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

#include "llvm/DebugInfo/DWARF/DWARFDebugRnglists.h"

#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"

using namespace llvm;

void DWARFDebugRnglists::clear() {
  HeaderData = {};
  Offsets.clear();
  Ranges.clear();
}

template <typename... Ts>
static Error createError(char const *Fmt, const Ts &... Vals) {
  std::string Buffer;
  raw_string_ostream Stream(Buffer);
  Stream << format(Fmt, Vals...);
  return make_error<StringError>(Stream.str(), inconvertibleErrorCode());
}

Error DWARFDebugRnglists::extract(DWARFDataExtractor Data,
                                  uint32_t *OffsetPtr) {
  clear();
  HeaderOffset = *OffsetPtr;

  // Read and verify the length field.
  if (!Data.isValidOffsetForDataOfSize(*OffsetPtr, sizeof(uint32_t)))
    return createError("section is not large enough to contain a "
                       ".debug_rnglists table length at offset 0x%" PRIx32,
                       *OffsetPtr);
  // TODO: Add support for DWARF64.
  HeaderData.Length = Data.getU32(OffsetPtr);
  if (HeaderData.Length == 0xffffffffu)
    return createError(
        "DWARF64 is not supported in .debug_rnglists at offset 0x%" PRIx32,
        HeaderOffset);
  if (HeaderData.Length + sizeof(uint32_t) < sizeof(Header))
    return createError(".debug_rnglists table at offset 0x%" PRIx32
                       " has too small length (0x%" PRIx32
                       ") to contain a complete header",
                       HeaderOffset, length());
  uint32_t End = HeaderOffset + length();
  if (!Data.isValidOffsetForDataOfSize(HeaderOffset, End - HeaderOffset))
    return createError(
        "section is not large enough to contain a .debug_rnglists table "
        "of length 0x%" PRIx32 " at offset 0x%" PRIx32,
        length(), HeaderOffset);

  HeaderData.Version = Data.getU16(OffsetPtr);
  HeaderData.AddrSize = Data.getU8(OffsetPtr);
  HeaderData.SegSize = Data.getU8(OffsetPtr);
  HeaderData.OffsetEntryCount = Data.getU32(OffsetPtr);

  // Perform basic validation of the remaining header fields.
  if (HeaderData.Version != 5)
    return createError("unrecognised .debug_rnglists table version %" PRIu16
                       " in table at offset 0x%" PRIx32,
                       HeaderData.Version, HeaderOffset);
  if (HeaderData.AddrSize != 4 && HeaderData.AddrSize != 8)
    return createError(".debug_rnglists table at offset 0x%" PRIx32
                       " has unsupported address size %hhu",
                       HeaderOffset, HeaderData.AddrSize);
  if (HeaderData.SegSize != 0)
    return createError(".debug_rnglists table at offset 0x%" PRIx32
                       " has unsupported segment selector size %" PRIu8,
                       HeaderOffset, HeaderData.SegSize);
  if (End < HeaderOffset + sizeof(HeaderData) +
                HeaderData.OffsetEntryCount * sizeof(uint32_t))
    return createError(".debug_rnglists table at offset 0x%" PRIx32
                       " has more offset entries (%" PRIu32
                       ") than there is space for",
                       HeaderOffset, HeaderData.OffsetEntryCount);

  Data.setAddressSize(HeaderData.AddrSize);

  for (uint32_t I = 0; I < HeaderData.OffsetEntryCount; ++I)
    Offsets.push_back(Data.getU32(OffsetPtr));

  DWARFRangeList CurrentRanges;
  while (*OffsetPtr < End) {
    uint32_t EntryOffset = *OffsetPtr;
    uint8_t Encoding = Data.getU8(OffsetPtr);
    MaxEncodingStringLength =
        std::max(MaxEncodingStringLength,
                 (uint8_t)dwarf::RangeListEncodingString(Encoding).size());
    switch (Encoding) {
    case dwarf::DW_RLE_end_of_list:
      CurrentRanges.push_back(RangeListEntry{ EntryOffset, Encoding, 0, 0 });
      Ranges.insert(Ranges.end(), std::move(CurrentRanges));
      CurrentRanges.clear();
      break;
    // TODO: Support other encodings.
    case dwarf::DW_RLE_base_addressx:
      return createError("unsupported rnglists encoding DW_RLE_base_addressx "
                         "at offset 0x%" PRIx32,
                         *OffsetPtr - 1);
    case dwarf::DW_RLE_startx_endx:
      return createError("unsupported rnglists encoding DW_RLE_startx_endx at "
                         "offset 0x%" PRIx32,
                         *OffsetPtr - 1);
    case dwarf::DW_RLE_startx_length:
      return createError("unsupported rnglists encoding DW_RLE_startx_length "
                         "at offset 0x%" PRIx32,
                         *OffsetPtr - 1);
    case dwarf::DW_RLE_offset_pair:
      return createError("unsupported rnglists encoding DW_RLE_offset_pair at "
                         "offset 0x%" PRIx32,
                         *OffsetPtr - 1);
    case dwarf::DW_RLE_base_address:
      return createError("unsupported rnglists encoding DW_RLE_base_address at "
                         "offset 0x%" PRIx32,
                         *OffsetPtr - 1);
    case dwarf::DW_RLE_start_end: {
      if ((End - *OffsetPtr) < unsigned(HeaderData.AddrSize * 2))
        return createError("insufficient space remaining in table for "
                           "DW_RLE_start_end encoding "
                           "at offset 0x%" PRIx32,
                           *OffsetPtr - 1);
      uint64_t Start = Data.getAddress(OffsetPtr);
      uint64_t End = Data.getAddress(OffsetPtr);
      CurrentRanges.push_back(
          RangeListEntry{EntryOffset, Encoding, Start, End});
      break;
    }
    case dwarf::DW_RLE_start_length: {
      uint32_t PreviousOffset = *OffsetPtr - 1;
      uint64_t Start = Data.getAddress(OffsetPtr);
      uint64_t Length = Data.getULEB128(OffsetPtr);
      if (End < *OffsetPtr)
        return createError("read past end of table when reading "
                           "DW_RLE_start_length encoding at offset 0x%" PRIx32,
                           PreviousOffset);
      CurrentRanges.push_back(
          RangeListEntry{EntryOffset, Encoding, Start, Length});
      break;
    }
    default:
      Ranges.insert(Ranges.end(), std::move(CurrentRanges));
      return createError("unknown rnglists encoding 0x%" PRIx32
                         " at offset 0x%" PRIx32,
                         uint32_t(Encoding), *OffsetPtr - 1);
    }
  }

