[binutils-gdb] gdbserver: Fix vAttach response when attaching is not supported

[binutils-gdb] gdbserver: Fix vAttach response when attaching is not supported

[Pedro Alves]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ef27d39dd2c2e7b6af70884895e6d751872ae305

commit ef27d39dd2c2e7b6af70884895e6d751872ae305
Author: Pedro Alves <pedro@palves.net>
Date:   Fri Apr 19 14:37:56 2024 +0100

    gdbserver: Fix vAttach response when attaching is not supported
    
    handle_v_attach calls attach_inferior, which says:
    
      "return -1 if attaching is unsupported, 0 if it succeeded, and call
      error() otherwise."
    
    So if attach_inferior return != 0, we have the unsupported case,
    meaning we should return the empty packet instead of an error.
    
    In practice, this shouldn't trigger, as vAttach support is supposed to
    be reported via qSupported.  But it doesn't hurt to be pedantic here.
    
    Change-Id: I99cce6fa678f2370571e6bca0657451300956127
    Approved-By: Tom Tromey <tom@tromey.com>

Diff:
---
 gdbserver/server.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index 2633df08ddb..789af36d9a4 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -3318,7 +3318,10 @@ handle_v_attach (char *own_buf)
 	    prepare_resume_reply (own_buf, cs.last_ptid, cs.last_status);
 	}
       else
-	write_enn (own_buf);
+	{
+	  /* Not supported.  */
+	  own_buf[0] = 0;
+	}
     }
   catch (const gdb_exception_error &exception)
     {