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97873a3d | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1b1ded57 | 2 | /* |
1b1ded57 BP |
3 | * |
4 | * Misc librarized functions for cmdline poking. | |
5 | */ | |
6 | #include <linux/kernel.h> | |
7 | #include <linux/string.h> | |
8 | #include <linux/ctype.h> | |
9 | #include <asm/setup.h> | |
10 | ||
11 | static inline int myisspace(u8 c) | |
12 | { | |
13 | return c <= ' '; /* Close enough approximation */ | |
14 | } | |
15 | ||
16 | /** | |
17 | * Find a boolean option (like quiet,noapic,nosmp....) | |
18 | * | |
19 | * @cmdline: the cmdline string | |
20 | * @option: option string to look for | |
21 | * | |
22 | * Returns the position of that @option (starts counting with 1) | |
02afeaae DH |
23 | * or 0 on not found. @option will only be found if it is found |
24 | * as an entire word in @cmdline. For instance, if @option="car" | |
25 | * then a cmdline which contains "cart" will not match. | |
1b1ded57 | 26 | */ |
8c051775 DH |
27 | static int |
28 | __cmdline_find_option_bool(const char *cmdline, int max_cmdline_size, | |
29 | const char *option) | |
1b1ded57 BP |
30 | { |
31 | char c; | |
02afeaae | 32 | int pos = 0, wstart = 0; |
1b1ded57 BP |
33 | const char *opptr = NULL; |
34 | enum { | |
35 | st_wordstart = 0, /* Start of word/after whitespace */ | |
36 | st_wordcmp, /* Comparing this word */ | |
37 | st_wordskip, /* Miscompare, skip */ | |
38 | } state = st_wordstart; | |
39 | ||
40 | if (!cmdline) | |
41 | return -1; /* No command line */ | |
42 | ||
02afeaae DH |
43 | /* |
44 | * This 'pos' check ensures we do not overrun | |
45 | * a non-NULL-terminated 'cmdline' | |
46 | */ | |
8c051775 | 47 | while (pos < max_cmdline_size) { |
1b1ded57 BP |
48 | c = *(char *)cmdline++; |
49 | pos++; | |
50 | ||
51 | switch (state) { | |
52 | case st_wordstart: | |
53 | if (!c) | |
54 | return 0; | |
55 | else if (myisspace(c)) | |
56 | break; | |
57 | ||
58 | state = st_wordcmp; | |
59 | opptr = option; | |
60 | wstart = pos; | |
61 | /* fall through */ | |
62 | ||
63 | case st_wordcmp: | |
02afeaae DH |
64 | if (!*opptr) { |
65 | /* | |
66 | * We matched all the way to the end of the | |
67 | * option we were looking for. If the | |
68 | * command-line has a space _or_ ends, then | |
69 | * we matched! | |
70 | */ | |
1b1ded57 BP |
71 | if (!c || myisspace(c)) |
72 | return wstart; | |
abcdc1c6 DH |
73 | /* |
74 | * We hit the end of the option, but _not_ | |
75 | * the end of a word on the cmdline. Not | |
76 | * a match. | |
77 | */ | |
02afeaae DH |
78 | } else if (!c) { |
79 | /* | |
80 | * Hit the NULL terminator on the end of | |
81 | * cmdline. | |
82 | */ | |
1b1ded57 | 83 | return 0; |
abcdc1c6 DH |
84 | } else if (c == *opptr++) { |
85 | /* | |
86 | * We are currently matching, so continue | |
87 | * to the next character on the cmdline. | |
88 | */ | |
89 | break; | |
02afeaae | 90 | } |
abcdc1c6 DH |
91 | state = st_wordskip; |
92 | /* fall through */ | |
1b1ded57 BP |
93 | |
94 | case st_wordskip: | |
95 | if (!c) | |
96 | return 0; | |
97 | else if (myisspace(c)) | |
98 | state = st_wordstart; | |
99 | break; | |
100 | } | |
101 | } | |
102 | ||
103 | return 0; /* Buffer overrun */ | |
104 | } | |
8c051775 | 105 | |
e505371d TL |
106 | /* |
107 | * Find a non-boolean option (i.e. option=argument). In accordance with | |
