From 70fd94b244573225cb04ae41101d495def78b9e6 Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Thu, 5 Oct 2023 13:12:42 +0100 Subject: gdb: fix reopen_exec_file for files with target: prefix Following on from this commit: commit f2c4f78c813a9cef38b7e9c9ad18822fb9e19345 Date: Thu Sep 21 16:35:30 2023 +0100 gdb: fix reread_symbols when an objfile has target: prefix In this commit I update reopen_exec_file to correctly handle executables with a target: prefix. Before this commit we used the system 'stat' call, which obviously isn't going to work for files with a target: prefix (files located on a possibly remote target machine). By switching to bfd_stat we will use remote fileio to stat the remote files, which means we should now correctly detect changes in a remote executable. The program_space::ebfd_mtime variable, with which we compare the result of bfd_stat is set with a call to bfd_get_mtime, which in turn calls bfd_stat, so comparing to the result of calling bfd_stat makes sense (I think). As I discussed in the commit f2c4f78c813a, if a BFD is an in-memory BFD, then calling bfd_stat will always return 0, while bfd_get_mtime will always return the time at which the BFD was created. As a result comparing the results will always show the file having changed. I don't believe that GDB can set the main executable to an in-memory BFD object, so, in this commit, I simply assert that the executable is not in-memory. If this ever changes then we would need to decide how to handle this case -- always reload, or never reload. The assert doesn't appear to trigger for our current test suite. Approved-By: Tom Tromey --- gdb/corefile.c | 17 ++++--- gdb/testsuite/gdb.server/target-exec-file.exp | 70 +++++++++++++++++++++++++++ 2 files changed, 80 insertions(+), 7 deletions(-) (limited to 'gdb') diff --git a/gdb/corefile.c b/gdb/corefile.c index 19a96bc..b9c204d 100644 --- a/gdb/corefile.c +++ b/gdb/corefile.c @@ -105,21 +105,24 @@ specify_exec_file_hook (void (*hook) (const char *)) void reopen_exec_file (void) { - int res; - struct stat st; + bfd *exec_bfd = current_program_space->exec_bfd (); /* Don't do anything if there isn't an exec file. */ - if (current_program_space->exec_bfd () == NULL) + if (exec_bfd == nullptr) return; + /* The main executable can't be an in-memory BFD object. If it was then + the use of bfd_stat below would not work as expected. */ + gdb_assert ((exec_bfd->flags & BFD_IN_MEMORY) == 0); + /* If the timestamp of the exec file has changed, reopen it. */ - std::string filename = bfd_get_filename (current_program_space->exec_bfd ()); - res = stat (filename.c_str (), &st); + struct stat st; + int res = bfd_stat (exec_bfd, &st); if (res == 0 - && current_program_space->ebfd_mtime + && current_program_space->ebfd_mtime != 0 && current_program_space->ebfd_mtime != st.st_mtime) - exec_file_attach (filename.c_str (), 0); + exec_file_attach (bfd_get_filename (exec_bfd), 0); } /* If we have both a core file and an exec file, diff --git a/gdb/testsuite/gdb.server/target-exec-file.exp b/gdb/testsuite/gdb.server/target-exec-file.exp index 9260df8..4086353 100644 --- a/gdb/testsuite/gdb.server/target-exec-file.exp +++ b/gdb/testsuite/gdb.server/target-exec-file.exp @@ -52,6 +52,19 @@ set target_exec [gdb_remote_download target $binfile] # prompt us if this is the right thing to do. gdb_test_no_output "set confirm off" +if { [allow_python_tests] } { + # Register an event handler for the executable changed event. + # This handler just copies the event into a global Python object. + gdb_test_multiline "Add connection_removed event" \ + "python" "" \ + "global_exec_changed_event = None" "" \ + "def executable_changed(event):" "" \ + " global global_exec_changed_event" "" \ + " global_exec_changed_event = event" "" \ + "gdb.events.executable_changed.connect (executable_changed)" "" \ + "end" "" +} + # Start gdbserver, but always in extended-remote mode, and then # connect to it from GDB. set res [gdbserver_start "--multi" $target_exec] @@ -59,6 +72,22 @@ set gdbserver_protocol "extended-remote" set gdbserver_gdbport [lindex $res 1] gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport +if { [allow_python_tests] } { + # When connecting to a remote target, if the user has not told GDB + # which executable to use, then GDB will figure out an executable + # from the remote target. + # + # As a result we expect to have seen an executable changed event. + with_test_prefix "after connecting" { + gdb_test "python print(global_exec_changed_event)" \ + "" + gdb_test "python print(global_exec_changed_event.progspace.executable_filename)" \ + [string_to_regexp target:$target_exec] + gdb_test "python print(global_exec_changed_event.reload)" "False" + gdb_test_no_output "python global_exec_changed_event = None" + } +} + # Issue a 'file' command and parse the output. We look for a couple # of specific things to ensure that we are correctly reading the exec # from the remote target. @@ -104,6 +133,20 @@ gdb_assert { $saw_read_of_remote_exec } \ gdb_assert { $saw_read_of_syms_from_exec } \ "symbols were read from remote exec file" +if { [allow_python_tests] } { + # The 'file' command forces GDB to always load the executable, + # even if the same filename is used. In this case, as the + # filename is the same, this will show as a reload event. + with_test_prefix "after 'file' command" { + gdb_test "python print(global_exec_changed_event)" \ + "" + gdb_test "python print(global_exec_changed_event.progspace.executable_filename)" \ + [string_to_regexp target:$target_exec] + gdb_test "python print(global_exec_changed_event.reload)" "True" + gdb_test_no_output "python global_exec_changed_event = None" + } +} + # Start the inferior (with the 'start' command), use TESTNAME for any # pass/fail calls. EXPECT_REREAD should be true or false and # indicates if we expect to too a line like: @@ -155,10 +198,24 @@ proc start_inferior { testname expect_reread } { # see the symbols re-read now. start_inferior "start inferior the first time" false +if { [allow_python_tests] } { + # The executable hasn't changed. + with_test_prefix "after starting inferior for the first time" { + gdb_test "python print(global_exec_changed_event)" "None" + } +} + # Re-start the inferior. The executable is unchanged so we should not # see the symbol file being re-read. start_inferior "start inferior a second time" false +if { [allow_python_tests] } { + # The executable still hasn't changed. + with_test_prefix "after starting inferior for the second time" { + gdb_test "python print(global_exec_changed_event)" "None" + } +} + # Delay for a short while so, when we touch the exec, we know the # timestamp will change. sleep 1 @@ -172,3 +229,16 @@ if { $status != 0 } { # Start the inferior again, we expect to see the symbols being re-read # from the remote file. start_inferior "start inferior a third time" true + +if { [allow_python_tests] } { + # The executable has now changed on disk. This will be a reload + # event. + with_test_prefix "after starting inferior for the third time" { + gdb_test "python print(global_exec_changed_event)" \ + "" + gdb_test "python print(global_exec_changed_event.progspace.executable_filename)" \ + [string_to_regexp target:$target_exec] + gdb_test "python print(global_exec_changed_event.reload)" "True" + gdb_test_no_output "python global_exec_changed_event = None" + } +} -- cgit v1.1