lldb/source/Plugins/Language/ObjC/NSString.cpp

//===-- NSString.cpp ----------------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "NSString.h"

#include "lldb/Core/DataBufferHeap.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/Stream.h"
#include "lldb/Core/ValueObject.h"
#include "lldb/Core/ValueObjectConstResult.h"
#include "lldb/DataFormatters/FormattersHelpers.h"
#include "lldb/DataFormatters/StringPrinter.h"
#include "lldb/Host/Endian.h"
#include "lldb/Symbol/ClangASTContext.h"
#include "lldb/Target/Language.h"
#include "lldb/Target/Target.h"
#include "lldb/Utility/ProcessStructReader.h"

using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::formatters;

std::map<ConstString, CXXFunctionSummaryFormat::Callback>&
NSString_Additionals::GetAdditionalSummaries ()
{
    static std::map<ConstString, CXXFunctionSummaryFormat::Callback> g_map;
    return g_map;
}

static CompilerType
GetNSPathStore2Type (Target &target)
{
    static ConstString g_type_name("__lldb_autogen_nspathstore2");
    
    ClangASTContext *ast_ctx = target.GetScratchClangASTContext();
    
    if (!ast_ctx)
        return CompilerType();
    
    CompilerType voidstar = ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType();
    CompilerType uint32 = ast_ctx->GetBuiltinTypeForEncodingAndBitSize(eEncodingUint, 32);
    
    return ast_ctx->GetOrCreateStructForIdentifier(g_type_name, {
        {"isa",voidstar},
        {"lengthAndRef",uint32},
        {"buffer",voidstar}
    });
}

bool
lldb_private::formatters::NSStringSummaryProvider (ValueObject& valobj, Stream& stream, const TypeSummaryOptions& summary_options)
{
    static ConstString g_TypeHint("NSString");
    
    ProcessSP process_sp = valobj.GetProcessSP();
    if (!process_sp)
        return false;
    
    ObjCLanguageRuntime* runtime = (ObjCLanguageRuntime*)process_sp->GetLanguageRuntime(lldb::eLanguageTypeObjC);
    
    if (!runtime)
        return false;
    
    ObjCLanguageRuntime::ClassDescriptorSP descriptor(runtime->GetClassDescriptor(valobj));
    
    if (!descriptor.get() || !descriptor->IsValid())
        return false;
    
    uint32_t ptr_size = process_sp->GetAddressByteSize();
    
    lldb::addr_t valobj_addr = valobj.GetValueAsUnsigned(0);
    
    if (!valobj_addr)
        return false;
    
    ConstString class_name_cs = descriptor->GetClassName();
    const char* class_name = class_name_cs.GetCString();
    
    if (!class_name || !*class_name)
        return false;
    
    bool is_tagged_ptr = (0 == strcmp(class_name,"NSTaggedPointerString")) && descriptor->GetTaggedPointerInfo();
    // for a tagged pointer, the descriptor has everything we need
    if (is_tagged_ptr)
        return NSTaggedString_SummaryProvider(valobj, descriptor, stream, summary_options);
    
    auto& additionals_map(NSString_Additionals::GetAdditionalSummaries());
    auto iter = additionals_map.find(class_name_cs), end = additionals_map.end();
    if (iter != end)
        return iter->second(valobj, stream, summary_options);
    
    // if not a tagged pointer that we know about, try the normal route
    uint64_t info_bits_location = valobj_addr + ptr_size;
    if (process_sp->GetByteOrder() != lldb::eByteOrderLittle)
        info_bits_location += 3;
    
    Error error;
    
    uint8_t info_bits = process_sp->ReadUnsignedIntegerFromMemory(info_bits_location, 1, 0, error);
    if (error.Fail())
        return false;
    
    bool is_mutable = (info_bits & 1) == 1;
    bool is_inline = (info_bits & 0x60) == 0;
    bool has_explicit_length = (info_bits & (1 | 4)) != 4;
    bool is_unicode = (info_bits & 0x10) == 0x10;
    bool is_path_store = strcmp(class_name,"NSPathStore2") == 0;
    bool has_null = (info_bits & 8) == 8;
    
    size_t explicit_length = 0;
    if (!has_null && has_explicit_length && !is_path_store)
    {
        lldb::addr_t explicit_length_offset = 2*ptr_size;
        if (is_mutable && !is_inline)
            explicit_length_offset = explicit_length_offset + ptr_size; //  notInlineMutable.length;
        else if (is_inline)
            explicit_length = explicit_length + 0; // inline1.length;
        else if (!is_inline && !is_mutable)
            explicit_length_offset = explicit_length_offset + ptr_size; // notInlineImmutable1.length;
        else
            explicit_length_offset = 0;
        
        if (explicit_length_offset)
        {
            explicit_length_offset = valobj_addr + explicit_length_offset;
            explicit_length = process_sp->ReadUnsignedIntegerFromMemory(explicit_length_offset, 4, 0, error);
        }
    }
    
    if (strcmp(class_name,"NSString") &&
        strcmp(class_name,"CFStringRef") &&
        strcmp(class_name,"CFMutableStringRef") &&
        strcmp(class_name,"__NSCFConstantString") &&
        strcmp(class_name,"__NSCFString") &&
        strcmp(class_name,"NSCFConstantString") &&
        strcmp(class_name,"NSCFString") &&
        strcmp(class_name,"NSPathStore2"))
    {
        // not one of us - but tell me class name
        stream.Printf("class name = %s",class_name);
        return true;
    }
    
    std::string prefix,suffix;
    if (Language* language = Language::FindPlugin(summary_options.GetLanguage()))
    {
        if (!language->GetFormatterPrefixSuffix(valobj, g_TypeHint, prefix, suffix))
        {
            prefix.clear();
            suffix.clear();
        }
    }
    
