35 | { |
| 36 | register const unsigned char *p1 = (const unsigned char *) s1; |
| 37 | register const unsigned char *p2 = (const unsigned char *) s2; |
| 38 | unsigned char c1, c2; |
| 39 | |
| 40 | if (p1 == p2 || n == 0) |
| 41 | return 0; |
| 42 | |
| 43 | do |
| 44 | { |
| 45 | c1 = TOLOWER (*p1); |
| 46 | c2 = TOLOWER (*p2); |
| 47 | |
| 48 | if (--n == 0 || c1 == '\0') |
| 49 | break; |
| 50 | |
| 51 | ++p1; |
| 52 | ++p2; |
| 53 | } |
| 54 | while (c1 == c2); |
| 55 | |
| 56 | if (UCHAR_MAX <= INT_MAX) |
| 57 | return c1 - c2; |
| 58 | else |
| 59 | /* On machines where 'char' and 'int' are types of the same size, the |
| 60 | difference of two 'unsigned char' values - including the sign bit - |
| 61 | doesn't fit in an 'int'. */ |
| 62 | return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0); |
| 63 | } |