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 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 */ 30 int __cmdline_find_option(unsigned long 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) 45 return -1; /* No command line */ 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 */ 102 int __cmdline_find_option_bool(unsigned long 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) 115 return -1; /* No command line */ 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