1 /* Case-insensitive string comparison function. 2 Copyright (C) 1998-1999, 2005-2008, 2010-2021 Free Software Foundation, Inc. 3 Written by Bruno Haible <bruno@clisp.org>, 2007. 4 5 This file is free software: you can redistribute it and/or modify 6 it under the terms of the GNU Lesser General Public License as 7 published by the Free Software Foundation; either version 3 of the 8 License, or (at your option) any later version. 9 10 This file is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public License 16 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 17 18 #include <config.h> 19 20 /* Specification. */ 21 #include <string.h> 22 23 #include <ctype.h> 24 25 #include "mbuiter.h" 26 27 #define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch)) 28 29 /* Compare the initial segment of the character string STRING consisting of 30 at most mbslen (PREFIX) characters with the character string PREFIX, 31 ignoring case. If the two match, return a pointer to the first byte 32 after this prefix in STRING. Otherwise, return NULL. 33 Note: This function may, in multibyte locales, return non-NULL if STRING 34 is of smaller length than PREFIX! */ 35 char * 36 mbspcasecmp (const char *string, const char *prefix) /* */ 37 { 38 /* This is essentially the same as 39 mbsncasecmp (string, prefix, mbslen (prefix)) 40 just with small optimizations. */ 41 if (string == prefix) 42 return (char *) (string + strlen (string)); 43 44 /* Be careful not to look at the entire extent of STRING or PREFIX until 45 needed. This is useful because when two strings differ, the difference is 46 most often already in the very few first characters. */ 47 if (MB_CUR_MAX > 1) 48 { 49 mbui_iterator_t iter1; 50 mbui_iterator_t iter2; 51 52 mbui_init (iter1, string); 53 mbui_init (iter2, prefix); 54 55 while (mbui_avail (iter1) && mbui_avail (iter2)) 56 { 57 int cmp = mb_casecmp (mbui_cur (iter1), mbui_cur (iter2)); 58 59 if (cmp != 0) 60 return NULL; 61 62 mbui_advance (iter1); 63 mbui_advance (iter2); 64 } 65 if (!mbui_avail (iter2)) 66 /* PREFIX equals STRING or is terminated before STRING. */ 67 return (char *) mbui_cur_ptr (iter1); 68 else 69 /* STRING terminated before PREFIX. */ 70 return NULL; 71 } 72 else 73 { 74 const unsigned char *p1 = (const unsigned char *) string; 75 const unsigned char *p2 = (const unsigned char *) prefix; 76 unsigned char c1, c2; 77 78 for (; ; p1++, p2++) 79 { 80 c1 = TOLOWER (*p1); 81 c2 = TOLOWER (*p2); 82 83 if (c2 == '\0' || c1 != c2) 84 break; 85 } 86 87 if (c2 == '\0') 88 /* PREFIX equals STRING or is terminated before STRING. */ 89 return (char *) p1; 90 else 91 /* STRING terminated before PREFIX. */ 92 return NULL; 93 } 94 }