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Reactos
1/***
2*mbsrev.c - Reverse a string in place (MBCS)
3*
4* Copyright (c) Microsoft Corporation. All rights reserved.
5*
6*Purpose:
7* Reverse a string in place (MBCS)
8*
9*******************************************************************************/
10#ifndef _MBCS
11 #error This file should only be compiled with _MBCS defined
12#endif
13
14#include <corecrt_internal_mbstring.h>
15#include <locale.h>
16#include <string.h>
17
18
19/***
20* _mbsrev - Reverse a string in place (MBCS)
21*
22*Purpose:
23* Reverses the order of characters in the string. The terminating
24* null character remains in place. The order of MBCS characters
25* is not changed.
26*
27*Entry:
28* unsigned char *string = string to reverse
29*
30*Exit:
31* returns string - now with reversed characters
32*
33*Exceptions:
34* Input parameters are validated. Refer to the validation section of the function.
35*
36*******************************************************************************/
37
38extern "C" unsigned char * __cdecl _mbsrev_l(
39 unsigned char *string,
40 _locale_t plocinfo
41 )
42{
43 unsigned char *start = string;
44 unsigned char *left = string;
45 unsigned char c;
46 _LocaleUpdate _loc_update(plocinfo);
47
48 /* validation section */
49 _VALIDATE_RETURN(string != nullptr, EINVAL, nullptr);
50
51 if (_loc_update.GetLocaleT()->mbcinfo->ismbcodepage == 0)
52 return (unsigned char *)_strrev((char *)string);
53
54
55 /* first go through and reverse the bytes in MBCS chars */
56 while ( *string ) {
57 if ( _ismbblead_l(*string++, _loc_update.GetLocaleT()) ) {
58 if ( *string ) {
59 c = *string;
60 *string = *(string - 1);
61 *(string - 1) = c;
62 string++;
63 }
64 else
65 {
66 /* second byte is EOS
67 There is nothing really satisfying to do here. We have a string
68 that ends in leadbyte,'\0'. Reversing this would lead to the leadbyte
69 becoming falsely attached to the character before it:
70 (XL0 -> LX0, X has suddenly become a trailbyte)
71
72 So what we choose to do is assert and purge the dud byte from within the
73 string.
74 */
75 errno = EINVAL;
76 _ASSERTE(("Bad MBCS string passed into _mbsrev",0));
77
78 /* String has at least moved once already, so this is safe */
79 _ASSERTE(string>start);
80
81 /* move back one to point at the dud leadbyte */
82 --string;
83
84 /* now truncate the string one byte earlier */
85 *string='\0';
86
87 break;
88 }
89 }
90 }
91
92 /* now reverse the whole string */
93 string--;
94 while ( left < string ) {
95 c = *left;
96 *left++ = *string;
97 *string-- = c;
98 }
99
100 return ( start );
101}
102
103extern "C" unsigned char * (__cdecl _mbsrev)(
104 unsigned char *string
105 )
106{
107 return _mbsrev_l(string, nullptr);
108}