Usermode/Applications/MultibootCheck_src/MultibootCheck.c

   1 /*
   2  */
   3
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6
   7 // === CONSTANTS ===
   8 #define SCAN_SPACE      8192
   9 #define MAGIC   0x1BADB002
  10
  11 // === TYPES ===
  12 typedef struct {
  13         unsigned long   Magic;
  14         unsigned long   Flags;
  15         unsigned long   Checksum;
  16 } tMBootImg;
  17
  18 // === PROTOTYPES ===
  19 void    CheckMultiboot(char *file);
  20
  21 // === CODE ===
  22 /**
  23  */
  24 int main(int argc, char *argv[])
  25 {
  26         if(argc != 2)
  27         {
  28                 fprintf(stderr, "Usage: %s <file>\n", argv[0]);
  29                 fprintf(stderr, " <file>        Path of file to validate\n");
  30                 fprintf(stderr, "\n");
  31         }
  32
  33         CheckMultiboot(argv[1]);
  34
  35         return 0;
  36 }
  37
  38 /**
  39  */
  40 void CheckMultiboot(char *file)
  41 {
  42         FILE    *fp = fopen(file, "rb");
  43          int    len, ofs;
  44         char    buf[SCAN_SPACE];
  45         tMBootImg       *img;
  46
  47         // Error Check
  48         if(fp == NULL) {
  49                 fprintf(stderr, "Unable to open '%s' for reading\n", file);
  50                 exit(EXIT_FAILURE);
  51         }
  52
  53         // Get file length
  54         fseek(fp, 0, SEEK_END);
  55         len = ftell(fp);
  56         fseek(fp, 0, SEEK_SET);
  57
  58         // Clip
  59         if(len > SCAN_SPACE)    len = SCAN_SPACE;
  60
  61         // Read
  62         fread(buf, len, 1, fp);
  63
  64         // Scan
  65         for(ofs = 0; ofs < len-sizeof(tMBootImg); ofs += 4)
  66         {
  67                 img = (void*)&buf[ofs];
  68                 // Check magic value
  69                 if(img->Magic != MAGIC) continue;
  70                 // Validate checksum
  71                 if(img->Magic + img->Flags + img->Checksum != 0) {
  72                         printf("Checksum fail at 0x%x\n", ofs);
  73                         continue;
  74                 }
  75                 // Check undefined feature flags
  76                 if(img->Flags & 0xFFF8) {
  77                         printf("Header at 0x%x uses undefined features (0x%lx)\n", ofs, img->Flags);
  78                         return ;
  79                 }
  80                 // Print success
  81                 printf("Found Multiboot header at 0x%x\n", ofs);
  82                 return ;
  83         }
  84
  85         printf("No multiboot header found\n");
  86 }