Hi Enrico,
Any suggestion/example how to add a data formatter for our own STL string?
>From the output below I can see we are using our own "*fbstring_core*"
which I assume I need to write a type summary for this type:
frame variable corpus -T
(const string &const) corpus = error: summary string parsing error: {
(std::*fbstring_core*<char>) store_ = {
(std::*fbstring_core*<char>::(anonymous union)) = {
(char [24]) small_ = "www"
(std::fbstring_core<char>::MediumLarge) ml_ = {
(char *) data_ = 0x0000000000777777
"H\x89U\xa8H\x89M\xa0L\x89E\x98H\x8bE\xa8H\x89��_U��D\x88e�H\x8bE\xa0H\x89��]U��H\x89�H\x8dE�H\x89�H\x89�����L\x8dm�H\x8bE\x98H\x89��IU��\x88]�L\x8be\xb0L\x89��
(std::size_t) size_ = 0
(std::size_t) capacity_ = 1441151880758558720
}
}
}
}
Thanks.
Jeffrey
On Mon, Mar 28, 2016 at 11:38 AM, Enrico Granata <egran...@apple.com> wrote:
> This is kind of orthogonal to your problem, but the reason why you are not
> seeing the kind of simplified printing Greg is suggesting, is because your
> std::string doesn’t look like any of the kinds we recognize
>
> Specifically, LLDB data formatters work by matching against type names,
> and once they recognize a typename, then they try to inspect the variable
> in order to grab a summary
> In your example, your std::string exposes a layout that we are not
> handling - hence we bail out of the formatter and we fall back to the raw
> view
>
> If you want pretty printing to work, you’ll need to write a data formatter
>
> There are a few avenues. The obvious easy one is to extend the existing
> std::string formatter to recognize your type’s internal layout.
> If one were signing up for more infrastructure work, they could decide to
> try and detect shared library loads and load formatters that match with
> whatever libraries are being loaded.
>
> On Mar 28, 2016, at 9:47 AM, Greg Clayton via lldb-dev <
> lldb-dev@lists.llvm.org> wrote:
>
> So you need to be prepared to escape any text that can have special
> characters. A "std::string" or any container can contain special
> characters. If you are encoding stuff into JSON, you will either need to
> escape any special characters, or hex encode the string into ASCII hex
> bytes.
>
> In debuggers we often get bogus data because variables are not
> initialized, but the compiler tells us that a variable is valid in address
> range [0x1000-0x2000), but it actually is [0x1200-0x2000). If we read a
> variable in this case, a std::string might contain bogus data and the bytes
> might not make sense. So you always have to be prepared for bad data.
>
> If we look at:
>
> store_ = {
> = {
> small_ = "www"
> ml_ = (data_ =
>
> "��UH\x89�H�}�H\x8bE�]ÐUH\x89�H��H\x89}�H\x8bE�H\x89��~\xb4��\x90��UH\x89�SH\x83�H\x89}�H�u�H�E�H���\x9e���H\x8b\x18H\x8bE�H���O\xb4��H\x89ƿ\b",
> size_ = 0, capacity_ = 1441151880758558720)
> }
> }
> }
>
> We can see the "size_" is zero, and capacity_ is 1441151880758558720
> (which is 0x1400000000000000). "data_" seems to be some random pointer.
