Simple Program Allowing MCPI level.dat Files To Be Used With NBT Editors

README.md

Pi-NBT

This is a simple command-line program that will remove or add the additional header information MCPI/Old MCPE uses in its level.dat files, this header information prevents many commonly used NBT ediors/libraries from reading MCPI/Old MCPE level.dat files.

Header Details

The header consists of 2 32-bit little-endian integers. The first integer is the "storage version", this is always equal to 3. The second integer is the remaining bytes in the file, this is used to detect file corruption.

Usage

pi-nbt add-header in.dat out.dat
pi-nbt remove-header in.dat out.dat

pi-nbt.c

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

#include <byteswap.h>

// Read Bytes From File And Then Reset Cursor Position
static int fread_and_reset(FILE *stream, unsigned char *buff, int size) {
    size = fread(buff, 1, size, stream);
    fseek(stream, -size, SEEK_CUR);
    return size;
}

// Copy File Contents
static void copy_file(FILE *input, FILE *output) {
    int c;
    while ((c = fgetc(input)) != EOF) {
        fputc(c, output);
    }
}

// Get File Size
static long int get_file_size(FILE *stream) {
    fseek(stream, 0, SEEK_END);
    long int size = ftell(stream);
    fseek(stream, 0, SEEK_SET);
    return size;
}

// Write Integer To File
static void write_int(FILE *stream, uint32_t x) {
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
    // Integer Must Be Little-Endian
    x = __bswap_32(x);
#endif
    fwrite(&x, 4, 1, stream);
}

#define STORAGE_VERSION 3

#define INVALID_ARGS() fprintf(stderr, "Invalid Arguments\n"); exit(1);
int main(int argc, char *argv[]) {
    if (argc == 4) {
        int add_header;
        if (strcmp(argv[1], "add-header") == 0) {
            add_header = 1;
        } else if (strcmp(argv[1], "remove-header") == 0) {
            add_header = 0;
        } else {
            INVALID_ARGS();
        }

        FILE *input = fopen(argv[2], "rb");
        FILE *output = fopen(argv[3], "wb");
        if (input == NULL || output == NULL) {
            fprintf(stderr, "Unable To Open Input/Output File(s)\n");
        }

        uint32_t first_byte = 0;
        int bytes_read = fread_and_reset(input, (unsigned char *) &first_byte, 4);
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
        // Convert Little-Endian To Big-Endian
        first_byte = __bswap_32(first_byte);
#endif
        int input_has_header = bytes_read == 4 && first_byte == STORAGE_VERSION;

        if ((add_header && input_has_header) || (!add_header && !input_has_header)) {
            fprintf(stderr, add_header ? "Header Already Exists\n" : "Header Is Already Removed\n");

            copy_file(input, output);
        } else if (add_header) {
            fprintf(stderr, "Adding Header...\n");

            write_int(output, STORAGE_VERSION);
            uint32_t size = get_file_size(input);
            write_int(output, size);
            copy_file(input, output);
        } else {
            fprintf(stderr, "Removing Header...\n");

            fseek(input, 8, SEEK_CUR);
            copy_file(input, output);
        }

        fprintf(stderr, "Done\n");

        fclose(input);
        fclose(output);
    } else if (argc == 1) {
        fprintf(stderr, "HELP:\n    %s <add-header|remove-header> <input-file> <output-file>\n", argv[0]);
        exit(1);
    } else {
        INVALID_ARGS();
    }
}