object 0.18.0

#[cfg(feature = "compression")]
use alloc::borrow::Cow;
use core::fmt::Debug;
use core::{iter, mem, slice, str};

use crate::elf;
use crate::endian::{self, RunTimeEndian};
use crate::pod::{Bytes, Pod};
use crate::read::{self, ObjectSection, ReadError, SectionFlags, SectionIndex, SectionKind};

use super::{ElfFile, ElfNoteIterator, ElfRelocationIterator, FileHeader};

/// An iterator over the sections of an `ElfFile32`.
pub type ElfSectionIterator32<'data, 'file, Endian = RunTimeEndian> =
    ElfSectionIterator<'data, 'file, elf::FileHeader32<Endian>>;
/// An iterator over the sections of an `ElfFile64`.
pub type ElfSectionIterator64<'data, 'file, Endian = RunTimeEndian> =
    ElfSectionIterator<'data, 'file, elf::FileHeader64<Endian>>;

/// An iterator over the sections of an `ElfFile`.
#[derive(Debug)]
pub struct ElfSectionIterator<'data, 'file, Elf>
where
    'data: 'file,
    Elf: FileHeader,
{
    pub(super) file: &'file ElfFile<'data, Elf>,
    pub(super) iter: iter::Enumerate<slice::Iter<'data, Elf::SectionHeader>>,
}

impl<'data, 'file, Elf: FileHeader> Iterator for ElfSectionIterator<'data, 'file, Elf> {
    type Item = ElfSection<'data, 'file, Elf>;

    fn next(&mut self) -> Option<Self::Item> {
        self.iter.next().map(|(index, section)| ElfSection {
            index: SectionIndex(index),
            file: self.file,
            section,
        })
    }
}

/// A section of an `ElfFile32`.
pub type ElfSection32<'data, 'file, Endian = RunTimeEndian> =
    ElfSection<'data, 'file, elf::FileHeader32<Endian>>;
/// A section of an `ElfFile64`.
pub type ElfSection64<'data, 'file, Endian = RunTimeEndian> =
    ElfSection<'data, 'file, elf::FileHeader64<Endian>>;

/// A section of an `ElfFile`.
#[derive(Debug)]
pub struct ElfSection<'data, 'file, Elf>
where
    'data: 'file,
    Elf: FileHeader,
{
    pub(super) file: &'file ElfFile<'data, Elf>,
    pub(super) index: SectionIndex,
    pub(super) section: &'data Elf::SectionHeader,
}

impl<'data, 'file, Elf: FileHeader> ElfSection<'data, 'file, Elf> {
    fn bytes(&self) -> read::Result<Bytes<'data>> {
        self.section
            .data(self.file.endian, self.file.data)
            .read_error("Invalid ELF section size or offset")
    }
}

impl<'data, 'file, Elf: FileHeader> read::private::Sealed for ElfSection<'data, 'file, Elf> {}

impl<'data, 'file, Elf: FileHeader> ObjectSection<'data> for ElfSection<'data, 'file, Elf> {
    type RelocationIterator = ElfRelocationIterator<'data, 'file, Elf>;

    #[inline]
    fn index(&self) -> SectionIndex {
        self.index
    }

    #[inline]
    fn address(&self) -> u64 {
        self.section.sh_addr(self.file.endian).into()
    }

    #[inline]
    fn size(&self) -> u64 {
        self.section.sh_size(self.file.endian).into()
    }

    #[inline]
    fn align(&self) -> u64 {
        self.section.sh_addralign(self.file.endian).into()
    }

    #[inline]
    fn file_range(&self) -> Option<(u64, u64)> {
        self.section.file_range(self.file.endian)
    }

    #[inline]
    fn data(&self) -> read::Result<&'data [u8]> {
        Ok(self.bytes()?.0)
    }

    fn data_range(&self, address: u64, size: u64) -> read::Result<Option<&'data [u8]>> {
        Ok(read::data_range(
            self.bytes()?,
            self.address(),
            address,
            size,
        ))
    }