    StringPrinter::ReadStringAndDumpToStreamOptions options(valobj);
    options.SetPrefixToken(prefix);
    options.SetSuffixToken(suffix);
    
    if (is_mutable)
    {
        uint64_t location = 2 * ptr_size + valobj_addr;
        location = process_sp->ReadPointerFromMemory(location, error);
        if (error.Fail())
            return false;
        if (has_explicit_length && is_unicode)
        {
            options.SetLocation(location);
            options.SetProcessSP(process_sp);
            options.SetStream(&stream);
            options.SetQuote('"');
            options.SetSourceSize(explicit_length);
            options.SetNeedsZeroTermination(false);
            options.SetIgnoreMaxLength(summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryUncapped);
            options.SetBinaryZeroIsTerminator(false);
            options.SetLanguage(summary_options.GetLanguage());
            return StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::UTF16>(options);
        }
        else
        {
            options.SetLocation(location+1);
            options.SetProcessSP(process_sp);
            options.SetStream(&stream);
            options.SetSourceSize(explicit_length);
            options.SetNeedsZeroTermination(false);
            options.SetIgnoreMaxLength(summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryUncapped);
            options.SetBinaryZeroIsTerminator(false);
            options.SetLanguage(summary_options.GetLanguage());
            return StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::ASCII>(options);
        }
    }
    else if (is_inline && has_explicit_length && !is_unicode && !is_path_store && !is_mutable)
    {
        uint64_t location = 3 * ptr_size + valobj_addr;
        
        options.SetLocation(location);
        options.SetProcessSP(process_sp);
        options.SetStream(&stream);
        options.SetQuote('"');
        options.SetSourceSize(explicit_length);
        options.SetIgnoreMaxLength(summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryUncapped);
        options.SetLanguage(summary_options.GetLanguage());
        return StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::ASCII> (options);
    }
    else if (is_unicode)
    {
        uint64_t location = valobj_addr + 2*ptr_size;
        if (is_inline)
        {
            if (!has_explicit_length)
            {
                stream.Printf("found new combo");
                return true;
            }
            else
                location += ptr_size;
        }
        else
        {
            location = process_sp->ReadPointerFromMemory(location, error);
            if (error.Fail())
                return false;
        }
        options.SetLocation(location);
        options.SetProcessSP(process_sp);
        options.SetStream(&stream);
        options.SetQuote('"');
        options.SetSourceSize(explicit_length);
        options.SetNeedsZeroTermination(has_explicit_length == false);
        options.SetIgnoreMaxLength(summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryUncapped);
        options.SetBinaryZeroIsTerminator(has_explicit_length == false);
        options.SetLanguage(summary_options.GetLanguage());
        return StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::UTF16> (options);
    }
    else if (is_path_store)
    {
        ProcessStructReader reader(valobj.GetProcessSP().get(), valobj.GetValueAsUnsigned(0), GetNSPathStore2Type(*valobj.GetTargetSP()));
        explicit_length = reader.GetField<uint32_t>(ConstString("lengthAndRef")) >> 20;
        lldb::addr_t location = valobj.GetValueAsUnsigned(0) + ptr_size + 4;
        
        options.SetLocation(location);
        options.SetProcessSP(process_sp);
        options.SetStream(&stream);
        options.SetQuote('"');
        options.SetSourceSize(explicit_length);
        options.SetNeedsZeroTermination(has_explicit_length == false);
        options.SetIgnoreMaxLength(summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryUncapped);
        options.SetBinaryZeroIsTerminator(has_explicit_length == false);
        options.SetLanguage(summary_options.GetLanguage());
        return StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::UTF16> (options);
    }
    else if (is_inline)
    {
        uint64_t location = valobj_addr + 2*ptr_size;
        if (!has_explicit_length)
        {
            // in this kind of string, the byte before the string content is a length byte
            // so let's try and use it to handle the embedded NUL case
            Error error;
            explicit_length = process_sp->ReadUnsignedIntegerFromMemory(location, 1, 0, error);
            if (error.Fail() || explicit_length == 0)
                has_explicit_length = false;
            else
                has_explicit_length = true;
            location++;
        }
        options.SetLocation(location);
        options.SetProcessSP(process_sp);
        options.SetStream(&stream);
        options.SetSourceSize(explicit_length);
        options.SetNeedsZeroTermination(!has_explicit_length);
        options.SetIgnoreMaxLength(summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryUncapped);
        options.SetBinaryZeroIsTerminator(!has_explicit_length);
        options.SetLanguage(summary_options.GetLanguage());
        if (has_explicit_length)
            return StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::UTF8>(options);
        else
            return StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::ASCII>(options);
    }
    else
    {
        uint64_t location = valobj_addr + 2*ptr_size;
        location = process_sp->ReadPointerFromMemory(location, error);
        if (error.Fail())
            return false;
        if (has_explicit_length && !has_null)
            explicit_length++; // account for the fact that there is no NULL and we need to have one added
        options.SetLocation(location);
        options.SetProcessSP(process_sp);
        options.SetStream(&stream);
        options.SetSourceSize(explicit_length);
        options.SetIgnoreMaxLength(summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryUncapped);
        options.SetLanguage(summary_options.GetLanguage());
        return StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::ASCII>(options);
    }
}

