[PATCH 08/16] gdb: move remote arg splitting and joining into gdbsupport/

[Andrew Burgess <aburgess@redhat.com>]

This is a refactoring commit.  When passing inferior arguments to
gdbserver we have two actions that need to be performed, splitting and
joining.

On the GDB side, we take the inferior arguments, a single string, and
split the string into a list of individual arguments.  These are then
sent to gdbserver over the remote protocol.

On the gdbserver side we receive the list of individual arguments and
join these back together into a single inferior argument string.

In a later commit I would like to add some unit testing for this
remote argument passing process.  Ideally, for unit testing, we want
to use the exact same code for splitting and joining the arguments as
is actually used -- we could duplicate the code within the unit test,
and this would validate the algorithm as it is today, but there is
always the risk that a future change would not be mirrored within the
tests, which makes the tests useless.

So in this commit I propose to move the splitting and joining logic
out into a separate file, we can then use this within GDB and
gdbserver when passing arguments between GDB and gdbserver, but we can
also use the exact same code for some unit tests.

In this commit I'm not adding the unit tests, they will be added later
in this series, so for now there should be no user visible changes
after this commit.
---
 gdb/remote.c              | 12 +++++------
 gdbserver/server.cc       |  4 ++--
 gdbsupport/Makefile.am    |  1 +
 gdbsupport/Makefile.in    | 13 +++++++-----
 gdbsupport/remote-args.cc | 43 ++++++++++++++++++++++++++++++++++++++
 gdbsupport/remote-args.h  | 44 +++++++++++++++++++++++++++++++++++++++
 6 files changed, 104 insertions(+), 13 deletions(-)
 create mode 100644 gdbsupport/remote-args.cc
 create mode 100644 gdbsupport/remote-args.h

diff --git a/gdb/remote.c b/gdb/remote.c
index dcc1a0d0639..ebef409ffed 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -79,6 +79,7 @@
 #include <unordered_map>
 #include "async-event.h"
 #include "gdbsupport/selftest.h"
+#include "gdbsupport/remote-args.h"
 
 /* The remote target.  */
 
@@ -10625,16 +10626,15 @@ remote_target::extended_remote_run (const std::string &args)
 
   if (!args.empty ())
     {
-      int i;
+      std::vector<std::string> split_args = gdb::remote_args::split (args);
 
-      gdb_argv argv (args.c_str ());
-      for (i = 0; argv[i] != NULL; i++)
+      for (const auto &a : split_args)
 	{
-	  if (strlen (argv[i]) * 2 + 1 + len >= get_remote_packet_size ())
+	  if (a.size () * 2 + 1 + len >= get_remote_packet_size ())
 	    error (_("Argument list too long for run packet"));
 	  rs->buf[len++] = ';';
-	  len += 2 * bin2hex ((gdb_byte *) argv[i], rs->buf.data () + len,
-			      strlen (argv[i]));
+	  len += 2 * bin2hex ((gdb_byte *) a.c_str (), rs->buf.data () + len,
+			      a.size ());
 	}
     }
 
diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index 52ce9240ca3..13abb0b7636 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -51,6 +51,7 @@
 #include "gdbsupport/gdb_select.h"
 #include "gdbsupport/scoped_restore.h"
 #include "gdbsupport/search.h"
+#include "gdbsupport/remote-args.h"
 
 /* PBUFSIZ must also be at least as big as IPA_CMD_BUF_SIZE, because
    the client state data is passed directly to some agent
@@ -3437,8 +3438,7 @@ handle_v_run (char *own_buf)
   else
     program_path.set (new_program_name.get ());
 
-  program_args = construct_inferior_arguments (new_argv,
-					       escape_shell_characters);
+  program_args = gdb::remote_args::join (new_argv);
   free_vector_argv (new_argv);
 