    #[cfg(feature = "compression")]
    fn uncompressed_data(&self) -> read::Result<Cow<'data, [u8]>> {
        Ok(if let Some(data) = self.maybe_decompress_data()? {
            data
        } else if let Some(data) = self.maybe_decompress_data_gnu()? {
            data
        } else {
            Cow::from(self.data()?)
        })
    }

    fn name(&self) -> read::Result<&str> {
        let name = self
            .file
            .section_strings
            .get(self.section.sh_name(self.file.endian))
            .read_error("Invalid ELF section name offset")?;
        str::from_utf8(name)
            .ok()
            .read_error("Non UTF-8 ELF section name")
    }

    #[inline]
    fn segment_name(&self) -> read::Result<Option<&str>> {
        Ok(None)
    }

    fn kind(&self) -> SectionKind {
        let flags = self.section.sh_flags(self.file.endian).into();
        match self.section.sh_type(self.file.endian) {
            elf::SHT_PROGBITS => {
                if flags & u64::from(elf::SHF_ALLOC) != 0 {
                    if flags & u64::from(elf::SHF_EXECINSTR) != 0 {
                        SectionKind::Text
                    } else if flags & u64::from(elf::SHF_TLS) != 0 {
                        SectionKind::Tls
                    } else if flags & u64::from(elf::SHF_WRITE) != 0 {
                        SectionKind::Data
                    } else if flags & u64::from(elf::SHF_STRINGS) != 0 {
                        SectionKind::ReadOnlyString
                    } else {
                        SectionKind::ReadOnlyData
                    }
                } else if flags & u64::from(elf::SHF_STRINGS) != 0 {
                    SectionKind::OtherString
                } else {
                    SectionKind::Other
                }
            }
            elf::SHT_NOBITS => {
                if flags & u64::from(elf::SHF_TLS) != 0 {
                    SectionKind::UninitializedTls
                } else {
                    SectionKind::UninitializedData
                }
            }
            elf::SHT_NULL
            | elf::SHT_SYMTAB
            | elf::SHT_STRTAB
            | elf::SHT_RELA
            | elf::SHT_HASH
            | elf::SHT_DYNAMIC
            | elf::SHT_REL
            | elf::SHT_DYNSYM => SectionKind::Metadata,
            _ => {
                // TODO: maybe add more specialised kinds based on sh_type (e.g. Unwind)
                SectionKind::Unknown
            }
        }
    }

    fn relocations(&self) -> ElfRelocationIterator<'data, 'file, Elf> {
        ElfRelocationIterator {
            section_index: self.file.relocations[self.index.0],
            file: self.file,
            relocations: None,
        }
    }

    fn flags(&self) -> SectionFlags {
        SectionFlags::Elf {
            sh_flags: self.section.sh_flags(self.file.endian).into(),
        }
    }
}

/// A trait for generic access to `SectionHeader32` and `SectionHeader64`.
#[allow(missing_docs)]
pub trait SectionHeader: Debug + Pod {
    type Word: Into<u64>;
    type Endian: endian::Endian;
    type Elf: FileHeader<Word = Self::Word, Endian = Self::Endian>;

    fn sh_name(&self, endian: Self::Endian) -> u32;
    fn sh_type(&self, endian: Self::Endian) -> u32;
    fn sh_flags(&self, endian: Self::Endian) -> Self::Word;
    fn sh_addr(&self, endian: Self::Endian) -> Self::Word;
    fn sh_offset(&self, endian: Self::Endian) -> Self::Word;
    fn sh_size(&self, endian: Self::Endian) -> Self::Word;
    fn sh_link(&self, endian: Self::Endian) -> u32;
    fn sh_info(&self, endian: Self::Endian) -> u32;
    fn sh_addralign(&self, endian: Self::Endian) -> Self::Word;
    fn sh_entsize(&self, endian: Self::Endian) -> Self::Word;

