debug_stl.cpp

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/* Copyright (c) 2010 Wildfire Games
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * portable debugging helper functions specific to the STL.
 */

#include "precompiled.h"
#include "lib/debug_stl.h"

#include <deque>
#include <map>
#include <set>
#include <cassert>
#include <list>

#include "lib/regex.h"

static const StatusDefinition debugStlStatusDefinitions[] = {
    { ERR::STL_CNT_UNKNOWN, L"Unknown STL container type_name" },
    { ERR::STL_CNT_UNSUPPORTED, L"Unsupported STL container" },
    { ERR::STL_CNT_INVALID, L"Container type is known but contents are invalid" }
};
STATUS_ADD_DEFINITIONS(debugStlStatusDefinitions);


// used in debug_stl_simplify_name.
// note: wcscpy_s is safe because replacement happens in-place and
// <what> is longer than <with> (otherwise, we wouldn't be replacing).
#define REPLACE(what, with)\
    else if(!wcsncmp(src, (what), ARRAY_SIZE(what)-1))\
    {\
        src += ARRAY_SIZE(what)-1-1; /* see preincrement rationale*/\
        wcscpy_s(dst, ARRAY_SIZE(with), (with));\
        dst += ARRAY_SIZE(with)-1;\
    }
#define STRIP(what)\
    else if(!wcsncmp(src, (what), ARRAY_SIZE(what)-1))\
    {\
        src += ARRAY_SIZE(what)-1-1;/* see preincrement rationale*/\
    }
#define STRIP_NESTED(what)\
    else if(!wcsncmp(src, (what), ARRAY_SIZE(what)-1))\
    {\
        /* remove preceding comma (if present) */\
        if(src != name && src[-1] == ',')\
            dst--;\
        src += ARRAY_SIZE(what)-1;\
        /* strip everything until trailing > is matched */\
        ENSURE(nesting == 0);\
        nesting = 1;\
    }

// reduce complicated STL names to human-readable form (in place).
// e.g. "std::basic_string<char, char_traits<char>, std::allocator<char> >" =>
//  "string". algorithm: strip undesired strings in one pass (fast).
// called from symbol_string_build.
//
// see http://www.bdsoft.com/tools/stlfilt.html and
// http://www.moderncppdesign.com/publications/better_template_error_messages.html
wchar_t* debug_stl_simplify_name(wchar_t* name)
{
    // used when stripping everything inside a < > to continue until
    // the final bracket is matched (at the original nesting level).
    int nesting = 0;

    const wchar_t* src = name-1;    // preincremented; see below.
    wchar_t* dst = name;

    // for each character: (except those skipped as parts of strings)
    for(;;)
    {
        wchar_t c = *(++src);
        // preincrement rationale: src++ with no further changes would
        // require all comparisons to subtract 1. incrementing at the
        // end of a loop would require a goto, instead of continue
        // (there are several paths through the loop, for speed).
        // therefore, preincrement. when skipping strings, subtract
        // 1 from the offset (since src is advanced directly after).

        // end of string reached - we're done.
        if(c == '\0')
        {
            *dst = '\0';
            break;
        }

        // we're stripping everything inside a < >; eat characters
        // until final bracket is matched (at the original nesting level).
        if(nesting)
        {
            if(c == '<')
                nesting++;
            else if(c == '>')
            {
                nesting--;
                ENSURE(nesting >= 0);
            }
            continue;
        }

        // start if chain (REPLACE and STRIP use else if)
        if(0) {}
        else if(!wcsncmp(src, L"::_Node", 7))
        {
            // add a space if not already preceded by one
            // (prevents replacing ">::_Node>" with ">>")
            if(src != name && src[-1] != ' ')
                *dst++ = ' ';
            src += 7;
        }
        REPLACE(L"unsigned short", L"u16")
        REPLACE(L"unsigned int", L"size_t")
        REPLACE(L"unsigned __int64", L"u64")
        STRIP(L",0> ")
        // early out: all tests after this start with s, so skip them
        else if(c != 's')
        {
            *dst++ = c;
            continue;
        }
        REPLACE(L"std::_List_nod", L"list")
        REPLACE(L"std::_Tree_nod", L"map")
        REPLACE(L"std::basic_string<char, ", L"string<")
        REPLACE(L"std::basic_string<__wchar_t, ", L"wstring<")
        REPLACE(L"std::basic_string<unsigned short, ", L"wstring<")
        STRIP(L"std::char_traits<char>, ")
        STRIP(L"std::char_traits<unsigned short>, ")
        STRIP(L"std::char_traits<__wchar_t>, ")
        STRIP(L"std::_Tmap_traits")
        STRIP(L"std::_Tset_traits")
        STRIP_NESTED(L"std::allocator<")
        STRIP_NESTED(L"std::less<")
        STRIP_NESTED(L"stdext::hash_compare<")
        STRIP(L"std::")
        STRIP(L"stdext::")
        else
            *dst++ = c;
    }

    return name;
}


//-----------------------------------------------------------------------------
// STL container debugging
//-----------------------------------------------------------------------------

