//===- GsymReader.h ---------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_DEBUGINFO_GSYM_GSYMREADER_H
#define LLVM_DEBUGINFO_GSYM_GSYMREADER_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/DebugInfo/GSYM/FileEntry.h"
#include "llvm/DebugInfo/GSYM/FunctionInfo.h"
#include "llvm/DebugInfo/GSYM/GlobalData.h"
#include "llvm/DebugInfo/GSYM/GsymDataExtractor.h"
#include "llvm/DebugInfo/GSYM/Header.h"
#include "llvm/DebugInfo/GSYM/LineEntry.h"
#include "llvm/DebugInfo/GSYM/StringTable.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/MemoryBuffer.h"
#include <inttypes.h>
#include <map>
#include <memory>
#include <stdint.h>
#include <vector>

namespace llvm {
class MemoryBuffer;
class raw_ostream;

namespace gsym {

/// GsymReader is used to read GSYM data from a file or buffer.
///
/// This class is optimized for very quick lookups when the endianness matches
/// the host system. The header and the address table are designed to be mmap'ed
/// as read only into memory and used without any parsing needed. If the
/// endianness doesn't match, we swap the byte order of the address table into a
/// separate buffer for efficient binary search. All the other data are parsed
/// on demand with the correct endianness.
///
/// GsymReader objects must use one of the static functions to create an
/// instance: GsymReader::openFile(...) and GsymReader::copyBuffer(...).

class GsymReader {
protected:
  std::unique_ptr<MemoryBuffer> MemBuffer;
  llvm::endianness Endian;
  /// Parsed GlobalData entries, keyed by type. Populated by
  /// parseHeaderAndGlobalDataEntries().
  std::map<GlobalInfoType, GlobalData> GlobalDataSections;
  ArrayRef<uint8_t> AddrOffsets;
  std::vector<uint8_t> SwappedAddrOffsets;
  GsymDataExtractor AddrInfoOffsetsData;
  GsymDataExtractor FileEntryData;
  StringTable StrTab;

  LLVM_ABI GsymReader(std::unique_ptr<MemoryBuffer> Buffer,
                      llvm::endianness Endian);

public:
  GsymReader(GsymReader &&RHS) = default;
  virtual ~GsymReader() = default;

  bool isLittleEndian() const { return Endian == llvm::endianness::little; }

  /// Get the GSYM version for this reader.
  virtual uint16_t getVersion() const = 0;

  /// Get the base address of this GSYM file.
  virtual uint64_t getBaseAddress() const = 0;

  /// Get the number of addresses in this GSYM file.
  virtual uint64_t getNumAddresses() const = 0;

  /// Get the address offset byte size for this GSYM file.
  virtual uint8_t getAddressOffsetSize() const = 0;

  /// Get the address info offset byte size for this GSYM file.
  virtual uint8_t getAddressInfoOffsetSize() const = 0;

  /// Get the string offset byte size for this GSYM file.
  virtual uint8_t getStringOffsetSize() const = 0;

  /// Construct a GsymReader from a file on disk.
  ///
  /// \param Path The file path the GSYM file to read.
  /// \returns An expected GsymReader that contains the object or an error
  /// object that indicates reason for failing to read the GSYM.
  LLVM_ABI static llvm::Expected<std::unique_ptr<GsymReader>>
  openFile(StringRef Path);

  /// Construct a GsymReader from a buffer.
  ///
  /// \param Bytes A set of bytes that will be copied and owned by the
  /// returned object on success.
  /// \returns An expected GsymReader that contains the object or an error
  /// object that indicates reason for failing to read the GSYM.
  LLVM_ABI static llvm::Expected<std::unique_ptr<GsymReader>>
  copyBuffer(StringRef Bytes);

  /// Get the full function info for an address.
  ///
  /// This should be called when a client will store a copy of the complete
  /// FunctionInfo for a given address. For one off lookups, use the lookup()
  /// function below.
  ///
  /// Symbolication server processes might want to parse the entire function
  /// info for a given address and cache it if the process stays around to
  /// service many symbolication addresses, like for parsing profiling
  /// information.
  ///
  /// \param Addr A virtual address from the orignal object file to lookup.
  ///
  /// \returns An expected FunctionInfo that contains the function info object
  /// or an error object that indicates reason for failing to lookup the
  /// address.
  LLVM_ABI llvm::Expected<FunctionInfo> getFunctionInfo(uint64_t Addr) const;

