src/include/port/win32_msvc/unistd.h - cloudberry - Git at Google

 /* src/include/port/win32_msvc/unistd.h */

 /*
  * MSVC does not define these, nor does _fileno(stdin) etc reliably work
  * (returns -1 if stdin/out/err are closed).
  */
 #define STDIN_FILENO	0
 #define STDOUT_FILENO	1
 #define STDERR_FILENO	2
	/* src/include/port/win32_msvc/unistd.h */

	/*
	* MSVC does not define these, nor does _fileno(stdin) etc reliably work
	* (returns -1 if stdin/out/err are closed).
	*/
	#define STDIN_FILENO 0
	#define STDOUT_FILENO 1
	#define STDERR_FILENO 2