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1/***
2*mbsnbset.c - Sets first n bytes of string to given character (MBCS)
3*
4* Copyright (c) Microsoft Corporation. All rights reserved.
5*
6*Purpose:
7* Sets first n bytes 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* _mbsnbset - Sets first n bytes of string to given character (MBCS)
20*
21*Purpose:
22* Sets the first n bytes of string to the supplied
23* character value. If the length of string is less than n,
24* the length of string is used in place of n. Handles
25* MBCS chars correctly.
26*
27* There are several factors that make this routine complicated:
28* (1) The fill value may be 1 or 2 bytes long.
29* (2) The fill operation may end by hitting the count value
30* or by hitting the end of the string.
31* (3) A null terminating char is NOT placed at the end of
32* the string.
33*
34* Cases to be careful of (both of these can occur at once):
35* (1) Leaving an "orphaned" trail byte in the string (e.g.,
36* overwriting a lead byte but not the corresponding trail byte).
37* (2) Writing only the 1st byte of a 2-byte fill value because the
38* end of string was encountered.
39*
40*Entry:
41* unsigned char *string = string to modify
42* unsigned int val = value to fill string with
43* size_t count = count of characters to fill
44*
45*
46*Exit:
47* Returns string = now filled with char val
48*
49*Uses:
50*
51*Exceptions:
52* Input parameters are validated. Refer to the validation section of the function.
53*
54*******************************************************************************/
55
56extern "C" unsigned char * __cdecl _mbsnbset_l(
57 unsigned char *string,
58 unsigned int val,
59 size_t count,
60 _locale_t plocinfo
61 )
62{
63 unsigned char *start = string;
64 unsigned char highval, lowval;
65 _LocaleUpdate _loc_update(plocinfo);
66
67_BEGIN_SECURE_CRT_DEPRECATION_DISABLE
68 if (_loc_update.GetLocaleT()->mbcinfo->ismbcodepage == 0)
69 return (unsigned char *)_strnset((char *)string, val, count);
70_END_SECURE_CRT_DEPRECATION_DISABLE
71
72 /* validation section */
73 _VALIDATE_RETURN(string != nullptr || count == 0, EINVAL, nullptr);
74
75 /*
76 * leadbyte flag indicates if the last byte we overwrote was
77 * a lead byte or not.
78 */
79
80 highval = static_cast<unsigned char>(val >> 8);
81 if (highval)
82 {
83 /* double byte value */
84
85 lowval = (unsigned char)(val & 0x00ff);
86
87 if(lowval=='\0')
88 {
89 _ASSERTE(("invalid MBCS pair passed to mbsnbset",0));
90
91 /* Ideally we would return nullptr here and signal an error
92 condition. But since this function has no other
93 error modes, there would be a good chance of crashing
94 the caller. So instead we fill the string with spaces
95 to ensure that no information leaks through
96 unexpectedly. Anyway, we do set errno to EINVAL.
97 */
98 errno = EINVAL;
99 lowval=highval=' ';
100 }
101
102 while ((count--) && *string) {
103
104 /* pad with ' ' if no room for both bytes -- odd len */
105 if ((!count--) || (!*(string+1))) {
106 *string = ' ';
107 break;
108 }
109
110 *string++ = highval;
111 *string++ = lowval;
112 }
113 }
114
115 else {
116 /* single byte value */
117
118 while (count-- && *string) {
119 *string++ = (unsigned char)val;
120 }
121
122 }
123
124 return( start );
125}
126
127extern "C" unsigned char * (__cdecl _mbsnbset)(
128 unsigned char *string,
129 unsigned int val,
130 size_t count
131 )
132{
133_BEGIN_SECURE_CRT_DEPRECATION_DISABLE
134 return _mbsnbset_l(string, val, count, nullptr);
135_END_SECURE_CRT_DEPRECATION_DISABLE
136}