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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> | |
65c24d7b | 10 | #include <asm/cmdline.h> |
1b1ded57 BP |
11 | |
12 | static inline int myisspace(u8 c) | |
13 | { | |
14 | return c <= ' '; /* Close enough approximation */ | |
15 | } | |
16 | ||
65c24d7b | 17 | /* |
1b1ded57 BP |
18 | * Find a boolean option (like quiet,noapic,nosmp....) |
19 | * | |
20 | * @cmdline: the cmdline string | |
65c24d7b | 21 | * @max_cmdline_size: the maximum size of cmdline |
1b1ded57 BP |
22 | * @option: option string to look for |
23 | * | |
24 | * Returns the position of that @option (starts counting with 1) | |
02afeaae DH |
25 | * or 0 on not found. @option will only be found if it is found |
26 | * as an entire word in @cmdline. For instance, if @option="car" | |
27 | * then a cmdline which contains "cart" will not match. | |
1b1ded57 | 28 | */ |
8c051775 DH |
29 | static int |
30 | __cmdline_find_option_bool(const char *cmdline, int max_cmdline_size, | |
31 | const char *option) | |
1b1ded57 BP |
32 | { |
33 | char c; | |
02afeaae | 34 | int pos = 0, wstart = 0; |
1b1ded57 BP |
35 | const char *opptr = NULL; |
36 | enum { | |
37 | st_wordstart = 0, /* Start of word/after whitespace */ | |
38 | st_wordcmp, /* Comparing this word */ | |
39 | st_wordskip, /* Miscompare, skip */ | |
40 | } state = st_wordstart; | |
41 | ||
42 | if (!cmdline) | |
43 | return -1; /* No command line */ | |
44 | ||
02afeaae DH |
45 | /* |
46 | * This 'pos' check ensures we do not overrun | |
47 | * a non-NULL-terminated 'cmdline' | |
48 | */ | |
8c051775 | 49 | while (pos < max_cmdline_size) { |
1b1ded57 BP |
50 | c = *(char *)cmdline++; |
51 | pos++; | |
52 | ||
53 | switch (state) { | |
54 | case st_wordstart: | |
55 | if (!c) | |
56 | return 0; | |
57 | else if (myisspace(c)) | |
58 | break; | |
59 | ||
60 | state = st_wordcmp; | |
61 | opptr = option; | |
62 | wstart = pos; | |
df561f66 | 63 | fallthrough; |
1b1ded57 BP |
64 | |
65 | case st_wordcmp: | |
02afeaae DH |
66 | if (!*opptr) { |
67 | /* | |
68 | * We matched all the way to the end of the | |
69 | * option we were looking for. If the | |
70 | * command-line has a space _or_ ends, then | |
71 | * we matched! | |
72 | */ | |
1b1ded57 BP |
73 | if (!c || myisspace(c)) |
74 | return wstart; | |
abcdc1c6 DH |
75 | /* |
76 | * We hit the end of the option, but _not_ | |
77 | * the end of a word on the cmdline. Not | |
78 | * a match. | |
79 | */ | |
02afeaae DH |
80 | } else if (!c) { |
81 | /* | |
82 | * Hit the NULL terminator on the end of | |
83 | * cmdline. | |
84 | */ | |
1b1ded57 | 85 | return 0; |
abcdc1c6 DH |
86 | } else if (c == *opptr++) { |
87 | /* | |
88 | * We are currently matching, so continue | |
89 | * to the next character on the cmdline. | |
90 | */ | |
91 | break; | |
02afeaae | 92 | } |
abcdc1c6 | 93 | state = st_wordskip; |
df561f66 | 94 | fallthrough; |
1b1ded57 BP |
95 | |
96 | case st_wordskip: | |
97 | if (!c) | |
98 | return 0; | |
99 | else if (myisspace(c)) | |
100 | state = st_wordstart; | |
101 | break; | |
102 | } | |
103 | } | |
104 | ||
105 | return 0; /* Buffer overrun */ | |
106 | } | |
8c051775 | 107 | |
e505371d TL |
108 | /* |
109 | * Find a non-boolean option (i.e. option=argument). In accordance with | |
