Find binary file inside other binary file

blobfind.c

#include <stdio.h>
#include <stdlib.h>

int main(int argc,char **argv)
{
   FILE *afile = NULL;
   FILE *bfile = NULL;
   unsigned char *bbuffer = NULL;
   int achar;
   int bsize;
   int acnt=0,bcnt=0,i;
  

   if(argc<3){
     printf("Usage: %s file1 file2\r\n Program tries to find file2 (binary) inside file1\r\n",argv[0]);
     return 1;
   }


   afile = fopen(argv[1], "rb");
   bfile = fopen(argv[2], "rb");


   if(afile == NULL || bfile == NULL){
      perror("Filename correct? ");
      goto shutdown;
   }

   fseek(bfile, 0L, SEEK_END);
   bsize = ftell(bfile);

   fseek(bfile, 0L, SEEK_SET);

   bbuffer = malloc(bsize);
   
   if(1 != fread(bbuffer,bsize,1,bfile)){
     perror("Unable to read file2");
     goto shutdown;
   }

  /* for(i=0;i<bsize;i++){
     printf("bbuffer[%i]=%i\r\n",i,bbuffer[i]);
   }*/
   //TODO: abort when not enugh bytes are left
   while(1)
     {
        achar = getc(afile);
        acnt++;
        if(achar == EOF){
          printf("Couldn't find blob2 inside blob1\r\n");
          goto shutdown;
        }

//      printf("achar: %u, acnt: %i, bbuffer[bcnt]: %u, bcnt: %i, bsize: %i\r\n",achar,acnt, bbuffer[bcnt],bcnt,bsize);

       if((unsigned char)achar == bbuffer[bcnt]){
         bcnt++;
       }else{
         bcnt = 0;
       }

      if(bcnt == bsize){
        printf("Found blob2 at offset 0x%08X\r\n",acnt-bcnt);
        goto shutdown;
      }
   }

shutdown:
   if(afile)
     fclose(afile);
   if(bfile)
     fclose(bfile);
   if(bbuffer)
     free(bbuffer);

   return 0;
}