  /// Get the full function info given an address index.
  ///
  /// \param AddrIdx A address index for an address in the address table.
  ///
  /// \returns An expected FunctionInfo that contains the function info object
  /// or an error object that indicates reason for failing get the function
  /// info object.
  LLVM_ABI llvm::Expected<FunctionInfo>
  getFunctionInfoAtIndex(uint64_t AddrIdx) const;

  /// Lookup an address in the a GSYM.
  ///
  /// Lookup just the information needed for a specific address \a Addr. This
  /// function is faster that calling getFunctionInfo() as it will only return
  /// information that pertains to \a Addr and allows the parsing to skip any
  /// extra information encoded for other addresses. For example the line table
  /// parsing can stop when a matching LineEntry has been fouhnd, and the
  /// InlineInfo can stop parsing early once a match has been found and also
  /// skip information that doesn't match. This avoids memory allocations and
  /// is much faster for lookups.
  ///
  /// \param Addr A virtual address from the orignal object file to lookup.
  ///
  /// \param MergedFuncsData A pointer to an optional GsymDataExtractor that, if
  /// non-null, will be set to the raw data of the MergedFunctionInfo, if
  /// present.
  ///
  /// \returns An expected LookupResult that contains only the information
  /// needed for the current address, or an error object that indicates reason
  /// for failing to lookup the address.
  LLVM_ABI llvm::Expected<LookupResult>
  lookup(uint64_t Addr,
         std::optional<GsymDataExtractor> *MergedFuncsData = nullptr) const;

  /// Lookup all merged functions for a given address.
  ///
  /// This function performs a lookup for the specified address and then
  /// retrieves additional LookupResults from any merged functions associated
  /// with the primary LookupResult.
  ///
  /// \param Addr The address to lookup.
  ///
  /// \returns A vector of LookupResult objects, where the first element is the
  /// primary result, followed by results for any merged functions
  LLVM_ABI llvm::Expected<std::vector<LookupResult>>
  lookupAll(uint64_t Addr) const;

  /// Get a string from the string table.
  ///
  /// \param Offset The string table offset for the string to retrieve.
  /// \returns The string from the strin table.
  StringRef getString(gsym_strp_t Offset) const { return StrTab[Offset]; }

  /// Get the a file entry for the suppplied file index.
  ///
  /// Used to convert any file indexes in the FunctionInfo data back into
  /// files. This function can be used for iteration, but is more commonly used
  /// for random access when doing lookups.
  ///
  /// \param Index An index into the file table.
  /// \returns An optional FileInfo that will be valid if the file index is
  /// valid, or std::nullopt if the file index is out of bounds,
  std::optional<FileEntry> getFile(uint32_t Index) const {
    uint64_t EntrySize =
        FileEntry::getEncodedSize(FileEntryData.getStringOffsetSize());
    uint64_t Offset = Index * EntrySize;
    if (!FileEntryData.isValidOffsetForDataOfSize(Offset, EntrySize))
      return std::nullopt;
    FileEntry FE;
    FE.Dir = FileEntryData.getStringOffset(&Offset);
    FE.Base = FileEntryData.getStringOffset(&Offset);
    return FE;
  }

  /// Dump the entire Gsym data contained in this object.
  ///
  /// \param  OS The output stream to dump to.
  virtual void dump(raw_ostream &OS) = 0;

  /// Dump a FunctionInfo object.
  ///
  /// This function will convert any string table indexes and file indexes
  /// into human readable format.
  ///
  /// \param  OS The output stream to dump to.
  ///
  /// \param FI The object to dump.
  ///
  /// \param Indent The indentation as number of spaces. Used when dumping as an
  /// item within MergedFunctionsInfo.
  LLVM_ABI void dump(raw_ostream &OS, const FunctionInfo &FI,
                     uint32_t Indent = 0);

  /// Dump a MergedFunctionsInfo object.
  ///
  /// This function will dump a MergedFunctionsInfo object - basically by
  /// dumping the contained FunctionInfo objects with indentation.
  ///
  /// \param  OS The output stream to dump to.
  ///
  /// \param MFI The object to dump.
  LLVM_ABI void dump(raw_ostream &OS, const MergedFunctionsInfo &MFI);

