[2/2] gdb/testsuite: new test for recent dwarf reader issue

  This commit provides a test for this commit:

  commit 55fc1623f942fba10362cb199f9356d75ca5835b
  Date:   Thu Nov 3 13:49:17 2022 -0600

      Add name canonicalization for C

Which resolves PR gdb/29105.  My reason for writing this test was a
desire to better understand the above commit, my process was to study
the commit until I thought I understood it, then write a test to
expose the issue.  As the original commit didn't have a test, I
thought it wouldn't hurt to commit this upstream.

The problem tested for here is already described in the above commit,
but I'll give a brief description here.  This description describes
GDB prior to the above commit:

  - Builtin types are added to GDB using their canonical name,
    e.g. "short", not "signed short",

  - When the user does something like 'p sizeof(short)', then this is
    handled in c-exp.y, and results in a call to lookup_signed_type
    for the name "int".  The "int" here is actually being looked up as
    the type for the result of the 'sizeof' expression,

  - In lookup_signed_type GDB first adds a 'signed' and looks for that
    type, so in this case 'signed int', and, if that lookup fails, GDB
    then looks up 'int',

  - The problem is that 'signed int' is not the canonical name for a
    signed int, so no builtin type with that name will be found, GDB
    will then go to each object file in turn looking for a matching
    type,

  - When checking each object file, GDB will first check the partial
    symtab to see if the full symtab should be expanded or not.
    Remember, at this point GDB is looking for 'signed int', there
    will be no partial symbols with that name, so GDB will not expand
    anything,

  - However, GDB checks each partial symbol using multiple languages,
    not just the current language (C in this case), so, when GDB
    checks using the C++ language, the symbol name is first demangled,
    the code that does this can be found
    lookup_name_info::language_lookup_name.  As the demangled form of
    'signed int' is just 'int', GDB then looks for any symbols with
    the name 'int', most partial symtabs will contain such a symbol,
    so GDB ends up expanding pretty much every symtab.

The above commit fixes this by avoiding the use of non-canonical names
with C, now the initial builtin type lookup will succeed, and GDB
never even considers whether to expand any additional symtabs.

The test case creates a library that includes char, short, int, and
long types, and a test program that links against the library.

In the test script we start the inferior, but don't allow it to
progress far enough that the debug information for the library has
been fully expanded yet.

Then we evaluate some 'sizeof(TYPE)' expressions.

In the buggy version of GDB this would cause the debug information
for the library to be fully expanded, while in the fixed version of
GDB this will not be the case.

We use 'info sources' to determine if the debug information has been
fully expanded or not.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29105
---
 .../gdb.base/signed-builtin-types-lib.c       |  30 +++++
 gdb/testsuite/gdb.base/signed-builtin-types.c |  25 ++++
 .../gdb.base/signed-builtin-types.exp         | 112 ++++++++++++++++++
 3 files changed, 167 insertions(+)
 create mode 100644 gdb/testsuite/gdb.base/signed-builtin-types-lib.c
 create mode 100644 gdb/testsuite/gdb.base/signed-builtin-types.c
 create mode 100644 gdb/testsuite/gdb.base/signed-builtin-types.exp
  

>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:

Thank you for doing this.

Andrew>   - However, GDB checks each partial symbol using multiple languages,
Andrew>     not just the current language (C in this case), so, when GDB
Andrew>     checks using the C++ language, the symbol name is first demangled,
Andrew>     the code that does this can be found
Andrew>     lookup_name_info::language_lookup_name.  As the demangled form of
Andrew>     'signed int' is just 'int', GDB then looks for any symbols with
Andrew>     the name 'int', most partial symtabs will contain such a symbol,
Andrew>     so GDB ends up expanding pretty much every symtab.

It's a pedantic point but what happens here is name canonicalization,
not demangling.  Demangling is just used to refer to the translation
from a name like "_Zmumble" to "something::else" -- that is, the input
is a linkage name and the output is a C++ name.  Canonicalization takes
a C++ name as input and returns the standard form, basically dealing
with the fact that C++ (and as we discovered, C) has multiple possible
spellings for some symbols.

Tom
  

Tom Tromey <tom@tromey.com> writes:

>>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
>
> Thank you for doing this.
>
> Andrew>   - However, GDB checks each partial symbol using multiple languages,
> Andrew>     not just the current language (C in this case), so, when GDB
> Andrew>     checks using the C++ language, the symbol name is first demangled,
> Andrew>     the code that does this can be found
> Andrew>     lookup_name_info::language_lookup_name.  As the demangled form of
> Andrew>     'signed int' is just 'int', GDB then looks for any symbols with
> Andrew>     the name 'int', most partial symtabs will contain such a symbol,
> Andrew>     so GDB ends up expanding pretty much every symtab.
>
> It's a pedantic point but what happens here is name canonicalization,
> not demangling.  Demangling is just used to refer to the translation
> from a name like "_Zmumble" to "something::else" -- that is, the input
> is a linkage name and the output is a C++ name.  Canonicalization takes
> a C++ name as input and returns the standard form, basically dealing
> with the fact that C++ (and as we discovered, C) has multiple possible
> spellings for some symbols.

Please, be pedantic.  My goal here was to better understand this code,
there's no point me understanding it wrong.

I'll reword that paragraph.

Thanks for taking a look.

Andrew
  

Hi Andrew,

On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
> Tom Tromey <tom@tromey.com> writes:
> 
>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
>>
>> Thank you for doing this.
>>
>> Andrew>   - However, GDB checks each partial symbol using multiple languages,
>> Andrew>     not just the current language (C in this case), so, when GDB
>> Andrew>     checks using the C++ language, the symbol name is first demangled,
>> Andrew>     the code that does this can be found
>> Andrew>     lookup_name_info::language_lookup_name.  As the demangled form of
>> Andrew>     'signed int' is just 'int', GDB then looks for any symbols with
>> Andrew>     the name 'int', most partial symtabs will contain such a symbol,
>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>
>> It's a pedantic point but what happens here is name canonicalization,
>> not demangling.  Demangling is just used to refer to the translation
>> from a name like "_Zmumble" to "something::else" -- that is, the input
>> is a linkage name and the output is a C++ name.  Canonicalization takes
>> a C++ name as input and returns the standard form, basically dealing
>> with the fact that C++ (and as we discovered, C) has multiple possible
>> spellings for some symbols.
> 
> Please, be pedantic.  My goal here was to better understand this code,
> there's no point me understanding it wrong.
> 
> I'll reword that paragraph.
> 
> Thanks for taking a look.
> 
> Andrew
> 

I'm not saying you should investigate this, as it is a new test, but I'm getting a lot of these messages for this test:

ERROR: internal buffer is full.
  

Luis Machado <luis.machado@arm.com> writes:

> Hi Andrew,
>
> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>> Tom Tromey <tom@tromey.com> writes:
>> 
>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
>>>
>>> Thank you for doing this.
>>>
>>> Andrew>   - However, GDB checks each partial symbol using multiple languages,
>>> Andrew>     not just the current language (C in this case), so, when GDB
>>> Andrew>     checks using the C++ language, the symbol name is first demangled,
>>> Andrew>     the code that does this can be found
>>> Andrew>     lookup_name_info::language_lookup_name.  As the demangled form of
>>> Andrew>     'signed int' is just 'int', GDB then looks for any symbols with
>>> Andrew>     the name 'int', most partial symtabs will contain such a symbol,
>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>
>>> It's a pedantic point but what happens here is name canonicalization,
>>> not demangling.  Demangling is just used to refer to the translation
>>> from a name like "_Zmumble" to "something::else" -- that is, the input
>>> is a linkage name and the output is a C++ name.  Canonicalization takes
>>> a C++ name as input and returns the standard form, basically dealing
>>> with the fact that C++ (and as we discovered, C) has multiple possible
>>> spellings for some symbols.
>> 
>> Please, be pedantic.  My goal here was to better understand this code,
>> there's no point me understanding it wrong.
>> 
>> I'll reword that paragraph.
>> 
>> Thanks for taking a look.
>> 
>> Andrew
>> 
>
> I'm not saying you should investigate this, as it is a new test, but I'm getting a lot of these messages for this test:
>
> ERROR: internal buffer is full.

Happy to take a look at the problem.

I guess the issue is coming from the gdb_test_multiple that I use in the
new test script.