  // If OffsetPtr does not indicate the End offset, then either the above loop
  // terminated prematurely, or we encountered a malformed encoding, but did not
  // report an error when we should have done.
  assert(*OffsetPtr == End &&
         "did not detect malformed data or loop ended unexpectedly");

  // If CurrentRanges is not empty, we have a malformed section, because we did
  // not find a DW_RLE_end_of_list marker at the end of the last list.
  if (!CurrentRanges.empty())
    return createError(
        "no end of list marker detected at end of .debug_rnglists table "
        "starting at offset 0x%" PRIx32,
        HeaderOffset);
  return Error::success();
}

static void dumpRangeEntry(raw_ostream &OS,
                           DWARFDebugRnglists::RangeListEntry Entry,
                           uint8_t AddrSize, uint8_t MaxEncodingStringLength,
                           DIDumpOptions DumpOpts) {
  if (DumpOpts.Verbose) {
    // Print the section offset in verbose mode.
    OS << format("0x%8.8" PRIx32 ":", Entry.Offset);
    auto EncodingString = dwarf::RangeListEncodingString(Entry.EntryKind);
    // Unsupported encodings should have been reported during parsing.
    assert(!EncodingString.empty() && "Unknown range entry encoding");
    OS << format(" [%s%*c", EncodingString.data(),
                 MaxEncodingStringLength - EncodingString.size() + 1, ']');
    if (Entry.EntryKind != dwarf::DW_RLE_end_of_list)
      OS << ": ";
  }

  switch (Entry.EntryKind) {
  case dwarf::DW_RLE_end_of_list:
    OS << (DumpOpts.Verbose ? "" : "<End of list>");
    break;
  case dwarf::DW_RLE_start_length:
    if (DumpOpts.Verbose) {
      // Make the address range display its contents in raw form rather than
      // as an interval (i.e. without brackets).
      DumpOpts.DisplayRawContents = true;
      DWARFAddressRange(Entry.Value0, Entry.Value1)
          .dump(OS, AddrSize, DumpOpts);
      OS << " => ";
    }
    DumpOpts.DisplayRawContents = false;
    DWARFAddressRange(Entry.Value0, Entry.Value0 + Entry.Value1)
        .dump(OS, AddrSize, DumpOpts);
    break;
  case dwarf::DW_RLE_start_end:
    DWARFAddressRange(Entry.Value0, Entry.Value1).dump(OS, AddrSize, DumpOpts);
    break;
  default:
    llvm_unreachable("Unsupported range list encoding");
  }
  OS << "\n";
}

void DWARFDebugRnglists::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
  if (DumpOpts.Verbose)
    OS << format("0x%8.8" PRIx32 ": ", HeaderOffset);
  OS << format("Range List Header: length = 0x%8.8" PRIx32
               ", version = 0x%4.4" PRIx16 ", "
               "addr_size = 0x%2.2" PRIx8 ", seg_size = 0x%2.2" PRIx8
               ", offset_entry_count = "
               "0x%8.8" PRIx32 "\n",
               HeaderData.Length, HeaderData.Version, HeaderData.AddrSize,
               HeaderData.SegSize, HeaderData.OffsetEntryCount);

  if (HeaderData.OffsetEntryCount > 0) {
    OS << "Offsets: [";
    for (const auto &Off : Offsets) {
      OS << format("\n0x%8.8" PRIx32, Off);
      if (DumpOpts.Verbose)
        OS << format(" => 0x%8.8" PRIx32,
                     Off + HeaderOffset + sizeof(HeaderData));
    }
    OS << "\n]\n";
  }
  OS << "Ranges:\n";

  for (const auto &List : Ranges)
    for (const auto &Entry : List)
      dumpRangeEntry(OS, Entry, HeaderData.AddrSize, MaxEncodingStringLength,
                     DumpOpts);
}

uint32_t DWARFDebugRnglists::length() const {
  if (HeaderData.Length == 0)
    return 0;
  // TODO: DWARF64 support.
  return HeaderData.Length + sizeof(uint32_t);
}