safec  2.1
Safe C Library - ISO TR24731 Bounds Checking Interface
strlastdiff_s.c
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1 /*------------------------------------------------------------------
2  * strlastdiff_s.c
3  *
4  * November 2008, Bo Berry
5  *
6  * Copyright (c) 2008-2011, 2013 by Cisco Systems, Inc
7  * All rights reserved.
8  *
9  * Permission is hereby granted, free of charge, to any person
10  * obtaining a copy of this software and associated documentation
11  * files (the "Software"), to deal in the Software without
12  * restriction, including without limitation the rights to use,
13  * copy, modify, merge, publish, distribute, sublicense, and/or
14  * sell copies of the Software, and to permit persons to whom the
15  * Software is furnished to do so, subject to the following
16  * conditions:
17  *
18  * The above copyright notice and this permission notice shall be
19  * included in all copies or substantial portions of the Software.
20  *
21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
22  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
23  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
24  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
25  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
26  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
27  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
28  * OTHER DEALINGS IN THE SOFTWARE.
29  *------------------------------------------------------------------
30  */
31 
32 #include "safeclib_private.h"
33 #include "safe_str_constraint.h"
34 #include "safe_str_lib.h"
35 
36 
71 errno_t
72 strlastdiff_s(const char *dest, rsize_t dmax,
73  const char *src, rsize_t *index)
74 {
75  const char *rp;
76  bool there_is_a_diff = false;
77 
78  if (index == NULL) {
79  invoke_safe_str_constraint_handler("strlastdiff_s: index is null",
80  NULL, ESNULLP);
81  return (ESNULLP);
82  }
83  *index = 0;
84 
85  if (dest == NULL) {
86  invoke_safe_str_constraint_handler("strlastdiff_s: dest is null",
87  NULL, ESNULLP);
88  return (ESNULLP);
89  }
90 
91  if (src == NULL) {
92  invoke_safe_str_constraint_handler("strlastdiff_s: src is null",
93  NULL, ESNULLP);
94  return (ESNULLP);
95  }
96 
97  if (dmax == 0 ) {
98  invoke_safe_str_constraint_handler("strlastdiff_s: dmax is 0",
99  NULL, ESZEROL);
100  return (ESZEROL);
101  }
102 
103  if (dmax > RSIZE_MAX_STR) {
104  invoke_safe_str_constraint_handler("strlastdiff_s: dmax exceeds max",
105  NULL, ESLEMAX);
106  return (ESLEMAX);
107  }
108 
109  /* hold reference point */
110  rp = dest;
111 
112  /*
113  * find the last diff
114  */
115  while (*dest && *src && dmax) {
116 
117  if (*dest != *src) {
118  there_is_a_diff = true;
119  *index = dest - rp;
120  }
121 
122  dest++;
123  src++;
124  dmax--;
125  }
126 
127  if (there_is_a_diff) {
128  return (EOK);
129  } else {
130  return (ESNODIFF);
131  }
132 }
void invoke_safe_str_constraint_handler(const char *msg, void *ptr, errno_t error)
Invokes the currently set constraint handler or the default.
errno_t strlastdiff_s(const char *dest, rsize_t dmax, const char *src, rsize_t *index)
Returns the index of the last character that is different between dest and src.
Definition: strlastdiff_s.c:72