Re: [rfa/testsuite] Extend signull to work with discriptors

[Andrew Cagney <cagney@gnu.org>]

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> 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.
> 

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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 \