2 files changed, 18 insertions, 0 deletions
diff --git a/win32/win32.c b/win32/win32.c
index b212d3874..1e30ffec9 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -3424,6 +3424,20 @@ rb_w32_snprintf(char *buf, size_t size, const char *format, ...)
     return ret;
 }
 
+int
+rb_w32_isatty(int fd)
+{
+    if (!(_osfile(fd) & FOPEN)) {
+	errno = EBADF;
+	return 0;
+    }
+    if (!(_osfile(fd) & FDEV)) {
+	errno = ENOTTY;
+	return 0;
+    }
+    return 1;
+}
+
 //
 // Fix bcc32's stdio bug
 //
diff --git a/win32/win32.h b/win32/win32.h
index e811a8bdd..16acd1c95 100644
--- a/win32/win32.h
+++ b/win32/win32.h
@@ -121,11 +121,14 @@ extern "C++" {
 #undef fsopen
 #define fsopen(p, m, sh)	rb_w32_fsopen(p, m, sh)
 #endif
+
 #define fsync(h)		_commit(h)
 #undef stat
 #define stat(path,st)		rb_w32_stat(path,st)
 #undef execv
 #define execv(path,argv)	rb_w32_aspawn(P_OVERLAY,path,argv)
+#undef isatty
+#define isatty(h)		rb_w32_isatty(h)
 
 #ifdef __MINGW32__
 struct timezone {
@@ -185,6 +188,7 @@ extern int rb_w32_aspawn(int, const char *, char *const *);
 extern int kill(int, int);
 extern int fcntl(int, int, ...);
 extern pid_t rb_w32_getpid(void);
+extern int rb_w32_isatty(int);
 
 #ifdef __BORLANDC__
 extern int rb_w32_fstat(int, struct stat *);