1 /*
2 * Copyright (c) Huawei Technologies Co., Ltd. 2014-2021. All rights reserved.
3 * Licensed under Mulan PSL v2.
4 * You can use this software according to the terms and conditions of the Mulan PSL v2.
5 * You may obtain a copy of Mulan PSL v2 at:
6 * http://license.coscl.org.cn/MulanPSL2
7 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
8 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
9 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
10 * See the Mulan PSL v2 for more details.
11 * Description: strncpy_s function
12 * Create: 2014-02-25
13 */
14 /*
15 * [Standardize-exceptions] Use unsafe function: Performance-sensitive
16 * [reason] Always used in the performance critical path,
17 * and sufficient input validation is performed before calling
18 */
19
20 #include "securecutil.h"
21
22 #if defined(SECUREC_COMPATIBLE_WIN_FORMAT)
23 #define SECUREC_STRNCPY_PARAM_OK(strDest, destMax, strSrc, count) \
24 (((destMax) > 0 && (destMax) <= SECUREC_STRING_MAX_LEN && (strDest) != NULL && (strSrc) != NULL && \
25 ((count) <= SECUREC_STRING_MAX_LEN || (count) == ((size_t)(-1))) && (count) > 0))
26 #else
27 #define SECUREC_STRNCPY_PARAM_OK(strDest, destMax, strSrc, count) \
28 (((destMax) > 0 && (destMax) <= SECUREC_STRING_MAX_LEN && (strDest) != NULL && (strSrc) != NULL && \
29 (count) <= SECUREC_STRING_MAX_LEN && (count) > 0))
30 #endif
31
32 /*
33 * Check Src Count Range
34 */
CheckSrcCountRange(char * strDest,size_t destMax,const char * strSrc,size_t count)35 SECUREC_INLINE errno_t CheckSrcCountRange(char *strDest, size_t destMax, const char *strSrc, size_t count)
36 {
37 size_t tmpDestMax = destMax;
38 size_t tmpCount = count;
39 const char *endPos = strSrc;
40
41 /* Use destMax and count as boundary checker and destMax must be greater than zero */
42 while (*(endPos) != '\0' && tmpDestMax > 0 && tmpCount > 0) {
43 ++endPos;
44 --tmpCount;
45 --tmpDestMax;
46 }
47 if (tmpDestMax == 0) {
48 strDest[0] = '\0';
49 SECUREC_ERROR_INVALID_RANGE("strncpy_s");
50 return ERANGE_AND_RESET;
51 }
52 return EOK;
53 }
54
55 /*
56 * Handling errors, when dest equal src return EOK
57 */
strncpy_error(char * strDest,size_t destMax,const char * strSrc,size_t count)58 errno_t strncpy_error(char *strDest, size_t destMax, const char *strSrc, size_t count)
59 {
60 if (destMax == 0 || destMax > SECUREC_STRING_MAX_LEN) {
61 SECUREC_ERROR_INVALID_RANGE("strncpy_s");
62 return ERANGE;
63 }
64 if (strDest == NULL || strSrc == NULL) {
65 SECUREC_ERROR_INVALID_PARAMTER("strncpy_s");
66 if (strDest != NULL) {
67 strDest[0] = '\0';
68 return EINVAL_AND_RESET;
69 }
70 return EINVAL;
71 }
72 if (count > SECUREC_STRING_MAX_LEN) {
73 strDest[0] = '\0'; /* Clear dest string */
74 SECUREC_ERROR_INVALID_RANGE("strncpy_s");
75 return ERANGE_AND_RESET;
76 }
77 if (count == 0) {
78 strDest[0] = '\0';
79 return EOK;
80 }
81 return CheckSrcCountRange(strDest, destMax, strSrc, count);
82 }
83
84 /*
85 * <FUNCTION DESCRIPTION>
86 * The strncpy_s function copies not more than n successive characters (not including the terminating null character)
87 * from the array pointed to by strSrc to the array pointed to by strDest.
88 *
89 * <INPUT PARAMETERS>
90 * strDest Destination string.
91 * destMax The size of the destination string, in characters.
92 * strSrc Source string.
93 * count Number of characters to be copied.
94 *
95 * <OUTPUT PARAMETERS>
96 * strDest is updated
97 *
98 * <RETURN VALUE>
99 * EOK Success
100 * EINVAL strDest is NULL and destMax != 0 and destMax <= SECUREC_STRING_MAX_LEN
101 * EINVAL_AND_RESET strDest != NULL and strSrc is NULL and destMax != 0 and destMax <= SECUREC_STRING_MAX_LEN
102 * ERANGE destMax is 0 and destMax > SECUREC_STRING_MAX_LEN
103 * ERANGE_AND_RESET strDest have not enough space and all other parameters are valid and not overlap
104 * EOVERLAP_AND_RESET dest buffer and source buffer are overlapped and all parameters are valid
105 *
106 * If there is a runtime-constraint violation, strDest[0] will be set to the '\0' when strDest and destMax valid
107 */
strncpy_s(char * strDest,size_t destMax,const char * strSrc,size_t count)108 errno_t strncpy_s(char *strDest, size_t destMax, const char *strSrc, size_t count)
109 {
110 if (SECUREC_STRNCPY_PARAM_OK(strDest, destMax, strSrc, count)) {
111 size_t minCpLen; /* Use it to store the maxi length limit */
112 if (count < destMax) {
113 SECUREC_CALC_STR_LEN(strSrc, count, &minCpLen); /* No ending terminator */
114 } else {
115 size_t tmpCount = destMax;
116 #ifdef SECUREC_COMPATIBLE_WIN_FORMAT
117 if (count == ((size_t)(-1))) {
118 tmpCount = destMax - 1;
119 }
120 #endif
121 SECUREC_CALC_STR_LEN(strSrc, tmpCount, &minCpLen); /* No ending terminator */
122 if (minCpLen == destMax) {
123 strDest[0] = '\0';
124 SECUREC_ERROR_INVALID_RANGE("strncpy_s");
125 return ERANGE_AND_RESET;
126 }
127 }
128 if (SECUREC_STRING_NO_OVERLAP(strDest, strSrc, minCpLen) || strDest == strSrc) {
129 /* Not overlap */
130 SECUREC_MEMCPY_WARP_OPT(strDest, strSrc, minCpLen); /* Copy string without terminator */
131 strDest[minCpLen] = '\0';
132 return EOK;
133 } else {
134 strDest[0] = '\0';
135 SECUREC_ERROR_BUFFER_OVERLAP("strncpy_s");
136 return EOVERLAP_AND_RESET;
137 }
138 }
139 return strncpy_error(strDest, destMax, strSrc, count);
140 }
141
142 #if SECUREC_EXPORT_KERNEL_SYMBOL
143 EXPORT_SYMBOL(strncpy_s);
144 #endif
145
146