// provide an iterator interface for arbitrary STL containers; this is
// used to display their contents in stack traces. their type and
// contents aren't known until runtime, so this is somewhat tricky.
//
// we assume STL containers aren't specialized on their content type and
// use their int instantiations's memory layout. vector<bool> will therefore
// not be displayed correctly, but it is frowned upon anyway (since
// address of its elements can't be taken).
// to be 100% correct, we'd have to write an Any_container_type__element_type
// class for each combination, but that is clearly infeasible.
//
// containers might still be uninitialized when we call get_container_info on
// them. we need to check if they are IsValid and only then use their contents.
// to that end, we derive a validator class from each container,
// cast the container's address to it, and call its IsValid() method.
//
// checks performed include: is size() realistic; does begin() come before
// end(), etc. we need to leverage all invariants because the values are
// random in release mode.
//
// we sometimes need to access protected members of the STL containers.
// granting access via friend is not possible since the system headers
// must not be changed. that leaves us with two alternatives:
// 1) write a 'shadow' class that has the same memory layout. this would
//    free us from the ugly Dinkumware naming conventions, but requires
//    more maintenance when the STL implementation changes.
// 2) derive from the container. while not entirely bulletproof due to the
//    lack of virtual dtors, this is safe in practice because pointers are
//    neither returned to users nor freed. the only requirement is that
//    classes must not include virtual functions, because a vptr would
//    change the memory layout in unknown ways.
//
// it is rather difficult to abstract away implementation details of various
// STL versions. we currently only really support Dinkumware due to
// significant differences in the implementations of set, map and string.


//----------------------------------------------------------------------------
// standard containers

// base class (slightly simplifies code by providing default implementations
// that can be used for most containers).
// Container is the complete type of the STL container (we can't pass this
// as a template because Dinkumware _Tree requires different parameters)
template<class Container>
struct ContainerBase : public Container
{
    bool IsValid(size_t UNUSED(el_size)) const
    {
        return true;
    }

    size_t NumElements(size_t UNUSED(el_size)) const
    {
        return this->size();
    }

    static const u8* DereferenceAndAdvance(typename Container::iterator& it, size_t UNUSED(el_size))
    {
        const u8* p = (const u8*)&*it;
        ++it;
        return p;
    }
};


struct Any_deque : public ContainerBase<std::deque<int> >
{
#if STL_DINKUMWARE == 405

    bool IsValid(size_t el_size) const
    {
        const size_t el_per_bucket = ElementsPerBucket(el_size);
        // initial element is beyond end of first bucket
        if(_Myoff >= el_per_bucket)
            return false;
        // more elements reported than fit in all buckets
        if(_Mysize > _Mapsize * el_per_bucket)
            return false;

        return true;
    }

    static const u8* DereferenceAndAdvance(iterator& stl_it, size_t el_size)
    {
        struct Iterator : public iterator
        {
            Any_deque& Container() const
            {
                return *(Any_deque*)_Mycont;
            }

            size_t CurrentIndex() const
            {
                return _Myoff;
            }
        };

        Iterator& it = *(Iterator*)&stl_it;
        Any_deque& container = it.Container();
        const size_t currentIndex = it.CurrentIndex();
        const u8* p = container.GetNthElement(currentIndex, el_size);
        ++it;
        return p;
    }

private:
    static size_t ElementsPerBucket(size_t el_size)
    {
        return std::max(16u / el_size, (size_t)1u); // see _DEQUESIZ
    }

    const u8* GetNthElement(size_t i, size_t el_size) const
    {
        const size_t el_per_bucket = ElementsPerBucket(el_size);
        const size_t bucket_idx = i / el_per_bucket;
        ENSURE(bucket_idx < _Mapsize);
        const size_t idx_in_bucket = i - bucket_idx * el_per_bucket;
        ENSURE(idx_in_bucket < el_per_bucket);
        const u8** map = (const u8**)_Map;
        const u8* bucket = map[bucket_idx];
        const u8* p = bucket + idx_in_bucket*el_size;
        return p;
    }

