1 /*
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright © 2024, Synopsys Inc.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following
15 * disclaimer in the documentation and/or other materials provided
16 * with the distribution.
17 *
18 * 3. Neither the name of the copyright holder nor the names of its
19 * contributors may be used to endorse or promote products derived
20 * from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
23 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
25 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
26 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
27 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
28 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
29 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
31 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
33 * OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35 #define __STDC_WANT_LIB_EXT1__ 1
36 #include <string.h>
37 #include <stdbool.h>
38 #include "string_private.h"
39
40 __errno_t
strcat_s(char * restrict s1,rsize_t s1max,const char * restrict s2)41 strcat_s(char *restrict s1, rsize_t s1max, const char *restrict s2)
42 {
43 const char *msg = "";
44 size_t s1_len = 0;
45 bool write_null = true;
46
47 if (s1 == NULL) {
48 msg = "strcat_s: dest is NULL";
49 write_null = false;
50 goto handle_error;
51 }
52
53 if ((s1max == 0) || (CHECK_RSIZE(s1max))) {
54 msg = "strcat_s: dest buffer size is 0 or exceeds RSIZE_MAX";
55 write_null = false;
56 goto handle_error;
57 }
58
59 if (s2 == NULL) {
60 msg = "strcat_s: source is NULL";
61 goto handle_error;
62 }
63
64 /* It is a constraint violation if s1max is not large enough to contain
65 * the concatenation s2: no truncation permitted.
66 * It is also a constraint violation if the string pointed to by s2
67 * overlaps s1 in any way.
68 * The C11 Rationale says we are permitted to proceed with the copy and
69 * detect dest buffer overrun and overlapping memory blocks as a byproduct
70 * of performing the copy operation. This is to avoid calling strlen on
71 * s2 to detect these violations prior to attempting the copy.
72 */
73 // compute chars available in s1
74 s1_len = strnlen_s(s1, s1max);
75 if (s1_len == s1max) {
76 msg = "strcat_s: string 1 length exceeds buffer size";
77 goto handle_error;
78 }
79
80 const char *overlap_point;
81 bool check_s1_for_overlap;
82 unsigned m = s1max - s1_len;
83 char *s1cp = s1 + s1_len;
84 const char *s2cp = s2;
85
86 if (s1 <= s2) {
87 // if we ever reach s2 when storing to s1 we have overlap
88 overlap_point = s2;
89 check_s1_for_overlap = true;
90 // make sure source does not lie within initial dest string.
91 if (s2 <= s1cp) {
92 msg = "strcat_s: overlapping copy";
93 goto handle_error;
94 }
95 } else {
96 // if we ever reach s1 when reading from s2 we have overlap
97 overlap_point = s1;
98 check_s1_for_overlap = false;
99 // issue with checking initial dest string does not apply in this
100 // case, overlap will be detected only by hitting overlap_point.
101 }
102
103 unsigned written = 0;
104 char c = '.';
105 while (written < m) {
106 if (check_s1_for_overlap) {
107 if (s1cp == overlap_point) {
108 msg = "strcat_s: overlapping copy";
109 goto handle_error;
110 }
111 } else if (s2cp == overlap_point) {
112 msg = "strcat_s: overlapping copy";
113 goto handle_error;
114 }
115
116 c = *s2cp++;
117 *s1cp++ = c;
118 written++;
119 if (c == '\0') {
120 break;
121 }
122 }
123
124 if (c != '\0') {
125 msg = "strcat_s: dest buffer size insufficent to append string";
126 goto handle_error;
127 }
128
129 // Normal return path
130 return 0;
131
132 handle_error:
133 if (write_null && s1 != NULL) {
134 *s1 = '\0';
135 }
136
137 if (__cur_handler != NULL) {
138 __cur_handler(msg, NULL, -1);
139 }
140
141 return -1;
142 }
143