I'm tried to write patterns that match and discard all the lines as they
arrive from GDB.  I guess you are seeing a pattern that I am not for
some reason.

Could you run just this test and attach the gdb.log file and I'll take a
look.  I probably just need to tweak one of the patterns a little.

Thanks,
Andrew
  

On 12/15/22 11:22, Andrew Burgess wrote:
> Luis Machado <luis.machado@arm.com> writes:
> 
>> Hi Andrew,
>>
>> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>>> Tom Tromey <tom@tromey.com> writes:
>>>
>>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
>>>>
>>>> Thank you for doing this.
>>>>
>>>> Andrew>   - However, GDB checks each partial symbol using multiple languages,
>>>> Andrew>     not just the current language (C in this case), so, when GDB
>>>> Andrew>     checks using the C++ language, the symbol name is first demangled,
>>>> Andrew>     the code that does this can be found
>>>> Andrew>     lookup_name_info::language_lookup_name.  As the demangled form of
>>>> Andrew>     'signed int' is just 'int', GDB then looks for any symbols with
>>>> Andrew>     the name 'int', most partial symtabs will contain such a symbol,
>>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>>
>>>> It's a pedantic point but what happens here is name canonicalization,
>>>> not demangling.  Demangling is just used to refer to the translation
>>>> from a name like "_Zmumble" to "something::else" -- that is, the input
>>>> is a linkage name and the output is a C++ name.  Canonicalization takes
>>>> a C++ name as input and returns the standard form, basically dealing
>>>> with the fact that C++ (and as we discovered, C) has multiple possible
>>>> spellings for some symbols.
>>>
>>> Please, be pedantic.  My goal here was to better understand this code,
>>> there's no point me understanding it wrong.
>>>
>>> I'll reword that paragraph.
>>>
>>> Thanks for taking a look.
>>>
>>> Andrew
>>>
>>
>> I'm not saying you should investigate this, as it is a new test, but I'm getting a lot of these messages for this test:
>>
>> ERROR: internal buffer is full.
> 
> Happy to take a look at the problem.
> 
> I guess the issue is coming from the gdb_test_multiple that I use in the
> new test script.
> 
> I'm tried to write patterns that match and discard all the lines as they
> arrive from GDB.  I guess you are seeing a pattern that I am not for
> some reason.
> 
> Could you run just this test and attach the gdb.log file and I'll take a
> look.  I probably just need to tweak one of the patterns a little.
> 
> Thanks,
> Andrew
> 

I briefly looked into this. The problem seems to arise from the fact that sometimes we don't have multiple lines for the "info sources" output.

Some sections are output in a single line. For example, one of them has 133K characters. But each entry seems to be separated by a comma character:

./elf/./elf/rtld.c, ./elf/../include/rtld-malloc.h, ./elf/../sysdeps/generic/ldsodefs.h, ./elf/../sysdeps/aarch64/dl-machine.h, ...

It might be best (for the testsuite) if gdb outputs this data across more lines.
  

Luis Machado <luis.machado@arm.com> writes:

> On 12/15/22 11:22, Andrew Burgess wrote:
>> Luis Machado <luis.machado@arm.com> writes:
>> 
>>> Hi Andrew,
>>>
>>> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>>>> Tom Tromey <tom@tromey.com> writes:
>>>>
>>>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
>>>>>
>>>>> Thank you for doing this.
>>>>>
>>>>> Andrew>   - However, GDB checks each partial symbol using multiple languages,
>>>>> Andrew>     not just the current language (C in this case), so, when GDB
>>>>> Andrew>     checks using the C++ language, the symbol name is first demangled,
>>>>> Andrew>     the code that does this can be found
>>>>> Andrew>     lookup_name_info::language_lookup_name.  As the demangled form of
>>>>> Andrew>     'signed int' is just 'int', GDB then looks for any symbols with
>>>>> Andrew>     the name 'int', most partial symtabs will contain such a symbol,
>>>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>>>
>>>>> It's a pedantic point but what happens here is name canonicalization,
>>>>> not demangling.  Demangling is just used to refer to the translation
>>>>> from a name like "_Zmumble" to "something::else" -- that is, the input
>>>>> is a linkage name and the output is a C++ name.  Canonicalization takes
>>>>> a C++ name as input and returns the standard form, basically dealing
>>>>> with the fact that C++ (and as we discovered, C) has multiple possible
>>>>> spellings for some symbols.
>>>>
>>>> Please, be pedantic.  My goal here was to better understand this code,
>>>> there's no point me understanding it wrong.
>>>>
>>>> I'll reword that paragraph.
>>>>
>>>> Thanks for taking a look.
>>>>
>>>> Andrew
>>>>
>>>
>>> I'm not saying you should investigate this, as it is a new test, but I'm getting a lot of these messages for this test:
>>>
>>> ERROR: internal buffer is full.
>> 
>> Happy to take a look at the problem.
>> 
>> I guess the issue is coming from the gdb_test_multiple that I use in the
>> new test script.
>> 
>> I'm tried to write patterns that match and discard all the lines as they
>> arrive from GDB.  I guess you are seeing a pattern that I am not for
>> some reason.
>> 
>> Could you run just this test and attach the gdb.log file and I'll take a
>> look.  I probably just need to tweak one of the patterns a little.
>> 
>> Thanks,
>> Andrew
>> 
>
> I briefly looked into this. The problem seems to arise from the fact that sometimes we don't have multiple lines for the "info sources" output.
>
> Some sections are output in a single line. For example, one of them has 133K characters. But each entry seems to be separated by a comma character:
>
> ./elf/./elf/rtld.c, ./elf/../include/rtld-malloc.h, ./elf/../sysdeps/generic/ldsodefs.h, ./elf/../sysdeps/aarch64/dl-machine.h, ...

Ahh, that would explain it.  We don't appear to use 'info sources' that
frequently in the testsuite.  I wonder if you are also seeing failures
on those other tests?

  gdb.asm/asm-source.exp
  gdb.dwarf2/dup-psym.exp
  gdb.dwarf2/dw2-filename.exp

> It might be best (for the testsuite) if gdb outputs this data across more lines.

The other option might be to extend 'info sources' to allow filtering
based on the objfile name, then we can use this in the testsuite to
limit the output...

... or I wonder if we could trick GDB by setting the width to something
small, the I guess the lines would be broken after the ',' characters.

I'll have a play and see what I can come up with.

