Usermode/Applications/MultibootCheck_src/MultibootCheck.c

   1 /*
   2  */
   3
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <stdint.h>
   7
   8 // === CONSTANTS ===
   9 #define SCAN_SPACE      8192
  10 #define MAGIC   0x1BADB002
  11
  12 // === TYPES ===
  13 typedef struct {
  14         uint32_t        Magic;
  15         uint32_t        Flags;
  16         uint32_t        Checksum;
  17 } __attribute__((packed)) tMBootImg;
  18
  19 // === PROTOTYPES ===
  20 void    CheckMultiboot(char *file);
  21
  22 // === CODE ===
  23 /**
  24  */
  25 int main(int argc, char *argv[])
  26 {
  27         if(argc != 2)
  28         {
  29                 fprintf(stderr, "Usage: %s <file>\n", argv[0]);
  30                 fprintf(stderr, " <file>        Path of file to validate\n");
  31                 fprintf(stderr, "\n");
  32         }
  33
  34         CheckMultiboot(argv[1]);
  35
  36         return 0;
  37 }
  38
  39 /**
  40  */
  41 void CheckMultiboot(char *file)
  42 {
  43         FILE    *fp = fopen(file, "rb");
  44          int    len, ofs;
  45         char    buf[SCAN_SPACE];
  46         tMBootImg       *img;
  47
  48         // Error Check
  49         if(fp == NULL) {
  50                 fprintf(stderr, "Unable to open '%s' for reading\n", file);
  51                 exit(EXIT_FAILURE);
  52         }
  53
  54         // Get file length
  55         fseek(fp, 0, SEEK_END);
  56         len = ftell(fp);
  57         fseek(fp, 0, SEEK_SET);
  58
  59         // Clip
  60         if(len > SCAN_SPACE)    len = SCAN_SPACE;
  61
  62         // Read
  63         fread(buf, len, 1, fp);
  64
  65         // Scan
  66         for(ofs = 0; ofs < len-sizeof(tMBootImg); ofs += 4)
  67         {
  68                 img = (void*)&buf[ofs];
  69                 // Check magic value
  70                 if(img->Magic != MAGIC) continue;
  71                 // Validate checksum
  72                 if(img->Magic + img->Flags + img->Checksum != 0) {
  73                         printf("Checksum fail at 0x%x\n", ofs);
  74                         continue;
  75                 }
  76                 // Check undefined feature flags
  77                 if(img->Flags & 0xFFF8) {
  78                         printf("Header at 0x%x uses undefined features (0x%lx)\n", ofs, img->Flags);
  79                         return ;
  80                 }
  81                 // Print success
  82                 printf("Found Multiboot header at 0x%x\n", ofs);
  83                 return ;
  84         }
  85
  86         printf("No multiboot header found\n");
  87 }