[libcxxabi] r238263 - Make sure !empty() before calling String::front().
Chaoren Lin
chaorenl at google.com
Wed May 27 00:25:28 PDT 2015
>
> I don't see an existing test which tries to demangle
> '_Z1FPiRiOiMS0_FiiE'. I think you should add it
> to test/test_demangle.pass.cpp
'_Z1FPiRiOiMS0_FiiE' is only an example, any mangled name with pointers or
references will do.
By my count there's exactly
1 instance of parsing pointer to member ('M'),
3 instances of parsing rvalue references ('O'),
17525 instances of parsing pointers ('P'), and
12149 instances of parsing references ('R')
in the current test suite that invokes a .front() on an empty string.
These would be exposed if you compiled libc++abi.so *itself* with libcxx
with asserts enabled, and as far as I can tell, this is not something that
can be achieved by adding to the test suite.
BTW, there's a problem with the out of tree build that causes the test
suite to use the wrong __cxa_demangle, since -lc++ (which includes its own
copy) comes before -lc++abi in the test suite.
On Tue, May 26, 2015 at 7:50 PM, David Majnemer <david.majnemer at gmail.com>
wrote:
>
>
> On Tue, May 26, 2015 at 7:22 PM, Chaoren Lin <chaorenl at google.com> wrote:
>
>> Hi David,
>>
>> Thanks for your concern.
>>
>> The commit was intentional. I was hoping this small commit would fall
>> under this part:
>>
>> smaller changes can be reviewed after commit
>>
>>
>> of the LLVM Developer Policy
>> <http://llvm.org/docs/DeveloperPolicy.html#code-reviews>
>>
>
> I'm afraid it doesn't because of the following proviso:
>
> Code review can be an iterative process, which continues until the patch
>> is ready to be committed. Specifically, once a patch is sent out for
>> review, it needs an explicit “looks good” before it is submitted. Do not
>> assume silent approval, or request active objections to the patch with a
>> deadline.
>
>
>
>
>> We inlined a copy of this file in LLDB for Windows, and I ran into a
>> problem where any mangled names with pointers or references in their
>> argument list would cause a crash. Turns out that on Linux, String::front()
>> consistently returns '\0' when empty, even though it should be undefined
>> behavior.
>>
>
>> It should be covered by existing tests if you enable asserts for libcxx
>> and try to demangle "_Z1FPiRiOiMS0_FiiE".
>>
>
> I don't see an existing test which tries to demangle
> '_Z1FPiRiOiMS0_FiiE'. I think you should add it
> to test/test_demangle.pass.cpp
>
>
>>
>> Thanks,
>> Chaoren
>>
>> On Tue, May 26, 2015 at 4:43 PM, David Majnemer <david.majnemer at gmail.com
>> > wrote:
>>
>>> I didn't see anyone LGTM the phabricator review and no test has been
>>> added for this change. Perhaps you accidentally committed this?
>>>
>>> On Tue, May 26, 2015 at 4:14 PM, Chaoren Lin <chaorenl at google.com>
>>> wrote:
>>>
>>>> Author: chaoren
>>>> Date: Tue May 26 18:14:26 2015
>>>> New Revision: 238263
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=238263&view=rev
>>>> Log:
>>>> Make sure !empty() before calling String::front().
>>>>
>>>> Reviewers: howard.hinnant
>>>>
>>>> Subscribers: cfe-commits
>>>>
>>>> Differential Revision: http://reviews.llvm.org/D9954
>>>>
>>>> Modified:
>>>> libcxxabi/trunk/src/cxa_demangle.cpp
>>>>
>>>> Modified: libcxxabi/trunk/src/cxa_demangle.cpp
>>>> URL:
>>>> http://llvm.org/viewvc/llvm-project/libcxxabi/trunk/src/cxa_demangle.cpp?rev=238263&r1=238262&r2=238263&view=diff
>>>>
>>>> ==============================================================================
>>>> --- libcxxabi/trunk/src/cxa_demangle.cpp (original)
>>>> +++ libcxxabi/trunk/src/cxa_demangle.cpp Tue May 26 18:14:26 2015
>>>> @@ -1671,7 +1671,7 @@ parse_pointer_to_member_type(const char*
>>>> auto func = std::move(db.names.back());
>>>> db.names.pop_back();
>>>> auto class_type = std::move(db.names.back());
>>>> - if (func.second.front() == '(')
>>>> + if (!func.second.empty() && func.second.front() == '(')
>>>> {
>>>> db.names.back().first = std::move(func.first) +
>>>> "(" + class_type.move_full() + "::*";
>>>> db.names.back().second = ")" +
>>>> std::move(func.second);
>>>> @@ -2018,7 +2018,8 @@ parse_type(const char* first, const char
>>>> db.names[k].first += " (";
>>>> db.names[k].second.insert(0, ")");
>>>> }
>>>> - else if (db.names[k].second.front() ==
>>>> '(')
>>>> + else if (!db.names[k].second.empty() &&
>>>> + db.names[k].second.front()
>>>> == '(')
>>>> {
>>>> db.names[k].first += "(";
>>>> db.names[k].second.insert(0, ")");
>>>> @@ -2045,7 +2046,8 @@ parse_type(const char* first, const char
>>>> db.names[k].first += " (";
>>>> db.names[k].second.insert(0, ")");
>>>> }
>>>> - else if (db.names[k].second.front() ==
>>>> '(')
>>>> + else if (!db.names[k].second.empty() &&
>>>> + db.names[k].second.front()
>>>> == '(')
>>>> {
>>>> db.names[k].first += "(";
>>>> db.names[k].second.insert(0, ")");
>>>> @@ -2079,7 +2081,8 @@ parse_type(const char* first, const char
>>>> db.names[k].first += " (";
>>>> db.names[k].second.insert(0, ")");
>>>> }
>>>> - else if (db.names[k].second.front() ==
>>>> '(')
>>>> + else if (!db.names[k].second.empty() &&
>>>> + db.names[k].second.front()
>>>> == '(')
>>>> {
>>>> db.names[k].first += "(";
>>>> db.names[k].second.insert(0, ")");
>>>>
>>>>
>>>> _______________________________________________
>>>> cfe-commits mailing list
>>>> cfe-commits at cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>>>>
>>>
>>>
>>
>
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