1 /* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright 2007 rPath, Inc. - All Rights Reserved
5 *
6 * This file is part of the Linux kernel, and is made available under
7 * the terms of the GNU General Public License version 2.
8 *
9 * ----------------------------------------------------------------------- */
10
11 /*
12 * Simple command-line parser for early boot.
13 */
14
15 #include "boot.h"
16
myisspace(u8 c)17 static inline int myisspace(u8 c)
18 {
19 return c <= ' '; /* Close enough approximation */
20 }
21
22 /*
23 * Find a non-boolean option, that is, "option=argument". In accordance
24 * with standard Linux practice, if this option is repeated, this returns
25 * the last instance on the command line.
26 *
27 * Returns the length of the argument (regardless of if it was
28 * truncated to fit in the buffer), or -1 on not found.
29 */
cmdline_find_option(const char * option,char * buffer,int bufsize)30 int cmdline_find_option(const char *option, char *buffer, int bufsize)
31 {
32 u32 cmdline_ptr = boot_params.hdr.cmd_line_ptr;
33 addr_t cptr;
34 char c;
35 int len = -1;
36 const char *opptr = NULL;
37 char *bufptr = buffer;
38 enum {
39 st_wordstart, /* Start of word/after whitespace */
40 st_wordcmp, /* Comparing this word */
41 st_wordskip, /* Miscompare, skip */
42 st_bufcpy /* Copying this to buffer */
43 } state = st_wordstart;
44
45 if (!cmdline_ptr || cmdline_ptr >= 0x100000)
46 return -1; /* No command line, or inaccessible */
47
48 cptr = cmdline_ptr & 0xf;
49 set_fs(cmdline_ptr >> 4);
50
51 while (cptr < 0x10000 && (c = rdfs8(cptr++))) {
52 switch (state) {
53 case st_wordstart:
54 if (myisspace(c))
55 break;
56
57 /* else */
58 state = st_wordcmp;
59 opptr = option;
60 /* fall through */
61
62 case st_wordcmp:
63 if (c == '=' && !*opptr) {
64 len = 0;
65 bufptr = buffer;
66 state = st_bufcpy;
67 } else if (myisspace(c)) {
68 state = st_wordstart;
69 } else if (c != *opptr++) {
70 state = st_wordskip;
71 }
72 break;
73
74 case st_wordskip:
75 if (myisspace(c))
76 state = st_wordstart;
77 break;
78
79 case st_bufcpy:
80 if (myisspace(c)) {
81 state = st_wordstart;
82 } else {
83 if (len < bufsize-1)
84 *bufptr++ = c;
85 len++;
86 }
87 break;
88 }
89 }
90
91 if (bufsize)
92 *bufptr = '\0';
93
94 return len;
95 }
96
97 /*
98 * Find a boolean option (like quiet,noapic,nosmp....)
99 *
100 * Returns the position of that option (starts counting with 1)
101 * or 0 on not found
102 */
cmdline_find_option_bool(const char * option)103 int cmdline_find_option_bool(const char *option)
104 {
105 u32 cmdline_ptr = boot_params.hdr.cmd_line_ptr;
106 addr_t cptr;
107 char c;
108 int pos = 0, wstart = 0;
109 const char *opptr = NULL;
110 enum {
111 st_wordstart, /* Start of word/after whitespace */
112 st_wordcmp, /* Comparing this word */
113 st_wordskip, /* Miscompare, skip */
114 } state = st_wordstart;
115
116 if (!cmdline_ptr || cmdline_ptr >= 0x100000)
117 return -1; /* No command line, or inaccessible */
118
119 cptr = cmdline_ptr & 0xf;
120 set_fs(cmdline_ptr >> 4);
121
122 while (cptr < 0x10000) {
123 c = rdfs8(cptr++);
124 pos++;
125
126 switch (state) {
127 case st_wordstart:
128 if (!c)
129 return 0;
130 else if (myisspace(c))
131 break;
132
133 state = st_wordcmp;
134 opptr = option;
135 wstart = pos;
136 /* fall through */
137
138 case st_wordcmp:
139 if (!*opptr)
140 if (!c || myisspace(c))
141 return wstart;
142 else
143 state = st_wordskip;
144 else if (!c)
145 return 0;
146 else if (c != *opptr++)
147 state = st_wordskip;
148 break;
149
150 case st_wordskip:
151 if (!c)
152 return 0;
153 else if (myisspace(c))
154 state = st_wordstart;
155 break;
156 }
157 }
158
159 return 0; /* Buffer overrun */
160 }
161