Add optional Win32 console allocation

This patch adds the optional --win32console command line option.
It does nothing on OSx and Linux, while is only useable on Win32.

On Win32 if the application was built as GUI (not console),
there is no way to view stdout and stderr. With windows.c's
subsurface_console_init() we are able to either redirect
stdout and stderr to the terminal from which subsurface.exe
was started (always happens; --win32console does nothing in
this case) or if --win32console is explicitly added to
a shortcut, create a dedicated console window and monitor
the output there.

if set, WIN32_CONSOLE_APP is a condition that will make the
subsurface_console_init() and subsurface_console_exit()
functions NOP on Windows. The definition will be created if
the user passes 'CONFIG += console' to qmake.

Fixes #436

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 77 insertions, 0 deletions

diff --git a/windows.c b/windows.c
index c76a73048..99720cf9d 100644
--- a/windows.c
+++ b/windows.c
@@ -2,6 +2,7 @@
 /* implements Windows specific functions */
 #include "dive.h"
 #include "display.h"
+#define _WIN32_WINNT 0x500
 #include <windows.h>
 #include <shlobj.h>
 #include <stdio.h>
@@ -199,3 +200,79 @@ int subsurface_zip_close(struct zip *zip)
 {
 	return zip_close(zip);
 }
+
+/* win32 console */
+static struct {
+	bool allocated;
+	UINT cp;
+	FILE *out, *err;
+} console_desc;
+
+void subsurface_console_init(bool dedicated)
+{
+	/* if this is a console app already, do nothing */
+#ifndef WIN32_CONSOLE_APP
+	/* just in case of multiple calls */
+	memset((void *)&console_desc, 0, sizeof(console_desc));
+	/* the AttachConsole(..) call can be used to determine if the parent process
+	 * is a terminal. if it succeeds, there is no need for a dedicated console
+	 * window and we don't need to call the AllocConsole() function. on the other
+	 * hand if the user has set the 'dedicated' flag to 'true' and if AttachConsole()
+	 * has failed, we create a dedicated console window.
+	 */
+	console_desc.allocated = AttachConsole(ATTACH_PARENT_PROCESS);
+	if (console_desc.allocated)
+		dedicated = false;
+	if (!console_desc.allocated && dedicated)
+		console_desc.allocated = AllocConsole();
+	if (!console_desc.allocated)
+		return;
+
+	console_desc.cp = GetConsoleCP();
+	SetConsoleOutputCP(CP_UTF8); /* make the ouput utf8 */
+
+	/* set some console modes; we don't need to reset these back.
+	 * ENABLE_EXTENDED_FLAGS = 0x0080, ENABLE_QUICK_EDIT_MODE = 0x0040 */
+	HANDLE h_in = GetStdHandle(STD_INPUT_HANDLE);
+	if (h_in) {
+		SetConsoleMode(h_in, 0x0080 | 0x0040);
+		CloseHandle(h_in);
+	}
+
+	/* dedicated only; disable the 'x' button as it will close the main process as well */
+	HWND h_cw = GetConsoleWindow();
+	if (h_cw && dedicated) {
+		SetWindowTextA(h_cw, "Subsurface Console");
+		HMENU h_menu = GetSystemMenu(h_cw, 0);
+		if (h_menu) {
+			EnableMenuItem(h_menu, SC_CLOSE, MF_BYCOMMAND | MF_DISABLED);
+			DrawMenuBar(h_cw);
+		}
+		SetConsoleCtrlHandler(NULL, TRUE); /* disable the CTRL handler */
+	}
+
+	/* redirect; on win32, CON is a reserved pipe target, like NUL */
+	console_desc.out = freopen("CON", "w", stdout);
+	console_desc.err = freopen("CON", "w", stderr);
+	if (!dedicated)
+		puts(""); /* add an empty line */
+#endif
+}
+
+void subsurface_console_exit(void)
+{
+#ifndef WIN32_CONSOLE_APP
+	if (!console_desc.allocated)
+		return;
+
+	/* close handles */
+	if (console_desc.out)
+		fclose(console_desc.out);
+	if (console_desc.err)
+		fclose(console_desc.err);
+
+	/* reset code page and free */
+	SetConsoleOutputCP(console_desc.cp);
+	FreeConsole();
+#endif
+}