Decryptor/App/FileIO.cpp

//
// Created by miti on 21/07/19.
//

#include "UntrustedInclude/FileIO.h"

namespace FileIO {
    int write_to_fd(int fd, uint8_t* msg, size_t* expected_msg_length)
    {
        ssize_t bytes_written;
        lseek(fd, 0, SEEK_SET);

        bytes_written = write(fd, msg, *expected_msg_length);
        if(bytes_written == -1)
            return -1;

        fsync(fd);
        *expected_msg_length = bytes_written;
        return 0;
    }

    int read_from_fd(int fd, uint8_t* msg, size_t* expected_msg_length)
    {
        ssize_t bytes_read;
        lseek(fd, 0, SEEK_SET);

        bytes_read = read(fd, msg, *expected_msg_length);
        if(bytes_read == -1)
            return -1;
        *expected_msg_length = bytes_read;
        return 0;
    }

    int write_to_filename(char* filename, uint8_t* msg, size_t* expected_msg_length)
    {
        ssize_t bytes_written;
        FILE* file;

        file = fopen(filename, "w");
        if(file == NULL)
            return 2;

        bytes_written = fwrite(msg, 1, *expected_msg_length, file);
        if(bytes_written == -1)
            return -1;

        fsync(fileno(file));
        *expected_msg_length = bytes_written;
        fclose(file);
        return 0;
    }

    int read_from_filename(char* filename, uint8_t* msg, size_t* expected_msg_length)
    {
        ssize_t bytes_read;
        FILE* file;

        file = fopen(filename, "r");
        if(file == NULL)
            return 2;

        bytes_read = fread(msg, 1, *expected_msg_length, file);
        if(bytes_read == -1)
            return -1;
        *expected_msg_length = bytes_read;
        fclose(file);
        return 0;
    }

    size_t check_if_file_exists_return_size(char* filename)
    {
        int fd, ret_status;
        FILE* file;
        struct stat st;

        file = fopen(filename, "r");
        if(file == NULL)
            return 0;

        fd = fileno(file);
        if(fd == -1)
            return 0;
        printf("\nSuccessfully opened a file to seal the signing key pair for the client.\n");
        fflush(stdout);

        ret_status = fstat(fd, &st);
        if(ret_status != 0)
        {
            perror("error in finding the file size. -  ");
            fflush(stderr);
            return 0;
        }
        fclose(file);
        return st.st_size;
    }
};