1 /* mbchk - a simple checker for the format of a Multiboot kernel */ 2 /* 3 * Copyright (C) 1999,2001,2002 Free Software Foundation, Inc. 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 18 */ 19 20 #include <config.h> 21 22 #include <stdio.h> 23 #include <stdlib.h> 24 #include <getopt.h> 25 #include <multiboot.h> 26 27 static int quiet = 0; 28 static char *optstring = "hvq"; 29 static struct option longopts[] = 30 { 31 {"help", no_argument, 0, 'h'}, 32 {"version", no_argument, 0, 'v'}, 33 {"quiet", no_argument, 0, 'q'}, 34 {0} 35 }; 36 37 static void 38 usage (int status) 39 { 40 if (status) 41 fprintf (stderr, "Try ``mbchk --help'' for more information.\n"); 42 else 43 printf ("Usage: mbchk [OPTION]... [FILE]...\n" 44 "Check if the format of FILE complies with the Multiboot Specification.\n" 45 "\n" 46 "-q, --quiet suppress all normal output\n" 47 "-h, --help display this help and exit\n" 48 "-v, --version output version information and exit.\n" 49 "\n" 50 "Report bugs to <bug-grub@gnu.org>.\n"); 51 52 exit (status); 53 } 54 55 static int 56 check_multiboot (const char *filename, FILE *fp) 57 { 58 multiboot_header_t *mbh = 0; 59 int i; 60 char buf[8192]; 61 62 if (fread (buf, 1, 8192, fp) < 0) 63 { 64 fprintf (stderr, "%s: Read error.\n", filename); 65 return 0; 66 } 67 68 for (i = 0; i < 8192 - sizeof (multiboot_header_t); i++) 69 { 70 unsigned long magic = *((unsigned long *) (buf + i)); 71 72 if (magic == MULTIBOOT_HEADER_MAGIC) 73 { 74 mbh = (multiboot_header_t *) (buf + i); 75 break; 76 } 77 } 78 79 if (! mbh) 80 { 81 fprintf (stderr, "%s: No Multiboot header.\n", filename); 82 return 0; 83 } 84 85 if (! quiet) 86 printf ("%s: The Multiboot header is found at the offset %d.\n", 87 filename, i); 88 89 /* Check for the checksum. */ 90 if (mbh->magic + mbh->flags + mbh->checksum != 0) 91 { 92 fprintf (stderr, 93 "%s: Bad checksum (0x%lx).\n", 94 filename, mbh->checksum); 95 return 0; 96 } 97 98 /* Reserved flags must be zero. */ 99 if (mbh->flags & ~0x00010003) 100 { 101 fprintf (stderr, 102 "%s: Non-zero is found in reserved flags (0x%lx).\n", 103 filename, mbh->flags); 104 return 0; 105 } 106 107 if (! quiet) 108 { 109 printf ("%s: Page alignment is turned %s.\n", 110 filename, (mbh->flags & 0x1)? "on" : "off"); 111 printf ("%s: Memory information is turned %s.\n", 112 filename, (mbh->flags & 0x2)? "on" : "off"); 113 printf ("%s: Address fields is turned %s.\n", 114 filename, (mbh->flags & 0x10000)? "on" : "off"); 115 } 116 117 /* Check for the address fields. */ 118 if (mbh->flags & 0x10000) 119 { 120 if (mbh->header_addr < mbh->load_addr) 121 { 122 fprintf (stderr, 123 "%s: header_addr is less than " 124 "load_addr (0x%lx > 0x%lx).\n", 125 filename, mbh->header_addr, mbh->load_addr); 126 return 0; 127 } 128 129 if (mbh->load_end_addr && mbh->load_addr >= mbh->load_end_addr) 130 { 131 fprintf (stderr, 132 "%s: load_addr is not less than load_end_addr" 133 " (0x%lx >= 0x%lx).\n", 134 filename, mbh->load_addr, mbh->load_end_addr); 135 return 0; 136 } 137 138 if (mbh->bss_end_addr && mbh->load_end_addr > mbh->bss_end_addr) 139 { 140 fprintf (stderr, 141 "%s: load_end_addr is greater than bss_end_addr" 142 " (0x%lx > 0x%lx).\n", 143 filename, mbh->load_end_addr, mbh->bss_end_addr); 144 return 0; 145 } 146 147 if (mbh->load_addr > mbh->entry_addr) 148 { 149 fprintf (stderr, 150 "%s: load_addr is greater than entry_addr" 151 " (0x%lx > 0x%lx).\n", 152 filename, mbh->load_addr, mbh->entry_addr); 153 return 0; 154 } 155 156 /* FIXME: It is better to check if the entry address is within the 157 file, especially when the load end address is zero. */ 158 if (mbh->load_end_addr && mbh->load_end_addr <= mbh->entry_addr) 159 { 160 fprintf (stderr, 161 "%s: load_end_addr is not greater than entry_addr" 162 " (0x%lx <= 0x%lx).\n", 163 filename, mbh->load_end_addr, mbh->entry_addr); 164 return 0; 165 } 166 167 /* This is a GRUB-specific limitation. */ 168 if (mbh->load_addr < 0x100000) 169 { 170 fprintf (stderr, 171 "%s: Cannot be loaded at less than 1MB by GRUB" 172 " (0x%lx).\n", 173 filename, mbh->load_addr); 174 return 0; 175 } 176 } 177 178 if (! quiet) 179 printf ("%s: All checks passed.\n", filename); 180 181 return 1; 182 } 183 184 int 185 main (int argc, char *argv[]) 186 { 187 int c; 188 189 do 190 { 191 c = getopt_long (argc, argv, optstring, longopts, 0); 192 switch (c) 193 { 194 case EOF: 195 break; 196 197 case 'h': 198 usage (0); 199 break; 200 201 case 'v': 202 printf ("mbchk (GNU GRUB " VERSION ")\n"); 203 exit (0); 204 break; 205 206 case 'q': 207 quiet = 1; 208 break; 209 210 default: 211 usage (1); 212 break; 213 } 214 } 215 while (c != EOF); 216 217 if (optind < argc) 218 { 219 while (optind < argc) 220 { 221 FILE *fp; 222 223 fp = fopen (argv[optind], "r"); 224 if (! fp) 225 { 226 fprintf (stderr, "%s: No such file.\n", argv[optind]); 227 exit (1); 228 } 229 230 if (! check_multiboot (argv[optind], fp)) 231 exit (1); 232 233 fclose (fp); 234 optind++; 235 } 236 } 237 else 238 { 239 if (! check_multiboot ("<stdin>", stdin)) 240 exit (1); 241 } 242 243 return 0; 244 } 245