msvcrt: _setmode should check if file descriptor is valid.

dlls/msvcrt/file.c

@@ -2833,6 +2833,11 @@ int CDECL MSVCRT__setmode(int fd,int mode)
         return -1;
     }
 
+    if(info == &MSVCRT___badioinfo) {
+        *MSVCRT__errno() = MSVCRT_EBADF;
+        return -1;
+    }
+
     if(mode == MSVCRT__O_BINARY) {
         info->wxflag &= ~WX_TEXT;
         info->exflag &= ~(EF_UTF8|EF_UTF16);

dlls/msvcrt/tests/file.c

@@ -1789,6 +1789,16 @@ static void test_setmode(void)
         return;
     }
 
+    errno = 0xdeadbeef;
+    ret = _setmode(-2, 0);
+    ok(ret == -1, "_setmode returned %x, expected -1\n", ret);
+    ok(errno == EINVAL, "errno = %d\n", errno);
+
+    errno = 0xdeadbeef;
+    ret = _setmode(-2, _O_TEXT);
+    ok(ret == -1, "_setmode returned %x, expected -1\n", ret);
+    ok(errno == EBADF, "errno = %d\n", errno);
+
     fd = _open(name, _O_CREAT|_O_WRONLY, _S_IWRITE);
     ok(fd != -1, "failed to open file\n");