gdb/testsuite: add inferior arguments test

Add a test for verifying different methods of passing arguments to the
inferior: the start, starti and run commands, as well as `set args`.

All these methods work naturally when using the unix or
native-extended-gdbserver target boards.  Since those are non-stub
boards, GDB runs new inferiors and therefore pass arguments to them.
With target boards where GDB connects to a stub, for example with
native-gdbserver, they don't really make sense.  The inferior process is
already started when GDB connects.

However, the "run" method is still tested with stub targets, because the
gdb_run_cmd procedure is adapted for stub targets.  Instead of issuing
the `run` command, it spawns whatever program is supposed to bring up
the stub (gdbserver, for example) using gdb_reload and makes GDB connect
to it.  So this allows us to exercise argument passing through the
gdbserver command line, when testing with the native-gdbserver board.

Note that there is already a gdb.base/args.exp, but this tests
specifically the --args switch of GDB.  Perhaps it could be integrated
in this new test, as a new "method".

gdb/testsuite/ChangeLog:

	* lib/gdb.exp (gdb_run_cmd): Return success or failure.
	* gdb.base/inferior-args.exp: New file.
	* gdb.base/inferior-args.c: New file.

Change-Id: Ib61ea6220a47f9f67aed2960dcacd240cb57af70

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2020-05-25  Simon Marchi  <simon.marchi@efficios.com>
+
+	* lib/gdb.exp (gdb_run_cmd): Return success or failure.
+	* gdb.base/inferior-args.exp: New file.
+	* gdb.base/inferior-args.c: New file.
+
 2020-05-25  Simon Marchi  <simon.marchi@efficios.com>
 
 	* lib/gdb.exp (gdb_run_cmd): Change argument from args to

gdb/testsuite/gdb.base/inferior-args.c

@@ -0,0 +1,26 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2020 Free Software Foundation, 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 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 <stdio.h>
+
+int main (int argc, char **argv)
+{
+  for (int i = 0; i < argc; i++)
+    printf ("[%d] %s\n", i, argv[i]);
+
+  return 0;
+}

gdb/testsuite/gdb.base/inferior-args.exp

@@ -0,0 +1,124 @@
+# Copyright 2020 Free Software Foundation, 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 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/>.
+
+# Test running an inferior with arguments.
+
+# This does not work on boards that don't support inferior arguments.
+if [target_info exists noargs] then {
+    verbose "skipping gdb.base/inferior-args.exp because of noargs"
+    return
+}
+
+standard_testfile .c
+
+if {[build_executable "failed to prepare" $testfile $srcfile debug] == -1} {
+    return
+}
+
+proc do_test { method } {
+    global binfile hex
+
+    # The second arg is an empty string on purpose.
+    set inferior_args { "first arg" "" "third-arg" }
+
+    clean_restart $binfile
+
+    if { $method == "start" } {
+	# The start command does not make sense for a stub.
+	if { [use_gdb_stub] } {
+	    return;
+	}
+
+	if { [gdb_start_cmd $inferior_args] < 0 } {
+	    fail "could not issue start command"
+	    return -1
+	}
+
+	# Consume up to the GDB prompt after the stop.
+	gdb_test "" ".*main.*" "stop at main"
+
+    } elseif { $method == "starti" } {
+	# The starti command does not make sense for a stub.
+	if { [use_gdb_stub] } {
+	    return;
+	}
+
+	if { [gdb_starti_cmd $inferior_args] < 0 } {
+	    fail "could not issue start command"
+	    return -1
+	}
+
+	# Consume up to the GDB prompt after the stop.
+	gdb_test "" "" "stop at first instruction"
+
+	# Put a breakpoint and continue until main.
+	if { ![gdb_breakpoint "main" message] } {
+	    fail "could not set breakpoint on main"
+	    return -1
+	}
+
+	if { [gdb_continue "main"] != 0 } {
+	    fail "could not continue to main"
+	    return -1
+	}
+
+    } elseif { $method == "run" } {
+	if { ![gdb_breakpoint "main" message] } {
+	    fail "could not set breakpoint on main"
+	    return -1
+	}
+
+	# The run command does not make sense for a stub, but GDB_RUN_CMD
+	# does the right thing when the target is a stub (start the stub,
+	# connect to it, and "continue").
+	#
+	# This allows us to test arguments passed on the gdbserver command
+	# line.
+	if { [gdb_run_cmd $inferior_args] < 0 } {
+	    fail "could not run"
+	    return -1
+	}
+
+	# Consume up to the GDB prompt after the stop.
+	gdb_test "" ".*main.*" "stop at main"
+
+    } elseif { $method == "set args" } {
+	# Using "set args" does not make sense with a stub.
+	if { [use_gdb_stub] } {
+	    return;
+	}
+
+	gdb_test_no_output "set args $inferior_args"
+
+	if { ![runto_main] } {
+	    fail "could not run to main"
+	    return -1
+	}
+
+    } else {
+	error "invalid method $method"
+    }
+
+    # Now that we are stopped at main, inspect argc/argv.
+    gdb_test "print argc" " = 4"
+    gdb_test "print argv\[0\]" " = $hex \".*\""
+    gdb_test "print argv\[1\]" " = $hex \"first arg\""
+    gdb_test "print argv\[2\]" " = $hex \"\""
+    gdb_test "print argv\[3\]" " = $hex \"third-arg\""
+}
+
+foreach_with_prefix method { "start" "starti" "run" "set args" } {
+    do_test $method
+}