Thanks,
Andrew
  

On 2022-12-19 13:52, Andrew Burgess via Gdb-patches wrote:
> Luis Machado <luis.machado@arm.com> writes:
> 
>> On 12/15/22 11:22, Andrew Burgess wrote:
>>> Luis Machado <luis.machado@arm.com> writes:
>>> 
>>>> Hi Andrew,
>>>> 
>>>> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>>>>> Tom Tromey <tom@tromey.com> writes:
>>>>> 
>>>>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches 
>>>>>>>>>>> <gdb-patches@sourceware.org> writes:
>>>>>> 
>>>>>> Thank you for doing this.
>>>>>> 
>>>>>> Andrew>   - However, GDB checks each partial symbol using multiple 
>>>>>> languages,
>>>>>> Andrew>     not just the current language (C in this case), so, 
>>>>>> when GDB
>>>>>> Andrew>     checks using the C++ language, the symbol name is 
>>>>>> first demangled,
>>>>>> Andrew>     the code that does this can be found
>>>>>> Andrew>     lookup_name_info::language_lookup_name.  As the 
>>>>>> demangled form of
>>>>>> Andrew>     'signed int' is just 'int', GDB then looks for any 
>>>>>> symbols with
>>>>>> Andrew>     the name 'int', most partial symtabs will contain such 
>>>>>> a symbol,
>>>>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>>>> 
>>>>>> It's a pedantic point but what happens here is name 
>>>>>> canonicalization,
>>>>>> not demangling.  Demangling is just used to refer to the 
>>>>>> translation
>>>>>> from a name like "_Zmumble" to "something::else" -- that is, the 
>>>>>> input
>>>>>> is a linkage name and the output is a C++ name.  Canonicalization 
>>>>>> takes
>>>>>> a C++ name as input and returns the standard form, basically 
>>>>>> dealing
>>>>>> with the fact that C++ (and as we discovered, C) has multiple 
>>>>>> possible
>>>>>> spellings for some symbols.
>>>>> 
>>>>> Please, be pedantic.  My goal here was to better understand this 
>>>>> code,
>>>>> there's no point me understanding it wrong.
>>>>> 
>>>>> I'll reword that paragraph.
>>>>> 
>>>>> Thanks for taking a look.
>>>>> 
>>>>> Andrew
>>>>> 
>>>> 
>>>> I'm not saying you should investigate this, as it is a new test, but 
>>>> I'm getting a lot of these messages for this test:
>>>> 
>>>> ERROR: internal buffer is full.
>>> 
>>> Happy to take a look at the problem.
>>> 
>>> I guess the issue is coming from the gdb_test_multiple that I use in 
>>> the
>>> new test script.
>>> 
>>> I'm tried to write patterns that match and discard all the lines as 
>>> they
>>> arrive from GDB.  I guess you are seeing a pattern that I am not for
>>> some reason.
>>> 
>>> Could you run just this test and attach the gdb.log file and I'll 
>>> take a
>>> look.  I probably just need to tweak one of the patterns a little.
>>> 
>>> Thanks,
>>> Andrew
>>> 
>> 
>> I briefly looked into this. The problem seems to arise from the fact 
>> that sometimes we don't have multiple lines for the "info sources" 
>> output.
>> 
>> Some sections are output in a single line. For example, one of them 
>> has 133K characters. But each entry seems to be separated by a comma 
>> character:
>> 
>> ./elf/./elf/rtld.c, ./elf/../include/rtld-malloc.h, 
>> ./elf/../sysdeps/generic/ldsodefs.h, 
>> ./elf/../sysdeps/aarch64/dl-machine.h, ...
> 
> Ahh, that would explain it.  We don't appear to use 'info sources' that
> frequently in the testsuite.  I wonder if you are also seeing failures
> on those other tests?
> 
>   gdb.asm/asm-source.exp
>   gdb.dwarf2/dup-psym.exp
>   gdb.dwarf2/dw2-filename.exp
> 
>> It might be best (for the testsuite) if gdb outputs this data across 
>> more lines.
> 
> The other option might be to extend 'info sources' to allow filtering
> based on the objfile name, then we can use this in the testsuite to
> limit the output...
> 
> ... or I wonder if we could trick GDB by setting the width to something
> small, the I guess the lines would be broken after the ',' characters.
> 
> I'll have a play and see what I can come up with.
> 

I also ran into this issue on ubuntu 22.04.1 x86_64.

AFAIK, the way we usually test for this type of information is "maint 
print objfile", which is less verbose, and doesn't have long lines.

Thanks,
- Tom

> Thanks,
> Andrew
  

tdevries <tdevries@suse.de> writes:

> On 2022-12-19 13:52, Andrew Burgess via Gdb-patches wrote:
>> Luis Machado <luis.machado@arm.com> writes:
>> 
>>> On 12/15/22 11:22, Andrew Burgess wrote:
>>>> Luis Machado <luis.machado@arm.com> writes:
>>>> 
>>>>> Hi Andrew,
>>>>> 
>>>>> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>>>>>> Tom Tromey <tom@tromey.com> writes:
>>>>>> 
>>>>>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches 
>>>>>>>>>>>> <gdb-patches@sourceware.org> writes:
>>>>>>> 
>>>>>>> Thank you for doing this.
>>>>>>> 
>>>>>>> Andrew>   - However, GDB checks each partial symbol using multiple 
>>>>>>> languages,
>>>>>>> Andrew>     not just the current language (C in this case), so, 
>>>>>>> when GDB
>>>>>>> Andrew>     checks using the C++ language, the symbol name is 
>>>>>>> first demangled,
>>>>>>> Andrew>     the code that does this can be found
>>>>>>> Andrew>     lookup_name_info::language_lookup_name.  As the 
>>>>>>> demangled form of
>>>>>>> Andrew>     'signed int' is just 'int', GDB then looks for any 
>>>>>>> symbols with
>>>>>>> Andrew>     the name 'int', most partial symtabs will contain such 
>>>>>>> a symbol,
>>>>>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>>>>> 
>>>>>>> It's a pedantic point but what happens here is name 
>>>>>>> canonicalization,
>>>>>>> not demangling.  Demangling is just used to refer to the 
>>>>>>> translation
>>>>>>> from a name like "_Zmumble" to "something::else" -- that is, the 
>>>>>>> input
>>>>>>> is a linkage name and the output is a C++ name.  Canonicalization 
>>>>>>> takes
>>>>>>> a C++ name as input and returns the standard form, basically 
>>>>>>> dealing
>>>>>>> with the fact that C++ (and as we discovered, C) has multiple 
>>>>>>> possible
>>>>>>> spellings for some symbols.
>>>>>> 
>>>>>> Please, be pedantic.  My goal here was to better understand this 
>>>>>> code,
>>>>>> there's no point me understanding it wrong.
>>>>>> 
>>>>>> I'll reword that paragraph.
>>>>>> 
>>>>>> Thanks for taking a look.
>>>>>> 
>>>>>> Andrew
>>>>>> 
>>>>> 
>>>>> I'm not saying you should investigate this, as it is a new test, but 
>>>>> I'm getting a lot of these messages for this test:
>>>>> 
>>>>> ERROR: internal buffer is full.
>>>> 
>>>> Happy to take a look at the problem.
>>>> 
>>>> I guess the issue is coming from the gdb_test_multiple that I use in 
>>>> the
>>>> new test script.
>>>> 
>>>> I'm tried to write patterns that match and discard all the lines as 
>>>> they
>>>> arrive from GDB.  I guess you are seeing a pattern that I am not for
>>>> some reason.
>>>> 
>>>> Could you run just this test and attach the gdb.log file and I'll 
>>>> take a
>>>> look.  I probably just need to tweak one of the patterns a little.
>>>> 
>>>> Thanks,
>>>> Andrew
>>>> 
>>> 
>>> I briefly looked into this. The problem seems to arise from the fact 
>>> that sometimes we don't have multiple lines for the "info sources" 
>>> output.
>>> 
>>> Some sections are output in a single line. For example, one of them 
>>> has 133K characters. But each entry seems to be separated by a comma 
>>> character:
>>> 
>>> ./elf/./elf/rtld.c, ./elf/../include/rtld-malloc.h, 
>>> ./elf/../sysdeps/generic/ldsodefs.h, 
>>> ./elf/../sysdeps/aarch64/dl-machine.h, ...
>> 
>> Ahh, that would explain it.  We don't appear to use 'info sources' that
>> frequently in the testsuite.  I wonder if you are also seeing failures
>> on those other tests?
>> 
>>   gdb.asm/asm-source.exp
>>   gdb.dwarf2/dup-psym.exp
>>   gdb.dwarf2/dw2-filename.exp
>> 
>>> It might be best (for the testsuite) if gdb outputs this data across 
>>> more lines.
>> 
>> The other option might be to extend 'info sources' to allow filtering
>> based on the objfile name, then we can use this in the testsuite to
>> limit the output...
>> 
>> ... or I wonder if we could trick GDB by setting the width to something
>> small, the I guess the lines would be broken after the ',' characters.
>> 
>> I'll have a play and see what I can come up with.
>> 
>
> I also ran into this issue on ubuntu 22.04.1 x86_64.
>
> AFAIK, the way we usually test for this type of information is "maint 
> print objfile", which is less verbose, and doesn't have long lines.

I'm looking at this issue today, I'll give 'maint print objfile' a go.
Thanks for the suggestion.

