[v2] Fixup gdb.python/py-value.exp for bare-metal aarch64-elf
Commit Message
I noticed that testing aarch64-elf gdb with a physical board
ran into issues with gdb.python/py-value.exp. Further investigation showed
that we were actually trying to dereference a NULL pointer (argv) when trying
to access argv[0].
Being bare-metal, argv is not guaranteed to be valid. So we need to make sure
argv is sane before accessing argv[0].
The following patch fixes up the test program to check for a NULL argv and also
improves the testcase a bit so it doesn't have to work with a hardcoded argc
value.
Regression-tested on x86-64 Ubuntu 16.04.
I've incorporated Yao's feedback in v2.
Does it look OK?
gdb/testsuite/ChangeLog:
2016-10-11 Luis Machado <lgustavo@codesourcery.com>
* gdb.python/py-value.c (main): Check if argv is NULL before using it.
* gdb.python/py-value.exp (test_value_in_inferior): Don't use a
hardcoded argc value.
---
gdb/testsuite/ChangeLog | 6 ++++++
gdb/testsuite/gdb.python/py-value.c | 10 +++++++++-
gdb/testsuite/gdb.python/py-value.exp | 5 +++--
3 files changed, 18 insertions(+), 3 deletions(-)
Comments
On Tue, Oct 11, 2016 at 9:55 PM, Luis Machado <lgustavo@codesourcery.com> wrote:
>
> Does it look OK?
>
> gdb/testsuite/ChangeLog:
>
> 2016-10-11 Luis Machado <lgustavo@codesourcery.com>
>
> * gdb.python/py-value.c (main): Check if argv is NULL before using it.
> * gdb.python/py-value.exp (test_value_in_inferior): Don't use a
> hardcoded argc value.
Yes, it is good to me.
On 10/11/2016 09:55 PM, Luis Machado wrote:
> + set argc_value [get_integer_valueof "argc" 0]
> gdb_test "python argc_lazy = gdb.parse_and_eval('argc')"
> gdb_test "python argc_notlazy = gdb.parse_and_eval('argc')"
> gdb_test "python argc_notlazy.fetch_lazy()"
> gdb_test "python print (argc_lazy.is_lazy)" "True"
> gdb_test "python print (argc_notlazy.is_lazy)" "False"
> - gdb_test "print argc" " = 1" "sanity check argc"
> + gdb_test "print argc" " = $argc_value" "sanity check argc"
> gdb_test "python print (argc_lazy.is_lazy)" "\r\nTrue"
> gdb_test_no_output "set argc=2"
Pedantically, $argc_value could be 2, so this would be better
something like
gdb_test_no_output "set argc=[expr $argc_value + 1]" "change argc"
> - gdb_test "python print (argc_notlazy)" "\r\n1"
> + gdb_test "python print (argc_notlazy)" "\r\n$argc_value"
> gdb_test "python print (argc_lazy)" "\r\n2"
Likewise.
> gdb_test "python print (argc_lazy.is_lazy)" "False"
Thanks,
Pedro Alves
On 10/12/2016 08:31 AM, Pedro Alves wrote:
> On 10/11/2016 09:55 PM, Luis Machado wrote:
>> + set argc_value [get_integer_valueof "argc" 0]
>> gdb_test "python argc_lazy = gdb.parse_and_eval('argc')"
>> gdb_test "python argc_notlazy = gdb.parse_and_eval('argc')"
>> gdb_test "python argc_notlazy.fetch_lazy()"
>> gdb_test "python print (argc_lazy.is_lazy)" "True"
>> gdb_test "python print (argc_notlazy.is_lazy)" "False"
>> - gdb_test "print argc" " = 1" "sanity check argc"
>> + gdb_test "print argc" " = $argc_value" "sanity check argc"
>> gdb_test "python print (argc_lazy.is_lazy)" "\r\nTrue"
>> gdb_test_no_output "set argc=2"
>
> Pedantically, $argc_value could be 2, so this would be better
> something like
>
> gdb_test_no_output "set argc=[expr $argc_value + 1]" "change argc"
>
>> - gdb_test "python print (argc_notlazy)" "\r\n1"
>> + gdb_test "python print (argc_notlazy)" "\r\n$argc_value"
>
>
>> gdb_test "python print (argc_lazy)" "\r\n2"
>
> Likewise.
>
Alright. I've addressed this and checked it in on master as
4dac951e11030b43b17f52df8bdfa7432e4bf73c.
Thanks Yao and Pedro.
@@ -1,3 +1,9 @@
+2016-10-11 Luis Machado <lgustavo@codesourcery.com>
+
+ * gdb.python/py-value.c (main): Check if argv is NULL before using it.
+ * gdb.python/py-value.exp (test_value_in_inferior): Adjust initial
+ argc value based on the existence of argv.
+
2016-10-11 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.arch/powerpc-prologue.c (optimized_1): New declaration.
@@ -82,7 +82,7 @@ char **save_argv;
int
main (int argc, char *argv[])
{
- char *cp = argv[0]; /* Prevent gcc from optimizing argv[] out. */
+ char *cp;
struct s s;
union u u;
PTR x = &s;
@@ -99,6 +99,14 @@ main (int argc, char *argv[])
const char *sn = 0;
struct str *xstr;
+ /* Prevent gcc from optimizing argv[] out. */
+
+ /* We also check for a NULL argv in case we are dealing with a target
+ executing in a freestanding environment, therefore there are no
+ guarantees about argc or argv. */
+ if (argv != NULL)
+ cp = argv[0];
+
s.a = 3;
s.b = 5;
u.a = 7;
@@ -274,15 +274,16 @@ proc test_value_in_inferior {} {
gdb_test "python inval2 = inval+1" "gdb.MemoryError: Cannot access memory at address 0x0.*" $test
gdb_test "python inval.fetch_lazy ()" "gdb.MemoryError: Cannot access memory at address 0x0.*" $test
}
+ set argc_value [get_integer_valueof "argc" 0]
gdb_test "python argc_lazy = gdb.parse_and_eval('argc')"
gdb_test "python argc_notlazy = gdb.parse_and_eval('argc')"
gdb_test "python argc_notlazy.fetch_lazy()"
gdb_test "python print (argc_lazy.is_lazy)" "True"
gdb_test "python print (argc_notlazy.is_lazy)" "False"
- gdb_test "print argc" " = 1" "sanity check argc"
+ gdb_test "print argc" " = $argc_value" "sanity check argc"
gdb_test "python print (argc_lazy.is_lazy)" "\r\nTrue"
gdb_test_no_output "set argc=2"
- gdb_test "python print (argc_notlazy)" "\r\n1"
+ gdb_test "python print (argc_notlazy)" "\r\n$argc_value"
gdb_test "python print (argc_lazy)" "\r\n2"
gdb_test "python print (argc_lazy.is_lazy)" "False"