Fix "run" failure handling with GDBserver

If starting the inferior process with "run" (vRun packet) fails,
GDBserver throws an error that escapes all the way to the top level.
When an error escapes all the way like that, GDBserver interprets it
as a disconnection, and either goes back to waiting for a new GDB
connection, or exits, if --once was specified.

E.g., with the testcase program added by this commit, we see:

On GDB side:

 ...
 (gdb) tar extended-remote :999
 ...
 Remote debugging using :9999
 (gdb) r
 Starting program:
 Running ".../gdb.base/run-fail-twice/run-fail-twice.nox" on the remote target failed
 (gdb)

On GDBserver side:

 $ gdbserver --once --multi :9999
 Remote debugging from host 127.0.0.1, port 34344
 bash: line 1: .../gdb.base/run-fail-twice/run-fail-twice.nox: Permission denied
 bash: line 1: exec: .../gdb.base/run-fail-twice/run-fail-twice.nox: cannot execute: Permission denied
 gdbserver: During startup program exited with code 126.
 $   # gdbserver exited

This is wrong, as we've connected with extended-remote/--multi.
GDBserver should just report an error to vCont, and continue connected
to GDB, waiting for other commands.

This commit fixes GDBserver by catching the error locally in
handle_v_run.

Change-Id: Ib386f267522603f554b52a885b15229c9639e870
Approved-By: Tom Tromey <tom@tromey.com>

gdb/testsuite/gdb.base/run-fail-twice.c

@@ -0,0 +1,20 @@
+/* Copyright 2024 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/>.  */
+
+int
+main (int argc, char **argv)
+{
+  return 0;
+}

gdb/testsuite/gdb.base/run-fail-twice.exp

@@ -0,0 +1,63 @@
+# Copyright 2024 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 doing a "run" that fails, and then another "run".
+
+require target_can_use_run_cmd
+
+standard_testfile
+
+if {[build_executable "failed to build" $testfile $srcfile {debug}]} {
+    return -1
+}
+
+proc test_run {testname} {
+    gdb_test_multiple "run" $testname {
+	-re -wrap "During startup program exited with code 126\\." {
+	    # What we get on GNU/Linux.
+	    pass $gdb_test_name
+	}
+	-re -wrap "Error creating process.*" {
+	    # What we get on Windows.
+	    pass $gdb_test_name
+	}
+	-re -wrap "Running .* on the remote target failed" {
+	    # What we get with remote targets.
+	    pass $gdb_test_name
+	}
+    }
+}
+
+proc_with_prefix test {} {
+    global gdb_prompt binfile
+
+    clean_restart $binfile
+
+    gdb_test_no_output "set confirm off"
+
+    gdb_remote_download host $binfile $binfile.nox
+    remote_exec target "chmod \"a-x\" $binfile.nox"
+    gdb_test_no_output \
+	"exec-file $binfile.nox" \
+	"exec-file \$binfile.nox"
+    gdb_test_no_output \
+	"set remote exec-file $binfile.nox" \
+	"set remote exec-file \$binfile.nox"
+
+    test_run "bad run 1"
+    test_run "bad run 2"
+}
+
+test

gdbserver/server.cc

@@ -3427,7 +3427,15 @@ handle_v_run (char *own_buf)
   free_vector_argv (program_args);
   program_args = new_argv;
 
-  target_create_inferior (program_path.get (), program_args);
+  try
+    {
+      target_create_inferior (program_path.get (), program_args);
+    }
+  catch (const gdb_exception_error &exception)
+    {
+      sprintf (own_buf, "E.%s", exception.what ());
+      return;
+    }
 
   if (cs.last_status.kind () == TARGET_WAITKIND_STOPPED)
     {