  /// Dump a CallSiteInfo object.
  ///
  /// This function will output the details of a CallSiteInfo object in a
  /// human-readable format.
  ///
  /// \param OS The output stream to dump to.
  ///
  /// \param CSI The CallSiteInfo object to dump.
  LLVM_ABI void dump(raw_ostream &OS, const CallSiteInfo &CSI);

  /// Dump a CallSiteInfoCollection object.
  ///
  /// This function will iterate over a collection of CallSiteInfo objects and
  /// dump each one.
  ///
  /// \param OS The output stream to dump to.
  ///
  /// \param CSIC The CallSiteInfoCollection object to dump.
  ///
  /// \param Indent The indentation as number of spaces. Used when dumping as an
  /// item from within MergedFunctionsInfo.
  LLVM_ABI void dump(raw_ostream &OS, const CallSiteInfoCollection &CSIC,
                     uint32_t Indent = 0);

  /// Dump a LineTable object.
  ///
  /// This function will convert any string table indexes and file indexes
  /// into human readable format.
  ///
  ///
  /// \param  OS The output stream to dump to.
  ///
  /// \param LT The object to dump.
  ///
  /// \param Indent The indentation as number of spaces. Used when dumping as an
  /// item from within MergedFunctionsInfo.
  LLVM_ABI void dump(raw_ostream &OS, const LineTable &LT, uint32_t Indent = 0);

  /// Dump a InlineInfo object.
  ///
  /// This function will convert any string table indexes and file indexes
  /// into human readable format.
  ///
  /// \param  OS The output stream to dump to.
  ///
  /// \param II The object to dump.
  ///
  /// \param Indent The indentation as number of spaces. Used for recurive
  /// dumping.
  LLVM_ABI void dump(raw_ostream &OS, const InlineInfo &II,
                     uint32_t Indent = 0);

  /// Dump a FileEntry object.
  ///
  /// This function will convert any string table indexes into human readable
  /// format.
  ///
  /// \param  OS The output stream to dump to.
  ///
  /// \param FE The object to dump.
  LLVM_ABI void dump(raw_ostream &OS, std::optional<FileEntry> FE);

  /// Gets an address from the address table.
  ///
  /// Addresses are stored as offsets frrom the gsym::Header::BaseAddress.
  ///
  /// \param Index A index into the address table.
  /// \returns A resolved virtual address for adddress in the address table
  /// or std::nullopt if Index is out of bounds.
  LLVM_ABI std::optional<uint64_t> getAddress(size_t Index) const;

protected:
  /// Get the GlobalData entry for a section type.
  ///
  /// \param Type The section type to retrieve.
  /// \returns The GlobalData entry, or std::nullopt if the section is not
  /// present.
  LLVM_ABI std::optional<GlobalData> getGlobalData(GlobalInfoType Type) const;

  /// Get the raw bytes for a required GlobalData section as a StringRef.
  ///
  /// \param Type The section type to retrieve.
  /// \returns The section data, or an error if the section is not present or
  /// any bytes are not present in the file.
  LLVM_ABI llvm::Expected<StringRef>
  getRequiredGlobalDataBytes(GlobalInfoType Type) const;

  /// Get the raw bytes for an optional GlobalData section as a StringRef.
  ///
  /// \param Type The section type to retrieve.
  /// \returns The section data, or std::nullopt if the section is not present
  /// or any bytes are not present in the file.
  LLVM_ABI std::optional<StringRef>
  getOptionalGlobalDataBytes(GlobalInfoType Type) const;

  /// Parse the GSYM data from the memory buffer.
  ///
  /// \returns Error on failure.
  LLVM_ABI llvm::Error parse();

  /// Parse the version-specific header and populate GlobalDataSections.
  ///
  /// \returns Error on failure.
  virtual llvm::Error parseHeaderAndGlobalDataEntries() = 0;