   target_create_inferior (program_path.get (), program_args);
diff --git a/gdbsupport/Makefile.am b/gdbsupport/Makefile.am
index f1a641308fe..6f5a5ef36c6 100644
--- a/gdbsupport/Makefile.am
+++ b/gdbsupport/Makefile.am
@@ -72,6 +72,7 @@ libgdbsupport_a_SOURCES = \
     pathstuff.cc \
     print-utils.cc \
     ptid.cc \
+    remote-args.cc \
     rsp-low.cc \
     run-time-clock.cc \
     safe-strerror.cc \
diff --git a/gdbsupport/Makefile.in b/gdbsupport/Makefile.in
index 9fdc23c39a9..5d860302baa 100644
--- a/gdbsupport/Makefile.in
+++ b/gdbsupport/Makefile.in
@@ -163,11 +163,12 @@ am_libgdbsupport_a_OBJECTS = agent.$(OBJEXT) btrace-common.$(OBJEXT) \
 	gdb_tilde_expand.$(OBJEXT) gdb_wait.$(OBJEXT) \
 	gdb_vecs.$(OBJEXT) job-control.$(OBJEXT) netstuff.$(OBJEXT) \
 	new-op.$(OBJEXT) pathstuff.$(OBJEXT) print-utils.$(OBJEXT) \
-	ptid.$(OBJEXT) rsp-low.$(OBJEXT) run-time-clock.$(OBJEXT) \
-	safe-strerror.$(OBJEXT) scoped_mmap.$(OBJEXT) search.$(OBJEXT) \
-	signals.$(OBJEXT) signals-state-save-restore.$(OBJEXT) \
-	tdesc.$(OBJEXT) thread-pool.$(OBJEXT) xml-utils.$(OBJEXT) \
-	$(am__objects_1) $(am__objects_2)
+	ptid.$(OBJEXT) remote-args.$(OBJEXT) rsp-low.$(OBJEXT) \
+	run-time-clock.$(OBJEXT) safe-strerror.$(OBJEXT) \
+	scoped_mmap.$(OBJEXT) search.$(OBJEXT) signals.$(OBJEXT) \
+	signals-state-save-restore.$(OBJEXT) tdesc.$(OBJEXT) \
+	thread-pool.$(OBJEXT) xml-utils.$(OBJEXT) $(am__objects_1) \
+	$(am__objects_2)
 libgdbsupport_a_OBJECTS = $(am_libgdbsupport_a_OBJECTS)
 AM_V_P = $(am__v_P_@AM_V@)
 am__v_P_ = $(am__v_P_@AM_DEFAULT_V@)
@@ -429,6 +430,7 @@ libgdbsupport_a_SOURCES = \
     pathstuff.cc \
     print-utils.cc \
     ptid.cc \
+    remote-args.cc \
     rsp-low.cc \
     run-time-clock.cc \
     safe-strerror.cc \
@@ -538,6 +540,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/pathstuff.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/print-utils.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/ptid.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/remote-args.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/rsp-low.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/run-time-clock.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/safe-strerror.Po@am__quote@
diff --git a/gdbsupport/remote-args.cc b/gdbsupport/remote-args.cc
new file mode 100644
index 00000000000..96c12ffac67
--- /dev/null
+++ b/gdbsupport/remote-args.cc
@@ -0,0 +1,43 @@
+/* Copyright (C) 2023 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+#include "gdbsupport/common-defs.h"
+#include "gdbsupport/remote-args.h"
+#include "gdbsupport/common-inferior.h"
+#include "gdbsupport/buildargv.h"
+
+/* See remote-args.h.  */
+
+std::vector<std::string>
+gdb::remote_args::split (std::string args)
+{
+  std::vector<std::string> results;
+
+  gdb_argv argv (args.c_str ());
+  for (int i = 0; argv[i] != nullptr; i++)
+    results.emplace_back (argv[i]);
+
+  return results;
+}
+
+/* See remote-args.h.  */
+
+std::string
+gdb::remote_args::join (std::vector<char *> &args)
+{
+  return construct_inferior_arguments (args, escape_shell_characters);
+}
diff --git a/gdbsupport/remote-args.h b/gdbsupport/remote-args.h
new file mode 100644
index 00000000000..c0acce9b7c4
--- /dev/null
+++ b/gdbsupport/remote-args.h
@@ -0,0 +1,44 @@
+/* Functions to help when passing arguments between GDB and gdbserver.
+
+   Copyright (C) 2023 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+namespace gdb
+{
+
+namespace remote_args
+{
+
+/* ARGS is an inferior argument string.  This function splits ARGS into
+   individual arguments and returns a vector containing each argument.  */
+
+extern std::vector<std::string> split (std::string args);
+
+/* Join together the separate arguments in ARGS and build a single
+   inferior argument string.  The string returned by this function will be
+   equivalent, but not necessarily identical to the string passed to
+   ::split, for example passing the string '"a b"' (without the single
+   quotes, but including the double quotes) to ::split, will return an
+   argument of 'a b' (without the single quotes).  When this argument is
+   passed through ::join we will get back the string 'a\ b' (without the
+   single quotes), that is, we choose to escape the white space, rather
+   than wrap the argument in quotes.  */
+extern std::string join (std::vector<char *> &args);
+
+} /* namespace remote_args */
+
+} /* namespac gdb */
-- 
2.25.4