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1/***
2*mbsnset.c - Sets first n charcaters of string to given character (MBCS)
3*
4* Copyright (c) Microsoft Corporation. All rights reserved.
5*
6*Purpose:
7* Sets first n charcaters of string to given character (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* _mbsnset - Sets first n charcaters of string to given character (MBCS)
21*
22*Purpose:
23* Sets the first n characters of string to the supplied
24* character value. If the length of string is less than n,
25* the length of string is used in place of n. Handles
26* MBCS chars correctly.
27*
28* There are several factors that make this routine complicated:
29* (1) The fill value may be 1 or 2 bytes long.
30* (2) The fill operation may end by hitting the count value
31* or by hitting the end of the string.
32* (3) A null terminating char is NOT placed at the end of
33* the string.
34*
35* Cases to be careful of (both of these can occur at once):
36* (1) Leaving an "orphaned" trail byte in the string (e.g.,
37* overwriting a lead byte but not the corresponding trail byte).
38* (2) Writing only the 1st byte of a 2-byte fill value because the
39* end of string was encountered.
40*
41*Entry:
42* unsigned char *string = string to modify
43* unsigned int val = value to fill string with
44* size_t count = count of characters to fill
45*
46*
47*Exit:
48* Returns string = now filled with char val
49*
50*Uses:
51*
52*Exceptions:
53* Input parameters are validated. Refer to the validation section of the function.
54*
55*******************************************************************************/
56
57extern "C" unsigned char * __cdecl _mbsnset_l(
58 unsigned char *string,
59 unsigned int val,
60 size_t count,
61 _locale_t plocinfo
62 )
63{
64 unsigned char *start = string;
65 unsigned int leadbyte = 0;
66 unsigned char highval, lowval;
67 _LocaleUpdate _loc_update(plocinfo);
68
69 /* validation section */
70 _VALIDATE_RETURN(string != nullptr || count == 0, EINVAL, nullptr);
71
72 /*
73 * leadbyte flag indicates if the last byte we overwrote was
74 * a lead byte or not.
75 */
76_BEGIN_SECURE_CRT_DEPRECATION_DISABLE
77 if (_loc_update.GetLocaleT()->mbcinfo->ismbcodepage == 0)
78 return (unsigned char *)_strnset((char *)string, val, count);
79_END_SECURE_CRT_DEPRECATION_DISABLE
80
81 highval = static_cast<unsigned char>(val >> 8);
82 if (highval != 0)
83 {
84
85 /* double byte value */
86
87 lowval = (unsigned char)(val & 0x00ff);
88
89 if(lowval=='\0')
90 {
91 _ASSERTE(("invalid MBCS pair passed to mbsnset",0));
92
93 /* Ideally we would return nullptr here and signal an error
94 condition. But since this function has no other
95 error modes, there would be a good chance of crashing
96 the caller. So instead we fill the string with spaces
97 to ensure that no information leaks through
98 unexpectedly. Anyway, we do set errno to EINVAL.
99 */
100 errno = EINVAL;
101 lowval=highval=' ';
102 }
103
104 while (count-- && *string) {
105 leadbyte = _ismbbtruelead_l(leadbyte, *string, _loc_update.GetLocaleT());
106 *string++ = highval;
107
108 if (*string) {
109 leadbyte = _ismbbtruelead_l(leadbyte, *string, _loc_update.GetLocaleT());
110 *string++ = lowval;
111 }
112 else
113 /* overwrite orphaned highval byte */
114 *(string-1) = ' ';
115 }
116 }
117
118 else {
119 /* single byte value */
120
121 while (count-- && *string) {
122 leadbyte = _ismbbtruelead_l(leadbyte, *string, _loc_update.GetLocaleT());
123 *string++ = (unsigned char)val;
124 }
125 }
126
127 /* overwrite orphaned trailing byte, if necessary */
128 if(leadbyte && *string)
129 *string = ' ';
130
131 return( start );
132}
133
134unsigned char * (__cdecl _mbsnset)(
135 unsigned char *string,
136 unsigned int val,
137 size_t count
138 )
139{
140_BEGIN_SECURE_CRT_DEPRECATION_DISABLE
141 return _mbsnset_l(string, val, count, nullptr);
142_END_SECURE_CRT_DEPRECATION_DISABLE
143}