110 | * standard Linux practice, if this option is repeated, this returns the | |
111 | * last instance on the command line. | |
112 | * | |
113 | * @cmdline: the cmdline string | |
114 | * @max_cmdline_size: the maximum size of cmdline | |
115 | * @option: option string to look for | |
116 | * @buffer: memory buffer to return the option argument | |
117 | * @bufsize: size of the supplied memory buffer | |
118 | * | |
119 | * Returns the length of the argument (regardless of if it was | |
120 | * truncated to fit in the buffer), or -1 on not found. | |
121 | */ | |
122 | static int | |
123 | __cmdline_find_option(const char *cmdline, int max_cmdline_size, | |
124 | const char *option, char *buffer, int bufsize) | |
125 | { | |
126 | char c; | |
127 | int pos = 0, len = -1; | |
128 | const char *opptr = NULL; | |
129 | char *bufptr = buffer; | |
130 | enum { | |
131 | st_wordstart = 0, /* Start of word/after whitespace */ | |
132 | st_wordcmp, /* Comparing this word */ | |
133 | st_wordskip, /* Miscompare, skip */ | |
134 | st_bufcpy, /* Copying this to buffer */ | |
135 | } state = st_wordstart; | |
136 | ||
137 | if (!cmdline) | |
138 | return -1; /* No command line */ | |
139 | ||
140 | /* | |
141 | * This 'pos' check ensures we do not overrun | |
142 | * a non-NULL-terminated 'cmdline' | |
143 | */ | |
144 | while (pos++ < max_cmdline_size) { | |
145 | c = *(char *)cmdline++; | |
146 | if (!c) | |
147 | break; | |
148 | ||
149 | switch (state) { | |
150 | case st_wordstart: | |
151 | if (myisspace(c)) | |
152 | break; | |
153 | ||
154 | state = st_wordcmp; | |
155 | opptr = option; | |
df561f66 | 156 | fallthrough; |
e505371d TL |
157 | |
158 | case st_wordcmp: | |
159 | if ((c == '=') && !*opptr) { | |
160 | /* | |
161 | * We matched all the way to the end of the | |
162 | * option we were looking for, prepare to | |
163 | * copy the argument. | |
164 | */ | |
165 | len = 0; | |
166 | bufptr = buffer; | |
167 | state = st_bufcpy; | |
168 | break; | |
169 | } else if (c == *opptr++) { | |
170 | /* | |
171 | * We are currently matching, so continue | |
172 | * to the next character on the cmdline. | |
173 | */ | |
174 | break; | |
175 | } | |
176 | state = st_wordskip; | |
df561f66 | 177 | fallthrough; |
e505371d TL |
178 | |
179 | case st_wordskip: | |
180 | if (myisspace(c)) | |
181 | state = st_wordstart; | |
182 | break; | |
183 | ||
184 | case st_bufcpy: | |
185 | if (myisspace(c)) { | |
186 | state = st_wordstart; | |
187 | } else { | |
188 | /* | |
189 | * Increment len, but don't overrun the | |
190 | * supplied buffer and leave room for the | |
191 | * NULL terminator. | |
192 | */ | |
193 | if (++len < bufsize) | |
194 | *bufptr++ = c; | |
195 | } | |
196 | break; | |
197 | } | |
198 | } | |
199 | ||
200 | if (bufsize) | |
201 | *bufptr = '\0'; | |
202 | ||
203 | return len; | |
204 | } | |
205 | ||
8c051775 DH |
206 | int cmdline_find_option_bool(const char *cmdline, const char *option) |
207 | { | |
208 | return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option); | |
209 | } | |
e505371d TL |
210 | |
211 | int cmdline_find_option(const char *cmdline, const char *option, char *buffer, | |
212 | int bufsize) | |
213 | { | |
214 | return __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option, | |
215 | buffer, bufsize); | |
216 | } |