sophos - level2

// by petter wahlman, http://www.twitter.com/badeip
// convert ascii hex to binary.
// usage:
// gcc tohex.c -o tohex
// tail -20 level2.txt | sed 's/[^a-f0-9]//g'| tr -d '\n' > level2.tmp
// tohex level2.tmp > level2.zip
//
// ugly code:

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

int main(int argc, char **argv)
{
    unsigned char *buf;
    char *target;
    struct stat st;
    int i;
    int fd;

    target = "./level2.tmp";
    if (argc > 1)
        target = argv[2];

    fd = open(target, O_RDONLY);
    if (-1 == fd) {
        perror(target);
        return 1;
    }

    fstat(fd, &st);

    buf = malloc(st.st_size);
    read(fd, buf, st.st_size);
    for (i = 0; i < st.st_size; i += 2) {
        char tmp[3];
        int val;

        strncpy(tmp, (const char *)&buf[i], 2);
        val = strtoul(tmp, NULL, 16);
        printf("%c", val);
    }

    close(fd);

    return 0;
}