[patch/rfc] Test SIGSEGV from a NULL pointer, replace gdb1467

[Andrew Cagney <cagney at gnu dot org>]

Hello,

The attached tests GDB's ability to both unwind from and through a NULL 
pointer SIGSEGV.  It tests both NULL code and data addresses.

Comments?  I'll give it a few days.
Andrew

2004-05-11  Andrew Cagney  <cagney@redhat.com>

	* gdb.base/signull.exp, gdb.base/signull.c: New files.
	* gdb.base/gdb1476.c, gdb.base/gdb1476.exp: Delete files.

Index: testsuite/gdb.base/gdb1476.c
===================================================================
RCS file: testsuite/gdb.base/gdb1476.c
diff -N testsuite/gdb.base/gdb1476.c
--- testsuite/gdb.base/gdb1476.c	5 Jan 2004 22:55:33 -0000	1.1
+++ /dev/null	1 Jan 1970 00:00:00 -0000
@@ -1,12 +0,0 @@
-void x()
-{
-  void (*fp)() = 0;
-  fp();
-}
-
-int
-main()
-{
-  x();
-  return 0;
-}
Index: testsuite/gdb.base/gdb1476.exp
===================================================================
RCS file: testsuite/gdb.base/gdb1476.exp
diff -N testsuite/gdb.base/gdb1476.exp
--- testsuite/gdb.base/gdb1476.exp	18 Jan 2004 16:35:11 -0000	1.4
+++ /dev/null	1 Jan 1970 00:00:00 -0000
@@ -1,72 +0,0 @@
-# Copyright 2004 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 2 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, write to the Free Software
-# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
-
-# Please email any bugs, comments, and/or additions to this file to:
-# bug-gdb@gnu.org
-
-# This file is part of the gdb testsuite.
-
-if $tracelevel {
-    strace $tracelevel
-}
-
-# Testcase for backtrace/gdb1476.
-
-set prms_id 0
-set bug_id 0
-
-set testfile "gdb1476"
-set srcfile ${testfile}.c
-set binfile ${objdir}/${subdir}/${testfile}
-if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
-    gdb_suppress_entire_file "Testcase compile failed, so all tests in this file will automatically fail."
-}
-
-gdb_exit
-gdb_start
-gdb_reinitialize_dir $srcdir/$subdir
-gdb_load ${binfile}
-
-#
-# Run to `main' where we begin our tests.
-#
-
-if ![runto_main] then {
-    gdb_suppress_tests
-}
-
-# If we can examine what's at memory address 0, it is possible that we
-# could also execute it.  This could probably make us run away,
-# executing random code, which could have all sorts of ill effects,
-# especially on targets without an MMU.  Don't run the tests in that
-# case.
-
-send_gdb "x 0\n"
-gdb_expect {
-    -re "0x0:.*Cannot access memory at address 0x0.*$gdb_prompt $" { }
-    -re "0x0:.*Error accessing memory address 0x0.*$gdb_prompt $" { }
-    -re ".*$gdb_prompt $" {
-	untested "Memory at address 0 is possibly executable"
-	return
-    }
-}
-
-gdb_test "continue" "Program received signal SIGSEGV.*" \
-	"continue to null pointer call"
-
-gdb_test "backtrace 10" \
-	"#0\[ \t\]*0x0* in .*\r\n#1\[ \t\]*$hex in x.*\r\n#2\[ \t\]*$hex in main.*" \
-	"backtrace from null pointer call"
Index: testsuite/gdb.base/signull.c
===================================================================
RCS file: testsuite/gdb.base/signull.c
diff -N testsuite/gdb.base/signull.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/signull.c	11 May 2004 22:12:02 -0000
@@ -0,0 +1,68 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 1996, 1999, 2003 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 2 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, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+   02111-1307, USA.  */
+
+#include <signal.h>
+#include <setjmp.h>
+
+enum tests {
+  code_entry_point, code_descriptor, data_pointer
+};
+
+static volatile enum tests test;
+
+/* Some basic types and zero buffers.  */
+
+typedef long data_t;
+typedef long code_t (void);
+static volatile data_t *data[10];
+static volatile code_t *code[10];
+
+jmp_buf env;
+
+extern void
+keeper (int sig)
+{
+  longjmp (env, 0);
+}
+
+extern long
+bowler (void)
+{
+  switch (test)
+    {
+    case data_pointer:
+      return *data[0];
+    case code_entry_point:
+      return code[0] ();
