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(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 */ 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