Is there a replacement for unistd.h for Windows (V

Question

I'm porting a relatively simple console program written for Unix to the Windows platform (Visual C++ 8.0). All the source files include "unistd.h", which doesn't exist. Removing it, I get complaints about misssing prototypes for 'srandom', 'random', and 'getopt'. I know I can replace the random functions, and I'm pretty sure I can find/hack-up a getopt implementation.

But I'm sure others have run into the same challenge. My question is: is there a port of "unistd.h" to Windows? At least one containg those functions which do have a native Windows implementation - I don't need pipes or forking.

EDIT:

I know I can create my very own "unistd.h" which contains replacements for the things I need - especially in this case, since it is a limited set. But since it seems like a common problem, I was wondering if someone had done the work already for a bigger subset of the functionality.

Switching to a different compiler or environment isn't possible at work - I'm stuck with Visual Studio.

Answer 1

Since we can't find a version on the Internet, let's start one here.
Most ports to Windows probably only need a subset of the complete Unix file.
Here's a starting point. Please add definitions as needed.

#ifndef _UNISTD_H
#define _UNISTD_H    1

/* This is intended as a drop-in replacement for unistd.h on Windows.
 * Please add functionality as neeeded.
 * https://stackoverflow.com/a/826027/1202830
 */

#include <stdlib.h>
#include <io.h>
#include <getopt.h> /* getopt at: https://gist.github.com/ashelly/7776712 */
#include <process.h> /* for getpid() and the exec..() family */
#include <direct.h> /* for _getcwd() and _chdir() */

#define srandom srand
#define random rand

/* Values for the second argument to access.
   These may be OR'd together.  */
#define R_OK    4       /* Test for read permission.  */
#define W_OK    2       /* Test for write permission.  */
//#define   X_OK    1       /* execute permission - unsupported in windows*/
#define F_OK    0       /* Test for existence.  */

#define access _access
#define dup2 _dup2
#define execve _execve
#define ftruncate _chsize
#define unlink _unlink
#define fileno _fileno
#define getcwd _getcwd
#define chdir _chdir
#define isatty _isatty
#define lseek _lseek
/* read, write, and close are NOT being #defined here, because while there are file handle specific versions for Windows, they probably don't work for sockets. You need to look at your app and consider whether to call e.g. closesocket(). */

#ifdef _WIN64
#define ssize_t __int64
#else
#define ssize_t long
#endif

#define STDIN_FILENO 0
#define STDOUT_FILENO 1
#define STDERR_FILENO 2
/* should be in some equivalent to <sys/types.h> */
typedef __int8            int8_t;
typedef __int16           int16_t; 
typedef __int32           int32_t;
typedef __int64           int64_t;
typedef unsigned __int8   uint8_t;
typedef unsigned __int16  uint16_t;
typedef unsigned __int32  uint32_t;
typedef unsigned __int64  uint64_t;

#endif /* unistd.h  */

Answer 2

I would recommend using mingw/msys as a development environment. Especially if you are porting simple console programs. Msys implements a Unix-like shell on Windows, and mingw is a port of the GNU compiler collection (GCC) and other GNU build tools to the Windows platform. It is an open-source project, and well-suited to the task. I currently use it to build utility programs and console applications for Windows XP, and it most certainly has that unistd.h header you are looking for.

The install procedure can be a little bit tricky, but I found that the best place to start is in MSYS.

Answer 3

Create your own unistd.h header and include the needed headers for function prototypes.

Answer 4

Try including the io.h file. It seems to be the Visual Studio's equivalent of unistd.h.

I hope this helps.

Answer 5

No, IIRC there is no getopt() on Windows.

Boost, however, has the program_options library... which works okay. It will seem like overkill at first, but it isn't terrible, especially considering it can handle setting program options in configuration files and environment variables in addition to command line options.

Answer 6

I stumbled on this thread while trying to find a Windows alternative for getpid() (defined in unistd.h). It turns out that including process.h does the trick. Maybe this helps people who find this thread in the future.