+    case code_descriptor:
+      return ((code_t *) &code) ();
+    }
+}
+
+int
+main ()
+{
+  static volatile int i;
+  signal (SIGSEGV, keeper);
+  for (i = 0; i < 10; i++)
+    {
+      setjmp (env);
+      bowler ();
+    }
+}
Index: testsuite/gdb.base/signull.exp
===================================================================
RCS file: testsuite/gdb.base/signull.exp
diff -N testsuite/gdb.base/signull.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/signull.exp	11 May 2004 22:12:02 -0000
@@ -0,0 +1,117 @@
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2004 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 2 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, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
+
+# Check that GDB can trigger and backtrace SIGSEGV signal stacks
+# caused by both accessing (data) and executing (code) at address
+# zero.
+
+# On function descriptor architectures, a zero descriptor, instead of
+# a NULL pointer, is used.  That way the NULL code test always
+# contains a zero code reference.
+
+# For recovery, sigjmp/longjmp are used.
+
+# This also tests backtrace/gdb1476.
+
+if $tracelevel {
+    strace $tracelevel
+}
+
+set prms_id 0
+set bug_id 0
+
+set testfile "signull"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+    gdb_suppress_entire_file "Testcase compile failed, so all tests in this file will automatically fail."
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+#
+# Run to `main' where we begin our tests.
+#
+
+if ![runto_main] then {
+    gdb_suppress_tests
+}
+
+# If we can examine what's at memory address 0, it is possible that we
+# could also execute it.  This could probably make us run away,
+# executing random code, which could have all sorts of ill effects,
+# especially on targets without an MMU.  Don't run the tests in that
+# case.
+
+send_gdb "x 0\n"
+gdb_expect {
+    -re "0x0:.*Cannot access memory at address 0x0.*$gdb_prompt $" { }
+    -re "0x0:.*Error accessing memory address 0x0.*$gdb_prompt $" { }
+    -re ".*$gdb_prompt $" {
+	untested "Memory at address 0 is possibly executable"
+	return
+    }
+}
+
+# If an attempt to call a NULL pointer leaves the inferior in main,
+# then function pointers are descriptors, probe this and remember the
+# result.
+
+gdb_test "set test = code_entry_point" "" "set for function pointer probe"
+set test "probe function pointer"
+set function_pointer code_entry_point
+gdb_test_multiple "continue" "$test" {
+    -re "Program received signal SIGSEGV.* bowler .$gdb_prompt $" {
+	set function_pointer code_descriptor
+	pass "$test (function descriptor)"
+    }
+    -re "Program received signal SIGSEGV.*0.*$gdb_prompt $" {
+	pass "$test (function entry-point)"
+    }
+}
+
+# Re-start from scratch, breakpoint the bowler so that control is
+# regained after each test, and run up to that.
+rerun_to_main
+gdb_test "break bowler"
+gdb_test "break keeper"
+# By default Stop:Yes Print:Yes Pass:Yes
+gdb_test "handle SIGSEGV" "SIGSEGV.*Yes.*Yes.*Yes.*Segmentation fault"
+
+# For the given signal type, check that: the SIGSEGV occures; a
+# backtrace from the SEGV works; the sigsegv is delivered; a backtrace
+# through the SEGV works.
+
+proc test_segv { name tag bt_from_segv bt_from_keeper } {
+    gdb_test continue "Breakpoint.* bowler.*" "${name} starts with the bowler"
+    gdb_test "set test = $tag"
+    gdb_test continue "Program received signal SIGSEGV.*" "${name} got SEGV"
+    gdb_test backtrace $bt_from_segv "backtrace segv for ${name}"
+    gdb_test continue "Breakpoint.* keeper.*" "${name} through to keeper"
+    gdb_test backtrace $bt_from_keeper "backtrace keeper for ${name}"
+}
+
+test_segv data data_pointer \
+    {#0 .* bowler .*#1  .* main .*} \
+    {#0 .* keeper .*#1  .* handler .*#2 .* bowler .*#3  .* main .*}
+test_segv code $function_pointer \
+    {#0 .* 0x0+ .*#1 .* bowler .*#2  .* main .*} \
+    {#0 .* keeper .*#1  .* handler .*#2 .* 0x0+ .*#3 .* bowler .*#4 .* main .*}