Thread: reading and writing problem

I'm having a problem with my program i'm writing that splices raw Starcraft map files.
chk.c (main file, the one thats not working right)

Code:

#include <stdio.h>
#include "ConsoleMenu.c"
typedef struct chkSection {
  char name[5];
  long length;
  void* data;
} chkSection;
int main (int argc, char** argv) {
  //Declarations
  FILE* chkFile;
  FILE* outputFile;
  long numSections = 0;
  long sectionLength, fileSize;
  short currSection, selectedSection;
  char** sectionMenu;
  char outputFileName[MAX_PATH];
  chkSection* mapSections;
  //Begin program
  system("cls"); //FIX THIS
  chkFile = fopen(argv[1],"rb");
  if (!chkFile) {
    printf("OmgErrored!!");
    exit(1);
  }
  fileSize = filesize(chkFile);
  while (ftell(chkFile) < fileSize) {
    fseek(chkFile,4,SEEK_CUR);
    fread(&sectionLength,4,1,chkFile);
    fseek(chkFile,sectionLength,SEEK_CUR);
    numSections++;
  }
  rewind(chkFile);
  sectionMenu = (char**)malloc(numSections*sizeof(void*));
  mapSections = (chkSection*)malloc(numSections*sizeof(chkSection));
  printf("%d sections: debug %d\n",numSections,sizeof(chkSection));
  for (currSection=0;currSection<numSections;currSection++) {
    fread(&(mapSections[currSection].name),4,1,chkFile);
    mapSections[currSection].name[4] = '\x00';
    fread(&(mapSections[currSection].length),4,1,chkFile);
    mapSections[currSection].data = malloc(mapSections[currSection].length);
    fread(mapSections[currSection].data,mapSections[currSection].length,1,chkFile);
    sectionMenu[currSection] = mapSections[currSection].name;
  }
  selectedSection = runLongMenu(1,2,6,20,numSections,sectionMenu);
  system("cls");
  printf("Save to? ");
  outputFile = fopen(gets(outputFileName),"wb");
  if (!outputFile) {
    printf("OmgErrored!!");
    exit(1);
  }
  if (fwrite((char*)mapSections[currSection].data,mapSections[currSection].length,1,outputFile)) {
    printf("sucess!"); // ^ ^ ^ ^ problem here
  } else {printf("Errored error: %d",GetLastError());}
  getchar();
  fclose(outputFile);
  fclose(chkFile);
}
int filesize(FILE* pFile) {
  int filesize;
  int origpos;
  origpos = fseek(pFile,0,SEEK_END);
  filesize = ftell (pFile);
  fseek(pFile,origpos,SEEK_SET);
  return filesize;
}

ConsoleMenu.c (general purpose, thats why not all the functions are used)

Code:

#include <stdio.h>
#include <windows.h>
#define false 0
#define true 1
#define bool char
typedef struct MenuItem {
  char* name;
  char x;
  char y;
} MenuItem;
//these functions by Pie_Sniper
void setColor( int color ) {
  HANDLE hOut = GetStdHandle( STD_OUTPUT_HANDLE );
  SetConsoleTextAttribute( hOut, color );
}
void setCursorPos( int x, int y ) {
  HANDLE hOut = GetStdHandle( STD_OUTPUT_HANDLE );
  COORD coord;
  coord.X = x;
  coord.Y = y;
  SetConsoleCursorPosition( hOut, coord );
}
bool keyDown( char *Key ) {
   INPUT_RECORD Event;
   DWORD NumberOfEvents, EventsRead, EventCounter;
   HANDLE hIn = GetStdHandle( STD_INPUT_HANDLE );
   GetNumberOfConsoleInputEvents( hIn, &NumberOfEvents );
   if( NumberOfEvents == 0 ) {
     return false;
   }
   for( EventCounter = 0; EventCounter < NumberOfEvents; EventCounter++ )
   {
     PeekConsoleInput( hIn, &Event, 1, &EventsRead );
     if( Event.EventType == KEY_EVENT && Event.Event.KeyEvent.bKeyDown )
     {
       ReadConsoleInput( hIn, &Event, 1, &EventsRead );
       *Key = Event.Event.KeyEvent.wVirtualKeyCode;
       if( !FlushConsoleInputBuffer( hIn ) )
       {
         exit( 0 );
       }
       return true;
     }
     else {
       ReadConsoleInput( hIn, &Event, 1, &EventsRead );
     }
   }
   return false;
}
//End functions by Pie_sniper
bool drawMenu(int numItems,MenuItem* menuItems,int selectedItem) {
  int currMenuNum;
  for (currMenuNum=0;currMenuNum<numItems;currMenuNum++) {
    setCursorPos(menuItems[currMenuNum].x,menuItems[currMenuNum].y);
    if (currMenuNum == selectedItem) {
      setColor(0x87);
    } else {setColor(0x07);}
    printf(menuItems[currMenuNum].name);
  }
}
int runMenu(int numItems, MenuItem menuItems[]) {
  char key;
  int selectedItem = 0;
  drawMenu(numItems,menuItems,selectedItem);
  while (1) {
    if (keyDown(&key)) {
      if (key == 38 && selectedItem != 0) {
        selectedItem--;
      } else if (key == 40 && selectedItem != numItems-1) {
        selectedItem++;
      } else if (key == 13) {
        setColor(0x07);
        return selectedItem;
      }
      drawMenu(numItems, menuItems,selectedItem);
    }
  }
}
void drawBox(char x,char y,char w,char h) {
  int i;
  setCursorPos(x,y);
  printf("\xC9");
  for (i=0;i<w;i++) {
    printf("\xCD");
  }
  printf("\xBB");
  for (i=1;i<=h;i++) {
    setCursorPos(x,y+i);
    printf("\xBA");
    setCursorPos(x+w+1,y+i);
    printf("\xBA");
  }
  setCursorPos(x,y+h+1);
  printf("\xC8");
  for (i=0;i<w;i++) {
    printf("\xCD");
  }
  printf("\xBC");
}
void drawLongMenu (char x, char y, char width, char height, int numItems,
                   char* menuItems[], int selectedItem, int topDispMenuItem) {
  // Add some clearing stuff here, and redraw box?
  int currMenuNum;
  for (currMenuNum=topDispMenuItem;currMenuNum<(topDispMenuItem+height);currMenuNum++) {
    setCursorPos(x,y+currMenuNum - topDispMenuItem);
    if (currMenuNum == selectedItem) {
      setColor(0x87);
    } else {setColor(0x07);}
    printf(menuItems[currMenuNum]);
  }
}
int runLongMenu(char x, char y, char width, char height, int numItems, char* menuItems[]) {
  char key;
  int selectedItem = 0;
  int topDispMenuItem = 0;
  drawLongMenu(x,y,width,height,numItems,menuItems,selectedItem,topDispMenuItem);
  drawBox(x-1,y-1,width,height);
  while (1) {

    if (keyDown(&key)) {
      if (key == 38 && selectedItem != 0) {
        if (topDispMenuItem == selectedItem) {
          topDispMenuItem--;
        }
        selectedItem--;
      } else if (key == 40 && selectedItem != numItems-1) {
        selectedItem++;
        if (topDispMenuItem+height == selectedItem) {
          topDispMenuItem++;
        }
      } else if (key == 13) {
        setColor(0x07);
        return selectedItem;
      }
      drawLongMenu(x,y,width,height,numItems,menuItems,selectedItem,topDispMenuItem);
    }
  }
}

The problem is, when it tries to parse the file it's supposed to parse (save target as), fwrite gives me error 1784 (invalid user buffer). I dont know why.