Thanks,
Andrew
  

Andrew Burgess <aburgess@redhat.com> writes:

> tdevries <tdevries@suse.de> writes:
>
>> On 2022-12-19 13:52, Andrew Burgess via Gdb-patches wrote:
>>> Luis Machado <luis.machado@arm.com> writes:
>>> 
>>>> On 12/15/22 11:22, Andrew Burgess wrote:
>>>>> Luis Machado <luis.machado@arm.com> writes:
>>>>> 
>>>>>> Hi Andrew,
>>>>>> 
>>>>>> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>>>>>>> Tom Tromey <tom@tromey.com> writes:
>>>>>>> 
>>>>>>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches 
>>>>>>>>>>>>> <gdb-patches@sourceware.org> writes:
>>>>>>>> 
>>>>>>>> Thank you for doing this.
>>>>>>>> 
>>>>>>>> Andrew>   - However, GDB checks each partial symbol using multiple 
>>>>>>>> languages,
>>>>>>>> Andrew>     not just the current language (C in this case), so, 
>>>>>>>> when GDB
>>>>>>>> Andrew>     checks using the C++ language, the symbol name is 
>>>>>>>> first demangled,
>>>>>>>> Andrew>     the code that does this can be found
>>>>>>>> Andrew>     lookup_name_info::language_lookup_name.  As the 
>>>>>>>> demangled form of
>>>>>>>> Andrew>     'signed int' is just 'int', GDB then looks for any 
>>>>>>>> symbols with
>>>>>>>> Andrew>     the name 'int', most partial symtabs will contain such 
>>>>>>>> a symbol,
>>>>>>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>>>>>> 
>>>>>>>> It's a pedantic point but what happens here is name 
>>>>>>>> canonicalization,
>>>>>>>> not demangling.  Demangling is just used to refer to the 
>>>>>>>> translation
>>>>>>>> from a name like "_Zmumble" to "something::else" -- that is, the 
>>>>>>>> input
>>>>>>>> is a linkage name and the output is a C++ name.  Canonicalization 
>>>>>>>> takes
>>>>>>>> a C++ name as input and returns the standard form, basically 
>>>>>>>> dealing
>>>>>>>> with the fact that C++ (and as we discovered, C) has multiple 
>>>>>>>> possible
>>>>>>>> spellings for some symbols.
>>>>>>> 
>>>>>>> Please, be pedantic.  My goal here was to better understand this 
>>>>>>> code,
>>>>>>> there's no point me understanding it wrong.
>>>>>>> 
>>>>>>> I'll reword that paragraph.
>>>>>>> 
>>>>>>> Thanks for taking a look.
>>>>>>> 
>>>>>>> Andrew
>>>>>>> 
>>>>>> 
>>>>>> I'm not saying you should investigate this, as it is a new test, but 
>>>>>> I'm getting a lot of these messages for this test:
>>>>>> 
>>>>>> ERROR: internal buffer is full.
>>>>> 
>>>>> Happy to take a look at the problem.
>>>>> 
>>>>> I guess the issue is coming from the gdb_test_multiple that I use in 
>>>>> the
>>>>> new test script.
>>>>> 
>>>>> I'm tried to write patterns that match and discard all the lines as 
>>>>> they
>>>>> arrive from GDB.  I guess you are seeing a pattern that I am not for
>>>>> some reason.
>>>>> 
>>>>> Could you run just this test and attach the gdb.log file and I'll 
>>>>> take a
>>>>> look.  I probably just need to tweak one of the patterns a little.
>>>>> 
>>>>> Thanks,
>>>>> Andrew
>>>>> 
>>>> 
>>>> I briefly looked into this. The problem seems to arise from the fact 
>>>> that sometimes we don't have multiple lines for the "info sources" 
>>>> output.
>>>> 
>>>> Some sections are output in a single line. For example, one of them 
>>>> has 133K characters. But each entry seems to be separated by a comma 
>>>> character:
>>>> 
>>>> ./elf/./elf/rtld.c, ./elf/../include/rtld-malloc.h, 
>>>> ./elf/../sysdeps/generic/ldsodefs.h, 
>>>> ./elf/../sysdeps/aarch64/dl-machine.h, ...
>>> 
>>> Ahh, that would explain it.  We don't appear to use 'info sources' that
>>> frequently in the testsuite.  I wonder if you are also seeing failures
>>> on those other tests?
>>> 
>>>   gdb.asm/asm-source.exp
>>>   gdb.dwarf2/dup-psym.exp
>>>   gdb.dwarf2/dw2-filename.exp
>>> 
>>>> It might be best (for the testsuite) if gdb outputs this data across 
>>>> more lines.
>>> 
>>> The other option might be to extend 'info sources' to allow filtering
>>> based on the objfile name, then we can use this in the testsuite to
>>> limit the output...
>>> 
>>> ... or I wonder if we could trick GDB by setting the width to something
>>> small, the I guess the lines would be broken after the ',' characters.
>>> 
>>> I'll have a play and see what I can come up with.
>>> 
>>
>> I also ran into this issue on ubuntu 22.04.1 x86_64.
>>
>> AFAIK, the way we usually test for this type of information is "maint 
>> print objfile", which is less verbose, and doesn't have long lines.
>
> I'm looking at this issue today, I'll give 'maint print objfile' a go.
> Thanks for the suggestion.

I was able to reproduce the buffer overflow errors.  The patch below
addresses the issue for me.

Thoughts?

Thanks,
Andrew

---

commit e1f51c1b3b37d96e679fa2698eb83a6a3a05eb53
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Tue Dec 20 12:51:50 2022 +0000

    gdb/testsuite: fix buffer overflow in gdb.base/signed-builtin-types.exp
    
    In commit:
    
      commit 9f50fe0835850645bd8ea9bb1efe1fe6c48dfb12
      Date:   Wed Dec 7 15:55:25 2022 +0000
    
          gdb/testsuite: new test for recent dwarf reader issue
    
    A new test (gdb.base/signed-builtin-types.exp) was added that made use
    of 'info sources' to figure out if the debug information for a
    particular object file had been fully expanded or not.  Unfortunately
    some lines of the 'info sources' output can be very long, this was
    observed on some systems where the debug information for the
    dynamic-linker was installed, in this case, the list of source files
    associated with the dynamic linker was so long it would cause expect's
    internal buffer to overflow.
    
    This commit switches from using 'info sources' to 'maint print
    objfile', the output from the latter command is more compact, but
    also, can be restricted to a named object file.
    
    With this change in place I am no longer seeing buffer overflow errors
    from expect when running gdb.base/signed-builtin-types.exp.

diff --git a/gdb/testsuite/gdb.base/signed-builtin-types.exp b/gdb/testsuite/gdb.base/signed-builtin-types.exp
index e9784330fee..fdb9251758e 100644
--- a/gdb/testsuite/gdb.base/signed-builtin-types.exp
+++ b/gdb/testsuite/gdb.base/signed-builtin-types.exp
@@ -21,7 +21,8 @@ standard_testfile .c -lib.c
 
 # Compile the shared library.
 set srcdso [file join $srcdir $subdir $srcfile2]
-set objdso [standard_output_file lib${gdb_test_file_name}.so]
+set libname "lib${gdb_test_file_name}.so"
+set objdso [standard_output_file $libname]
 if {[gdb_compile_shlib $srcdso $objdso {debug}] != ""} {
     untested "failed to compile dso"
     return -1
@@ -47,45 +48,39 @@ if {[readnow]} {
 # information has NOT been fully expanded (which is what we want for this
 # test).
 proc shared_library_debug_not_fully_expanded {} {
-    set library_expanded ""
-    gdb_test_multiple "info sources" "" {
-	-re "^info sources\r\n" {
+    set not_expanded true
+    gdb_test_multiple "maint print objfiles $::libname" "" {
+	-re "^maint print objfiles \[^\r\n\]+\r\n" {
 	    exp_continue
 	}
-	-re "^(\[^\r\n\]+):\r\n\\(Full debug information has not yet been read for this file\\.\\)\r\n\r\n" {
-	    set libname $expect_out(1,string)
-	    if {$libname == $::objdso} {
-		set library_expanded "no"
-	    }
+
+	-re "^\\s*\r\n" {
+	    exp_continue
+	}
+
+	-re "^Object file \[^\r\n\]+\r\n" {
 	    exp_continue
 	}
-	-re "^(\[^\r\n\]+):\r\n\\(Objfile has no debug information\\.\\)\r\n\r\n" {
-	    set libname $expect_out(1,string)
-	    if {$libname == $::objdso} {
-		# For some reason the shared library has no debug
-		# information, this is not expected.
-		set library_expanded "missing debug"
-	    }
+
+	-re "^Cooked index in use\r\n" {
 	    exp_continue
 	}
-	-re "^(\[^\r\n\]+):\r\n\r\n" {
-	    set libname $expect_out(1,string)
-	    if {$libname == $::objdso} {
-		set library_expanded "yes"
-	    }
+
+	-re "^Symtabs:\r\n" {
+	    set not_expanded false
 	    exp_continue
 	}
+
 	-re "^$::gdb_prompt $" {
-	    gdb_assert {[string equal $library_expanded "yes"] \
-			    || [string equal $library_expanded "no"]} \
-		$gdb_test_name
+	    pass $gdb_test_name
 	}
-	-re "^(\[^\r\n:\]*)\r\n" {
+
+	-re "^\[^\r\n\]+\r\n" {
 	    exp_continue
 	}
     }
 