bool
lldb_private::formatters::NSAttributedStringSummaryProvider (ValueObject& valobj, Stream& stream, const TypeSummaryOptions& options)
{
    TargetSP target_sp(valobj.GetTargetSP());
    if (!target_sp)
        return false;
    uint32_t addr_size = target_sp->GetArchitecture().GetAddressByteSize();
    uint64_t pointer_value = valobj.GetValueAsUnsigned(0);
    if (!pointer_value)
        return false;
    pointer_value += addr_size;
    CompilerType type(valobj.GetCompilerType());
    ExecutionContext exe_ctx(target_sp,false);
    ValueObjectSP child_ptr_sp(valobj.CreateValueObjectFromAddress("string_ptr", pointer_value, exe_ctx, type));
    if (!child_ptr_sp)
        return false;
    DataExtractor data;
    Error error;
    child_ptr_sp->GetData(data, error);
    if (error.Fail())
        return false;
    ValueObjectSP child_sp(child_ptr_sp->CreateValueObjectFromData("string_data", data, exe_ctx, type));
    child_sp->GetValueAsUnsigned(0);
    if (child_sp)
        return NSStringSummaryProvider(*child_sp, stream, options);
    return false;
}

bool
lldb_private::formatters::NSMutableAttributedStringSummaryProvider (ValueObject& valobj, Stream& stream, const TypeSummaryOptions& options)
{
    return NSAttributedStringSummaryProvider(valobj, stream, options);
}

bool
lldb_private::formatters::NSTaggedString_SummaryProvider (ValueObject& valobj, ObjCLanguageRuntime::ClassDescriptorSP descriptor, Stream& stream, const TypeSummaryOptions& summary_options)
{
    static ConstString g_TypeHint("NSString");
    
    if (!descriptor)
        return false;
    uint64_t len_bits = 0, data_bits = 0;
    if (!descriptor->GetTaggedPointerInfo(&len_bits,&data_bits,nullptr))
        return false;
    
    static const int g_MaxNonBitmaskedLen = 7; //TAGGED_STRING_UNPACKED_MAXLEN
    static const int g_SixbitMaxLen = 9;
    static const int g_fiveBitMaxLen = 11;
    
    static const char *sixBitToCharLookup = "eilotrm.apdnsIc ufkMShjTRxgC4013" "bDNvwyUL2O856P-B79AFKEWV_zGJ/HYX";
    
    if (len_bits > g_fiveBitMaxLen)
        return false;
    
    std::string prefix,suffix;
    if (Language* language = Language::FindPlugin(summary_options.GetLanguage()))
    {
        if (!language->GetFormatterPrefixSuffix(valobj, g_TypeHint, prefix, suffix))
        {
            prefix.clear();
            suffix.clear();
        }
    }
    
    // this is a fairly ugly trick - pretend that the numeric value is actually a char*
    // this works under a few assumptions:
    // little endian architecture
    // sizeof(uint64_t) > g_MaxNonBitmaskedLen
    if (len_bits <= g_MaxNonBitmaskedLen)
    {
        stream.Printf("%s",prefix.c_str());
        stream.Printf("\"%s\"",(const char*)&data_bits);
        stream.Printf("%s",suffix.c_str());
        return true;
    }
    
    // if the data is bitmasked, we need to actually process the bytes
    uint8_t bitmask = 0;
    uint8_t shift_offset = 0;
    
    if (len_bits <= g_SixbitMaxLen)
    {
        bitmask = 0x03f;
        shift_offset = 6;
    }
    else
    {
        bitmask = 0x01f;
        shift_offset = 5;
    }
    
    std::vector<uint8_t> bytes;
    bytes.resize(len_bits);
    for (; len_bits > 0; data_bits >>= shift_offset, --len_bits)
    {
        uint8_t packed = data_bits & bitmask;
        bytes.insert(bytes.begin(), sixBitToCharLookup[packed]);
    }
    
    stream.Printf("%s",prefix.c_str());
    stream.Printf("\"%s\"",&bytes[0]);
    stream.Printf("%s",suffix.c_str());
    return true;
}