108 | * standard Linux practice, if this option is repeated, this returns the | |
109 | * last instance on the command line. | |
110 | * | |
111 | * @cmdline: the cmdline string | |
112 | * @max_cmdline_size: the maximum size of cmdline | |
113 | * @option: option string to look for | |
114 | * @buffer: memory buffer to return the option argument | |
115 | * @bufsize: size of the supplied memory buffer | |
116 | * | |
117 | * Returns the length of the argument (regardless of if it was | |
118 | * truncated to fit in the buffer), or -1 on not found. | |
119 | */ | |
120 | static int | |
121 | __cmdline_find_option(const char *cmdline, int max_cmdline_size, | |
122 | const char *option, char *buffer, int bufsize) | |
123 | { | |
124 | char c; | |
125 | int pos = 0, len = -1; | |
126 | const char *opptr = NULL; | |
127 | char *bufptr = buffer; | |
128 | enum { | |
129 | st_wordstart = 0, /* Start of word/after whitespace */ | |
130 | st_wordcmp, /* Comparing this word */ | |
131 | st_wordskip, /* Miscompare, skip */ | |
132 | st_bufcpy, /* Copying this to buffer */ | |
133 | } state = st_wordstart; | |
134 | ||
135 | if (!cmdline) | |
136 | return -1; /* No command line */ | |
137 | ||
138 | /* | |
139 | * This 'pos' check ensures we do not overrun | |
140 | * a non-NULL-terminated 'cmdline' | |
141 | */ | |
142 | while (pos++ < max_cmdline_size) { | |
143 | c = *(char *)cmdline++; | |
144 | if (!c) | |
145 | break; | |
146 | ||
147 | switch (state) { | |
148 | case st_wordstart: | |
149 | if (myisspace(c)) | |
150 | break; | |
151 | ||
152 | state = st_wordcmp; | |
153 | opptr = option; | |
154 | /* fall through */ | |
155 | ||
156 | case st_wordcmp: | |
157 | if ((c == '=') && !*opptr) { | |
158 | /* | |
159 | * We matched all the way to the end of the | |
160 | * option we were looking for, prepare to | |
161 | * copy the argument. | |
162 | */ | |
163 | len = 0; | |
164 | bufptr = buffer; | |
165 | state = st_bufcpy; | |
166 | break; | |
167 | } else if (c == *opptr++) { | |
168 | /* | |
169 | * We are currently matching, so continue | |
170 | * to the next character on the cmdline. | |
171 | */ | |
172 | break; | |
173 | } | |
174 | state = st_wordskip; | |
175 | /* fall through */ | |
176 | ||
177 | case st_wordskip: | |
178 | if (myisspace(c)) | |
179 | state = st_wordstart; | |
180 | break; | |
181 | ||
182 | case st_bufcpy: | |
183 | if (myisspace(c)) { | |
184 | state = st_wordstart; | |
185 | } else { | |
186 | /* | |
187 | * Increment len, but don't overrun the | |
188 | * supplied buffer and leave room for the | |
189 | * NULL terminator. | |
190 | */ | |
191 | if (++len < bufsize) | |
192 | *bufptr++ = c; | |
193 | } | |
194 | break; | |
195 | } | |
196 | } | |
197 | ||
198 | if (bufsize) | |
199 | *bufptr = '\0'; | |
200 | ||
201 | return len; | |
202 | } | |
203 | ||
8c051775 DH |
204 | int cmdline_find_option_bool(const char *cmdline, const char *option) |
205 | { | |
206 | return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option); | |
207 | } | |
e505371d TL |
208 | |
209 | int cmdline_find_option(const char *cmdline, const char *option, char *buffer, | |
210 | int bufsize) | |
211 | { | |
212 | return __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option, | |
213 | buffer, bufsize); | |
214 | } |