-    return [expr $library_expanded == "no"]
+    return $not_expanded
 }
 
 foreach_with_prefix type_name {"short" "int" "long" "char"} {
  

On 12/20/22 13:20, Andrew Burgess wrote:
> Andrew Burgess <aburgess@redhat.com> writes:
> 
>> tdevries <tdevries@suse.de> writes:
>>
>>> On 2022-12-19 13:52, Andrew Burgess via Gdb-patches wrote:
>>>> Luis Machado <luis.machado@arm.com> writes:
>>>>
>>>>> On 12/15/22 11:22, Andrew Burgess wrote:
>>>>>> Luis Machado <luis.machado@arm.com> writes:
>>>>>>
>>>>>>> Hi Andrew,
>>>>>>>
>>>>>>> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>>>>>>>> Tom Tromey <tom@tromey.com> writes:
>>>>>>>>
>>>>>>>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches
>>>>>>>>>>>>>> <gdb-patches@sourceware.org> writes:
>>>>>>>>>
>>>>>>>>> Thank you for doing this.
>>>>>>>>>
>>>>>>>>> Andrew>   - However, GDB checks each partial symbol using multiple
>>>>>>>>> languages,
>>>>>>>>> Andrew>     not just the current language (C in this case), so,
>>>>>>>>> when GDB
>>>>>>>>> Andrew>     checks using the C++ language, the symbol name is
>>>>>>>>> first demangled,
>>>>>>>>> Andrew>     the code that does this can be found
>>>>>>>>> Andrew>     lookup_name_info::language_lookup_name.  As the
>>>>>>>>> demangled form of
>>>>>>>>> Andrew>     'signed int' is just 'int', GDB then looks for any
>>>>>>>>> symbols with
>>>>>>>>> Andrew>     the name 'int', most partial symtabs will contain such
>>>>>>>>> a symbol,
>>>>>>>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>>>>>>>
>>>>>>>>> It's a pedantic point but what happens here is name
>>>>>>>>> canonicalization,
>>>>>>>>> not demangling.  Demangling is just used to refer to the
>>>>>>>>> translation
>>>>>>>>> from a name like "_Zmumble" to "something::else" -- that is, the
>>>>>>>>> input
>>>>>>>>> is a linkage name and the output is a C++ name.  Canonicalization
>>>>>>>>> takes
>>>>>>>>> a C++ name as input and returns the standard form, basically
>>>>>>>>> dealing
>>>>>>>>> with the fact that C++ (and as we discovered, C) has multiple
>>>>>>>>> possible
>>>>>>>>> spellings for some symbols.
>>>>>>>>
>>>>>>>> Please, be pedantic.  My goal here was to better understand this
>>>>>>>> code,
>>>>>>>> there's no point me understanding it wrong.
>>>>>>>>
>>>>>>>> I'll reword that paragraph.
>>>>>>>>
>>>>>>>> Thanks for taking a look.
>>>>>>>>
>>>>>>>> Andrew
>>>>>>>>
>>>>>>>
>>>>>>> I'm not saying you should investigate this, as it is a new test, but
>>>>>>> I'm getting a lot of these messages for this test:
>>>>>>>
>>>>>>> ERROR: internal buffer is full.
>>>>>>
>>>>>> Happy to take a look at the problem.
>>>>>>
>>>>>> I guess the issue is coming from the gdb_test_multiple that I use in
>>>>>> the
>>>>>> new test script.
>>>>>>
>>>>>> I'm tried to write patterns that match and discard all the lines as
>>>>>> they
>>>>>> arrive from GDB.  I guess you are seeing a pattern that I am not for
>>>>>> some reason.
>>>>>>
>>>>>> Could you run just this test and attach the gdb.log file and I'll
>>>>>> take a
>>>>>> look.  I probably just need to tweak one of the patterns a little.
>>>>>>
>>>>>> Thanks,
>>>>>> Andrew
>>>>>>
>>>>>
>>>>> I briefly looked into this. The problem seems to arise from the fact
>>>>> that sometimes we don't have multiple lines for the "info sources"
>>>>> output.
>>>>>
>>>>> Some sections are output in a single line. For example, one of them
>>>>> has 133K characters. But each entry seems to be separated by a comma
>>>>> character:
>>>>>
>>>>> ./elf/./elf/rtld.c, ./elf/../include/rtld-malloc.h,
>>>>> ./elf/../sysdeps/generic/ldsodefs.h,
>>>>> ./elf/../sysdeps/aarch64/dl-machine.h, ...
>>>>
>>>> Ahh, that would explain it.  We don't appear to use 'info sources' that
>>>> frequently in the testsuite.  I wonder if you are also seeing failures
>>>> on those other tests?
>>>>
>>>>    gdb.asm/asm-source.exp
>>>>    gdb.dwarf2/dup-psym.exp
>>>>    gdb.dwarf2/dw2-filename.exp
>>>>
>>>>> It might be best (for the testsuite) if gdb outputs this data across
>>>>> more lines.
>>>>
>>>> The other option might be to extend 'info sources' to allow filtering
>>>> based on the objfile name, then we can use this in the testsuite to
>>>> limit the output...
>>>>
>>>> ... or I wonder if we could trick GDB by setting the width to something
>>>> small, the I guess the lines would be broken after the ',' characters.
>>>>
>>>> I'll have a play and see what I can come up with.
>>>>
>>>
>>> I also ran into this issue on ubuntu 22.04.1 x86_64.
>>>
>>> AFAIK, the way we usually test for this type of information is "maint
>>> print objfile", which is less verbose, and doesn't have long lines.
>>
>> I'm looking at this issue today, I'll give 'maint print objfile' a go.
>> Thanks for the suggestion.
> 
> I was able to reproduce the buffer overflow errors.  The patch below
> addresses the issue for me.
> 
> Thoughts?
> 
> Thanks,
> Andrew
> 
> ---
> 
> commit e1f51c1b3b37d96e679fa2698eb83a6a3a05eb53
> Author: Andrew Burgess <aburgess@redhat.com>
> Date:   Tue Dec 20 12:51:50 2022 +0000
> 
>      gdb/testsuite: fix buffer overflow in gdb.base/signed-builtin-types.exp
>      
>      In commit:
>      
>        commit 9f50fe0835850645bd8ea9bb1efe1fe6c48dfb12
>        Date:   Wed Dec 7 15:55:25 2022 +0000
>      
>            gdb/testsuite: new test for recent dwarf reader issue
>      
>      A new test (gdb.base/signed-builtin-types.exp) was added that made use
>      of 'info sources' to figure out if the debug information for a
>      particular object file had been fully expanded or not.  Unfortunately
>      some lines of the 'info sources' output can be very long, this was
>      observed on some systems where the debug information for the
>      dynamic-linker was installed, in this case, the list of source files
>      associated with the dynamic linker was so long it would cause expect's
>      internal buffer to overflow.
>      
>      This commit switches from using 'info sources' to 'maint print
>      objfile', the output from the latter command is more compact, but
>      also, can be restricted to a named object file.
>      
>      With this change in place I am no longer seeing buffer overflow errors
>      from expect when running gdb.base/signed-builtin-types.exp.
> 
> diff --git a/gdb/testsuite/gdb.base/signed-builtin-types.exp b/gdb/testsuite/gdb.base/signed-builtin-types.exp
> index e9784330fee..fdb9251758e 100644
> --- a/gdb/testsuite/gdb.base/signed-builtin-types.exp
> +++ b/gdb/testsuite/gdb.base/signed-builtin-types.exp
> @@ -21,7 +21,8 @@ standard_testfile .c -lib.c
>   
>   # Compile the shared library.
>   set srcdso [file join $srcdir $subdir $srcfile2]
> -set objdso [standard_output_file lib${gdb_test_file_name}.so]
> +set libname "lib${gdb_test_file_name}.so"
> +set objdso [standard_output_file $libname]
>   if {[gdb_compile_shlib $srcdso $objdso {debug}] != ""} {
>       untested "failed to compile dso"
>       return -1
> @@ -47,45 +48,39 @@ if {[readnow]} {
>   # information has NOT been fully expanded (which is what we want for this
>   # test).
>   proc shared_library_debug_not_fully_expanded {} {
> -    set library_expanded ""
> -    gdb_test_multiple "info sources" "" {
> -	-re "^info sources\r\n" {
> +    set not_expanded true
> +    gdb_test_multiple "maint print objfiles $::libname" "" {
> +	-re "^maint print objfiles \[^\r\n\]+\r\n" {
>   	    exp_continue
>   	}
> -	-re "^(\[^\r\n\]+):\r\n\\(Full debug information has not yet been read for this file\\.\\)\r\n\r\n" {
> -	    set libname $expect_out(1,string)
> -	    if {$libname == $::objdso} {
> -		set library_expanded "no"
> -	    }
> +
> +	-re "^\\s*\r\n" {
> +	    exp_continue
> +	}
> +
> +	-re "^Object file \[^\r\n\]+\r\n" {
>   	    exp_continue
>   	}
> -	-re "^(\[^\r\n\]+):\r\n\\(Objfile has no debug information\\.\\)\r\n\r\n" {
> -	    set libname $expect_out(1,string)
> -	    if {$libname == $::objdso} {
> -		# For some reason the shared library has no debug
> -		# information, this is not expected.
> -		set library_expanded "missing debug"
> -	    }
> +
> +	-re "^Cooked index in use\r\n" {
>   	    exp_continue
>   	}
> -	-re "^(\[^\r\n\]+):\r\n\r\n" {
> -	    set libname $expect_out(1,string)
> -	    if {$libname == $::objdso} {
> -		set library_expanded "yes"
> -	    }
> +
> +	-re "^Symtabs:\r\n" {
> +	    set not_expanded false
>   	    exp_continue
>   	}
> +
>   	-re "^$::gdb_prompt $" {
> -	    gdb_assert {[string equal $library_expanded "yes"] \
> -			    || [string equal $library_expanded "no"]} \
> -		$gdb_test_name
> +	    pass $gdb_test_name
>   	}
> -	-re "^(\[^\r\n:\]*)\r\n" {
> +
> +	-re "^\[^\r\n\]+\r\n" {
>   	    exp_continue
>   	}
>       }
>   
> -    return [expr $library_expanded == "no"]
> +    return $not_expanded
>   }
>   
>   foreach_with_prefix type_name {"short" "int" "long" "char"} {
> 