#endif
};


struct Any_list : public ContainerBase<std::list<int> >
{
};


#if STL_DINKUMWARE == 405

template<class _Traits>
struct Any_tree : public std::_Tree<_Traits>
{
    Any_tree()  // (required because default ctor cannot be generated)
    {
    }

    bool IsValid(size_t UNUSED(el_size)) const
    {
        return true;
    }

    size_t NumElements(size_t UNUSED(el_size)) const
    {
        return size();
    }

    static const u8* DereferenceAndAdvance(iterator& stl_it, size_t el_size)
    {
        struct Iterator : public const_iterator
        {
            _Nodeptr Node() const
            {
                return _Ptr;
            }

            void SetNode(_Nodeptr node)
            {
                _Ptr = node;
            }
        };

        Iterator& it = *(Iterator*)&stl_it;
        _Nodeptr node = it.Node();
        const u8* p = (const u8*)&*it;

        // end() shouldn't be incremented, don't move
        if(_Isnil(node, el_size))
            return p;

        // return smallest (leftmost) node of right subtree
        _Nodeptr _Pnode = _Right(node);
        if(!_Isnil(_Pnode, el_size))
        {
            while(!_Isnil(_Left(_Pnode), el_size))
                _Pnode = _Left(_Pnode);
        }
        // climb looking for right subtree
        else
        {
            while (!_Isnil(_Pnode = _Parent(node), el_size) && node == _Right(_Pnode))
                node = _Pnode;  // ==> parent while right subtree
        }
        it.SetNode(_Pnode);
        return p;
    };

private:
    // return reference to the given node's nil flag.
    // reimplemented because this member is stored after _Myval, so it's
    // dependent on el_size.
    static _Charref _Isnil(_Nodeptr _Pnode, size_t el_size)
    {
        const u8* p = (const u8*)&_Pnode->_Isnil;   // correct for int specialization
        p += el_size - sizeof(value_type);  // adjust for difference in el_size
        assert(*p <= 1);    // bool value
        return (_Charref)*p;
    }
};


struct Any_map : public Any_tree<std::_Tmap_traits<int, int, std::less<int>, std::allocator<std::pair<const int, int> >, false> >
{
};


struct Any_multimap : public Any_map
{
};


struct Any_set: public Any_tree<std::_Tset_traits<int, std::less<int>, std::allocator<int>, false> >
{
};


struct Any_multiset: public Any_set
{
};

#endif


struct Any_vector: public ContainerBase<std::vector<int> >
{
    bool IsValid(size_t UNUSED(el_size)) const
    {
        // more elements reported than reserved
        if(size() > capacity())
            return false;
        // front/back pointers incorrect
        if(&front() > &back())
            return false;
        return true;
    }

#if STL_DINKUMWARE == 405

    size_t NumElements(size_t el_size) const
    {
        // vectors store front and back pointers and calculate their
        // element count as the difference between them. since we are
        // derived from a template specialization, the pointer arithmetic
        // is incorrect. we fix it by taking el_size into account.
        return ((u8*)_Mylast - (u8*)_Myfirst) * el_size;
    }

    static const u8* DereferenceAndAdvance(iterator& stl_it, size_t el_size)
    {
        struct Iterator : public const_iterator
        {
            void Advance(size_t numBytes)
            {
                (u8*&)_Myptr += numBytes;
            }
        };

        Iterator& it = *(Iterator*)&stl_it;
        const u8* p = (const u8*)&*it;
        it.Advance(el_size);
        return p;
    }

#endif
};


#if STL_DINKUMWARE == 405

struct Any_basic_string : public ContainerBase<std::string>
{
    bool IsValid(size_t el_size) const
    {
        // less than the small buffer reserved - impossible
        if(_Myres < (16/el_size)-1)
            return false;
        // more elements reported than reserved
        if(_Mysize > _Myres)
            return false;
        return true;
    }
};

#endif


//
// standard container adapters
//

// debug_stl_get_container_info makes sure this was actually instantiated with
// container = deque as we assume.
struct Any_queue : public Any_deque
{
};


// debug_stl_get_container_info makes sure this was actually instantiated with
// container = deque as we assume.
struct Any_stack : public Any_deque
{
};


//-----------------------------------------------------------------------------

// generic iterator - returns next element. dereferences and increments the
// specific container iterator stored in it_mem.
template<class T> const u8* stl_iterator(void* it_mem, size_t el_size)
{
    typedef typename T::iterator iterator;
    iterator& stl_it = *(iterator*)it_mem;
    return T::DereferenceAndAdvance(stl_it, el_size);
}


// basic sanity checks that apply to all containers.
template<class T>
static bool IsContainerValid(const T& t, size_t el_count)
{
    // note: don't test empty() because vector's implementation of it
    // depends on el_size.

