Re: [patch/rfc] Test sigaltstack

[Andrew Cagney <cagney at gnu dot org>]

> Hello,
>
> This tests GDB doing a backtrace, and then finishing, an out-of-order sequence of sigaltstacks.  It turns up a few bugs so I'd better fix them before committing :-)

I've fixed the bugs (and fixed a few bugs in the testcase).  It now 
passes on i386 GNU/Linux and PPC/NetBSD (with that other sigtramp patch 
applied).

committed,
Andrew

2004-04-05  Andrew Cagney  <cagney@redhat.com>

	* gdb.base/sigaltstack.c: New file.
	* gdb.base/sigaltstack.exp: New file.

Index: gdb.base/sigaltstack.c
===================================================================
RCS file: gdb.base/sigaltstack.c
diff -N gdb.base/sigaltstack.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gdb.base/sigaltstack.c	5 Apr 2004 20:57:10 -0000
@@ -0,0 +1,95 @@
+/* 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.
+
+   Please email any bugs, comments, and/or additions to this file to:
+   bug-gdb@prep.ai.mit.edu  */
+
+#include <signal.h>
+#include <stdio.h>
+#include <sys/time.h>
+
+enum level { MAIN, OUTER, INNER, LEAF, NR_LEVELS };
+
+/* Levels completed flag.  */
+volatile enum level level = NR_LEVELS;
+
+void catcher (int signal);
+
+void
+thrower (enum level next_level, int sig, int itimer, int on_stack)
+{
+  level = next_level;
+  /* Set up the signal handler.  */
+  {
+    struct sigaction act;
+    memset (&act, 0, sizeof (act));
+    act.sa_handler = catcher;
+    act.sa_flags |= on_stack;
+    sigaction (sig, &act, NULL);
+  }
+  /* Set up a one-off timer.  A timer, rather than SIGSEGV, is used as
+     after a timer handler finishes the interrupted code can safely
+     resume.  */
+  {
+    struct itimerval itime;
+    memset (&itime, 0, sizeof (itime));
+    itime.it_value.tv_usec = 250 * 1000;
+    setitimer (itimer, &itime, NULL);
+  }
+  /* Wait.  */
+  while (level != LEAF);
+}
+
+void
+catcher (int signal)
+{
+  /* Find the next level.  */
+  switch (level)
+    {
+    case MAIN:
+      thrower (OUTER, SIGALRM, ITIMER_REAL, SA_ONSTACK);
+      break;
+    case OUTER:
+      thrower (INNER, SIGVTALRM, ITIMER_VIRTUAL, SA_ONSTACK);
+      break;
+    case INNER:
+      level = LEAF;
+      return;
+    }
+}
+
+
+main ()
+{
+  /* Set up the altstack.  */
+  {
+    static char stack[SIGSTKSZ * NR_LEVELS];
+    struct sigaltstack alt;
+    memset (&alt, 0, sizeof (alt));
+    alt.ss_sp = stack;
+    alt.ss_size = SIGSTKSZ;
+    alt.ss_flags = 0;
+    if (sigaltstack (&alt, NULL) < 0)
+      {
+	perror ("sigaltstack");
+	exit (0);
+      }
+  }
+  level = MAIN;
+  catcher (0);
+}
Index: gdb.base/sigaltstack.exp
===================================================================
RCS file: gdb.base/sigaltstack.exp
diff -N gdb.base/sigaltstack.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gdb.base/sigaltstack.exp	5 Apr 2004 20:57:11 -0000
@@ -0,0 +1,88 @@
+# 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.  
+
+
+# The program sigaltstack.c creates a backtrace containing nested
+# signal handlers on an alternative stack.  This in turn leads to a
+# non-contiguous (and possibly non-monotonic) backtrace - stack
+# address jump at the normal-alt stack boundary.
+
+# This test confirms that GDB can both backtrace through and finish
+# such a stack.
+
+if [target_info exists gdb,nosignals] {
+    verbose "Skipping signals.exp because of nosignals."
+    continue
+}
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+set prms_id 0
+set bug_id 0
+
+set testfile sigaltstack
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+    untested "Couldn't compile ${module}.c"
+    return -1
+}
+
+# get things started
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+# Pass all the alarms straight through (but verbosely)
+gdb_test "handle SIGALRM print pass nostop"
+gdb_test "handle SIGVTALRM print pass nostop"
+gdb_test "handle SIGPROF print pass nostop"
+
+# Advance to main
+if { ![runto_main] } then {
+    gdb_suppress_tests;
+}
+
+# Stop in handle, when at the inner most level
+gdb_test "break catcher if level == INNER"
+gdb_test "continue" ".* catcher .*" "continue to catch"
+# step off the assignment
+gdb_test "next"
+
+# Full backtrace?
+send_gdb "bt\n"
+gdb_expect_list "backtrace" ".*$gdb_prompt $" {
+    "\[\r\n\]+.0 \[^\r\n\]* catcher "
+    "\[\r\n\]+.1  .signal handler called."
+    "\[\r\n\]+.2 \[^\r\n\]* thrower .next_level=INNER"
+    "\[\r\n\]+.3 \[^\r\n\]* catcher "
+    "\[\r\n\]+.4  .signal handler called."
+    "\[\r\n\]+.5 \[^\r\n\]* thrower .next_level=OUTER"
+    "\[\r\n\]+.6 \[^\r\n\]* catcher "
+    "\[\r\n\]+.7 \[^\r\n\]* main .*"
+}
+
+# Finish?
+gdb_test "finish" "signal handler called." "finish from catch LEAF"
+gdb_test "finish" "thrower .next_level=INNER, .*" "finish to throw INNER"
+gdb_test "finish" "catcher .*" "finish to catch INNER"
+gdb_test "finish" "signal handler called.*" "finish from catch INNER"
+gdb_test "finish" "thrower .next_level=OUTER, .*" "finish to OUTER"
+gdb_test "finish" "catcher .*" "finish to catch MAIN"
+gdb_test "finish" "main .*" "finish to MAIN"