/// <summary>
/// Initializes a new instance of the <see cref="ElfFile"/> class.
/// </summary>
///
/// <param name="header">
/// The ELF file header.
/// </param>
///
/// <param name="segments">
/// The program header table.
/// </param>
///
/// <param name="sections">
/// The section header table.
/// </param>
internal ElfFile(ElfHeader header, ElfProgramHeaderTable segments, ElfSectionHeaderTable sections)
{
Header = header;
Segments = segments;
Sections = sections;
}
/// <summary>
/// Initializes a new instance of the <see cref="ElfProgramHeaderTable"/> class by examining an ELF header.
/// </summary>
///
/// <param name="reader">
/// The reader used to extract the data needed to parse the ELF file.
/// </param>
///
/// <param name="header">
/// The ELF header used to extract the metadata about this program header table.
/// </param>
///
/// <param name="sections">
/// The list of sections which will be parsed to extract the sections corresponding to this segment.
/// </param>
internal ElfProgramHeaderTable(BinaryReader reader, ElfHeader header, ElfSectionHeaderTable sections)
{
// Initialize all segments
for (var i = 0; i < header.ProgramHeaderEntryCount; i++)
{
ElfSegment segment;
switch (header.Class)
{
case ElfClass.Elf32:
{
segment = new Bit32.ElfSegment(reader, (long)(header.ProgramHeaderOffset + (ulong)(i * header.ProgramHeaderSize)));
break;
}
case ElfClass.Elf64:
{
segment = new Bit64.ElfSegment(reader, (long)(header.ProgramHeaderOffset + (ulong)(i * header.ProgramHeaderSize)));
break;
}
default:
{
throw new InvalidOperationException("Unreachable case reached");
}
}
segment.Sections = sections.Where(s => s.Address >= segment.VirtualAddress && s.Address < segment.VirtualAddress + segment.MemorySize).ToList().AsReadOnly();
segments.Add(segment);
}
}
/// <summary>
/// Reads an ELF file from a binary reader.
/// </summary>
///
/// <param name="reader">
/// The reader used to extract the data needed to parse the ELF file.
/// </param>
///
/// <returns>
/// The ELF file parsed from the binary reader.
/// </returns>
///
/// <exception cref="FileFormatException">
/// <paramref name="reader"/> base stream does not represent a valid ELF file.
/// </exception>
public static ElfFile ReadElfFile(BinaryReader reader)
{
try
{
long savedPosition = reader.BaseStream.Position;
byte magic0 = reader.ReadByte();
byte magic1 = reader.ReadByte();
byte magic2 = reader.ReadByte();
byte magic3 = reader.ReadByte();
if (magic0 != ElfHeader.ELFMAG0 || magic1 != ElfHeader.ELFMAG1 || magic2 != ElfHeader.ELFMAG2 || magic3 != ElfHeader.ELFMAG3)
{
throw new FileFormatException($"Invalid ELF magic bytes: 0x{magic0,0:X2} 0x{magic1,0:X2} 0x{magic2,0:X2} 0x{magic3,0:X2}");
}
byte @class = reader.ReadByte();
if (@class != ElfHeader.ELFCLASS32 && @class != ElfHeader.ELFCLASS64)
{
throw new FileFormatException($"Invalid ELF class: 0x{@class,0:X2}");
}
byte endianness = reader.ReadByte();
if (endianness != ElfHeader.ELFDATA2LSB && endianness != ElfHeader.ELFDATA2MSB)
{
throw new FileFormatException($"Invalid ELF endianness: 0x{endianness,0:X2}");
}
// Re-materialize the reader with the parsed endianness
reader = new EndianBinaryReader(reader.BaseStream, endianness == ElfHeader.ELFDATA2MSB ? Endianness.BigEndian : Endianness.LittleEndian, Encoding.UTF8, true);
ElfHeader header;
switch (@class)
{
case ElfHeader.ELFCLASS32:
{
header = new Bit32.ElfHeader(reader, savedPosition);
break;
}
case ElfHeader.ELFCLASS64:
{
header = new Bit64.ElfHeader(reader, savedPosition);
break;
}
default:
{
throw new InvalidOperationException("Unreachable case reached");
}
}
var sections = new ElfSectionHeaderTable(reader, header);
var segments = new ElfProgramHeaderTable(reader, header, sections);
reader.BaseStream.Position = savedPosition;
return(new ElfFile(header, segments, sections));
}
catch (InaccessibleAddressException exception)
{
throw new FileFormatException(exception.Message, exception);
}
}