    // size must be reasonable
    if(el_count > 0x1000000)
        return false;

    if(el_count != 0)
    {
        // valid pointer
        const u8* front = (const u8*)&*t.begin();   // (note: map doesn't have front)
        if(debug_IsPointerBogus(front))
            return false;

        // note: don't test back() because that depends on el_size and
        // requires container-specific code.
    }

    return true;
}

// check if the container is IsValid and return # elements and an iterator;
// this is instantiated once for each type of container.
// we don't do this in the Any_* ctors because we need to return bool IsValid and
// don't want to throw an exception (may confuse the debug code).
template<class T> bool get_container_info(const T& t, size_t size, size_t el_size,
    size_t& el_count, DebugStlIterator& el_iterator, void* it_mem)
{
    typedef typename T::iterator iterator;
    typedef typename T::const_iterator const_iterator;
    
    ENSURE(sizeof(T) == size);
    ENSURE(sizeof(iterator) < DEBUG_STL_MAX_ITERATOR_SIZE);

    el_count = t.NumElements(el_size);

    // bail if the container is uninitialized/invalid.
    if(!IsContainerValid(t, el_count))
        return false;

    el_iterator = stl_iterator<T>;

    // construct a copy of begin() at it_mem. placement new is necessary
    // because VC8's secure copy ctor apparently otherwise complains about
    // invalid values in the (uninitialized) destination memory.
    new(it_mem) const_iterator(t.begin());
    return true;
}


// if <wtype_name> indicates the object <p, size> to be an STL container,
// and given the size of its value_type (retrieved via debug information),
// return number of elements and an iterator (any data it needs is stored in
// it_mem, which must hold DEBUG_STL_MAX_ITERATOR_SIZE bytes).
// returns 0 on success or an StlContainerError.
Status debug_stl_get_container_info(const wchar_t* type_name, const u8* p, size_t size,
    size_t el_size, size_t* el_count, DebugStlIterator* el_iterator, void* it_mem)
{
#if MSC_VERSION >= 1400
    UNUSED2(type_name);
    UNUSED2(p);
    UNUSED2(size);
    UNUSED2(el_size);
    UNUSED2(el_count);
    UNUSED2(el_iterator);
    UNUSED2(it_mem);
    return ERR::STL_CNT_UNSUPPORTED;    // NOWARN
#else

    bool handled = false, IsValid = false;
#define CONTAINER(name, type_name_pattern)\
    else if(match_wildcard(type_name, type_name_pattern))\
    {\
        handled = true;\
        IsValid = get_container_info<Any_##name>(*(Any_##name*)p, size, el_size, *el_count, *el_iterator, it_mem);\
    }
#define STD_CONTAINER(name) CONTAINER(name, L"std::" WIDEN(#name) L"<*>")

    // workaround for preprocessor limitation: what we're trying to do is
    // stringize the defined value of a macro. prepending and pasting L
    // apparently isn't possible because macro args aren't expanded before
    // being pasted; we therefore compare as chars[].
#define STRINGIZE2(id) # id
#define STRINGIZE(id) STRINGIZE2(id)

    if(0) {}    // kickoff
    // standard containers
    STD_CONTAINER(deque)
    STD_CONTAINER(list)
    STD_CONTAINER(vector)
#if STL_DINKUMWARE == 405
    STD_CONTAINER(map)
    STD_CONTAINER(multimap)
    STD_CONTAINER(set)
    STD_CONTAINER(multiset)
    STD_CONTAINER(basic_string)
#endif
    // standard container adapters
    // (note: Any_queue etc. assumes the underlying container is a deque.
    // we make sure of that here and otherwise refuse to display it, because
    // doing so is lots of work for little gain.)
    CONTAINER(queue, L"std::queue<*,std::deque<*> >")
    CONTAINER(stack, L"std::stack<*,std::deque<*> >")

    // note: do not raise warnings - these can happen for new
    // STL classes or if the debuggee's memory is corrupted.
    if(!handled)
        return ERR::STL_CNT_UNKNOWN;    // NOWARN
    if(!IsValid)
        return ERR::STL_CNT_INVALID;    // NOWARN
    return INFO::OK;

#endif
}