[binutils-gdb] gdb/mi: fix ^running record with multiple MI interpreters

[binutils-gdb] gdb/mi: fix ^running record with multiple MI interpreters

[Simon Marchi]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f818c32ba4596a60e77b464cb690aea65ed31346

commit f818c32ba4596a60e77b464cb690aea65ed31346
Author: Simon Marchi <simon.marchi@efficios.com>
Date:   Fri Apr 21 12:08:42 2023 -0400

    gdb/mi: fix ^running record with multiple MI interpreters
    
    I stumbled on the mi_proceeded and running_result_record_printed
    globals, which are shared by all MI interpreter instances (it's unlikely
    that people use multiple MI interpreter instances, but it's possible).
    After poking at it, I found this bug:
    
    1. Start GDB in MI mode
    2. Add a second MI interpreter with the new-ui command
    3. Use -exec-run on the second interpreter
    
    This is the output I get on the first interpreter:
    
        =thread-group-added,id="i1"
        ~"Reading symbols from a.out...\n"
        ~"New UI allocated\n"
        (gdb)
        =thread-group-started,id="i1",pid="94718"
        =thread-created,id="1",group-id="i1"
        ^running
        *running,thread-id="all"
    
    And this is the output I get on the second intepreter:
    
        =thread-group-added,id="i1"
        (gdb)
        -exec-run
        =thread-group-started,id="i1",pid="94718"
        =thread-created,id="1",group-id="i1"
        *running,thread-id="all"
    
    The problem here is that the `^running` reply to the -exec-run command
    is printed on the wrong UI.  It is printed on the first one, it should
    be printed on the second (the one on which we sent the -exec-run).
    
    What happens under the hood is that captured_mi_execute_command, while
    executing a command for the second intepreter, clears the
    running_result_record_printed and mi_proceeded globals.
    mi_about_to_proceed then sets mi_proceeded.  Then, mi_on_resume_1 gets
    called for the first intepreter first.  Since the
    
        !running_result_record_printed && mi_proceeded
    
    condition is true, it prints a ^running, and sets
    running_result_record_printed.  When mi_on_resume_1 gets called for the
    second interpreter, running_result_record_printed is already set, so
    ^running is not printed there.
    
    It took me a while to understand the relationship between these two
    variables.  I think that in the end, this is what we want to track:
    
     1. When executing an MI command, take note if that command causes a
        "proceed".  This is done in mi_about_to_proceed.
     2. In mi_on_resume_1, if the command indeed caused a "proceed", we want
        to output a ^running record.  And we want to remember that we did,
        because...
     3. Back in captured_mi_execute_command, if we did not output a
        ^running, we want to output a ^done.
    
    Moving those two variables to the mi_interp struture appears to fix it.
    Only for the interpreter doing the -exec-run command does the
    running_result_record_printed flag get cleared, and therefore only or
    that one does the ^running record get printed.
    
    Add a new test for this, that does pretty much what the reproducer above
    shows.  Without the fix, the test fails because
    mi_send_resuming_command_raw never sees the ^running record.
    
    Change-Id: I63ea30e6cb61a8e1dd5ef03377e6003381a9209b
    Tested-By: Alexandra Petlanova Hajkova <ahajkova@redhat.com>

Diff:
---
 gdb/mi/mi-interp.c                           | 13 ++++--
 gdb/mi/mi-interp.h                           |  6 +++
 gdb/mi/mi-main.c                             | 14 ++----
 gdb/mi/mi-main.h                             |  3 --
 gdb/testsuite/gdb.mi/run-with-two-mi-uis.c   |  7 +++
 gdb/testsuite/gdb.mi/run-with-two-mi-uis.exp | 67 ++++++++++++++++++++++++++++
 gdb/testsuite/lib/mi-support.exp             | 26 +++++++----
 7 files changed, 111 insertions(+), 25 deletions(-)

diff --git a/gdb/mi/mi-interp.c b/gdb/mi/mi-interp.c
index 47aeabd8f00..d8b49ae644a 100644
--- a/gdb/mi/mi-interp.c
+++ b/gdb/mi/mi-interp.c
@@ -677,7 +677,12 @@ mi_about_to_proceed (void)
 	return;
     }
 
-  mi_proceeded = 1;
+  mi_interp *mi = as_mi_interp (top_level_interpreter ());
+
+  if (mi == nullptr)
+    return;
+
+  mi->mi_proceeded = 1;
 }
 
 /* When the element is non-zero, no MI notifications will be emitted in
@@ -961,7 +966,7 @@ mi_on_resume_1 (struct mi_interp *mi,
      will make it impossible for frontend to know what's going on.
 
