summaryrefslogtreecommitdiff
path: root/payloads/libpayload/libc/string.c
blob: ad0a17755a692db6a9667a5b883b7d3a6406c94b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
/*
 * This file is part of the libpayload project.
 *
 * Copyright (C) 2007 Uwe Hermann <uwe@hermann-uwe.de>
 * Copyright (C) 2008 Advanced Micro Devices, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <libpayload.h>

/**
 * Calculate the length of a fixed-size string.
 *
 * @param str The input string.
 * @param maxlen Return at most maxlen characters as length of the string.
 * @return The length of the string, not including the final NUL character.
 * 	   The maximum length returned is maxlen.
 */
size_t strnlen(const char *str, size_t maxlen)
{
	size_t len = 0;

	/* NULL and empty strings have length 0. */
	if (!str)
		return 0;

	/* Loop until we find a NUL character, or maxlen is reached. */
	while ((*str++ != '\0') && (len < maxlen))
		len++;

	return len;
}

/**
 * Calculate the length of a string.
 *
 * @param str The input string.
 * @return The length of the string, not including the final NUL character.
 */
size_t strlen(const char *str)
{
	size_t len = 0;

	/* NULL and empty strings have length 0. */
	if (!str)
		return 0;

	/* Loop until we find a NUL character. */
	while (*str++ != '\0')
		len++;

	return len;
}

/**
 * Compare two strings.
 *
 * @param s1 The first string.
 * @param s2 The second string.
 * @return Returns a value less than zero, if s1 is shorter than s2. Returns
 * 	   zero, if s1 equals s2. Returns a value greater than zero, if
 * 	   s1 is longer than s2.
 */
int strcmp(const char *s1, const char *s2)
{
	char c1, c2;

	/* Set c1 == c2, so that we can enter the while loop. */
	c1 = 0;
	c2 = 0;

	/* Compare characters until they differ, or one of the strings ends. */
	while (c1 == c2) {
		/* Read the next character from each string. */
		c1 = *s1++;
		c2 = *s2++;

		/* Return something negative (if s1 is shorter than s2), or
		   zero (if s1 equals s2). */
		if (c1 == '\0')
			return c1 - c2;
	}

	/* Return someting positive (if s1 is longer than s2), or zero (if s1
	   and s2 are equal). */
	return c1 - c2;
}

/**
 * Compare two strings with fixed length.
 *
 * @param s1 The first string.
 * @param s2 The second string.
 * @param maxlen Return at most maxlen characters as length of the string.
 * @return A non-zero value if s1 and s2 differ, or zero if s1 equals s2.
 */
int strncmp(const char *s1, const char *s2, int maxlen)
{
	int i;

	for (i = 0; i < maxlen; i++) {
		if (s1[i] != s2[i])
			return s1[i] - s2[i];
	}

	return 0;
}

char *strncpy(char *d, const char *s, int n)
{
	/* Use +1 to get the NUL terminator. */
	int max = n > strlen(s) + 1 ? strlen(s) + 1 : n;
	int i;

	for (i = 0; i < max; i++)
		d[i] = (char)s[i];

	return d;
}

char *strcpy(char *d, const char *s)
{
	return strncpy(d, s, strlen(s) + 1);
}

char *strncat(char *d, const char *s, int n)
{
	char *p = d + strlen(d);
	int max = n > strlen(s) ? strlen(s) : n;
	int i;

	for (i = 0; i < max; i++)
		p[i] = s[i];

	p[i] = '\0';
	return d;
}

char *strchr(const char *s, int c)
{
	char *p = (char *)s;

	for (; *p != 0; p++) {
		if (*p == c)
			return p;
	}

	return NULL;
}

char *strdup(const char *s)
{
	int n = strlen(s);
	char *p = malloc(n);

	if (p != NULL)
		strncpy(p, s, n);

	return p;
}

char *strstr(const char *h, const char *n)
{
	int hn = strlen(h);
	int nn = strlen(n);
	int i;

	for (i = 0; i <= hn - nn; i++)
		if (!strcmp(&h[i], n))
			return (char *)&h[i];

	return NULL;
}