1 // SPDX-License-Identifier: GPL-2.0-only
2 /* -*- linux-c -*- ------------------------------------------------------- *
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright 2007 rPath, Inc. - All Rights Reserved
6 *
7 * ----------------------------------------------------------------------- */
8
9 /*
10 * Simple command-line parser for early boot.
11 */
12
13 #include "boot.h"
14
15 static inline int myisspace(u8 c)
16 {
17 return c <= ' '; /* Close enough approximation */
18 }
19
20 /*
21 * Find a non-boolean option, that is, "option=argument". In accordance
22 * with standard Linux practice, if this option is repeated, this returns
23 * the last instance on the command line.
24 *
25 * Returns the length of the argument (regardless of if it was
26 * truncated to fit in the buffer), or -1 on not found.
27 */
28 int __cmdline_find_option(unsigned long cmdline_ptr, const char *option, char *buffer, int bufsize)
29 {
30 addr_t cptr;
31 char c;
32 int len = -1;
33 const char *opptr = NULL;
34 char *bufptr = buffer;
35 enum {
36 st_wordstart, /* Start of word/after whitespace */
37 st_wordcmp, /* Comparing this word */
38 st_wordskip, /* Miscompare, skip */
39 st_bufcpy /* Copying this to buffer */
40 } state = st_wordstart;
41
42 if (!cmdline_ptr)
43 return -1; /* No command line */
44
45 cptr = cmdline_ptr & 0xf;
46 set_fs(cmdline_ptr >> 4);
47
48 while (cptr < 0x10000 && (c = rdfs8(cptr++))) {
49 switch (state) {
50 case st_wordstart:
51 if (myisspace(c))
52 break;
53
54 /* else */
55 state = st_wordcmp;
56 opptr = option;
57 fallthrough;
58
59 case st_wordcmp:
60 if (c == '=' && !*opptr) {
61 len = 0;
62 bufptr = buffer;
63 state = st_bufcpy;
64 } else if (myisspace(c)) {
65 state = st_wordstart;
66 } else if (c != *opptr++) {
67 state = st_wordskip;
68 }
69 break;
70
71 case st_wordskip:
72 if (myisspace(c))
73 state = st_wordstart;
74 break;
75
76 case st_bufcpy:
77 if (myisspace(c)) {
78 state = st_wordstart;
79 } else {
80 if (len < bufsize-1)
81 *bufptr++ = c;
82 len++;
83 }
84 break;
85 }
86 }
87
88 if (bufsize)
89 *bufptr = '\0';
90
91 return len;
92 }
93
94 /*
95 * Find a boolean option (like quiet,noapic,nosmp....)
96 *
97 * Returns the position of that option (starts counting with 1)
98 * or 0 on not found
99 */
100 int __cmdline_find_option_bool(unsigned long cmdline_ptr, const char *option)
101 {
102 addr_t cptr;
103 char c;
104 int pos = 0, wstart = 0;
105 const char *opptr = NULL;
106 enum {
107 st_wordstart, /* Start of word/after whitespace */
108 st_wordcmp, /* Comparing this word */
109 st_wordskip, /* Miscompare, skip */
110 } state = st_wordstart;
111
112 if (!cmdline_ptr)
113 return -1; /* No command line */
114
115 cptr = cmdline_ptr & 0xf;
116 set_fs(cmdline_ptr >> 4);
117
118 while (cptr < 0x10000) {
119 c = rdfs8(cptr++);
120 pos++;
121
122 switch (state) {
123 case st_wordstart:
124 if (!c)
125 return 0;
126 else if (myisspace(c))
127 break;
128
129 state = st_wordcmp;
130 opptr = option;
131 wstart = pos;
132 fallthrough;
133
134 case st_wordcmp:
135 if (!*opptr)
136 if (!c || myisspace(c))
137 return wstart;
138 else
139 state = st_wordskip;
140 else if (!c)
141 return 0;
142 else if (c != *opptr++)
143 state = st_wordskip;
144 break;
145
146 case st_wordskip:
147 if (!c)
148 return 0;
149 else if (myisspace(c))
150 state = st_wordstart;
151 break;
152 }
153 }
154
155 return 0; /* Buffer overrun */
156 }
157
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