LGTM, and it fixes things for me as well. Thanks a lot for looking into this.
  

On 2022-12-20 13:20, Andrew Burgess wrote:
> Andrew Burgess <aburgess@redhat.com> writes:
> 
>> tdevries <tdevries@suse.de> writes:
>> 
>>> On 2022-12-19 13:52, Andrew Burgess via Gdb-patches wrote:
>>>> Luis Machado <luis.machado@arm.com> writes:
>>>> 
>>>>> On 12/15/22 11:22, Andrew Burgess wrote:
>>>>>> Luis Machado <luis.machado@arm.com> writes:
>>>>>> 
>>>>>>> Hi Andrew,
>>>>>>> 
>>>>>>> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>>>>>>>> Tom Tromey <tom@tromey.com> writes:
>>>>>>>> 
>>>>>>>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches
>>>>>>>>>>>>>> <gdb-patches@sourceware.org> writes:
>>>>>>>>> 
>>>>>>>>> Thank you for doing this.
>>>>>>>>> 
>>>>>>>>> Andrew>   - However, GDB checks each partial symbol using 
>>>>>>>>> multiple
>>>>>>>>> languages,
>>>>>>>>> Andrew>     not just the current language (C in this case), so,
>>>>>>>>> when GDB
>>>>>>>>> Andrew>     checks using the C++ language, the symbol name is
>>>>>>>>> first demangled,
>>>>>>>>> Andrew>     the code that does this can be found
>>>>>>>>> Andrew>     lookup_name_info::language_lookup_name.  As the
>>>>>>>>> demangled form of
>>>>>>>>> Andrew>     'signed int' is just 'int', GDB then looks for any
>>>>>>>>> symbols with
>>>>>>>>> Andrew>     the name 'int', most partial symtabs will contain 
>>>>>>>>> such
>>>>>>>>> a symbol,
>>>>>>>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>>>>>>> 
>>>>>>>>> It's a pedantic point but what happens here is name
>>>>>>>>> canonicalization,
>>>>>>>>> not demangling.  Demangling is just used to refer to the
>>>>>>>>> translation
>>>>>>>>> from a name like "_Zmumble" to "something::else" -- that is, 
>>>>>>>>> the
>>>>>>>>> input
>>>>>>>>> is a linkage name and the output is a C++ name.  
>>>>>>>>> Canonicalization
>>>>>>>>> takes
>>>>>>>>> a C++ name as input and returns the standard form, basically
>>>>>>>>> dealing
>>>>>>>>> with the fact that C++ (and as we discovered, C) has multiple
>>>>>>>>> possible
>>>>>>>>> spellings for some symbols.
>>>>>>>> 
>>>>>>>> Please, be pedantic.  My goal here was to better understand this
>>>>>>>> code,
>>>>>>>> there's no point me understanding it wrong.
>>>>>>>> 
>>>>>>>> I'll reword that paragraph.
>>>>>>>> 
>>>>>>>> Thanks for taking a look.
>>>>>>>> 
>>>>>>>> Andrew
>>>>>>>> 
>>>>>>> 
>>>>>>> I'm not saying you should investigate this, as it is a new test, 
>>>>>>> but
>>>>>>> I'm getting a lot of these messages for this test:
>>>>>>> 
>>>>>>> ERROR: internal buffer is full.
>>>>>> 
>>>>>> Happy to take a look at the problem.
>>>>>> 
>>>>>> I guess the issue is coming from the gdb_test_multiple that I use 
>>>>>> in
>>>>>> the
>>>>>> new test script.
>>>>>> 
>>>>>> I'm tried to write patterns that match and discard all the lines 
>>>>>> as
>>>>>> they
>>>>>> arrive from GDB.  I guess you are seeing a pattern that I am not 
>>>>>> for
>>>>>> some reason.
>>>>>> 
>>>>>> Could you run just this test and attach the gdb.log file and I'll
>>>>>> take a
>>>>>> look.  I probably just need to tweak one of the patterns a little.
>>>>>> 
>>>>>> Thanks,
>>>>>> Andrew
>>>>>> 
>>>>> 
>>>>> I briefly looked into this. The problem seems to arise from the 
>>>>> fact
>>>>> that sometimes we don't have multiple lines for the "info sources"
>>>>> output.
>>>>> 
>>>>> Some sections are output in a single line. For example, one of them
>>>>> has 133K characters. But each entry seems to be separated by a 
>>>>> comma
>>>>> character:
>>>>> 
>>>>> ./elf/./elf/rtld.c, ./elf/../include/rtld-malloc.h,
>>>>> ./elf/../sysdeps/generic/ldsodefs.h,
>>>>> ./elf/../sysdeps/aarch64/dl-machine.h, ...
>>>> 
>>>> Ahh, that would explain it.  We don't appear to use 'info sources' 
>>>> that
>>>> frequently in the testsuite.  I wonder if you are also seeing 
>>>> failures
>>>> on those other tests?
>>>> 
>>>>   gdb.asm/asm-source.exp
>>>>   gdb.dwarf2/dup-psym.exp
>>>>   gdb.dwarf2/dw2-filename.exp
>>>> 
>>>>> It might be best (for the testsuite) if gdb outputs this data 
>>>>> across
>>>>> more lines.
>>>> 
>>>> The other option might be to extend 'info sources' to allow 
>>>> filtering
>>>> based on the objfile name, then we can use this in the testsuite to
>>>> limit the output...
>>>> 
>>>> ... or I wonder if we could trick GDB by setting the width to 
>>>> something
>>>> small, the I guess the lines would be broken after the ',' 
>>>> characters.
>>>> 
>>>> I'll have a play and see what I can come up with.
>>>> 
>>> 
>>> I also ran into this issue on ubuntu 22.04.1 x86_64.
>>> 
>>> AFAIK, the way we usually test for this type of information is "maint
>>> print objfile", which is less verbose, and doesn't have long lines.
>> 
>> I'm looking at this issue today, I'll give 'maint print objfile' a go.
>> Thanks for the suggestion.
> 
> I was able to reproduce the buffer overflow errors.  The patch below
> addresses the issue for me.
> 
> Thoughts?

LGTM.

Though I wonder if we can make do with being less precise, and just do 
something like:
...
proc assert_shared_library_debug_not_fully_expanded {} {
     gdb_test_lines "maint print objfiles $::libname" "" \
         "Object file \[^\r\n\]*$::libname" \
         -re-not "Symtabs:"
}
...

