unpacker.c

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

#define NOB_IMPLEMENTATION
#include "nob.h"

#include "tar.h"

void print_usage(const char *program_name)
{
    fprintf(stderr, "Usage: %s <input.tar> <output/>\n", program_name);
}

int main(int argc, char **argv)
{
    const char *program_name = shift(argv, argc);

    if (argc <= 0) {
        print_usage(program_name);
        fprintf(stderr, "ERROR: no input is provided\n");
        return 1;
    }
    const char *input_path = shift(argv, argc);

    if (argc <= 0) {
        print_usage(program_name);
        fprintf(stderr, "ERROR: no output is provided\n");
        return 1;
    }
    const char *output_path = shift(argv, argc);

    String_Builder sb = {0};
    if (!read_entire_file(input_path, &sb)) return 1;
    printf("%s contains %zu bytes (%zu)\n", input_path, sb.count, sb.count%512);
    assert(sb.count%512 == 0);
    Header *records = (Header *)sb.items;
    size_t mark = temp_save();
    while (records->file_path[0]) {
        temp_rewind(mark);
        size_t file_path_len = strlen(records->file_path);
        char *output_file_path = temp_sprintf("%s/%s", output_path, records->file_path);
        if (records->file_path[file_path_len - 1] == '/') {
            if (!mkdir_if_not_exists(output_file_path)) return 1;
            records += 1;
        } else {
            unsigned long long file_size = strtoull(records->file_size, NULL, 8);
            records += 1;
            if (!write_entire_file(output_file_path, records, file_size)) return 1;
            nob_log(INFO, "created file `%s`", output_file_path);
            records += (file_size + 511)/512;
        }
    }
    return 0;
}