  /// Parse and validate the header from the beginning of the memory buffer.
  ///
  /// \param OutHdr Output pointer to the parsed header.
  /// \param OutSwappedHdr Storage for byte-swapped header if needed.
  /// \returns Error on failure.
  template <class HeaderT>
  llvm::Error parseHeader(const HeaderT *&OutHdr,
                          std::unique_ptr<HeaderT> &OutSwappedHdr) {
    const StringRef Buf = MemBuffer->getBuffer();
    if (Buf.size() < HeaderT::getEncodedSize())
      return createStringError(std::errc::invalid_argument,
                               "not enough data for a GSYM header");
    if (Endian == llvm::endianness::native) {
      // Non-swap case. Mmap the header.
      OutHdr = reinterpret_cast<const HeaderT *>(Buf.data());
    } else {
      // Swap case. Decode with a GsymDataExtractor with the correct endianness.
      GsymDataExtractor Data(Buf, isLittleEndian());
      OutSwappedHdr = std::make_unique<HeaderT>();
      auto ExpectedHdr = HeaderT::decode(Data);
      if (!ExpectedHdr)
        return ExpectedHdr.takeError();
      *OutSwappedHdr = *ExpectedHdr;
      OutHdr = OutSwappedHdr.get();
    }
    if (Error Err = OutHdr->checkForError())
      return Err;
    return Error::success();
  }

  /// Parse GlobalData entries starting at \p Offset into GlobalDataSections.
  ///
  /// This should only be called by any GSYM version >= 2. If called by V1, an
  /// error will be returned.
  ///
  /// \param Offset The byte offset where GlobalData entries begin.
  /// \returns Error on failure.
  LLVM_ABI llvm::Error parseGlobalDataEntries(uint64_t Offset);

  /// Parse address offsets section bytes into AddrOffsets.
  ///
  /// \param Bytes The raw section bytes.
  /// \returns Error on failure.
  LLVM_ABI llvm::Error parseAddrOffsets(StringRef Bytes);

  /// Set address info offsets section bytes into AddrInfoOffsetsData.
  ///
  /// \param Bytes The raw section bytes.
  /// \returns Error on failure.
  LLVM_ABI llvm::Error setAddrInfoOffsetsData(StringRef Bytes);

  /// Set string table section bytes into StrTab.
  ///
  /// \param Bytes The raw section bytes.
  /// \returns Error on failure.
  LLVM_ABI llvm::Error setStringTableData(StringRef Bytes);

  /// Set file table section bytes into FileEntryData.
  ///
  /// \param Bytes The raw section bytes.
  /// \returns Error on failure.
  LLVM_ABI llvm::Error setFileTableData(StringRef Bytes);

  /// Get an appropriate address info offsets array.
  ///
  /// The address table in the GSYM file is stored as array of 1, 2, 4 or 8
  /// byte offsets from the The gsym::Header::BaseAddress. The table is stored
  /// internally as a array of bytes that are in the correct endianness. When
  /// we access this table we must get an array that matches those sizes. This
  /// templatized helper function is used when accessing address offsets in the
  /// AddrOffsets member variable.
  ///
  /// \returns An ArrayRef of an appropriate address offset size.
  template <class T> ArrayRef<T>
  getAddrOffsets() const {
    return ArrayRef<T>(reinterpret_cast<const T *>(AddrOffsets.data()),
                       AddrOffsets.size()/sizeof(T));
  }

  /// Get an appropriate address from the address table.
  ///
  /// The address table in the GSYM file is stored as array of 1, 2, 4 or 8
  /// byte address offsets from the The gsym::Header::BaseAddress. The table is
  /// stored internally as a array of bytes that are in the correct endianness.
  /// In order to extract an address from the address table we must access the
  /// address offset using the correct size and then add it to the BaseAddress
  /// in the header.
  ///
  /// \param Index An index into the AddrOffsets array.
  /// \returns An virtual address that matches the original object file for the
  /// address as the specified index, or std::nullopt if Index is out of bounds.
  template <class T>
  std::optional<uint64_t> addressForIndex(size_t Index) const {
    ArrayRef<T> AIO = getAddrOffsets<T>();
    if (Index < AIO.size())
      return AIO[Index] + getBaseAddress();
    return std::nullopt;
  }

