Make out and error streams be per UI

stderr_fileopen () references stderr directly, which doesn't work when
we have a separate UI with its own stderr-like stream.  So this also
adds a "errstream" to "struct ui", and plumbs stderr_fileopen to take
a stream parameter.

gdb/ChangeLog:
2016-06-21  Pedro Alves  <palves@redhat.com>

	* event-top.c (gdb_setup_readline): Pass the UI's outstream and
	errstream to stdout_fileopen and stderr_fileopen.
	* exceptions.c: Include top.h.
	(print_flush): Open the current UI's outstream file descriptor,
	instead of hardcoding file descriptor 1.
	* main.c (captured_main): Save the main UI's out and error
	streams.  Adjust stderr_fileopen call.
	* top.h (struct ui) <outstream, errstream>: New fields.
	* ui-file.c (stderr_fileopen): Add stream parameter.  Use it
	instead of stderr.
	* ui-file.h (stderr_fileopen): Add stream parameter and update
	comment.

gdb/ChangeLog

@@ -1,3 +1,18 @@
+2016-06-21  Pedro Alves  <palves@redhat.com>
+
+	* event-top.c (gdb_setup_readline): Pass the UI's outstream and
+	errstream to stdout_fileopen and stderr_fileopen.
+	* exceptions.c: Include top.h.
+	(print_flush): Open the current UI's outstream file descriptor,
+	instead of hardcoding file descriptor 1.
+	* main.c (captured_main): Save the main UI's out and error
+	streams.  Adjust stderr_fileopen call.
+	* top.h (struct ui) <outstream, errstream>: New fields.
+	* ui-file.c (stderr_fileopen): Add stream parameter.  Use it
+	instead of stderr.
+	* ui-file.h (stderr_fileopen): Add stream parameter and update
+	comment.
+
 2016-06-21  Pedro Alves  <palves@redhat.com>
 
 	* event-top.c (input_fd): Delete.

gdb/event-top.c

@@ -1237,8 +1237,8 @@ gdb_setup_readline (void)
      mess it up here.  The sync stuff should really go away over
      time.  */
   if (!batch_silent)
-    gdb_stdout = stdio_fileopen (stdout);
+    gdb_stdout = stdio_fileopen (ui->outstream);
-  gdb_stderr = stderr_fileopen ();
+  gdb_stderr = stderr_fileopen (ui->errstream);
   gdb_stdlog = gdb_stderr;  /* for moment */
   gdb_stdtarg = gdb_stderr; /* for moment */
   gdb_stdtargerr = gdb_stderr; /* for moment */

gdb/exceptions.c

@@ -26,10 +26,12 @@
 #include "ui-out.h"
 #include "serial.h"
 #include "gdbthread.h"
+#include "top.h"
 
 static void
 print_flush (void)
 {
+  struct ui *ui = current_ui;
   struct serial *gdb_stdout_serial;
   struct cleanup *old_chain = make_cleanup (null_cleanup, NULL);
 
@@ -56,7 +58,7 @@ print_flush (void)
   gdb_flush (gdb_stderr);
 
   /* 3.  The system-level buffer.  */
-  gdb_stdout_serial = serial_fdopen (1);
+  gdb_stdout_serial = serial_fdopen (fileno (ui->outstream));
   if (gdb_stdout_serial)
     {
       serial_drain_output (gdb_stdout_serial);

gdb/main.c

@@ -507,7 +507,11 @@ captured_main (void *data)
   ndir = 0;
 
   saved_command_line = (char *) xstrdup ("");
+
   ui->instream = stdin;
+  ui->outstream = stdout;
+  ui->errstream = stderr;
+
   ui->input_fd = fileno (stdin);
 
 #ifdef __MINGW32__
@@ -517,7 +521,7 @@ captured_main (void *data)
 #endif
 
   gdb_stdout = stdio_fileopen (stdout);
-  gdb_stderr = stderr_fileopen ();
+  gdb_stderr = stderr_fileopen (stderr);
 
   gdb_stdlog = gdb_stderr;	/* for moment */
   gdb_stdtarg = gdb_stderr;	/* for moment */

gdb/top.h

@@ -73,6 +73,10 @@ struct ui
      Set to NULL if we are executing a user-defined command or
      interacting via a GUI.  */
   FILE *instream;
+  /* Standard output stream.  */
+  FILE *outstream;
+  /* Standard error stream.  */
+  FILE *errstream;
 
   /* The file descriptor for the input stream, so that we can register
      it with the event loop.  */

gdb/ui-file.c

@@ -681,9 +681,9 @@ stderr_file_fputs (const char *linebuffer, struct ui_file *file)
 #endif
 
 struct ui_file *
-stderr_fileopen (void)
+stderr_fileopen (FILE *stream)
 {
-  struct ui_file *ui_file = stdio_fileopen (stderr);
+  struct ui_file *ui_file = stdio_fileopen (stream);
 
 #ifdef __MINGW32__
   /* There is no real line-buffering on Windows, see

gdb/ui-file.h

@@ -135,8 +135,8 @@ extern struct ui_file *mem_fileopen (void);
 /* Open/create a STDIO based UI_FILE using the already open FILE.  */
 extern struct ui_file *stdio_fileopen (FILE *file);
 
-/* Create a ui_file from stderr.  */
+/* Likewise, for stderr-like streams.  */
-extern struct ui_file *stderr_fileopen (void);
+extern struct ui_file *stderr_fileopen (FILE *file);
 
 
 /* Open NAME returning an STDIO based UI_FILE.  */