Lock a file in Borland C++ (Command Line Version)

I think this is cross-platform:

fd = open(filename.c_str(), O_RDWR | O_CREAT);

if(fd == -1)
{
  switch(errno)
  {
    case EACCES:
      throw std::runtime_error("You do not have access to this file.");
      
    case EISDIR:
      throw std::runtime_error("Cannot use a directory");

    default:
      throw std::runtime_error("Unknown error occurred.");
    }
  }
      
  // Set a read/write lock on the file
  struct flock fl;

  fl.l_type   = F_WRLCK | F_RDLCK;
  fl.l_whence = SEEK_SET;
  fl.l_start  = 0;
  fl.l_len    = 0;
  fl.l_pid    = getpid();

  fcntl(fd, F_SETLKW, fl); // Wait for a Lock

Looks like unix only...

this is what I tried:

#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <cstring.h>
#include <function.h>
#include <string.h>
#include <iostream.h>
#include <fcntl.h>

int main()
{

fd = open("myfile.txt", O_RDWR | O_CREAT);

if(fd == -1)
{
 switch(errno)
 {
   case EACCES:
     throw std::runtime_error("You do not have access to this file.");
   
    case EISDIR:
     throw std::runtime_error("Cannot use a directory");

   default:
     throw std::runtime_error("Unknown error occurred.");
   }
 }
   
  // Set a read/write lock on the file
 struct flock fl;

 fl.l_type   = F_WRLCK | F_RDLCK;
 fl.l_whence = SEEK_SET;
 fl.l_start  = 0;
 fl.l_len    = 0;
 fl.l_pid    = getpid();

 fcntl(fd, F_SETLKW, fl); // Wait for a Lock


}

-------------------------------------------------------------
ERRORS:
-------------------------------------------------------------

C:\Borland\BCC55\Bin>bcc32 read_only
Borland C++ 5.5.1 for Win32 Copyright (c) 1993, 2000 Borland
read_only.cpp:
Error E2451 read_only.cpp 13: Undefined symbol 'fd' in function main()
Error E2268 read_only.cpp 13: Call to undefined function 'open' in function main
()
Error E2451 read_only.cpp 19: Undefined symbol 'EACCES' in function main()
Error E2451 read_only.cpp 22: Undefined symbol 'EISDIR' in function main()
Error E2172 read_only.cpp 22: Duplicate case in function main()
Error E2450 read_only.cpp 31: Undefined structure 'flock' in function main()
Error E2449 read_only.cpp 31: Size of 'fl' is unknown or zero in function main()

Error E2450 read_only.cpp 31: Undefined structure 'flock' in function main()
Error E2315 read_only.cpp 33: 'l_type' is not a member of 'flock', because the t
ype is not yet defined in function main()
Error E2451 read_only.cpp 33: Undefined symbol 'F_WRLCK' in function main()
Error E2451 read_only.cpp 33: Undefined symbol 'F_RDLCK' in function main()
Error E2315 read_only.cpp 34: 'l_whence' is not a member of 'flock', because the
 type is not yet defined in function main()
Error E2315 read_only.cpp 35: 'l_start' is not a member of 'flock', because the
type is not yet defined in function main()
Error E2315 read_only.cpp 36: 'l_len' is not a member of 'flock', because the ty
pe is not yet defined in function main()
Error E2315 read_only.cpp 37: 'l_pid' is not a member of 'flock', because the ty
pe is not yet defined in function main()
Error E2268 read_only.cpp 37: Call to undefined function 'getpid' in function ma
in()
Error E2268 read_only.cpp 39: Call to undefined function 'fcntl' in function mai
n()
Error E2451 read_only.cpp 39: Undefined symbol 'F_SETLKW' in function main()
*** 18 errors in Compile ***

sorry, you will need to define

FILE* fd;

at the beginning.

Also, EACCES/EISDIR is in <io.h> in borland C++.

and you want to use

_rtl_open(filename, O_RDRW | SH_DENYRW)

instead of open