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1// SPDX-License-Identifier: GPL-2.0-only
2/*
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#include <asm/cmdline.h>
11
12static inline int myisspace(u8 c)
13{
14 return c <= ' '; /* Close enough approximation */
15}
16
17/*
18 * Find a boolean option (like quiet,noapic,nosmp....)
19 *
20 * @cmdline: the cmdline string
21 * @max_cmdline_size: the maximum size of cmdline
22 * @option: option string to look for
23 *
24 * Returns the position of that @option (starts counting with 1)
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.
28 */
29static int
30__cmdline_find_option_bool(const char *cmdline, int max_cmdline_size,
31 const char *option)
32{
33 char c;
34 int pos = 0, wstart = 0;
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
45 /*
46 * This 'pos' check ensures we do not overrun
47 * a non-NULL-terminated 'cmdline'
48 */
49 while (pos < max_cmdline_size) {
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;
63 fallthrough;
64
65 case st_wordcmp:
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 */
73 if (!c || myisspace(c))
74 return wstart;
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 */
80 } else if (!c) {
81 /*
82 * Hit the NULL terminator on the end of
83 * cmdline.
84 */
85 return 0;
86 } else if (c == *opptr++) {
87 /*
88 * We are currently matching, so continue
89 * to the next character on the cmdline.
90 */
91 break;
92 }
93 state = st_wordskip;
94 fallthrough;
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}
107
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 */
122static 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;
156 fallthrough;
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;
177 fallthrough;
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
206int cmdline_find_option_bool(const char *cmdline, const char *option)
207{
208 return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option);
209}
210
211int 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}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
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#include <asm/cmdline.h>
11
12static inline int myisspace(u8 c)
13{
14 return c <= ' '; /* Close enough approximation */
15}
16
17/*
18 * Find a boolean option (like quiet,noapic,nosmp....)
19 *
20 * @cmdline: the cmdline string
21 * @max_cmdline_size: the maximum size of cmdline
22 * @option: option string to look for
23 *
24 * Returns the position of that @option (starts counting with 1)
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.
28 */
29static int
30__cmdline_find_option_bool(const char *cmdline, int max_cmdline_size,
31 const char *option)
32{
33 char c;
34 int pos = 0, wstart = 0;
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
45 /*
46 * This 'pos' check ensures we do not overrun
47 * a non-NULL-terminated 'cmdline'
48 */
49 while (pos < max_cmdline_size) {
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;
63 fallthrough;
64
65 case st_wordcmp:
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 */
73 if (!c || myisspace(c))
74 return wstart;
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 */
80 } else if (!c) {
81 /*
82 * Hit the NULL terminator on the end of
83 * cmdline.
84 */
85 return 0;
86 } else if (c == *opptr++) {
87 /*
88 * We are currently matching, so continue
89 * to the next character on the cmdline.
90 */
91 break;
92 }
93 state = st_wordskip;
94 fallthrough;
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}
107
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 */
122static 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;
156 fallthrough;
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;
177 fallthrough;
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
206int cmdline_find_option_bool(const char *cmdline, const char *option)
207{
208 return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option);
209}
210
211int 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}