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Re: [rfa/testsuite] Extend signull to work with discriptors
- From: Andrew Cagney <cagney at gnu dot org>
- To: Michael Elizabeth Chastain <mec dot gnu at mindspring dot com>
- Cc: gdb-patches at sources dot redhat dot com
- Date: Wed, 16 Jun 2004 10:54:19 -0400
- Subject: Re: [rfa/testsuite] Extend signull to work with discriptors
- References: <20040616050213.94BCC4B104@berman.michael-chastain.com>
Needs more work:
- copyright year 2004 in signull.c
- did you test it on ia64 and/or ppc?
can't quite tell from your wording
yep, and also tested on fc2 i386.
- this code has ISO problems.
That's to put it mildly. The trick it's pulling with function
descriptors isn't valid ISO-C (but by knowing how descriptors work does
lead to predictable behavior ... :-)
We're going to have to live with this - the testsuite needs to include
deliberately erroneous programs.
% cat ptr.c
typedef long data_t;
typedef long code_t (void);
volatile data_t zero[10];
volatile code_t *desc = (void *) zero;
% gcc-340 -Wall -S -pedantic -std=iso9899:1990 ptr.c
ptr.c:4: warning: ISO C forbids qualified function types
ptr.c:4: warning: ISO C forbids initialization between function pointer and `void *'
What about:
code_t * volatile desc = 0;
But that's semantically different from what you wrote. Hmmm. I don't
think it's possible in ISO C to initialize a pointer-to-code with the
address of a data object. Any ideas?
This:
code_t *volatile desc = (code_t *) (void *) zero;
does appear to fool the compiler.
see attched,
Andrew
===
2004-06-15 Andrew Cagney <cagney@gnu.org>
* gdb.base/signull.c (bowler): Replace data_pointer with data_read
and data_write cases. Add code_descriptor case.
(zero, desc): New array and pointer.
(data, code): Change to simple pointers.
* gdb.base/signull.exp: Fix probe pattern matching a function
descriptor SIGSEGV. Replace data_pointer with data_read and
data_write tests.
2004-06-16 Andrew Cagney <cagney@gnu.org>
* gdb.base/signull.c: Update copyright. Include <string.h>.
(bowler): Replace data_pointer with data_read
and data_write cases. Add code_descriptor case.
(zero, desc): New array and pointer.
(data, code): Change to simple pointers.
* gdb.base/signull.exp: Fix probe pattern matching a function
descriptor SIGSEGV. Replace data_pointer with data_read and
data_write tests.
Index: gdb.base/signull.c
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/signull.c,v
retrieving revision 1.3
diff -p -u -r1.3 signull.c
--- gdb.base/signull.c 22 May 2004 13:14:22 -0000 1.3
+++ gdb.base/signull.c 16 Jun 2004 14:44:19 -0000
@@ -1,6 +1,6 @@
/* This testcase is part of GDB, the GNU debugger.
- Copyright 1996, 1999, 2003 Free Software Foundation, Inc.
+ Copyright 1996, 1999, 2003, 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
@@ -20,9 +20,10 @@
#include <signal.h>
#include <setjmp.h>
#include <stdlib.h>
+#include <string.h>
enum tests {
- code_entry_point, code_descriptor, data_pointer
+ code_entry_point, code_descriptor, data_read, data_write
};
static volatile enum tests test;
@@ -31,8 +32,10 @@ static volatile enum tests test;
typedef long data_t;
typedef long code_t (void);
-static volatile data_t *data[10];
-static volatile code_t *code[10];
+data_t *volatile data;
+code_t *volatile code;
+data_t zero[10];
+code_t *volatile desc = (code_t *) (void *) zero;
sigjmp_buf env;
@@ -47,12 +50,21 @@ bowler (void)
{
switch (test)
{
- case data_pointer:
- return *data[0];
+ case data_read:
+ /* Try to read address zero. */
+ return (*data);
+ case data_write:
+ /* Try to write (the assignment) to address zero. */
+ return (*data) = 1;
case code_entry_point:
- return code[0] ();
+ /* For typical architectures, call a function at address
+ zero. */
+ return (*code) ();
case code_descriptor:
- return ((code_t *) &code) ();
+ /* For atypical architectures that use function descriptors,
+ call a function descriptor, the code field of which is zero
+ (which has the effect of jumping to address zero). */
+ return (*desc) ();
}
}
Index: gdb.base/signull.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/signull.exp,v
retrieving revision 1.1
diff -p -u -r1.1 signull.exp
--- gdb.base/signull.exp 13 May 2004 18:12:07 -0000 1.1
+++ gdb.base/signull.exp 16 Jun 2004 14:44:19 -0000
@@ -79,7 +79,7 @@ gdb_test "set test = code_entry_point" "
set test "probe function pointer"
set function_pointer code_entry_point
gdb_test_multiple "continue" "$test" {
- -re "Program received signal SIGSEGV.* bowler .$gdb_prompt $" {
+ -re "Program received signal SIGSEGV.*bowler .*$gdb_prompt $" {
set function_pointer code_descriptor
pass "$test (function descriptor)"
}
@@ -109,7 +109,10 @@ proc test_segv { name tag bt_from_segv b
gdb_test backtrace $bt_from_keeper "backtrace keeper for ${name}"
}
-test_segv data data_pointer \
+test_segv data-read data_read \
+ {#0 .* bowler .*#1 .* main .*} \
+ {#0 .* keeper .*#1 .* handler .*#2 .* bowler .*#3 .* main .*}
+test_segv data-write data_write \
{#0 .* bowler .*#1 .* main .*} \
{#0 .* keeper .*#1 .* handler .*#2 .* bowler .*#3 .* main .*}
test_segv code $function_pointer \