[gdb/testsuite] Fix compare-sections.exp FAIL

  Hi Pedro,

Thanks for the review. Please find an updated patch attached. Updated ChangeLog 
entry and description are as follow:

compare-sections.exp has two cases that are not handled appropriately:
1) value read from read-only section is negative
2) error while patching that section

This patch adapts the regular expression to allow a minus sign to deal
with 1) and test for the error message to not set written if read-only
section cannot be written to so as to solve 2).

ChangeLog entry is as follows:

*** gdb/testsuite/ChangeLog ***

2017-09-11  Thomas Preud'homme  <thomas.preudhomme@arm.com>
	    Pedro Alves  <palves@redhat.com>

	* gdb.base/compare-sections.exp (get value of read-only section): Read
	as unsigned value.
	(corrupt read-only section): Don't set written if patching failed.

Without this patch I get a Tcl error on the first test while it now
PASSes and the second one is marked UNSUPPORTED.

Is this ok for master?

Best regards,

Thomas

On 06/09/17 18:13, Pedro Alves wrote:
> On 09/06/2017 05:58 PM, Thomas Preudhomme wrote:
> 
>>
>> diff --git a/gdb/testsuite/gdb.base/compare-sections.exp b/gdb/testsuite/gdb.base/compare-sections.exp
>> index e4b99216408f86745a890f80175e2f26c39303b5..8a0cf89a4c7c51299c59f59175865b5eb211f213 100644
>> --- a/gdb/testsuite/gdb.base/compare-sections.exp
>> +++ b/gdb/testsuite/gdb.base/compare-sections.exp
>> @@ -118,7 +118,7 @@ with_test_prefix "read-only" {
>>   
>>       set test "get value of read-only section"
>>       gdb_test_multiple "print /d *(unsigned char *) $ro_address" "$test" {
>> -	-re " = (\[0-9\]*).*$gdb_prompt $" {
>> +	-re " = (-?\[0-9\]+).*$gdb_prompt $" {
> 
> This is reading bytes off of memory, as we can infer from
> use of "unsigned char".   The test is most probably using
> explicit /d to avoid printing the number as a character.
> I think it'd be clearer to change the "/d" to "/u", here
> and below too.
> 
> Also, I think treating as negative integer would actually
> be buggy because if the value happens to be 0xff, then you
> get back -1, which would incorrectly match here:
> 
>      if {$orig == -1} {
> 	untested "couldn't read address of read-only section"
> 	return -1
>      }
>>   	    set orig $expect_out(1,string)
>>   	    pass "$test"
>>   	}
>> @@ -136,6 +136,8 @@ with_test_prefix "read-only" {
>>       set written -1
>>       set test "corrupt read-only section"
>>       gdb_test_multiple "print /d *(unsigned char *) $ro_address = $patch" "$test" {
>> +	-re " = .*Cannot access memory at address $ro_address.*$gdb_prompt $" {
> 
> Add:
>   	    pass "$test (cannot write)"
> 
>> +	}
>>   	-re " = (\[0-9\]*).*$gdb_prompt $" {
>>   	    set written $expect_out(1,string)
>>   	    pass "$test"
>>
> 
> Thanks,
> Pedro Alves
>
  

Hi Thomas,

On 09/12/2017 04:24 PM, Thomas Preudhomme wrote:
> Hi Pedro,
> 
> Thanks for the review. Please find an updated patch attached. Updated
> ChangeLog entry and description are as follow:
> 
> compare-sections.exp has two cases that are not handled appropriately:
> 1) value read from read-only section is negative
> 2) error while patching that section
> 
> This patch adapts the regular expression to allow a minus sign to deal
> with 1) 

The above is stale.  It should now talk about /d vs /u.
Could you please update?

> Is this ok for master?

OK with commit log fixed, and ...

On 09/12/2017 04:24 PM, Thomas Preudhomme wrote:
> @@ -136,6 +136,9 @@ with_test_prefix "read-only" {
>      set written -1
>      set test "corrupt read-only section"
>      gdb_test_multiple "print /d *(unsigned char *) $ro_address = $patch" "$test" {

... this should be switched to "/u" too.

> +	-re " = .*Cannot access memory at address $ro_address.*$gdb_prompt $" {
> +	    pass "$test (cannot write)"

Thanks,
Pedro Alves