      In future (MI3), we'll be outputting "^done" here.  */
-  if (!running_result_record_printed && mi_proceeded)
+  if (!mi->running_result_record_printed && mi->mi_proceeded)
     {
       gdb_printf (mi->raw_stdout, "%s^running\n",
 		  current_token ? current_token : "");
@@ -977,9 +982,9 @@ mi_on_resume_1 (struct mi_interp *mi,
     for (thread_info *tp : all_non_exited_threads (targ, ptid))
       mi_output_running (tp);
 
-  if (!running_result_record_printed && mi_proceeded)
+  if (!mi->running_result_record_printed && mi->mi_proceeded)
     {
-      running_result_record_printed = 1;
+      mi->running_result_record_printed = 1;
       /* This is what gdb used to do historically -- printing prompt
 	 even if it cannot actually accept any input.  This will be
 	 surely removed for MI3, and may be removed even earlier.  */
diff --git a/gdb/mi/mi-interp.h b/gdb/mi/mi-interp.h
index e07be12f87a..eb81cbe6cad 100644
--- a/gdb/mi/mi-interp.h
+++ b/gdb/mi/mi-interp.h
@@ -64,6 +64,12 @@ public:
 
   /* MI's CLI builder (wraps OUT).  */
   struct ui_out *cli_uiout;
+
+  int running_result_record_printed = 1;
+
+  /* Flag indicating that the target has proceeded since the last
+     command was issued.  */
+  int mi_proceeded;
 };
 
 /* Output the shared object attributes to UIOUT.  */
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index 7a8c35c8c49..dc7d717ef60 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -84,12 +84,6 @@ char *current_token;
    command including all option, and make it possible.  */
 static struct mi_parse *current_context;
 
-int running_result_record_printed = 1;
-
-/* Flag indicating that the target has proceeded since the last
-   command was issued.  */
-int mi_proceeded;
-
 static void mi_cmd_execute (struct mi_parse *parse);
 
 static void mi_execute_async_cli_command (const char *cli_command,
@@ -1818,8 +1812,8 @@ captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context)
   scoped_restore save_token = make_scoped_restore (&current_token,
 						   context->token);
 
-  running_result_record_printed = 0;
-  mi_proceeded = 0;
+  mi->running_result_record_printed = 0;
+  mi->mi_proceeded = 0;
   switch (context->op)
     {
     case MI_COMMAND:
@@ -1837,7 +1831,7 @@ captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context)
 	 to directly use the mi_interp's uiout, since the command
 	 could have reset the interpreter, in which case the current
 	 uiout will most likely crash in the mi_out_* routines.  */
-      if (!running_result_record_printed)
+      if (!mi->running_result_record_printed)
 	{
 	  gdb_puts (context->token, mi->raw_stdout);
 	  /* There's no particularly good reason why target-connect results
@@ -1876,7 +1870,7 @@ captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context)
 	    || current_interp_named_p (INTERP_MI3)
 	    || current_interp_named_p (INTERP_MI4))
 	  {
-	    if (!running_result_record_printed)
+	    if (!mi->running_result_record_printed)
 	      {
 		gdb_puts (context->token, mi->raw_stdout);
 		gdb_puts ("^done", mi->raw_stdout);
diff --git a/gdb/mi/mi-main.h b/gdb/mi/mi-main.h
index 18687d59aad..1741f48b3ee 100644
--- a/gdb/mi/mi-main.h
+++ b/gdb/mi/mi-main.h
@@ -36,9 +36,6 @@ extern int mi_async_p (void);
 
 extern char *current_token;
 
