win32: better handling of console state

When 'stty size' was run in a command substitution with stderr
redirected or 'stty -echo' with stdin redirected, it failed to
work properly.  The redirections broke its connection to the
terminal.

To fix this, ioctl/tcsetattr/tcgetattr have been modified to use
CONIN$ or CONOUT$ to access the screen buffer.  Using CON isn't
an adequate substitute in this case.

Also, if ioctl(fd, TIOCGWINSZ) fails, set errno.

Adds 112-116 bytes.

(GitHub issue #594)

Signed-off-by: Ron Yorston <rmy@pobox.com>

2 files changed, 35 insertions, 25 deletions

diff --git a/win32/ioctl.c b/win32/ioctl.c
index 12b7dd714..55b0c9e0d 100644
--- a/win32/ioctl.c
+++ b/win32/ioctl.c
@@ -11,16 +11,18 @@ static int mingw_get_terminal_width_height(struct winsize *win)
         win->ws_row = 0;
         win->ws_col = 0;
 
-        for (fd=STDOUT_FILENO; fd<=STDERR_FILENO; ++fd) {
-                handle = (HANDLE)_get_osfhandle(fd);
-                if (handle != INVALID_HANDLE_VALUE &&
-                                GetConsoleScreenBufferInfo(handle, &sbi) != 0) {
-                        win->ws_row = sbi.srWindow.Bottom - sbi.srWindow.Top + 1;
-                        win->ws_col = sbi.srWindow.Right - sbi.srWindow.Left + 1;
-                        return 0;
-                }
+        fd = open("CONOUT$", O_RDWR);
+        handle = (HANDLE)_get_osfhandle(fd);
+
+        if (fd != -1 && GetConsoleScreenBufferInfo(handle, &sbi) != 0) {
+                win->ws_row = sbi.srWindow.Bottom - sbi.srWindow.Top + 1;
+                win->ws_col = sbi.srWindow.Right - sbi.srWindow.Left + 1;
+
+                close(fd);
+                return 0;
         }
 
+        errno = err_win_to_posix();
         return -1;
 }
 #endif
diff --git a/win32/termios.c b/win32/termios.c
index c846dc165..dd64d95b6 100644
--- a/win32/termios.c
+++ b/win32/termios.c
@@ -3,32 +3,40 @@
 int FAST_FUNC
 tcsetattr(int fd, int mode UNUSED_PARAM, const struct termios *t)
 {
-        HANDLE h = (HANDLE)_get_osfhandle(fd);
-        if (!SetConsoleMode(h, t->w_mode)) {
-                errno = err_win_to_posix();
-                return -1;
+        HANDLE h;
+
+        fd = open("CONIN$", O_RDWR);
+        h = (HANDLE)_get_osfhandle(fd);
+        if (fd != -1 && SetConsoleMode(h, t->w_mode) != 0) {
+                close(fd);
+                return 0;
         }
 
-        return 0;
+        errno = err_win_to_posix();
+        return -1;
 }
 
 int FAST_FUNC tcgetattr(int fd, struct termios *t)
 {
-        HANDLE h = (HANDLE)_get_osfhandle(fd);
-        if (!GetConsoleMode(h, &t->w_mode)) {
-                errno = err_win_to_posix();
-                return -1;
-        }
+        HANDLE h;
+
+        fd = open("CONOUT$", O_RDWR);
+        h = (HANDLE)_get_osfhandle(fd);
+        if (fd != -1 && GetConsoleMode(h, &t->w_mode) != 0) {
+                t->c_cc[VINTR] = 3;     // ctrl-c
+                t->c_cc[VEOF] = 4;      // ctrl-d
 
-        t->c_cc[VINTR] = 3;     // ctrl-c
-        t->c_cc[VEOF] = 4;      // ctrl-d
+                if (t->w_mode & ENABLE_ECHO_INPUT)
+                        t->c_lflag |= ECHO;
+                else
+                        t->c_lflag &= ~ECHO;
 
-        if (t->w_mode & ENABLE_ECHO_INPUT)
-                t->c_lflag |= ECHO;
-        else
-                t->c_lflag &= ~ECHO;
+                close(fd);
+                return 0;
+        }
 
-        return 0;
+        errno = err_win_to_posix();
+        return -1;
 }
 
 int64_t FAST_FUNC windows_read_key(int fd, char *buf UNUSED_PARAM, int timeout)