Не могу записать буффер в файл через fwrite - C (Си) - Ответ 8566806

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
 
#include "steglib.h"
 
int main(int argc, char *argv[]){
 
     char* message;
 
     char* mkr = "MKR";
 
     char* source_file_name;
 
     char* stego_file_name;
 
     int copy_result = 0;
     
     if ( argc <= 2 ) {
 
        printf("Error: no input or output specified\n");
 
    return -1;
     }
     else
     if ( argc > 3 ) {
 
        printf("Error: unknown arguments present\n");
 
    return -1;
     }
     else
     if ( argc == 3 ){
 
      /* Allocating memory for strings */
      message = (char *)malloc( 4096 );
      if (!message)
      {
        printf( "Error: cannot allocate memory for message\n ");
        return -1;
      }
 
      source_file_name = (char *)malloc( 4096 );
      if (!source_file_name)
      {
        printf( "Error: cannot allocate memory for source_file_name\n ");
        return -1;
      }
 
      stego_file_name = (char *)malloc( 4096 );
      if (!stego_file_name)
      {
        printf( "Error: cannot allocate memory for stego_file_name\n ");
        return -1;
      }
 
      source_file_name = argv[1];
 
      stego_file_name = argv[2];
 
      /* Protection from accidentally overwriting important user data */
      copy_result = cp(stego_file_name, source_file_name);
      
      if(copy_result != 0){
        printf("Cannot make a clean copy of file or pointing to already existing file. Exiting.\n");
        return -1;
      }
 
      printf("Type your phrase: ");
 
      scanf("%s", message);
 
      hide_msg(message, stego_file_name, mkr);
 
     }
 
     return 0;
}

/* Including standard libraries */
 
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <ctype.h>
 
/* Including our own function headers */
 
#include "steglib.h"
 
/*
 * Function to hide a message inside a BMP image file.
 * Returns: size of buffer / file contents
 */
 
int hide_msg(char* secret_msg, char* filename, char* MARKER){
 
     int i = 0;
     
     int place_required;
 
     void* buffer;
 
     char* secret;
 
     size_t fileLen;
 
     size_t file_length = 0;
 
     secret = (char *)malloc(sizeof(3*sizeof(MARKER)+sizeof(filename)+sizeof(secret_msg)));
 
     /* Concatenating strings in format: MARKER + src_filename + MARKER + secret_msg + MARKER */ 
 
     strcpy(secret, MARKER);
 
     strcat(secret, filename);
 
     strcat(secret, MARKER);
 
     strcat(secret, secret_msg);
 
     strcat(secret, MARKER);
 
     file_length = read_file( filename, buffer );
 
     place_required = 8 * sizeof(secret) - file_length;
 
     if(place_required > 0){
        printf("BMP size is not sufficient! Another %d bytes required!", place_required);
     }
 
//     dump_buffer(buffer, file_length);
     write_file(filename, buffer, file_length);
    
     return 0;
}
 
/*
 * Function to write contents of a buffer in a file
 * and get its size.
 * Returns: result of I/O operations 
 */
 
int write_file( char *name, void *buf, size_t buffer_size){
 
  FILE *pFile;
  int function_result;
  pFile = fopen(name, "wb");
  printf("DEBUG: WFILE"); 
  function_result = fwrite (buf, 1, buffer_size, pFile);
  printf("DEBUG: WFILE1");
  fclose (pFile);
  return function_result;
}
 
/*
 * Function to read contents of a file in a buffer
 * and get its size.
 * Returns: size of buffer / flie contents 
 */
 
size_t read_file( char *name, void *buffer )
{
    FILE *file1;
        size_t fileLen;
  
    //Open file
    file1 = fopen(name, "rb");
    if (!file1)
    {
        fprintf(stderr, "Unable to open file %s", name);
        return;
    }
    
    //Get file length
    fseek(file1, 0, SEEK_END);
    fileLen = ftell(file1);
    fseek(file1, 0, SEEK_SET);
 
    //Allocate memory
    buffer = (void *)malloc(fileLen+1);
    if (!buffer)
    {
        fprintf(stderr, "Error: cannot allocate memory for picture\n");
                fclose(file1);
        return;
    }
 
    //Read file contents into buffer
    fread(buffer, fileLen, 1, file1);
    fclose(file1);
 
    return fileLen;
}
 
/* 
 * Function to view current memory(buffer) dump 
 * in hex. Returns nothing.
 */
 
void dump_buffer(void *buffer, int buffer_size)
{
  int i;
 
  for( i = 0; i < 200; i++)
     printf("%02X ", ((char *)buffer)[i]);
}