# header.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/xmas-elf-0.7.0/src/header.rs`.
Keywords: rust, rustlang, rust-lang

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    use core::fmt;
    use core::mem;

    use {P32, P64, ElfFile};
    use zero::{read, Pod};

    pub fn parse_header<'a>(input: &'a [u8]) -> Result<Header<'a>, &'static str> {
        let size_pt1 = mem::size_of::<HeaderPt1>();
        if input.len() < size_pt1 {
            return Err("File is shorter than the first ELF header part");
        }

        let header_1: &'a HeaderPt1 = read(&input[..size_pt1]);
        if header_1.magic != MAGIC {
            return Err("Did not find ELF magic number");
        }

        let header_2 = match header_1.class() {
            Class::None | Class::Other(_) => return Err("Invalid ELF class"),
            Class::ThirtyTwo => {
                let header_2: &'a HeaderPt2_<P32> =
                    read(&input[size_pt1..size_pt1 + mem::size_of::<HeaderPt2_<P32>>()]);
                HeaderPt2::Header32(header_2)
            }
            Class::SixtyFour => {
                let header_2: &'a HeaderPt2_<P64> =
                    read(&input[size_pt1..size_pt1 + mem::size_of::<HeaderPt2_<P64>>()]);
                HeaderPt2::Header64(header_2)
            }
        };
        Ok(Header {
            pt1: header_1,
            pt2: header_2,
        })
    }

    pub const MAGIC: [u8; 4] = [0x7f, b'E', b'L', b'F'];

    #[derive(Clone, Copy, Debug)]
    pub struct Header<'a> {
        pub pt1: &'a HeaderPt1,
        pub pt2: HeaderPt2<'a>,
    }

    // TODO add Header::section_count, because if sh_count = 0, then the real count is in the first section.

    impl<'a> fmt::Display for Header<'a> {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            try!(writeln!(f, "ELF header:"));
            try!(writeln!(f, "    magic:            {:?}", self.pt1.magic));
            try!(writeln!(f, "    class:            {:?}", self.pt1.class));
            try!(writeln!(f, "    data:             {:?}", self.pt1.data));
            try!(writeln!(f, "    version:          {:?}", self.pt1.version));
            try!(writeln!(f, "    os abi:           {:?}", self.pt1.os_abi));
            try!(writeln!(f, "    abi version:      {:?}", self.pt1.abi_version));
            try!(writeln!(f, "    padding:          {:?}", self.pt1.padding));
            try!(write!(f, "{}", self.pt2));
            Ok(())
        }
    }

    #[derive(Copy, Clone, Debug)]
    #[repr(C)]
    pub struct HeaderPt1 {
        pub magic: [u8; 4],
        pub class: Class_,
        pub data: Data_,
        pub version: Version_,
        pub os_abi: OsAbi_,
        // Often also just padding.
        pub abi_version: u8,
        pub padding: [u8; 7],
    }

    unsafe impl Pod for HeaderPt1 {}

    impl HeaderPt1 {
        pub fn class(&self) -> Class {
            self.class.as_class()
        }

        pub fn data(&self) -> Data {
            self.data.as_data()
        }

        pub fn version(&self) -> Version {
            self.version.as_version()
        }

        pub fn os_abi(&self) -> OsAbi {
            self.os_abi.as_os_abi()
        }
    }

    #[derive(Clone, Copy, Debug)]
    pub enum HeaderPt2<'a> {
        Header32(&'a HeaderPt2_<P32>),
        Header64(&'a HeaderPt2_<P64>),
    }

    macro_rules! getter {
        ($name: ident, $typ: ident) => {
            pub fn $name(&self) -> $typ {
                match *self {
                    HeaderPt2::Header32(h) => h.$name as $typ,
                    HeaderPt2::Header64(h) => h.$name as $typ,
                }
            }
        }
    }

    impl<'a> HeaderPt2<'a> {
        pub fn size(&self) -> usize {
            match *self {
                HeaderPt2::Header32(_) => mem::size_of::<HeaderPt2_<P32>>(),
                HeaderPt2::Header64(_) => mem::size_of::<HeaderPt2_<P64>>(),
            }
        }