Thanks,
- Tom

> Thanks,
> Andrew
> 
> ---
> 
> commit e1f51c1b3b37d96e679fa2698eb83a6a3a05eb53
> Author: Andrew Burgess <aburgess@redhat.com>
> Date:   Tue Dec 20 12:51:50 2022 +0000
> 
>     gdb/testsuite: fix buffer overflow in 
> gdb.base/signed-builtin-types.exp
> 
>     In commit:
> 
>       commit 9f50fe0835850645bd8ea9bb1efe1fe6c48dfb12
>       Date:   Wed Dec 7 15:55:25 2022 +0000
> 
>           gdb/testsuite: new test for recent dwarf reader issue
> 
>     A new test (gdb.base/signed-builtin-types.exp) was added that made 
> use
>     of 'info sources' to figure out if the debug information for a
>     particular object file had been fully expanded or not.  
> Unfortunately
>     some lines of the 'info sources' output can be very long, this was
>     observed on some systems where the debug information for the
>     dynamic-linker was installed, in this case, the list of source 
> files
>     associated with the dynamic linker was so long it would cause 
> expect's
>     internal buffer to overflow.
> 
>     This commit switches from using 'info sources' to 'maint print
>     objfile', the output from the latter command is more compact, but
>     also, can be restricted to a named object file.
> 
>     With this change in place I am no longer seeing buffer overflow 
> errors
>     from expect when running gdb.base/signed-builtin-types.exp.
> 
> diff --git a/gdb/testsuite/gdb.base/signed-builtin-types.exp
> b/gdb/testsuite/gdb.base/signed-builtin-types.exp
> index e9784330fee..fdb9251758e 100644
> --- a/gdb/testsuite/gdb.base/signed-builtin-types.exp
> +++ b/gdb/testsuite/gdb.base/signed-builtin-types.exp
> @@ -21,7 +21,8 @@ standard_testfile .c -lib.c
> 
>  # Compile the shared library.
>  set srcdso [file join $srcdir $subdir $srcfile2]
> -set objdso [standard_output_file lib${gdb_test_file_name}.so]
> +set libname "lib${gdb_test_file_name}.so"
> +set objdso [standard_output_file $libname]
>  if {[gdb_compile_shlib $srcdso $objdso {debug}] != ""} {
>      untested "failed to compile dso"
>      return -1
> @@ -47,45 +48,39 @@ if {[readnow]} {
>  # information has NOT been fully expanded (which is what we want for 
> this
>  # test).
>  proc shared_library_debug_not_fully_expanded {} {
> -    set library_expanded ""
> -    gdb_test_multiple "info sources" "" {
> -	-re "^info sources\r\n" {
> +    set not_expanded true
> +    gdb_test_multiple "maint print objfiles $::libname" "" {
> +	-re "^maint print objfiles \[^\r\n\]+\r\n" {
>  	    exp_continue
>  	}
> -	-re "^(\[^\r\n\]+):\r\n\\(Full debug information has not yet been
> read for this file\\.\\)\r\n\r\n" {
> -	    set libname $expect_out(1,string)
> -	    if {$libname == $::objdso} {
> -		set library_expanded "no"
> -	    }
> +
> +	-re "^\\s*\r\n" {
> +	    exp_continue
> +	}
> +
> +	-re "^Object file \[^\r\n\]+\r\n" {
>  	    exp_continue
>  	}
> -	-re "^(\[^\r\n\]+):\r\n\\(Objfile has no debug 
> information\\.\\)\r\n\r\n" {
> -	    set libname $expect_out(1,string)
> -	    if {$libname == $::objdso} {
> -		# For some reason the shared library has no debug
> -		# information, this is not expected.
> -		set library_expanded "missing debug"
> -	    }
> +
> +	-re "^Cooked index in use\r\n" {
>  	    exp_continue
>  	}
> -	-re "^(\[^\r\n\]+):\r\n\r\n" {
> -	    set libname $expect_out(1,string)
> -	    if {$libname == $::objdso} {
> -		set library_expanded "yes"
> -	    }
> +
> +	-re "^Symtabs:\r\n" {
> +	    set not_expanded false
>  	    exp_continue
>  	}
> +
>  	-re "^$::gdb_prompt $" {
> -	    gdb_assert {[string equal $library_expanded "yes"] \
> -			    || [string equal $library_expanded "no"]} \
> -		$gdb_test_name
> +	    pass $gdb_test_name
>  	}
> -	-re "^(\[^\r\n:\]*)\r\n" {
> +
> +	-re "^\[^\r\n\]+\r\n" {
>  	    exp_continue
>  	}
>      }
> 
> -    return [expr $library_expanded == "no"]
> +    return $not_expanded
>  }
> 
>  foreach_with_prefix type_name {"short" "int" "long" "char"} {
  

tdevries <tdevries@suse.de> writes:

> On 2022-12-20 13:20, Andrew Burgess wrote:
>> Andrew Burgess <aburgess@redhat.com> writes:
>> 
>>> tdevries <tdevries@suse.de> writes:
>>> 
>>>> On 2022-12-19 13:52, Andrew Burgess via Gdb-patches wrote:
>>>>> Luis Machado <luis.machado@arm.com> writes:
>>>>> 
>>>>>> On 12/15/22 11:22, Andrew Burgess wrote:
>>>>>>> Luis Machado <luis.machado@arm.com> writes:
>>>>>>> 
>>>>>>>> Hi Andrew,
>>>>>>>> 
>>>>>>>> On 12/9/22 19:24, Andrew Burgess via Gdb-patches wrote:
>>>>>>>>> Tom Tromey <tom@tromey.com> writes:
>>>>>>>>> 
>>>>>>>>>>>>>>> "Andrew" == Andrew Burgess via Gdb-patches
>>>>>>>>>>>>>>> <gdb-patches@sourceware.org> writes:
>>>>>>>>>> 
>>>>>>>>>> Thank you for doing this.
>>>>>>>>>> 
>>>>>>>>>> Andrew>   - However, GDB checks each partial symbol using 
>>>>>>>>>> multiple
>>>>>>>>>> languages,
>>>>>>>>>> Andrew>     not just the current language (C in this case), so,
>>>>>>>>>> when GDB
>>>>>>>>>> Andrew>     checks using the C++ language, the symbol name is
>>>>>>>>>> first demangled,
>>>>>>>>>> Andrew>     the code that does this can be found
>>>>>>>>>> Andrew>     lookup_name_info::language_lookup_name.  As the
>>>>>>>>>> demangled form of
>>>>>>>>>> Andrew>     'signed int' is just 'int', GDB then looks for any
>>>>>>>>>> symbols with
>>>>>>>>>> Andrew>     the name 'int', most partial symtabs will contain 
>>>>>>>>>> such
>>>>>>>>>> a symbol,
>>>>>>>>>> Andrew>     so GDB ends up expanding pretty much every symtab.
>>>>>>>>>> 
>>>>>>>>>> It's a pedantic point but what happens here is name
>>>>>>>>>> canonicalization,
>>>>>>>>>> not demangling.  Demangling is just used to refer to the
>>>>>>>>>> translation
>>>>>>>>>> from a name like "_Zmumble" to "something::else" -- that is, 
>>>>>>>>>> the
>>>>>>>>>> input
>>>>>>>>>> is a linkage name and the output is a C++ name.  
>>>>>>>>>> Canonicalization
>>>>>>>>>> takes
>>>>>>>>>> a C++ name as input and returns the standard form, basically
>>>>>>>>>> dealing
>>>>>>>>>> with the fact that C++ (and as we discovered, C) has multiple
>>>>>>>>>> possible
>>>>>>>>>> spellings for some symbols.
>>>>>>>>> 
>>>>>>>>> Please, be pedantic.  My goal here was to better understand this
>>>>>>>>> code,
>>>>>>>>> there's no point me understanding it wrong.
>>>>>>>>> 
>>>>>>>>> I'll reword that paragraph.
>>>>>>>>> 
>>>>>>>>> Thanks for taking a look.
>>>>>>>>> 
>>>>>>>>> Andrew
>>>>>>>>> 
>>>>>>>> 
>>>>>>>> I'm not saying you should investigate this, as it is a new test, 
>>>>>>>> but
>>>>>>>> I'm getting a lot of these messages for this test:
>>>>>>>> 
>>>>>>>> ERROR: internal buffer is full.
>>>>>>> 
>>>>>>> Happy to take a look at the problem.
>>>>>>> 
>>>>>>> I guess the issue is coming from the gdb_test_multiple that I use 
>>>>>>> in
>>>>>>> the
>>>>>>> new test script.
>>>>>>> 
>>>>>>> I'm tried to write patterns that match and discard all the lines 
>>>>>>> as
>>>>>>> they
>>>>>>> arrive from GDB.  I guess you are seeing a pattern that I am not 
>>>>>>> for
>>>>>>> some reason.
>>>>>>> 
>>>>>>> Could you run just this test and attach the gdb.log file and I'll
>>>>>>> take a
>>>>>>> look.  I probably just need to tweak one of the patterns a little.
>>>>>>> 
>>>>>>> Thanks,
>>>>>>> Andrew
>>>>>>> 
>>>>>> 
>>>>>> I briefly looked into this. The problem seems to arise from the 
>>>>>> fact
>>>>>> that sometimes we don't have multiple lines for the "info sources"
>>>>>> output.
>>>>>> 
>>>>>> Some sections are output in a single line. For example, one of them
>>>>>> has 133K characters. But each entry seems to be separated by a 
>>>>>> comma
>>>>>> character:
>>>>>> 
>>>>>> ./elf/./elf/rtld.c, ./elf/../include/rtld-malloc.h,
>>>>>> ./elf/../sysdeps/generic/ldsodefs.h,
>>>>>> ./elf/../sysdeps/aarch64/dl-machine.h, ...
>>>>> 
>>>>> Ahh, that would explain it.  We don't appear to use 'info sources' 
>>>>> that
>>>>> frequently in the testsuite.  I wonder if you are also seeing 
>>>>> failures
>>>>> on those other tests?
>>>>> 
>>>>>   gdb.asm/asm-source.exp
>>>>>   gdb.dwarf2/dup-psym.exp
>>>>>   gdb.dwarf2/dw2-filename.exp
>>>>> 
>>>>>> It might be best (for the testsuite) if gdb outputs this data 
>>>>>> across
>>>>>> more lines.
>>>>> 
>>>>> The other option might be to extend 'info sources' to allow 
>>>>> filtering
>>>>> based on the objfile name, then we can use this in the testsuite to
>>>>> limit the output...
>>>>> 
>>>>> ... or I wonder if we could trick GDB by setting the width to 
>>>>> something
>>>>> small, the I guess the lines would be broken after the ',' 
>>>>> characters.
>>>>> 
>>>>> I'll have a play and see what I can come up with.
>>>>> 
>>>> 
>>>> I also ran into this issue on ubuntu 22.04.1 x86_64.
>>>> 
>>>> AFAIK, the way we usually test for this type of information is "maint
>>>> print objfile", which is less verbose, and doesn't have long lines.
>>> 
>>> I'm looking at this issue today, I'll give 'maint print objfile' a go.
>>> Thanks for the suggestion.
>> 
>> I was able to reproduce the buffer overflow errors.  The patch below
>> addresses the issue for me.
>> 
>> Thoughts?
>
> LGTM.
>
> Though I wonder if we can make do with being less precise, and just do 
> something like:
> ...
> proc assert_shared_library_debug_not_fully_expanded {} {
>      gdb_test_lines "maint print objfiles $::libname" "" \
>          "Object file \[^\r\n\]*$::libname" \
>          -re-not "Symtabs:"
> }
> ...
>