-extern int running_result_record_printed;
-extern int mi_proceeded;
-
 struct mi_suppress_notification
 {
   /* Breakpoint notification suppressed?  */
diff --git a/gdb/testsuite/gdb.mi/run-with-two-mi-uis.c b/gdb/testsuite/gdb.mi/run-with-two-mi-uis.c
new file mode 100644
index 00000000000..1e2428e0d54
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/run-with-two-mi-uis.c
@@ -0,0 +1,7 @@
+#include <unistd.h>
+
+int
+main (void)
+{
+  sleep (1234);
+}
diff --git a/gdb/testsuite/gdb.mi/run-with-two-mi-uis.exp b/gdb/testsuite/gdb.mi/run-with-two-mi-uis.exp
new file mode 100644
index 00000000000..9a049c98ea7
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/run-with-two-mi-uis.exp
@@ -0,0 +1,67 @@
+# Copyright 2023 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 an -exec-run while there are two MI UIs.
+
+load_lib mi-support.exp
+
+standard_testfile
+
+if {[build_executable $testfile.exp $testfile ${srcfile} "debug"] == -1} {
+    untested "failed to compile"
+    return
+}
+
+# Run one configuration of the test.
+#
+# UI_TO_RUN is the UI that should issue the run command.
+
+proc do_test { ui_to_run } {
+    if {[mi_clean_restart $::binfile "separate-mi-tty"] != 0} {
+	fail "could not start gdb"
+	return
+    }
+
+    with_spawn_id $::gdb_main_spawn_id {
+	lassign [create_mi_ui] second_mi_spawn_id second_mi_tty_name
+    }
+
+    with_spawn_id $second_mi_spawn_id {
+	gdb_expect {
+	    -re "=thread-group-added,id=\"i1\"\r\n$::mi_gdb_prompt$" {
+		pass "consume"
+	    }
+	}
+    }
+
+    if { $ui_to_run == "first" } {
+	set spawn_id_to_run $::mi_spawn_id
+    } elseif { $ui_to_run == "second" } {
+	set spawn_id_to_run $second_mi_spawn_id
+    } else {
+	error "invalid ui_to_run value"
+    }
+
+    with_spawn_id $spawn_id_to_run {
+	# mi_runto_main implicitly verifies that the UI doing the -exec-run gets
+	# the expected ^running record.
+	mi_runto_main
+    }
+}
+
+foreach_with_prefix ui_to_run {first second} {
+    do_test $ui_to_run
+}
+
diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index 0d830d8e4ae..2ff4ab93ea8 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -131,6 +131,21 @@ proc mi_create_inferior_pty {} {
     }
 }
 
+# Create a new pty, and reate a new MI UI (using the new-ui command) on it.
+#
+# Return a list with the spawn id for that pty and the pty file name.
+
+proc create_mi_ui {} {
+    spawn -pty
+    set tty_name $spawn_out(slave,name)
+    gdb_test_multiple "new-ui mi $tty_name" "new-ui" {
+	-re "New UI allocated\r\n$::gdb_prompt $" {
+	}
+    }
+
+    return [list $spawn_id $tty_name]
+}
+
 #
 # Like default_mi_gdb_start below, but the MI is created as a separate
 # ui in a new tty.  The global MI_SPAWN_ID is updated to point at the
@@ -154,13 +169,7 @@ proc mi_gdb_start_separate_mi_tty { { flags {} } } {
     gdb_start
 
     # Create the new PTY for the MI UI.
-    spawn -pty
-    set mi_spawn_id $spawn_id
-    set mi_tty_name $spawn_out(slave,name)
-    gdb_test_multiple "new-ui mi $mi_tty_name" "new-ui" {
-	-re "New UI allocated\r\n$gdb_prompt $" {
-	}
-    }
+    lassign [create_mi_ui] mi_spawn_id mi_tty_name
 
     # Switch to the MI channel.
     set gdb_main_spawn_id $gdb_spawn_id
@@ -822,7 +831,7 @@ proc mi_gdb_test { args } {
 	    fail "$errmsg"
 	    return -1
 	}
-	 -re ".*$mi_gdb_prompt\[ \]*$" {
+	 -re "(.*$mi_gdb_prompt\[ \]*)$" {
 	    if {![string match "" $message]} {
 		fail "$message (unexpected output)"
 	    }
@@ -1082,6 +1091,7 @@ proc mi_runto_helper {func run_or_continue args} {
       # file.", etc. to the CLI stream.
       set extra_output "&\"\[^\r\n\]+\"\r\n"
   }
+
   mi_gdb_test "200-break-insert [join $extra_opts " "] -t $func" "${extra_output}200\\^done,$bp" \
       "breakpoint at $func"