        // TODO move to impl Header
        getter!(type_, Type_);
        getter!(machine, Machine_);
        getter!(version, u32);
        getter!(header_size, u16);
        getter!(entry_point, u64);
        getter!(ph_offset, u64);
        getter!(sh_offset, u64);
        getter!(ph_entry_size, u16);
        getter!(ph_count, u16);
        getter!(sh_entry_size, u16);
        getter!(sh_count, u16);
        getter!(sh_str_index, u16);
    }

    impl<'a> fmt::Display for HeaderPt2<'a> {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            match *self {
                HeaderPt2::Header32(h) => write!(f, "{}", h),
                HeaderPt2::Header64(h) => write!(f, "{}", h),
            }
        }
    }

    #[derive(Debug)]
    #[repr(C)]
    pub struct HeaderPt2_<P> {
        pub type_: Type_,
        pub machine: Machine_,
        pub version: u32,
        pub entry_point: P,
        pub ph_offset: P,
        pub sh_offset: P,
        pub flags: u32,
        pub header_size: u16,
        pub ph_entry_size: u16,
        pub ph_count: u16,
        pub sh_entry_size: u16,
        pub sh_count: u16,
        pub sh_str_index: u16,
    }

    unsafe impl<P> Pod for HeaderPt2_<P> {}

    impl<P: fmt::Display> fmt::Display for HeaderPt2_<P> {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            try!(writeln!(f, "    type:             {:?}", self.type_));
            try!(writeln!(f, "    machine:          {:?}", self.machine));
            try!(writeln!(f, "    version:          {}", self.version));
            try!(writeln!(f, "    entry_point:      {}", self.entry_point));
            try!(writeln!(f, "    ph_offset:        {}", self.ph_offset));
            try!(writeln!(f, "    sh_offset:        {}", self.sh_offset));
            try!(writeln!(f, "    flags:            {}", self.flags));
            try!(writeln!(f, "    header_size:      {}", self.header_size));
            try!(writeln!(f, "    ph_entry_size:    {}", self.ph_entry_size));
            try!(writeln!(f, "    ph_count:         {}", self.ph_count));
            try!(writeln!(f, "    sh_entry_size:    {}", self.sh_entry_size));
            try!(writeln!(f, "    sh_count:         {}", self.sh_count));
            try!(writeln!(f, "    sh_str_index:     {}", self.sh_str_index));
            Ok(())
        }
    }

    #[derive(Clone, Copy, Eq, PartialEq)]
    pub struct Class_(u8);

    impl Class_ {
        pub fn as_class(self) -> Class {
            match self.0 {
                0 => Class::None,
                1 => Class::ThirtyTwo,
                2 => Class::SixtyFour,
                other => Class::Other(other),
            }
        }

        pub fn is_none(self) -> bool {
            self.0 == 0
        }
    }

    impl fmt::Debug for Class_ {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.as_class().fmt(f)
        }
    }

    #[derive(Copy, Clone, Debug, Eq, PartialEq)]
    pub enum Class {
        None,
        ThirtyTwo,
        SixtyFour,
        Other(u8),
    }

    impl Class {
        pub fn is_none(&self) -> bool {
            if let Class::None = *self { true } else { false }
        }
    }

    #[derive(Clone, Copy)]
    pub struct Data_(u8);

    impl Data_ {
        pub fn as_data(self) -> Data {
            match self.0 {
                0 => Data::None,
                1 => Data::LittleEndian,
                2 => Data::BigEndian,
                other => Data::Other(other),
            }
        }

        pub fn is_none(self) -> bool {
            self.0 == 0
        }
    }

    impl fmt::Debug for Data_ {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.as_data().fmt(f)
        }
    }

    #[derive(Copy, Clone, Debug, Eq, PartialEq)]
    pub enum Data {
        None,
        LittleEndian,
        BigEndian,
        Other(u8),
    }

    impl Data {
        pub fn is_none(&self) -> bool {
            if let Data::None = *self { true } else { false }
        }
    }

    #[derive(Clone, Copy)]
    pub struct Version_(u8);

    impl Version_ {
        pub fn as_version(self) -> Version {
            match self.0 {
                0 => Version::None,
                1 => Version::Current,
                other => Version::Other(other),
            }
        }

        pub fn is_none(self) -> bool {
            self.0 == 0
        }
    }

    impl fmt::Debug for Version_ {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.as_version().fmt(f)
        }
    }

    #[derive(Copy, Clone, Debug, Eq, PartialEq)]
    pub enum Version {
        None,
        Current,
        Other(u8),
    }

    impl Version {
        pub fn is_none(&self) -> bool {
            if let Version::None = *self {
                true
            } else {
                false
            }
        }
    }