  /// Lookup an address offset in the AddrOffsets table.
  ///
  /// Given an address offset, look it up using a binary search of the
  /// AddrOffsets table.
  ///
  /// \param AddrOffset An address offset, that has already been computed by
  /// subtracting the gsym::Header::BaseAddress.
  /// \returns The matching address offset index. This index will be used to
  /// extract the FunctionInfo data's offset from the AddrInfoOffsets array.
  template <class T>
  std::optional<uint64_t>
  getAddressOffsetIndex(const uint64_t AddrOffset) const {
    ArrayRef<T> AIO = getAddrOffsets<T>();
    const auto Begin = AIO.begin();
    const auto End = AIO.end();
    auto Iter = std::lower_bound(Begin, End, AddrOffset);
    // Watch for addresses that fall between the gsym::Header::BaseAddress and
    // the first address offset.
    if (Iter == Begin && AddrOffset < *Begin)
      return std::nullopt;
    if (Iter == End || AddrOffset < *Iter)
      --Iter;

    // GSYM files have sorted function infos with the most information (line
    // table and/or inline info) first in the array of function infos, so
    // always backup as much as possible as long as the address offset is the
    // same as the previous entry.
    while (Iter != Begin) {
      auto Prev = Iter - 1;
      if (*Prev == *Iter)
        Iter = Prev;
      else
        break;
    }

    return std::distance(Begin, Iter);
  }

  /// Create a GSYM from a memory buffer.
  ///
  /// Called by both openFile() and copyBuffer(), this function does all of the
  /// work of parsing the GSYM file and returning an error.
  ///
  /// \param MemBuffer A memory buffer that will transfer ownership into the
  /// GsymReader.
  /// \returns An expected GsymReader that contains the object or an error
  /// object that indicates reason for failing to read the GSYM.
  LLVM_ABI static llvm::Expected<std::unique_ptr<GsymReader>>
  create(std::unique_ptr<MemoryBuffer> &MemBuffer);

  /// Given an address, find the address index.
  ///
  /// Binary search the address table and find the matching address index.
  ///
  /// \param Addr A virtual address that matches the original object file
  /// to lookup.
  /// \returns An index into the address table. This index can be used to
  /// extract the FunctionInfo data's offset from the AddrInfoOffsets array.
  /// Returns an error if the address isn't in the GSYM with details of why.
  LLVM_ABI Expected<uint64_t> getAddressIndex(const uint64_t Addr) const;

  /// Given an address index, get the offset for the FunctionInfo.
  ///
  /// Looking up an address is done by finding the corresponding address
  /// index for the address. This index is then used to get the offset of the
  /// FunctionInfo data that we will decode using this function.
  ///
  /// \param Index An index into the address table.
  /// \returns An optional GSYM data offset for the offset of the FunctionInfo
  /// that needs to be decoded.
  LLVM_ABI std::optional<uint64_t> getAddressInfoOffset(size_t Index) const;

  /// Given an address, find the correct function info data and function
  /// address.
  ///
  /// Binary search the address table and find the matching address info
  /// and make sure that the function info contains the address. GSYM allows
  /// functions to overlap, and the most debug info is contained in the first
  /// entries due to the sorting when GSYM files are created. We can have
  /// multiple function info that start at the same address only if their
  /// address range doesn't match. So find the first entry that matches \a Addr
  /// and iterate forward until we find one that contains the address.
  ///
  /// \param[in] Addr A virtual address that matches the original object file
  /// to lookup.
  ///
  /// \param[out] FuncStartAddr A virtual address that is the base address of
  /// the function that is used for decoding the FunctionInfo.
  ///
  /// \returns An valid data extractor on success, or an error if we fail to
  /// find the address in a function info or corrrectly decode the data
  LLVM_ABI llvm::Expected<GsymDataExtractor>
  getFunctionInfoDataForAddress(uint64_t Addr, uint64_t &FuncStartAddr) const;

  /// Get the function data and address given an address index.
  ///
  /// \param AddrIdx A address index from the address table.
  ///
  /// \returns An expected FunctionInfo that contains the function info object
  /// or an error object that indicates reason for failing to lookup the
  /// address.
  LLVM_ABI llvm::Expected<GsymDataExtractor>
  getFunctionInfoDataAtIndex(uint64_t AddrIdx, uint64_t &FuncStartAddr) const;
};

} // namespace gsym
} // namespace llvm

#endif // LLVM_DEBUGINFO_GSYM_GSYMREADER_H