[Bug gdb/19558] Trying to attach the same process twice borks gdbserver

[Bug gdb/19558] Trying to attach the same process twice borks gdbserver

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=19558

--- Comment #6 from Simon Marchi <simark at simark dot ca> ---
I just stumbled on this again, it's still present.

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[Bug gdb/19558] Trying to attach the same process twice borks gdbserver

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=19558

--- Comment #7 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Simon Marchi <simark@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=4b0cf3d6d0ff4a737f8aee2ed388fbc72ba941be

commit 4b0cf3d6d0ff4a737f8aee2ed388fbc72ba941be
Author: Simon Marchi <simon.marchi@polymtl.ca>
Date:   Thu Jun 10 10:47:40 2021 -0400

    gdb/testsuite: gdb.base/attach.exp: expose bug when testing with
native-extended-gdbserver

    In gdb.base/attach.exp, proc do_attach_failure_tests, we attach to a
    process.  When then try to attach to the same process in another
    inferior, expecting it to fail.  We then come back to the first inferior
    and try to kill it, to clean up the test.  When using the
    native-extended-gdbserver board, this "kill" test passes, even though it
    didn't actually work:

        add-inferior
        [New inferior 2]
        Added inferior 2 on connection 1 (extended-remote localhost:2347)
        (gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: add empty
inferior 2
        inferior 2
        [Switching to inferior 2 [<null>] (<noexec>)]
        (gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: switch to
inferior 2
        attach 817032
        Attaching to process 817032
        Attaching to process 817032 failed
        (gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: fail to
attach again
        inferior 1
        [Switching to inferior 1 [process 817032]
(/home/simark/build/binutils-gdb/gdb/testsuite/outputs/gdb.base/attach/attach)]
        [Switching to thread 1.1 (Thread 817032.817032)]
        #0  main () at
/home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/attach.c:19
        19    while (! should_exit)
        (gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: switch to
inferior 1
        kill
        Kill the program being debugged? (y or n) y
        Remote connection closed  <==== That's unexpected
        (gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: exit after
attach failures

    When the second attach fails, gdbserver seems to break the connection
    (it hangs up on the existing remote target) and start listening again
    for incoming connections.  This is documented in PR 19558 [1].

    Make the expected output regexp for the kill command tighter (it
    currently accepts anything).  Use "set confirm off" so we don't have to
    deal with the confirmation.  And to be really sure the extended-remote
    target still works, try to run the inferior again after killing.  The
    now tests are kfail'ed when the target is gdbserver.

    [1] https://sourceware.org/bugzilla/show_bug.cgi?id=19558

    gdb/testsuite/ChangeLog:

            * gdb.base/attach.exp (do_attach_failure_tests): Make kill
            regexp tighter, run inferior after killing it.  Kfail when
            target is gdbserver.

    Change-Id: I99c5cd3968ce2ec962ace35b016f842a243b7a0d

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[Bug gdb/19558] Trying to attach the same process twice borks gdbserver

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=19558

--- Comment #8 from Sourceware Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Pedro Alves <palves@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f1fc8dc2dccb4a224cdd1c3973c7a09a752aa95b

commit f1fc8dc2dccb4a224cdd1c3973c7a09a752aa95b
Author: Pedro Alves <pedro@palves.net>
Date:   Wed Apr 17 19:26:32 2024 +0100

    Fix "attach" failure handling with GDBserver

    This fixes the same issue as the previous patch, but for "attach"
    instead of "run".

    If attaching to a process with "attach" (vAttach 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.

    Here's an example:

    On the GDB side:

     ...
     (gdb) tar extended-remote :9999
     ...
     Remote debugging using :9999
     (gdb) attach 1
     Attaching to process 1
     Attaching to process 1 failed
     (gdb)

    On the GDBserver side:

     $ gdbserver --once --multi :9999
     Listening on port 9999
     Remote debugging from host 127.0.0.1, port 37464
     gdbserver: Cannot attach to process 1: Operation not permitted (1)
     $   # gdbserver exited

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

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

    Note we now let pid == 0 pass down to attach_inferior.  That is so we
    get a useful textual error message to report to GDB.

    This fixes a couple KFAILs in gdb.base/attach.exp.  Still, I thought
    it would be useful to add a new testcase specifically for this
    scenario, in case gdb.base/attach.exp is ever split and stops trying
    to attach again after a failed attach, with the same GDB session.

    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19558
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31554

    Change-Id: I25314c7e5f1435eff69cb84d57ecac13d8de3393
    Approved-By: Tom Tromey <tom@tromey.com>

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[Bug gdb/19558] Trying to attach the same process twice borks gdbserver

[pedro at palves dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=19558

Pedro Alves <pedro at palves dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #9 from Pedro Alves <pedro at palves dot net> ---
Should be fixed now.

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