    /// Return the offset and size of the section in the file.
    ///
    /// Returns `None` for sections that have no data in the file.
    fn file_range(&self, endian: Self::Endian) -> Option<(u64, u64)> {
        if self.sh_type(endian) == elf::SHT_NOBITS {
            None
        } else {
            Some((self.sh_offset(endian).into(), self.sh_size(endian).into()))
        }
    }

    /// Return the section data.
    ///
    /// Returns `Ok(&[])` if the section has no data.
    /// Returns `Err` for invalid values.
    fn data<'data>(&self, endian: Self::Endian, data: Bytes<'data>) -> Result<Bytes<'data>, ()> {
        if let Some((offset, size)) = self.file_range(endian) {
            data.read_bytes_at(offset as usize, size as usize)
        } else {
            Ok(Bytes(&[]))
        }
    }

    /// Return the section data as a slice of the given type.
    ///
    /// Allows padding at the end of the data.
    /// Returns `Ok(&[])` if the section has no data.
    /// Returns `Err` for invalid values, including bad alignment.
    fn data_as_array<'data, T: Pod>(
        &self,
        endian: Self::Endian,
        data: Bytes<'data>,
    ) -> Result<&'data [T], ()> {
        let mut data = self.data(endian, data)?;
        data.read_slice(data.len() / mem::size_of::<T>())
    }

    /// Return a note iterator for the section data.
    ///
    /// Returns `Ok(None)` if the section does not contain notes.
    /// Returns `Err` for invalid values.
    fn notes<'data>(
        &self,
        endian: Self::Endian,
        data: Bytes<'data>,
    ) -> read::Result<Option<ElfNoteIterator<'data, Self::Elf>>> {
        if self.sh_type(endian) != elf::SHT_NOTE {
            return Ok(None);
        }
        let data = self
            .data(endian, data)
            .read_error("Invalid ELF note section offset or size")?;
        let notes = ElfNoteIterator::new(endian, self.sh_addralign(endian), data)?;
        Ok(Some(notes))
    }
}

impl<Endian: endian::Endian> SectionHeader for elf::SectionHeader32<Endian> {
    type Word = u32;
    type Endian = Endian;
    type Elf = elf::FileHeader32<Endian>;

    #[inline]
    fn sh_name(&self, endian: Self::Endian) -> u32 {
        self.sh_name.get(endian)
    }

    #[inline]
    fn sh_type(&self, endian: Self::Endian) -> u32 {
        self.sh_type.get(endian)
    }

    #[inline]
    fn sh_flags(&self, endian: Self::Endian) -> Self::Word {
        self.sh_flags.get(endian)
    }

    #[inline]
    fn sh_addr(&self, endian: Self::Endian) -> Self::Word {
        self.sh_addr.get(endian)
    }

    #[inline]
    fn sh_offset(&self, endian: Self::Endian) -> Self::Word {
        self.sh_offset.get(endian)
    }

    #[inline]
    fn sh_size(&self, endian: Self::Endian) -> Self::Word {
        self.sh_size.get(endian)
    }

    #[inline]
    fn sh_link(&self, endian: Self::Endian) -> u32 {
        self.sh_link.get(endian)
    }

    #[inline]
    fn sh_info(&self, endian: Self::Endian) -> u32 {
        self.sh_info.get(endian)
    }

    #[inline]
    fn sh_addralign(&self, endian: Self::Endian) -> Self::Word {
        self.sh_addralign.get(endian)
    }

    #[inline]
    fn sh_entsize(&self, endian: Self::Endian) -> Self::Word {
        self.sh_entsize.get(endian)
    }
}

impl<Endian: endian::Endian> SectionHeader for elf::SectionHeader64<Endian> {
    type Word = u64;
    type Endian = Endian;
    type Elf = elf::FileHeader64<Endian>;

    #[inline]
    fn sh_name(&self, endian: Self::Endian) -> u32 {
        self.sh_name.get(endian)
    }

    #[inline]
    fn sh_type(&self, endian: Self::Endian) -> u32 {
        self.sh_type.get(endian)
    }

