[binutils-gdb] infcmd.c: Don't attempt to record a NULL value after a finish command.

[Kevin Buettner <kevinb at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=aca20ec47359776488863193660cf9fd2fe3cfe7

commit aca20ec47359776488863193660cf9fd2fe3cfe7
Author: Kevin Buettner <kevinb@redhat.com>
Date:   Wed Sep 30 05:54:15 2015 -0700

    infcmd.c: Don't attempt to record a NULL value after a finish command.
    
    Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a
    NULL return value after executing a finish command.  See get_return_value()
    in infcmd.c.
    
    This patch avoids an eventual SIGSEV (caused by attempting to
    derefrence a NULL pointer) by adding a suitable test to
    finish_command_fsm_should_stop().
    
    I encountered this problem while testing msp430:
    
    (gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc
    finish
    Run till exit from #0  fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125
    ERROR: Process no longer exists
    
    gdb/ChangeLog:
        	* infcmd.c (finish_command_fsm_should_stop): Don't attempt to
        	record a NULL value.

Diff:
---
 gdb/ChangeLog | 5 +++++
 gdb/infcmd.c  | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 667bf27..b6355e7 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2015-09-29  Kevin Buettner  <kevinb@redhat.com>
 
+	* infcmd.c (finish_command_fsm_should_stop): Don't attempt to
+	record a NULL value.
+
+2015-09-29  Kevin Buettner  <kevinb@redhat.com>
+
 	* msp430-tdep.c (msp430_push_dummy_call): Treat reference, struct,
 	and union arguments the same as pointer arguments when determining
 	size of argument.
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index c4d7d8b..54aa1ef 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -1794,7 +1794,8 @@ finish_command_fsm_should_stop (struct thread_fsm *self)
 
 	  func = read_var_value (f->function, NULL, get_current_frame ());
 	  rv->value = get_return_value (func, rv->type);
-	  rv->value_history_index = record_latest_value (rv->value);
+	  if (rv->value != NULL)
+	    rv->value_history_index = record_latest_value (rv->value);
 	}
     }
   else if (tp->control.stop_step)