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(u32 cmdline_ptr,const char * option,char * buffer,int bufsize)30 int __cmdline_find_option(u32 cmdline_ptr, const char *option, char *buffer, int bufsize)
31 {
32 addr_t cptr;
33 char c;
34 int len = -1;
35 const char *opptr = NULL;
36 char *bufptr = buffer;
37 enum {
38 st_wordstart, /* Start of word/after whitespace */
39 st_wordcmp, /* Comparing this word */
40 st_wordskip, /* Miscompare, skip */
41 st_bufcpy /* Copying this to buffer */
42 } state = st_wordstart;
43
44 if (!cmdline_ptr || cmdline_ptr >= 0x100000)
45 return -1; /* No command line, or inaccessible */
46
47 cptr = cmdline_ptr & 0xf;
48 set_fs(cmdline_ptr >> 4);
49
50 while (cptr < 0x10000 && (c = rdfs8(cptr++))) {
51 switch (state) {
52 case st_wordstart:
53 if (myisspace(c))
54 break;
55
56 /* else */
57 state = st_wordcmp;
58 opptr = option;
59 /* fall through */
60
61 case st_wordcmp:
62 if (c == '=' && !*opptr) {
63 len = 0;
64 bufptr = buffer;
65 state = st_bufcpy;
66 } else if (myisspace(c)) {
67 state = st_wordstart;
68 } else if (c != *opptr++) {
69 state = st_wordskip;
70 }
71 break;
72
73 case st_wordskip:
74 if (myisspace(c))
75 state = st_wordstart;
76 break;
77
78 case st_bufcpy:
79 if (myisspace(c)) {
80 state = st_wordstart;
81 } else {
82 if (len < bufsize-1)
83 *bufptr++ = c;
84 len++;
85 }
86 break;
87 }
88 }
89
90 if (bufsize)
91 *bufptr = '\0';
92
93 return len;
94 }
95
96 /*
97 * Find a boolean option (like quiet,noapic,nosmp....)
98 *
99 * Returns the position of that option (starts counting with 1)
100 * or 0 on not found
101 */
__cmdline_find_option_bool(u32 cmdline_ptr,const char * option)102 int __cmdline_find_option_bool(u32 cmdline_ptr, const char *option)
103 {
104 addr_t cptr;
105 char c;
106 int pos = 0, wstart = 0;
107 const char *opptr = NULL;
108 enum {
109 st_wordstart, /* Start of word/after whitespace */
110 st_wordcmp, /* Comparing this word */
111 st_wordskip, /* Miscompare, skip */
112 } state = st_wordstart;
113
114 if (!cmdline_ptr || cmdline_ptr >= 0x100000)
115 return -1; /* No command line, or inaccessible */
116
117 cptr = cmdline_ptr & 0xf;
118 set_fs(cmdline_ptr >> 4);
119
120 while (cptr < 0x10000) {
121 c = rdfs8(cptr++);
122 pos++;
123
124 switch (state) {
125 case st_wordstart:
126 if (!c)
127 return 0;
128 else if (myisspace(c))
129 break;
130
131 state = st_wordcmp;
132 opptr = option;
133 wstart = pos;
134 /* fall through */
135
136 case st_wordcmp:
137 if (!*opptr)
138 if (!c || myisspace(c))
139 return wstart;
140 else
141 state = st_wordskip;
142 else if (!c)
143 return 0;
144 else if (c != *opptr++)
145 state = st_wordskip;
146 break;
147
148 case st_wordskip:
149 if (!c)
150 return 0;
151 else if (myisspace(c))
152 state = st_wordstart;
153 break;
154 }
155 }
156
157 return 0; /* Buffer overrun */
158 }
159