Adjust coredump-filter.exp to account for NT_FILE note handling

This commit makes adjustments to coredump-filter.exp to account
for the fact that NT_FILE file-backed mappings are now available
when a core file is loaded.  Thus, a test which was expected
to PASS when a memory region was determined to be unavailable
(due to no file-backed mappings being available) will now FAIL
due to those mappings being available from having loaded the
NT_FILE note.

I had originally marked the test as XFAIL, but Mihails Strasuns
suggested a much better approach:

    1) First test that it still works if file is accessible in the
       filesystem.
    2) Temporarily move / rename the file and test that disassembly
       doesn't work anymore.

That's what this commit implements.

gdb/testsuite/ChangeLog:

	* gdb.base/coredump-filter.exp: Add second
	non-Private-Shared-Anon-File test.
	(test_disasm): Rename binfile for test which is expected
	to fail.

2 files changed, 24 insertions, 1 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 5ed9969..b074741 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,12 @@
 2020-07-22  Kevin Buettner  <kevinb@redhat.com>
 
+	* gdb.base/coredump-filter.exp: Add second
+	non-Private-Shared-Anon-File test.
+	(test_disasm): Rename binfile for test which is expected
+	to fail.
+
+2020-07-22  Kevin Buettner  <kevinb@redhat.com>
+
 	* gdb.base/corefile.exp: Add test "accessing read-only mmapped
 	data in core file".
 	* gdb.base/coremaker.c (buf2ro): New global.
diff --git a/gdb/testsuite/gdb.base/coredump-filter.exp b/gdb/testsuite/gdb.base/coredump-filter.exp
index ff398f2..5407d11 100644
--- a/gdb/testsuite/gdb.base/coredump-filter.exp
+++ b/gdb/testsuite/gdb.base/coredump-filter.exp
@@ -80,15 +80,26 @@ proc do_load_and_test_core { core var working_var working_value dump_excluded }
 # disassemble of a function (i.e., the binary's .text section).  GDB
 # should fail in this case.  However, it must succeed if the binary is
 # provided along with the corefile.  This is what we test here.
+#
+# A further complication is that Linux NT_FILE notes are now read from
+# the corefile.  This note allows GDB to find the binary for file
+# backed mappings even though the binary wasn't loaded by GDB in the
+# conventional manner.  In order to see the expected failure for this
+# case, we rename the binary in order to perform this test.
 
 proc test_disasm { core address should_fail } {
-    global testfile hex
+    global testfile hex binfile
 
     # Restart GDB without loading the binary.
     with_test_prefix "no binary" {
 	gdb_exit
 	gdb_start
 
+	set hide_binfile [standard_output_file "${testfile}.hide"]
+	if { $should_fail == 1 } {
+	    remote_exec host "mv -f $binfile $hide_binfile"
+	}
+
 	set core_loaded [gdb_core_cmd "$core" "load core"]
 	if { $core_loaded == -1 } {
 	    fail "loading $core"
@@ -96,6 +107,7 @@ proc test_disasm { core address should_fail } {
 	}
 
 	if { $should_fail == 1 } {
+	    remote_exec host "mv -f $hide_binfile $binfile"
 	    gdb_test "x/i \$pc" "=> $hex:\tCannot access memory at address $hex" \
 		"disassemble function with corefile and without a binary"
 	} else {
@@ -225,5 +237,9 @@ foreach item $all_anon_corefiles {
 }
 
 with_test_prefix "loading and testing corefile for non-Private-Shared-Anon-File" {
+    test_disasm $non_private_shared_anon_file_core $main_addr 0
+}
+
+with_test_prefix "loading and testing corefile for non-Private-Shared-Anon-File with renamed binary" {
     test_disasm $non_private_shared_anon_file_core $main_addr 1
 }