gdb/testsuite/lib/gdb.exp

@@ -242,6 +242,8 @@ proc target_can_use_run_cmd {} {
 
 # Generic run command.
 #
+# Return 0 if we could start the program, -1 if we could not.
+#
 # The second pattern below matches up to the first newline *only*.
 # Using ``.*$'' could swallow up output that we attempt to match
 # elsewhere.
@@ -269,14 +271,14 @@ proc gdb_run_cmd { {inferior_args {}} } {
     if $use_gdb_stub {
 	if [target_info exists gdb,do_reload_on_run] {
 	    if { [gdb_reload $inferior_args] != 0 } {
-		return
+		return -1
 	    }
 	    send_gdb "continue\n"
 	    gdb_expect 60 {
 		-re "Continu\[^\r\n\]*\[\r\n\]" {}
 		default {}
 	    }
-	    return
+	    return 0
 	}
 
 	if [target_info exists gdb,start_symbol] {
@@ -292,7 +294,7 @@ proc gdb_run_cmd { {inferior_args {}} } {
 	    # clever and not send a command when it has failed.
 	    if [expr $start_attempt > 3] {
 		perror "Jump to start() failed (retry count exceeded)"
-		return
+		return -1
 	    }
 	    set start_attempt [expr $start_attempt + 1]
 	    gdb_expect 30 {
@@ -301,7 +303,7 @@ proc gdb_run_cmd { {inferior_args {}} } {
 		}
 		-re "No symbol \"_start\" in current.*$gdb_prompt $" {
 		    perror "Can't find start symbol to run in gdb_run"
-		    return
+		    return -1
 		}
 		-re "No symbol \"start\" in current.*$gdb_prompt $" {
 		    send_gdb "jump *_start\n"
@@ -314,22 +316,23 @@ proc gdb_run_cmd { {inferior_args {}} } {
 		}
 		-re "The program is not being run.*$gdb_prompt $" {
 		    if { [gdb_reload $inferior_args] != 0 } {
-			return
+			return -1
 		    }
 		    send_gdb "jump *$start\n"
 		}
 		timeout {
 		    perror "Jump to start() failed (timeout)"
-		    return
+		    return -1
 		}
 	    }
 	}
-	return
+
+	return 0
     }
 
     if [target_info exists gdb,do_reload_on_run] {
 	if { [gdb_reload $inferior_args] != 0 } {
-	    return
+	    return -1
 	}
     }
     send_gdb "run $inferior_args\n"
@@ -346,6 +349,8 @@ proc gdb_run_cmd { {inferior_args {}} } {
 	    # There is no more input expected.
 	}
     }
+
+    return 0
 }
 
 # Generic start command.  Return 0 if we could start the program, -1