/* c-strcasecmp.c -- case insensitive string comparator in C locale
   Copyright (C) 1998-1999, 2005-2006, 2009-2021 Free Software Foundation, Inc.

   Character handling in C locale.
   Copyright (C) 2000-2003, 2006, 2008-2021 Free Software Foundation, Inc.

   Stripped down copy of gnulib c-ctype and c-strcasecmp modules for
   conditional fallback use.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>
#include <limits.h>

#undef HAVE_G_ASCII_STRCASECMP
#include "util.h"

/* The functions defined in this file assume the "C" locale and a character
   set without diacritics (ASCII-US or EBCDIC-US or something like that).
   Even if the "C" locale on a particular system is an extension of the ASCII
   character set (like on BeOS, where it is UTF-8, or on AmigaOS, where it
   is ISO-8859-1), the functions in this file recognize only the ASCII
   characters.  */

#if (' ' == 32) && ('!' == 33) && ('"' == 34) && ('#' == 35) \
    && ('%' == 37) && ('&' == 38) && ('\'' == 39) && ('(' == 40) \
    && (')' == 41) && ('*' == 42) && ('+' == 43) && (',' == 44) \
    && ('-' == 45) && ('.' == 46) && ('/' == 47) && ('0' == 48) \
    && ('1' == 49) && ('2' == 50) && ('3' == 51) && ('4' == 52) \
    && ('5' == 53) && ('6' == 54) && ('7' == 55) && ('8' == 56) \
    && ('9' == 57) && (':' == 58) && (';' == 59) && ('<' == 60) \
    && ('=' == 61) && ('>' == 62) && ('?' == 63) && ('A' == 65) \
    && ('B' == 66) && ('C' == 67) && ('D' == 68) && ('E' == 69) \
    && ('F' == 70) && ('G' == 71) && ('H' == 72) && ('I' == 73) \
    && ('J' == 74) && ('K' == 75) && ('L' == 76) && ('M' == 77) \
    && ('N' == 78) && ('O' == 79) && ('P' == 80) && ('Q' == 81) \
    && ('R' == 82) && ('S' == 83) && ('T' == 84) && ('U' == 85) \
    && ('V' == 86) && ('W' == 87) && ('X' == 88) && ('Y' == 89) \
    && ('Z' == 90) && ('[' == 91) && ('\\' == 92) && (']' == 93) \
    && ('^' == 94) && ('_' == 95) && ('a' == 97) && ('b' == 98) \
    && ('c' == 99) && ('d' == 100) && ('e' == 101) && ('f' == 102) \
    && ('g' == 103) && ('h' == 104) && ('i' == 105) && ('j' == 106) \
    && ('k' == 107) && ('l' == 108) && ('m' == 109) && ('n' == 110) \
    && ('o' == 111) && ('p' == 112) && ('q' == 113) && ('r' == 114) \
    && ('s' == 115) && ('t' == 116) && ('u' == 117) && ('v' == 118) \
    && ('w' == 119) && ('x' == 120) && ('y' == 121) && ('z' == 122) \
    && ('{' == 123) && ('|' == 124) && ('}' == 125) && ('~' == 126)
/* The character set is ASCII or one of its variants or extensions, not EBCDIC.
   Testing the value of '\n' and '\r' is not relevant.  */
# define C_CTYPE_ASCII 1
#elif ! (' ' == '\x40' && '0' == '\xf0'                     \
         && 'A' == '\xc1' && 'J' == '\xd1' && 'S' == '\xe2' \
         && 'a' == '\x81' && 'j' == '\x91' && 's' == '\xa2')
# error "Only ASCII and EBCDIC are supported"
#endif

#if 'A' < 0
# error "EBCDIC and char is signed -- not supported"
#endif

/* Cases for lowercase hex letters, and lowercase letters, all offset by N.  */

#define C_CTYPE_LOWER_A_THRU_F_N(N) \
   case 'a' + (N): case 'b' + (N): case 'c' + (N): case 'd' + (N): \
   case 'e' + (N): case 'f' + (N)
#define C_CTYPE_LOWER_N(N) \
   C_CTYPE_LOWER_A_THRU_F_N(N): \
   case 'g' + (N): case 'h' + (N): case 'i' + (N): case 'j' + (N): \
   case 'k' + (N): case 'l' + (N): case 'm' + (N): case 'n' + (N): \
   case 'o' + (N): case 'p' + (N): case 'q' + (N): case 'r' + (N): \
   case 's' + (N): case 't' + (N): case 'u' + (N): case 'v' + (N): \
   case 'w' + (N): case 'x' + (N): case 'y' + (N): case 'z' + (N)

#define C_CTYPE_LOWER C_CTYPE_LOWER_N(0)
#define C_CTYPE_UPPER C_CTYPE_LOWER_N ('A' - 'a')


/* Function definitions.  */

/* Unlike the functions in <ctype.h>, which require an argument in the range
   of the 'unsigned char' type, the functions here operate on values that are
   in the 'unsigned char' range or in the 'char' range.  In other words,
   when you have a 'char' value, you need to cast it before using it as
   argument to a <ctype.h> function:

         const char *s = ...;
         if (isalpha ((unsigned char) *s)) ...

   but you don't need to cast it for the functions defined in this file:

         const char *s = ...;
         if (c_isalpha (*s)) ...
 */

static int c_tolower(int c)
{
	switch (c) {
	C_CTYPE_UPPER:
		return c - 'A' + 'a';
	default:
		return c;
	}
}

static int c_toupper(int c)
{
	switch (c) {
	C_CTYPE_LOWER:
		return c - 'a' + 'A';
	default:
		return c;
	}
}

char *gob_strup(char *str)
{
	char *s;

	for (s = str; *s; s++)
		*s = c_toupper(*s);

	return str;
}

char *gob_strdown(char *str)
{
	char *s;

	for (s = str; *s; s++)
		*s = c_tolower(*s);

	return str;
}

int gob_strcasecmp(const char *s1, const char *s2)
{
	register const unsigned char *p1 = (const unsigned char *)s1;
	register const unsigned char *p2 = (const unsigned char *)s2;
	unsigned char c1, c2;

	if (p1 == p2)
		return 0;

	do {
		c1 = c_tolower (*p1);
		c2 = c_tolower (*p2);

		if (c1 == '\0')
			break;

		++p1;
		++p2;
	} while (c1 == c2);

	if (UCHAR_MAX <= INT_MAX) {
		return c1 - c2;
	} else {
		/*
		 * On machines where 'char' and 'int' are types of the
		 * same size, the difference of two 'unsigned char' values
		 * - including the sign bit - doesn't fit in an 'int'.
		 */
		return _GL_CMP (c1, c2);
	}
}