[PATCH 3/4] GDBServer: introduce --server-stderr command line option

[Cleber Rosa <crosa@redhat.com>]

This command line option will redirect all of the gdbserver's own
output (always sent to stderr) to a separate file. This feature
makes it possible to distinguish between the inferior process stderr
and gdbserver's own stderr.

gdb/doc/ChangeLog:
2015-03-20  Cleber Rosa  <crosa@redhat.com>

	* gdb.texinfo (info): Added section on command line and monitor
	commands.
	(gdbserver man): Added section on new command line option.

gdb/gdbserver/ChangeLog:
2015-03-20  Cleber Rosa  <crosa@redhat.com>

	* server.c (set_server_stderr): New utility function.
	(gdbserver_usage): Add help on '--server-stderr' option.
	(captured_main): Add command line option parsing for
	'--server-stderr'. Replace stderr with gdbserver's own
	stderr.
---
 gdb/doc/gdb.texinfo    | 10 ++++++++++
 gdb/gdbserver/server.c | 28 +++++++++++++++++++++++++++-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 552da31..2834794 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -19205,6 +19205,12 @@ The @option{--remote-debug} option tells @code{gdbserver} to display
 remote protocol debug output.  These options are intended for
 @code{gdbserver} development and for bug reports to the developers.
 
+@cindex @option{--server-stderr}, @code{gdbserver} option
+The @option{--server-stderr} option tells @code{gdbserver} that any content
+that it would normally generate itself to its own @code{stderr} should be
+redirected to another file. This is useful if you want to keep the
+inferior @code{stderr} separate from the one generated by @code{gdbserver}.
+
 @cindex @option{--debug-format}, @code{gdbserver} option
 The @option{--debug-format=option1[,option2,...]} option tells
 @code{gdbserver} to include additional information in each output.
@@ -40886,6 +40892,10 @@ Instruct @code{gdbserver} to include extra information in each line
 of debugging output.
 @xref{Other Command-Line Arguments for gdbserver}.
 
+@item --server-stderr
+Instruct @code{gdbserver} to redirect its own @code{stderr} to another
+file.
+
 @item --wrapper
 Specify a wrapper to launch programs
 for debugging.  The option should be followed by the name of the
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 9dec972..db26f24 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -723,6 +723,25 @@ get_features_xml (const char *annex)
   return NULL;
 }
 
+/* Opens a file and redirects the server own stderr to it */
+
+static int
+set_server_stderr (char *path)
+{
+  FILE *tmp;
+
+  tmp = fopen (path, "w");
+  if (tmp == NULL)
+    {
+      fprintf (stderr,
+	       "Could not open server stderr file '%s': %s\n",
+	       path, strerror(errno));
+      return -1;
+    }
+  server_stderr = tmp;
+  return 0;
+}
+
 void
 monitor_show_help (void)
 {
@@ -3017,6 +3036,7 @@ gdbserver_usage (FILE *stream)
 	   "                            none\n"
 	   "                            timestamp\n"
 	   "  --remote-debug        Enable remote protocol debugging output.\n"
+	   "  --server-stderr=PATH  Redirect server's STDERR to file at PATH.\n"
 	   "  --version             Display version information and exit.\n"
 	   "  --wrapper WRAPPER --  Run WRAPPER to start new programs.\n"
 	   "  --once                Exit after the first connection has "
@@ -3186,7 +3206,13 @@ captured_main (int argc, char *argv[])
 
   while (*next_arg != NULL && **next_arg == '-')
     {
-      if (strcmp (*next_arg, "--version") == 0)
+      if (strncmp (*next_arg, "--server-stderr=",
+		   sizeof ("--server-stderr=") - 1) == 0)
+	{
+	  char *path = *next_arg + (sizeof ("--server-stderr=") - 1);
+	  set_server_stderr (path);
+	}
+      else if (strcmp (*next_arg, "--version") == 0)
 	{
 	  gdbserver_version ();
 	  exit (0);
-- 
1.9.3