Re: Can't read stdout of bash with GSubprocess on MSYS2

[Fan, Chun-wei (范君維) <fanc999 yahoo com tw>]

Hi Gang,

You can take a look at https://support.microsoft.com/en-US/kb/105305.  
Basically, you need to have a console attached to the GUI app for your 
case to work.

By running your code, and by adding AllocConsole() just before you spawn 
the subprocess, I was able to get the output.

Hope this helps.  With blessings.



Gang Chen 於 2015/9/28 上午 10:01 寫道:
> Hi,
> I'm writing a GTK+ application with MINGW-W64, which spawns a 
> subprocess running bash to execute some commands with GSubprocess and 
> reads stdout of bash (installed from MSYS2). I found that if compiled 
> without "-mwindows" compilation option the main process can read the 
> stdout, while with "-mwindows", the read function always returns 0 
> bytes read. If the main process runs a normal console program, or like 
> "mingw32/bin/gcc.exe", then it can read stdout even if compiled with 
> "-mwindows".
> The code:
>
> #include  <glib.h>
> #include  <gio/gio.h>
> #include  <gtk/gtk.h>
> #include  <stdio.h>
>
> char  buffer[100];
> GtkTextView *text;
>
> void  ondataread(GObject *s, GAsyncResult *r, gpointer p)
> {
>      GError *error =NULL;
>      int  l =g_input_stream_read_finish(G_INPUT_STREAM(s), r, &error);
>      if  (error)
>          printf("read error: %s\n", error->message);
>      else  if  (l >0)
>      {
>          gtk_text_buffer_insert_at_cursor(gtk_text_view_get_buffer(text), buffer, l);
>          g_input_stream_read_async(G_INPUT_STREAM(s), buffer,100, G_PRIORITY_DEFAULT,NULL, ondataread,NULL);
>      }
> }
>
> int  main(int  argc,char  **argv)
> {
>      char  *subpargv[8] = {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL  };
> subpargv[0] = "D:\\msys64\\usr\\bin\\bash.exe";
> subpargv[1] = "-c";
> subpargv[2] = "echo good; sleep 10; pwd";
> // subpargv[0] = "C:\\Windows\\system32\\cmd.exe";
> // subpargv[1] = "/c";
> // subpargv[2] = "echo good";
> // subpargv[0] = "D:\\msys64\\mingw32\\bin\\gcc.exe";
> // subpargv[1] = "notfile";
>      GSubprocessLauncher *l =g_subprocess_launcher_new(G_SUBPROCESS_FLAGS_STDOUT_PIPE | 
> G_SUBPROCESS_FLAGS_STDERR_PIPE);
>      GError *error =NULL;
>      GSubprocess *p =g_subprocess_launcher_spawnv(l, subpargv, &error);
>      if  (!p)
>      {
>          printf("spawn error: %s\n", error->message);
>          return  -1;
>      }
>      g_object_unref(l);
>      g_input_stream_read_async(g_subprocess_get_stdout_pipe(p), buffer,100, G_PRIORITY_DEFAULT,NULL, 
> ondataread,NULL);
>      g_input_stream_read_async(g_subprocess_get_stderr_pipe(p), buffer,100, G_PRIORITY_DEFAULT,NULL, 
> ondataread,NULL);
>      gtk_init(&argc, &argv);
>      GtkWidget *win =gtk_window_new(GTK_WINDOW_TOPLEVEL);
>      GtkWidget *t =gtk_text_view_new();
>      gtk_container_add(GTK_CONTAINER(win), t);
>      text =GTK_TEXT_VIEW(t);
>      gtk_widget_show_all(win);
>      gtk_main();
>      return  0;
> }
>
> How to read stdout correctly?
> Thanks,
> Gang
>
>
>
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