>
> On MacOSX, we have a special formatting code that displays std::string in
> CPlusPlusLanguage.cpp that gets installed in the LoadLibCxxFormatters() or
> LoadLibStdcppFormatters() functions with code like:
>
> lldb::TypeSummaryImplSP std_string_summary_sp(new
> CXXFunctionSummaryFormat(stl_summary_flags,
> lldb_private::formatters::LibcxxStringSummaryProvider, "std::string summary
> provider"));
>
> cpp_category_sp->GetTypeSummariesContainer()->Add(ConstString("std::__1::string"),
> std_string_summary_sp);
>
> Special flags are set on std::string to say "don't show children of this
> and just show a summary" So if a std::string contained "hello". So for the
> following code:
>
> std::string h ("hello");
>
> You should just see:
>
> (lldb) fr var h
> (std::__1::string) h = "hello"
>
> If you take a look at the normal value in the raw we see:
>
> (lldb) fr var --raw h
> (std::__1::string) h = {
> __r_ = {
> std::__1::__libcpp_compressed_pair_imp<std::__1::basic_string<char,
> std::__1::char_traits<char>, std::__1::allocator<char> >::__rep,
> std::__1::allocator<char>, 2> = {
> __first_ = {
> = {
> __l = {
> __cap_ = 122511465736202
> __size_ = 0
> __data_ = 0x0000000000000000
> }
> __s = {
> = {
> __size_ = '\n'
> __lx = '\n'
> }
> __data_ = {
> [0] = 'h'
> [1] = 'e'
> [2] = 'l'
> [3] = 'l'
> [4] = 'o'
> [5] = '\0'
> [6] = '\0'
> [7] = '\0'
> [8] = '\0'
> [9] = '\0'
> [10] = '\0'
> [11] = '\0'
> [12] = '\0'
> [13] = '\0'
> [14] = '\0'
> [15] = '\0'
> [16] = '\0'
> [17] = '\0'
> [18] = '\0'
> [19] = '\0'
> [20] = '\0'
> [21] = '\0'
> [22] = '\0'
> }
> }
> __r = {
> __words = {
> [0] = 122511465736202
> [1] = 0
> [2] = 0
> }
> }
> }
> }
> }
> }
> }
>
> So the main question is why are our "std::string" formatters not kicking
> in for you. That comes down to a typename match, or the format of the
> string isn't what the formatter is expecting.
>
> But again, since you std::string can contain anything, you will need to
> escape any and all text that is encoded into JSON to ensure it doesn't
> contain anything JSON can't deal with.
>
> On Mar 27, 2016, at 9:20 PM, Jeffrey Tan via lldb-dev <
> lldb-dev@lists.llvm.org> wrote:
>
> Thanks Siva. All the DW_TAG_member related errors seems to go away after
> patching with your fix. The current problem is handling the decoding.
>
> Here is the correct decoding from gdb whic might be useful:
> (gdb) p corpus
> $3 = (const std::string &) @0x7fd133cfb888: {
> static npos = 18446744073709551615, store_ = {
> static kIsLittleEndian = <optimized out>,
> static kIsBigEndian = <optimized out>, {
> small_ = "www", '\000' <repeats 20 times>, "\024", ml_ = {
> data_ = 0x777777 <std::_Any_data::_M_access<void
> folly::fibers::Baton::waitFiber<folly::fibers::FirstArgOf<facebook::servicerouter::RequestDispatcherBase<facebook::servicerouter::ThriftDispatcher>::prepareForSelection(facebook::servicerouter::DispatchContext&)::{lambda(folly::fibers::Promise<facebook::servicerouter::RequestDispatcherBase<facebook::servicerouter::ThriftDispatcher>::prepareForSelection(facebook::servicerouter::DispatchContext&)::SelectionResult>)#1},
> void>::type::value_type
> folly::fibers::await<facebook::servicerouter::RequestDispatcherBase<facebook::servicerouter::ThriftDispatcher>::prepareForSelection(facebook::servicerouter::DispatchContext&)::{lambda(folly::fibers::Promise<facebook::servicerouter::RequestDispatcherBase<facebook::servicerouter::ThriftDispatcher>::prepareForSelection(facebook::servicerouter::DispatchContext&)::SelectionResult>)#1}>(folly::fibers::FirstArgOf&&)::{lambda()#1}>(folly::fibers::FiberManager&,