    #[inline]
    fn sh_flags(&self, endian: Self::Endian) -> Self::Word {
        self.sh_flags.get(endian)
    }

    #[inline]
    fn sh_addr(&self, endian: Self::Endian) -> Self::Word {
        self.sh_addr.get(endian)
    }

    #[inline]
    fn sh_offset(&self, endian: Self::Endian) -> Self::Word {
        self.sh_offset.get(endian)
    }

    #[inline]
    fn sh_size(&self, endian: Self::Endian) -> Self::Word {
        self.sh_size.get(endian)
    }

    #[inline]
    fn sh_link(&self, endian: Self::Endian) -> u32 {
        self.sh_link.get(endian)
    }

    #[inline]
    fn sh_info(&self, endian: Self::Endian) -> u32 {
        self.sh_info.get(endian)
    }

    #[inline]
    fn sh_addralign(&self, endian: Self::Endian) -> Self::Word {
        self.sh_addralign.get(endian)
    }

    #[inline]
    fn sh_entsize(&self, endian: Self::Endian) -> Self::Word {
        self.sh_entsize.get(endian)
    }
}

#[cfg(feature = "compression")]
mod compression {
    use alloc::vec::Vec;
    use flate2::{Decompress, FlushDecompress};

    use crate::endian::U32;
    use crate::read::elf::CompressionHeader;
    use crate::read::Error;

    use super::*;

    impl<'data, 'file, Elf: FileHeader> ElfSection<'data, 'file, Elf> {
        pub(super) fn maybe_decompress_data(&self) -> read::Result<Option<Cow<'data, [u8]>>> {
            let endian = self.file.endian;
            if (self.section.sh_flags(endian).into() & u64::from(elf::SHF_COMPRESSED)) == 0 {
                return Ok(None);
            }

            let mut data = self
                .section
                .data(endian, self.file.data)
                .read_error("Invalid ELF compressed section offset or size")?;
            let header = data
                .read::<Elf::CompressionHeader>()
                .read_error("Invalid ELF compression header size or alignment")?;
            if header.ch_type(endian) != elf::ELFCOMPRESS_ZLIB {
                return Err(Error("Unsupported ELF compression type"));
            }

            let uncompressed_size: u64 = header.ch_size(endian).into();
            let mut decompressed = Vec::with_capacity(uncompressed_size as usize);
            let mut decompress = Decompress::new(true);
            if decompress
                .decompress_vec(data.0, &mut decompressed, FlushDecompress::Finish)
                .is_err()
            {
                return Err(Error("Invalid ELF compressed data"));
            }
            Ok(Some(Cow::Owned(decompressed)))
        }

        /// Try GNU-style "ZLIB" header decompression.
        pub(super) fn maybe_decompress_data_gnu(&self) -> read::Result<Option<Cow<'data, [u8]>>> {
            let name = match self.name() {
                Ok(name) => name,
                // I think it's ok to ignore this error?
                Err(_) => return Ok(None),
            };
            if !name.starts_with(".zdebug_") {
                return Ok(None);
            }
            let mut data = self.bytes()?;
            // Assume ZLIB-style uncompressed data is no more than 4GB to avoid accidentally
            // huge allocations. This also reduces the chance of accidentally matching on a
            // .debug_str that happens to start with "ZLIB".
            if data
                .read_bytes(8)
                .read_error("ELF GNU compressed section is too short")?
                .0
                != b"ZLIB\0\0\0\0"
            {
                return Err(Error("Invalid ELF GNU compressed section header"));
            }
            let uncompressed_size = data
                .read::<U32<_>>()
                .read_error("ELF GNU compressed section is too short")?
                .get(endian::BigEndian);
            let mut decompressed = Vec::with_capacity(uncompressed_size as usize);
            let mut decompress = Decompress::new(true);
            if decompress
                .decompress_vec(data.0, &mut decompressed, FlushDecompress::Finish)
                .is_err()
            {
                return Err(Error("Invalid ELF GNU compressed data"));
            }
            Ok(Some(Cow::Owned(decompressed)))
        }
    }
}