The best solution I have found so far is to have two executables.
program.exe is the GUI application.program.com is a helper command-line application that spawns program.exe and passes standard I/O to it. (It's not a COM executable from DOS, it's just a renamed standard PE executable; since .com is before .exe in the default preference order of cmd.exe, you can type program and it will automatically call program.com instead of program.exe if both are in the path.)
With this setup, you can type program at the Windows command prompt, write to the standard output in program.exe, and it will correctly appear on the console; no console windows will be spawned when you open program.exe from the GUI.
Here is an example implementation of the helper program, taken from Inkscape:
http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/view/head:/src/winconsole.cpp
The helper creates three pipes, and spawns the GUI program with CreateProcess, giving it the appropriate ends of the pipes. Then it creates three threads that copy data between the pipes and the standard I/O of the helper program in an infinite loop. The helper is compiled as a console application (important) - the -mconsole switch in MinGW.
/**
* \file
* Command-line wrapper for Windows.
*
* Windows has two types of executables: GUI and console.
* The GUI executables detach immediately when run from the command
* prompt (cmd.exe), and whatever you write to standard output
* disappears into a black hole. Console executables
* do display standard output and take standard input from the console,
* but when you run them from the GUI, an extra console window appears.
* It's possible to hide it, but it still flashes for a fraction
* of a second.
*
* To provide an Unix-like experience, where the application will behave
* correctly in command line mode and at the same time won't create
* the ugly console window when run from the GUI, we have to have two
* executables. The first one, inkscape.exe, is the GUI application.
* Its entry points are in main.cpp and winmain.cpp. The second one,
* called inkscape.com, is a small helper application contained in
* this file. It spawns the GUI application and redirects its output
* to the console.
*
* Note that inkscape.com has nothing to do with "compact executables"
* from DOS. It's a normal PE executable renamed to .com. The trick
* is that cmd.exe picks .com over .exe when both are present in PATH,
* so when you type "inkscape" into the command prompt, inkscape.com
* gets run. The Windows program loader does not inspect the extension,
* just like an Unix program loader; it determines the binary format
* based on the contents of the file.
*
*//*
* Authors:
* Jos Hirth <[email protected]>
* Krzysztof Kosinski <[email protected]>
*
* Copyright (C) 2008-2010 Authors
*
* Released under GNU GPL, read the file 'COPYING' for more information
*/
#ifdef WIN32
#undef DATADIR
#include <windows.h>
struct echo_thread_info {
HANDLE echo_read;
HANDLE echo_write;
unsigned buffer_size;
};
// thread function for echoing from one file handle to another
DWORD WINAPI echo_thread(void *info_void)
{
echo_thread_info *info = static_cast<echo_thread_info*>(info_void);
char *buffer = reinterpret_cast<char *>(LocalAlloc(LMEM_FIXED, info->buffer_size));
DWORD bytes_read, bytes_written;
while(true){
if (!ReadFile(info->echo_read, buffer, info->buffer_size, &bytes_read, NULL) || bytes_read == 0)
if (GetLastError() == ERROR_BROKEN_PIPE)
break;
if (!WriteFile(info->echo_write, buffer, bytes_read, &bytes_written, NULL)) {
if (GetLastError() == ERROR_NO_DATA)
break;
}
}
LocalFree(reinterpret_cast<HLOCAL>(buffer));
CloseHandle(info->echo_read);
CloseHandle(info->echo_write);
return 1;
}
int main()
{
// structs that will store information for our I/O threads
echo_thread_info stdin = {NULL, NULL, 4096};
echo_thread_info stdout = {NULL, NULL, 4096};
echo_thread_info stderr = {NULL, NULL, 4096};
// handles we'll pass to inkscape.exe
HANDLE inkscape_stdin, inkscape_stdout, inkscape_stderr;
HANDLE stdin_thread, stdout_thread, stderr_thread;
SECURITY_ATTRIBUTES sa;
sa.nLength=sizeof(SECURITY_ATTRIBUTES);
sa.lpSecurityDescriptor=NULL;
sa.bInheritHandle=TRUE;
// Determine the path to the Inkscape executable.
// Do this by looking up the name of this one and redacting the extension to ".exe"
const int pathbuf = 2048;
WCHAR *inkscape = reinterpret_cast<WCHAR*>(LocalAlloc(LMEM_FIXED, pathbuf * sizeof(WCHAR)));
GetModuleFileNameW(NULL, inkscape, pathbuf);
WCHAR *dot_index = wcsrchr(inkscape, L'.');
wcsncpy(dot_index, L".exe", 4);
// we simply reuse our own command line for inkscape.exe
// it guarantees perfect behavior w.r.t. quoting
WCHAR *cmd = GetCommandLineW();
// set up the pipes and handles
stdin.echo_read = GetStdHandle(STD_INPUT_HANDLE);
stdout.echo_write = GetStdHandle(STD_OUTPUT_HANDLE);
stderr.echo_write = GetStdHandle(STD_ERROR_HANDLE);
CreatePipe(&inkscape_stdin, &stdin.echo_write, &sa, 0);
CreatePipe(&stdout.echo_read, &inkscape_stdout, &sa, 0);
CreatePipe(&stderr.echo_read, &inkscape_stderr, &sa, 0);
// fill in standard IO handles to be used by the process
PROCESS_INFORMATION pi;
STARTUPINFOW si;
ZeroMemory(&si,sizeof(STARTUPINFO));
si.cb = sizeof(STARTUPINFO);
si.dwFlags = STARTF_USESTDHANDLES;
si.hStdInput = inkscape_stdin;
si.hStdOutput = inkscape_stdout;
si.hStdError = inkscape_stderr;
// spawn inkscape.exe
CreateProcessW(inkscape, // path to inkscape.exe
cmd, // command line as a single string
NULL, // process security attributes - unused
NULL, // thread security attributes - unused
TRUE, // inherit handles
0, // flags
NULL, // environment - NULL = inherit from us
NULL, // working directory - NULL = inherit ours
&si, // startup info - see above
&pi); // information about the created process - unused
// clean up a bit
LocalFree(reinterpret_cast<HLOCAL>(inkscape));
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
CloseHandle(inkscape_stdin);
CloseHandle(inkscape_stdout);
CloseHandle(inkscape_stderr);
// create IO echo threads
DWORD unused;
stdin_thread = CreateThread(NULL, 0, echo_thread, (void*) &stdin, 0, &unused);
stdout_thread = CreateThread(NULL, 0, echo_thread, (void*) &stdout, 0, &unused);
stderr_thread = CreateThread(NULL, 0, echo_thread, (void*) &stderr, 0, &unused);
// wait until the standard output thread terminates
WaitForSingleObject(stdout_thread, INFINITE);
return 0;
}
#endif