> folly::fibers::FirstArgOf<folly::fibers::FirstArgOf<facebook::servicerouter::RequestDispatcherBase<facebook::servicerouter::ThriftDispatcher>::prepareForSelection(facebook::servicerouter::DispatchContext&)::{lambda(folly::fibers::Promise<facebook::servicerouter::RequestDispatcherBase<facebook::servicerouter::ThriftDispatcher>::prepareForSelection(facebook::servicerouter::DispatchContext&)::SelectionResult>)#1},
> void>::type::value_type
> folly::fibers::await<facebook::servicerouter::RequestDispatcherBase<facebook::servicerouter::ThriftDispatcher>::prepareForSelection(facebook::servicerouter::DispatchContext&)::{lambda(folly::fibers::Promise<facebook::servicerouter::RequestDispatcherBase<facebook::servicerouter::ThriftDispatcher>::prepareForSelection(facebook::servicerouter::DispatchContext&)::SelectionResult>)#1}>(folly::fibers::FirstArgOf&&)::{lambda()#1},
> void>::type::value_type)::{lambda(folly::fibers::Fiber&)#1}*>() const+25>
> "\311\303UH\211\345H\211}\370H\213E\370]ÐUH\211\345H\203\354\020H\211}\370H\213E\370H\211\307\350~\264\312\377\220\311\303UH\211\345SH\203\354\030H\211}\350H\211u\340H\213E\340H\211\307\350\236\377\377\377H\213\030H\213E\350H\211\307\350O\264\312\377H\211ƿ\b",
> size_ = 0,
> capacity_ = 1441151880758558720}}}}
>
> Utf-16 does not seem to decode it, while 'latin-1' does:
>
> '\xc9'.decode('utf-16')
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File
> "/mnt/gvfs/third-party2/python/55c1fd79d91c77c95932db31a4769919611c12bb/2.7.8/centos6-native/da39a3e/lib/python2.7/encodings/utf_16.py",
> line 16, in decode
> return codecs.utf_16_decode(input, errors, True)
> UnicodeDecodeError: 'utf16' codec can't decode byte 0xc9 in position 0:
> truncated data
>
> '\xc9'.decode('latin-1')
>
> u'\xc9'
>
> Instead of guessing what kind of decoding I should use, I would use
> 'ensure_ascii=False' to prevent the crash for now.
>
> I tried to reproduce this crash, but it seems that the crash might be
> related with some internal stl implementation we are using. I will see if I
> can narrow down to a small repro later.
>
> Thanks
> Jeffrey
>
> On Sun, Mar 27, 2016 at 2:49 PM, Siva Chandra <sivachan...@gmail.com>
> wrote:
> On Sat, Mar 26, 2016 at 11:58 PM, Jeffrey Tan <jeffrey.fu...@gmail.com>
> wrote:
>
> Btw: after patching with Siva's fix http://reviews.llvm.org/D18008, the
> first field 'small_' is fixed, however the second field 'ml_' still emits
> garbage:
>
> (lldb) fr v corpus
> (const string &const) corpus = error: summary string parsing error: {
> store_ = {
> = {
> small_ = "www"
> ml_ = (data_ =
>
> "��UH\x89�H�}�H\x8bE�]ÐUH\x89�H��H\x89}�H\x8bE�H\x89��~\xb4��\x90��UH\x89�SH\x83�H\x89}�H�u�H�E�H���\x9e���H\x8b\x18H\x8bE�H���O\xb4��H\x89ƿ\b",
> size_ = 0, capacity_ = 1441151880758558720)
> }
> }
> }
>
>
> Do you still see the DW_TAG_member related error?
>
> A wild (and really wild at that) guess: Is it utf16 data that is being
> decoded as utf8?
>
> As David Blaikie mentioned on the other thread, it would really help
> if you provide us with a minimal example to repro this. Atleast, repro
> instructions.
>
> _______________________________________________
> lldb-dev mailing list
> lldb-dev@lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>
>
> _______________________________________________
> lldb-dev mailing list
> lldb-dev@lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>
>
>
> Thanks,
> *- Enrico*
> 📩 egranata@.com ☎️ 27683
>
>
_______________________________________________
lldb-dev mailing list
lldb-dev@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
