[Spice-devel] [PATCH] Add utility to help redirecting output from remote-viewer/virt-viewer

[Victor Toso]

Hi,

On Tue, Mar 01, 2016 at 01:29:13PM +0000, Frediano Ziglio wrote:
> These utility use some trick to use console even if they are GUI
> application (not supposed to have a console by default).
> This make output redirection harder as output by default will tend
> to go to console of parent process instead of using redirected output.
> This utility avoid remote-viewer/virt-viewer to see the calling process
> console keeping the wanted redirection.
>

And this is how you get free beers :)

Not sure what is better, this or having some handling to redirect logs
to file. What works is good for me!

I'll be testing this very soon! Thanks!

> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> ---
>  src/Makefile.am               |  4 ++
>  src/output-redirect-wrapper.c | 92 +++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 96 insertions(+)
>  create mode 100644 src/output-redirect-wrapper.c
> 
> diff --git a/src/Makefile.am b/src/Makefile.am
> index e76f5bc..01b9bc8 100644
> --- a/src/Makefile.am
> +++ b/src/Makefile.am
> @@ -155,6 +155,10 @@ bin_PROGRAMS += windows-cmdline-wrapper
>  windows_cmdline_wrapper_SOURCES = windows-cmdline-wrapper.c
>  windows_cmdline_wrapper_LDFLAGS = -lpsapi
>  
> +bin_PROGRAMS += output-redirect-wrapper
> +output_redirect_wrapper_SOURCES  = output-redirect-wrapper.c
> +output_redirect_wrapper_CPPFLAGS = -DUNICODE -D_UNICODE
> +
>  virt-viewer_rc.$(OBJEXT): $(VIRT_VIEWER_RES) $(ICONDIR)/virt-viewer.ico
>  	$(AM_V_GEN)$(WINDRES)				\
>  		-DICONDIR='\"$(ICONDIR)\"'		\
> diff --git a/src/output-redirect-wrapper.c b/src/output-redirect-wrapper.c
> new file mode 100644
> index 0000000..ed807bb
> --- /dev/null
> +++ b/src/output-redirect-wrapper.c
> @@ -0,0 +1,92 @@
> +/*
> + * Windows cmd: a command line wrapper for GUI applications
> + *
> + * Copyright (C) 2012-2016 Red Hat, Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + *
> + * Usage:
> + * This wrapper allows to redirect output even if your application
> + * tries to redirect its output to console.
> + *
> + * For instance you can use from console with a syntax like
> + *
> + *   output-redirect-wrapper remote-viewer.exe --debug > log.txt
> + *
> + * Based on Marc-André Lureau wrappers
> + */
> +
> +#include <windows.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <tchar.h>
> +
> +int main(void)
> +{
> +    STARTUPINFO si = { 0, };
> +    PROCESS_INFORMATION pi = { 0, };
> +
> +    // pass same input/output handles
> +    si.cb = sizeof(si);
> +    si.dwFlags = STARTF_USESTDHANDLES;
> +    si.hStdInput  = GetStdHandle(STD_INPUT_HANDLE);
> +    // redirect all to single output
> +    si.hStdError = si.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
> +    SetHandleInformation(si.hStdInput,  HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT);
> +    SetHandleInformation(si.hStdOutput, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT);
> +
> +    // parse command line, strip executable
> +    TCHAR *cmdline = GetCommandLine();
> +    cmdline += _tcsspn(cmdline, _T(" \t\v"));
> +    TCHAR *end = _tcsstr(cmdline, cmdline[0] == _T('\"') ? _T("\" ") : _T(" "));
> +    if (!end) {
> +        fprintf(stderr, "Please pass executable to call\n");
> +        return 1;
> +    }
> +    cmdline = end + 1;
> +    cmdline += _tcsspn(cmdline, _T(" \t\v"));
> +
> +    // release console so program launched do not redirect to it
> +    FreeConsole();
> +
> +    if (!CreateProcess(NULL,
> +                       cmdline,
> +                       NULL,           // Process handle not inheritable
> +                       NULL,           // Thread handle not inheritable
> +                       TRUE,           // Handle inheritance
> +                       0,              // No creation flags
> +                       NULL,           // Use parent's environment block
> +                       NULL,           // Use parent's starting directory
> +                       &si,
> +                       &pi)) {
> +        fprintf(stderr, "CreateProcess failed (%ld).\n", (long) GetLastError());
> +        return 1;
> +    }
> +    // Close unneeded handle
> +    CloseHandle(pi.hThread);
> +
> +    // Wait until child process exits.
> +    WaitForSingleObject(pi.hProcess, INFINITE);
> +
> +    DWORD exit_code;
> +    GetExitCodeProcess(pi.hProcess, &exit_code);
> +
> +    // Close process handle
> +    CloseHandle(pi.hProcess);
> +
> +    // return same output of application
> +    ExitProcess(exit_code);
> +    return 0;
> +}
> -- 
> 2.5.0
> 
> _______________________________________________
> Spice-devel mailing list
> Spice-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/spice-devel