Błąd rozpoznania pliku, zwraca wartosc 1

Question

Cześć,
mam upragniony program do ukrywania tekstu w bitmapie napisany w czystym C(wymagania projektu).

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int get_image_data_offset(FILE* bmp_offset) {
    fseek(bmp_offset,10,0);
    int offset;
    offset=(int)fgetc(bmp_offset);
    return offset;
}
 
int get_message_length(FILE *fp) {
    fseek(fp, 0L, SEEK_END);
    int size = ftell(fp);
    fseek(fp, 0L, SEEK_SET);
    return(size);
}
int get_bit(char the_byte,int which_bit) {
    return((the_byte>>8-which_bit)&1);
}
 
int main(int argc,char** argv) {
    unsigned char mask_table[] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };
    int i, j;
    FILE *file_handle;
    FILE *message_handle;
    FILE *hidden_message_handle;
 
    if(argc!=5) {
        printf(" -e: Add text to image\n -d : Get text from image\n",argv[0]);
        exit(1);
    }
 
    int mode;
    if(!strcmp(argv[1],"-e"))
        mode=1;
    else if(!strcmp(argv[1],"-d"))
        mode=0;
    else {
        printf(" - e = encrypt \n d= decrypt \n",argv[0]);
        exit(1);
    }
 
    /* HANDLING FILE OPENING AND ERRORS */
    file_handle=fopen(argv[2],"r");
    if (file_handle == NULL) {
        fprintf(stderr, "Can't open input file %s\n",argv[2]);
        exit(1);
    }
 
    hidden_message_handle=fopen(argv[3],"w");
    if (hidden_message_handle== NULL) {
        fprintf(stderr, "Cannot create output file %s\n",argv[3]);
        exit(1);
    }
 
    int c=0;
 
    /* Generate file with the same header. Copy first 128 bytes */
    char tmp_sig_cpy;
    int offset=get_image_data_offset(file_handle);
 
    rewind(file_handle);
 
    for(i=0;i<offset;i++) {
        tmp_sig_cpy=fgetc(file_handle);
        fputc(tmp_sig_cpy,hidden_message_handle);
        c++;
    }
    /* Made file as .bmp */
 
    char file_buffer;           // Temp variable for one byte from file
    char message_buffer;        // Temp buffer for one byte of message
 
    if(mode) {
        message_handle=fopen(argv[4],"r");
        if (message_handle== NULL) {
            fprintf(stderr, "Can't open text input file %s\n",argv[4]);
            exit(1);
        }
        int hidden_message_length=get_message_length(message_handle);
 
    /*
    After offset has been read and the file header has been written as is for the virgin image - the length of the hidden message is written as the first byte. This length is then used while decrypting the text from the image.
    */
        fputc(hidden_message_length,hidden_message_handle);
        c++;
        do {
            int bit_of_message;
            if(!feof(message_handle)) {
                message_buffer=fgetc(message_handle);
                for(i=1;i<=8;i++) {  //Do this for every bit in every byte of the virgin-image
 
                    file_buffer=fgetc(file_handle);
                    c++;
                    int file_byte_lsb = file_buffer & 1; // AND WITH 1 TO GET THE VALUE OF LSB. AND MAKES IT 0 IF LSB IS 0 OR 1 IF IT IS 1
 
                    bit_of_message=get_bit(message_buffer,i);
                    //bit_of_message=mask_table[i] & message_buffer;
                    if(file_byte_lsb==bit_of_message) {
                        fputc(file_buffer,hidden_message_handle);
                    }
                    else {
                        if(file_byte_lsb==0)
                            file_buffer = (file_buffer | 1);
                        else
                            file_buffer = (file_buffer & ~1);
                        //  logic to flip the LSB bit of file_buffer and put it into a file with putc()
                        fputc(file_buffer,hidden_message_handle);
                    }
                }
            }
            else {
                tmp_sig_cpy=fgetc(file_handle);
                fputc(tmp_sig_cpy,hidden_message_handle);
                c++;
            }
        } while(!feof(file_handle));
        fclose(message_handle);
    }
    else {
        message_handle=fopen(argv[4],"w");
        if (message_handle== NULL) {
            fprintf(stderr, "Can't open text input file %s\n",argv[4]);
            exit(1);
        }
 
        /* Grab LSB of all bytes for length specified at fgetc */
        int message_length=fgetc(file_handle);
        for(i=0;i<message_length;i++) {
            char temp_ch='\0';
            for(j=0;j<8;j++) {
                temp_ch=temp_ch<<1;
                file_buffer=fgetc(file_handle);
                int file_byte_lsb = file_buffer & 1;
                temp_ch|=file_byte_lsb;
            }
            fputc(temp_ch,message_handle);
        }
        fclose(message_handle);
    }
 
    /* Clean up before exit */
    fclose(file_handle);
    fclose(hidden_message_handle);
return 0;
}

Miał on być  uruchamiany z konsoli komendami odpowiednio dla ukrywania tekstu w bitmapie i odczytywania z niej informacji:

-e sample.bmp stegano_sample.bmp message.txt
-d stegano_sample.bmp intermediate.bmp original_message.txt

Problem polega na tym, że wywala mi komunikat, że nie rozpoznaje pliku stegano_sample.bmp. Nie wiem o co chodzi. Program docelowo ma działać na Linuksie, ja go odpalam na Windowsie. Gdyby ktoś mógł sprawdzić jego działanie na tym pierwszym byłbym wdzięczny. Dodatkowo wyswietla błąd o zwracaniu 1. Zmieniałem wartości w exit(1) na exit(0), wtedy zwraca 0, ale nadal nie działa poprawnie. Argc cały czas przyjmuje wartosc 1.