    #[derive(Clone, Copy)]
    pub struct OsAbi_(u8);

    impl OsAbi_ {
        pub fn as_os_abi(self) -> OsAbi {
            match self.0 {
                0x00 => OsAbi::SystemV,
                0x01 => OsAbi::HpUx,
                0x02 => OsAbi::NetBSD,
                0x03 => OsAbi::Linux,
                0x06 => OsAbi::Solaris,
                0x07 => OsAbi::Aix,
                0x08 => OsAbi::Irix,
                0x09 => OsAbi::FreeBSD,
                0x0C => OsAbi::OpenBSD,
                0x0D => OsAbi::OpenVMS,
                other => OsAbi::Other(other),
            }
        }
    }

    impl fmt::Debug for OsAbi_ {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.as_os_abi().fmt(f)
        }
    }

    #[derive(Copy, Clone, Debug, Eq, PartialEq)]
    pub enum OsAbi {
        // or None
        SystemV,
        HpUx,
        NetBSD,
        Linux,
        Solaris,
        Aix,
        Irix,
        FreeBSD,
        OpenBSD,
        OpenVMS,
        Other(u8), // FIXME there are many, many more of these
    }

    #[derive(Clone, Copy)]
    pub struct Type_(pub u16);

    impl Type_ {
        pub fn as_type(self) -> Type {
            match self.0 {
                0 => Type::None,
                1 => Type::Relocatable,
                2 => Type::Executable,
                3 => Type::SharedObject,
                4 => Type::Core,
                x => Type::ProcessorSpecific(x),
            }
        }
    }

    impl fmt::Debug for Type_ {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.as_type().fmt(f)
        }
    }

    #[derive(Copy, Clone, Debug, PartialEq, Eq)]
    pub enum Type {
        None,
        Relocatable,
        Executable,
        SharedObject,
        Core,
        ProcessorSpecific(u16), // TODO OsSpecific
    }

    #[derive(Clone, Copy)]
    pub struct Machine_(u16);

    impl Machine_ {
        pub fn as_machine(self) -> Machine {
            match self.0 {
                0x00 => Machine::None,
                0x02 => Machine::Sparc,
                0x03 => Machine::X86,
                0x08 => Machine::Mips,
                0x14 => Machine::PowerPC,
                0x28 => Machine::Arm,
                0x2A => Machine::SuperH,
                0x32 => Machine::Ia64,
                0x3E => Machine::X86_64,
                0xB7 => Machine::AArch64,
                0xF7 => Machine::BPF,
                other => Machine::Other(other),
            }
        }
    }

    impl fmt::Debug for Machine_ {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.as_machine().fmt(f)
        }
    }

    #[allow(non_camel_case_types)]
    #[derive(Debug, Clone, Copy, Eq, PartialEq)]
    pub enum Machine {
        None,
        Sparc,
        X86,
        Mips,
        PowerPC,
        Arm,
        SuperH,
        Ia64,
        X86_64,
        AArch64,
        BPF,
        Other(u16), // FIXME there are many, many more of these
    }

    // TODO any more constants that need to go in here?

    pub fn sanity_check(file: &ElfFile) -> Result<(), &'static str> {
        check!(mem::size_of::<HeaderPt1>() == 16);
        check!(file.header.pt1.magic == MAGIC, "bad magic number");
        let pt2 = &file.header.pt2;
        check!(mem::size_of::<HeaderPt1>() + pt2.size() == pt2.header_size() as usize,
               "header_size does not match size of header");
        match (&file.header.pt1.class(), &file.header.pt2) {
            (&Class::None, _) => return Err("No class"),
            (&Class::ThirtyTwo, &HeaderPt2::Header32(_)) |
            (&Class::SixtyFour, &HeaderPt2::Header64(_)) => {}
            _ => return Err("Mismatch between specified and actual class"),
        }
        check!(!file.header.pt1.version.is_none(), "no version");
        check!(!file.header.pt1.data.is_none(), "no data format");

        check!(pt2.ph_offset() + (pt2.ph_entry_size() as u64) * (pt2.ph_count() as u64) <=
               file.input.len() as u64,
               "program header table out of range");
        check!(pt2.sh_offset() + (pt2.sh_entry_size() as u64) * (pt2.sh_count() as u64) <=
               file.input.len() as u64,
               "section header table out of range");

        // TODO check that SectionHeader_ is the same size as sh_entry_size, depending on class

        Ok(())
    }