Shell Programming and Scripting

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

#define err(x) {printf("\nError: %s... Exiting...\n", x); exit(1);}

static unsigned char pat1[] = {0x99, 0x11, 0x45, 0x27};
static unsigned char pat2[] = {0x73, 0x49};

int main(int argc, char **argv)
{

        if(argc < 2)
                err("File name missing");

        unsigned char buf[32];
        unsigned char *ptr = buf;
        int pos = 0;

        FILE *fp = fopen(argv[1], "rb");
        if(!fp) err("Unable to open the file");

        while(!feof(fp)){
                fread(ptr, sizeof(char), 1, fp);
                pos = ftell(fp);
                if(buf[0] == 0x32){
                        fread(ptr+1, sizeof(char), 19, fp);
                        if(memcmp(buf+4, pat1, 4) && memcmp(buf+12, pat2, 2)){
                                fseek(fp, pos, SEEK_SET);
                                continue;
                        }else{
                                int i=0;
                                for(i=0;i<=19;i++) printf("%02x ", buf[i]);
                                printf("\n");
                        }
                }
        }
        return 0;
}

user@Imperfecto_:~$ gcc extract.c -o extract 
user@Imperfecto_:~$ ./extract binfile.txt 
32 00 00 01 99 11 45 27 89 34 55 0f 73 49 45 49 23 2f ff ff 
32 00 00 02 99 11 45 27 89 34 55 1f 73 49 45 54 76 8f ff ff 
user@Imperfecto_:~$

1- Each block begins with the hex 32 (1 byte) and ends with FF. After the FF of the last block, it follows 33.
2- Next sequence to extract is the correlative (3 bytes) --> I mean, 1, 2, 3...N
3- Next sequence to extract is Product Series (8 bytes) --> The first 4 bytes are always "99 11 45 27"
4- Next sequence to extract is Product Model (8 bytes) --> The first 2 bytes are always "73 49"

static unsigned char pat3[] = {0x03, 0x8};