Thanks for that suggestion Tom, that really is much better that what I
had.

I've taken your suggestion and pushed the fix to master.  My final patch
is below.

Thanks,
Andrew

---

commit 3a98808c164b36c7023bd80fc6b019cbe6274365
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Tue Dec 20 12:51:50 2022 +0000

    gdb/testsuite: fix buffer overflow in gdb.base/signed-builtin-types.exp
    
    In commit:
    
      commit 9f50fe0835850645bd8ea9bb1efe1fe6c48dfb12
      Date:   Wed Dec 7 15:55:25 2022 +0000
    
          gdb/testsuite: new test for recent dwarf reader issue
    
    A new test (gdb.base/signed-builtin-types.exp) was added that made use
    of 'info sources' to figure out if the debug information for a
    particular object file had been fully expanded or not.  Unfortunately
    some lines of the 'info sources' output can be very long, this was
    observed on some systems where the debug information for the
    dynamic-linker was installed, in this case, the list of source files
    associated with the dynamic linker was so long it would cause expect's
    internal buffer to overflow.
    
    This commit switches from using 'info sources' to 'maint print
    objfile', the output from the latter command is more compact, but
    also, can be restricted to a single named object file.
    
    With this change in place I am no longer seeing buffer overflow errors
    from expect when running gdb.base/signed-builtin-types.exp.

diff --git a/gdb/testsuite/gdb.base/signed-builtin-types.exp b/gdb/testsuite/gdb.base/signed-builtin-types.exp
index e9784330fee..30e224fb439 100644
--- a/gdb/testsuite/gdb.base/signed-builtin-types.exp
+++ b/gdb/testsuite/gdb.base/signed-builtin-types.exp
@@ -21,7 +21,8 @@ standard_testfile .c -lib.c
 
 # Compile the shared library.
 set srcdso [file join $srcdir $subdir $srcfile2]
-set objdso [standard_output_file lib${gdb_test_file_name}.so]
+set libname "lib${gdb_test_file_name}.so"
+set objdso [standard_output_file $libname]
 if {[gdb_compile_shlib $srcdso $objdso {debug}] != ""} {
     untested "failed to compile dso"
     return -1
@@ -46,46 +47,10 @@ if {[readnow]} {
 # library has been fully expanded or not.  Return true if the debug
 # information has NOT been fully expanded (which is what we want for this
 # test).
-proc shared_library_debug_not_fully_expanded {} {
-    set library_expanded ""
-    gdb_test_multiple "info sources" "" {
-	-re "^info sources\r\n" {
-	    exp_continue
-	}
-	-re "^(\[^\r\n\]+):\r\n\\(Full debug information has not yet been read for this file\\.\\)\r\n\r\n" {
-	    set libname $expect_out(1,string)
-	    if {$libname == $::objdso} {
-		set library_expanded "no"
-	    }
-	    exp_continue
-	}
-	-re "^(\[^\r\n\]+):\r\n\\(Objfile has no debug information\\.\\)\r\n\r\n" {
-	    set libname $expect_out(1,string)
-	    if {$libname == $::objdso} {
-		# For some reason the shared library has no debug
-		# information, this is not expected.
-		set library_expanded "missing debug"
-	    }
-	    exp_continue
-	}
-	-re "^(\[^\r\n\]+):\r\n\r\n" {
-	    set libname $expect_out(1,string)
-	    if {$libname == $::objdso} {
-		set library_expanded "yes"
-	    }
-	    exp_continue
-	}
-	-re "^$::gdb_prompt $" {
-	    gdb_assert {[string equal $library_expanded "yes"] \
-			    || [string equal $library_expanded "no"]} \
-		$gdb_test_name
-	}
-	-re "^(\[^\r\n:\]*)\r\n" {
-	    exp_continue
-	}
-    }
-
-    return [expr $library_expanded == "no"]
+proc assert_shared_library_debug_not_fully_expanded {} {
+    gdb_test_lines "maint print objfiles $::libname" "" \
+	"Object file \[^\r\n\]*$::libname" \
+	-re-not "Symtabs:"
 }
 
 foreach_with_prefix type_name {"short" "int" "long" "char"} {
@@ -93,7 +58,7 @@ foreach_with_prefix type_name {"short" "int" "long" "char"} {
 	with_test_prefix "before sizeof expression" {
 	    # Check that the debug information for the shared library has
 	    # not yet been read in.
-	    gdb_assert { [shared_library_debug_not_fully_expanded] }
+	    assert_shared_library_debug_not_fully_expanded
 	}
 
 	# Evaluate a sizeof expression for a builtin type.  At one point GDB
@@ -106,7 +71,7 @@ foreach_with_prefix type_name {"short" "int" "long" "char"} {
 	with_test_prefix "after sizeof expression" {
 	    # Check that the debug information for the shared library has not
 	    # yet been read in.
-	    gdb_assert { [shared_library_debug_not_fully_expanded] }
+	    assert_shared_library_debug_not_fully_expanded
 	}
     }
 }