1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Taken from:
4 *  linux/lib/string.c
5 *
6 *  Copyright (C) 1991, 1992  Linus Torvalds
7 */
8
9#include <linux/ctype.h>
10#include <linux/kernel.h>
11#include <linux/types.h>
12#include <linux/string.h>
13
14#ifndef EFI_HAVE_STRLEN
15/**
16 * strlen - Find the length of a string
17 * @s: The string to be sized
18 */
19size_t strlen(const char *s)
20{
21	const char *sc;
22
23	for (sc = s; *sc != '\0'; ++sc)
24		/* nothing */;
25	return sc - s;
26}
27#endif
28
29#ifndef EFI_HAVE_STRNLEN
30/**
31 * strnlen - Find the length of a length-limited string
32 * @s: The string to be sized
33 * @count: The maximum number of bytes to search
34 */
35size_t strnlen(const char *s, size_t count)
36{
37	const char *sc;
38
39	for (sc = s; count-- && *sc != '\0'; ++sc)
40		/* nothing */;
41	return sc - s;
42}
43#endif
44
45/**
46 * strstr - Find the first substring in a %NUL terminated string
47 * @s1: The string to be searched
48 * @s2: The string to search for
49 */
50char *strstr(const char *s1, const char *s2)
51{
52	size_t l1, l2;
53
54	l2 = strlen(s2);
55	if (!l2)
56		return (char *)s1;
57	l1 = strlen(s1);
58	while (l1 >= l2) {
59		l1--;
60		if (!memcmp(s1, s2, l2))
61			return (char *)s1;
62		s1++;
63	}
64	return NULL;
65}
66
67#ifndef EFI_HAVE_STRCMP
68/**
69 * strcmp - Compare two strings
70 * @cs: One string
71 * @ct: Another string
72 */
73int strcmp(const char *cs, const char *ct)
74{
75	unsigned char c1, c2;
76
77	while (1) {
78		c1 = *cs++;
79		c2 = *ct++;
80		if (c1 != c2)
81			return c1 < c2 ? -1 : 1;
82		if (!c1)
83			break;
84	}
85	return 0;
86}
87#endif
88
89/**
90 * strncmp - Compare two length-limited strings
91 * @cs: One string
92 * @ct: Another string
93 * @count: The maximum number of bytes to compare
94 */
95int strncmp(const char *cs, const char *ct, size_t count)
96{
97	unsigned char c1, c2;
98
99	while (count) {
100		c1 = *cs++;
101		c2 = *ct++;
102		if (c1 != c2)
103			return c1 < c2 ? -1 : 1;
104		if (!c1)
105			break;
106		count--;
107	}
108	return 0;
109}
110
111/* Works only for digits and letters, but small and fast */
112#define TOLOWER(x) ((x) | 0x20)
113
114static unsigned int simple_guess_base(const char *cp)
115{
116	if (cp[0] == '0') {
117		if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
118			return 16;
119		else
120			return 8;
121	} else {
122		return 10;
123	}
124}
125
126/**
127 * simple_strtoull - convert a string to an unsigned long long
128 * @cp: The start of the string
129 * @endp: A pointer to the end of the parsed string will be placed here
130 * @base: The number base to use
131 */
132
133unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
134{
135	unsigned long long result = 0;
136
137	if (!base)
138		base = simple_guess_base(cp);
139
140	if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
141		cp += 2;
142
143	while (isxdigit(*cp)) {
144		unsigned int value;
145
146		value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
147		if (value >= base)
148			break;
149		result = result * base + value;
150		cp++;
151	}
152	if (endp)
153		*endp = (char *)cp;
154
155	return result;
156}
157
158long simple_strtol(const char *cp, char **endp, unsigned int base)
159{
160	if (*cp == '-')
161		return -simple_strtoull(cp + 1, endp, base);
162
163	return simple_strtoull(cp, endp, base);
164}
165
166#ifdef CONFIG_EFI_PARAMS_FROM_FDT
167#ifndef EFI_HAVE_STRRCHR
168/**
169 * strrchr - Find the last occurrence of a character in a string
170 * @s: The string to be searched
171 * @c: The character to search for
172 */
173char *strrchr(const char *s, int c)
174{
175	const char *last = NULL;
176	do {
177		if (*s == (char)c)
178			last = s;
179	} while (*s++);
180	return (char *)last;
181}
182#endif
183#ifndef EFI_HAVE_MEMCHR
184/**
185 * memchr - Find a character in an area of memory.
186 * @s: The memory area
187 * @c: The byte to search for
188 * @n: The size of the area.
189 *
190 * returns the address of the first occurrence of @c, or %NULL
191 * if @c is not found
192 */
193void *memchr(const void *s, int c, size_t n)
194{
195	const unsigned char *p = s;
196	while (n-- != 0) {
197		if ((unsigned char)c == *p++) {
198			return (void *)(p - 1);
199		}
200	}
201	return NULL;
202}
203#endif
204#endif
205