Vendor things

third-party/vendor/object/src/read/elf/note.rs

@@ -0,0 +1,271 @@
+use core::fmt::Debug;
+use core::mem;
+
+use crate::elf;
+use crate::endian::{self, U32};
+use crate::pod::Pod;
+use crate::read::util;
+use crate::read::{self, Bytes, Error, ReadError};
+
+use super::FileHeader;
+
+/// An iterator over the notes in an ELF section or segment.
+///
+/// Returned [`ProgramHeader::notes`](super::ProgramHeader::notes)
+/// and [`SectionHeader::notes`](super::SectionHeader::notes).
+#[derive(Debug)]
+pub struct NoteIterator<'data, Elf>
+where
+    Elf: FileHeader,
+{
+    endian: Elf::Endian,
+    align: usize,
+    data: Bytes<'data>,
+}
+
+impl<'data, Elf> NoteIterator<'data, Elf>
+where
+    Elf: FileHeader,
+{
+    /// An iterator over the notes in an ELF section or segment.
+    ///
+    /// `align` should be from the `p_align` field of the segment,
+    /// or the `sh_addralign` field of the section. Supported values are
+    /// either 4 or 8, but values less than 4 are treated as 4.
+    /// This matches the behaviour of binutils.
+    ///
+    /// Returns `Err` if `align` is invalid.
+    pub fn new(endian: Elf::Endian, align: Elf::Word, data: &'data [u8]) -> read::Result<Self> {
+        let align = match align.into() {
+            0u64..=4 => 4,
+            8 => 8,
+            _ => return Err(Error("Invalid ELF note alignment")),
+        };
+        // TODO: check data alignment?
+        Ok(NoteIterator {
+            endian,
+            align,
+            data: Bytes(data),
+        })
+    }
+
+    /// Returns the next note.
+    pub fn next(&mut self) -> read::Result<Option<Note<'data, Elf>>> {
+        let mut data = self.data;
+        if data.is_empty() {
+            return Ok(None);
+        }
+
+        let header = data
+            .read_at::<Elf::NoteHeader>(0)
+            .read_error("ELF note is too short")?;
+
+        // The name has no alignment requirement.
+        let offset = mem::size_of::<Elf::NoteHeader>();
+        let namesz = header.n_namesz(self.endian) as usize;
+        let name = data
+            .read_bytes_at(offset, namesz)
+            .read_error("Invalid ELF note namesz")?
+            .0;
+
+        // The descriptor must be aligned.
+        let offset = util::align(offset + namesz, self.align);
+        let descsz = header.n_descsz(self.endian) as usize;
+        let desc = data
+            .read_bytes_at(offset, descsz)
+            .read_error("Invalid ELF note descsz")?
+            .0;
+
+        // The next note (if any) must be aligned.
+        let offset = util::align(offset + descsz, self.align);
+        if data.skip(offset).is_err() {
+            data = Bytes(&[]);
+        }
+        self.data = data;
+
+        Ok(Some(Note { header, name, desc }))
+    }
+}
+
+/// A parsed [`NoteHeader`].
+#[derive(Debug)]
+pub struct Note<'data, Elf>
+where
+    Elf: FileHeader,
+{
+    header: &'data Elf::NoteHeader,
+    name: &'data [u8],
+    desc: &'data [u8],
+}
+
+impl<'data, Elf: FileHeader> Note<'data, Elf> {
+    /// Return the `n_type` field of the `NoteHeader`.
+    ///
+    /// The meaning of this field is determined by `name`.
+    pub fn n_type(&self, endian: Elf::Endian) -> u32 {
+        self.header.n_type(endian)
+    }
+
+    /// Return the `n_namesz` field of the `NoteHeader`.
+    pub fn n_namesz(&self, endian: Elf::Endian) -> u32 {
+        self.header.n_namesz(endian)
+    }
+
+    /// Return the `n_descsz` field of the `NoteHeader`.
+    pub fn n_descsz(&self, endian: Elf::Endian) -> u32 {
+        self.header.n_descsz(endian)
+    }
+
+    /// Return the bytes for the name field following the `NoteHeader`.
+    ///
+    /// This field is usually a string including one or more trailing null bytes
+    /// (but it is not required to be).
+    ///
+    /// The length of this field is given by `n_namesz`.
+    pub fn name_bytes(&self) -> &'data [u8] {
+        self.name
+    }
+
+    /// Return the bytes for the name field following the `NoteHeader`,
+    /// excluding all trailing null bytes.
+    pub fn name(&self) -> &'data [u8] {
+        let mut name = self.name;
+        while let [rest @ .., 0] = name {
+            name = rest;
+        }
+        name
+    }
+
+    /// Return the bytes for the desc field following the `NoteHeader`.
+    ///
+    /// The length of this field is given by `n_descsz`. The meaning
+    /// of this field is determined by `name` and `n_type`.
+    pub fn desc(&self) -> &'data [u8] {
+        self.desc
+    }
+
+    /// Return an iterator for properties if this note's type is [`elf::NT_GNU_PROPERTY_TYPE_0`].
+    pub fn gnu_properties(
+        &self,
+        endian: Elf::Endian,
+    ) -> Option<GnuPropertyIterator<'data, Elf::Endian>> {
+        if self.name() != elf::ELF_NOTE_GNU || self.n_type(endian) != elf::NT_GNU_PROPERTY_TYPE_0 {
+            return None;
+        }
+        // Use the ELF class instead of the section alignment.
+        // This matches what other parsers do.
+        let align = if Elf::is_type_64_sized() { 8 } else { 4 };
+        Some(GnuPropertyIterator {
+            endian,
+            align,
+            data: Bytes(self.desc),
+        })
+    }
+}
+
+/// A trait for generic access to [`elf::NoteHeader32`] and [`elf::NoteHeader64`].
+#[allow(missing_docs)]
+pub trait NoteHeader: Debug + Pod {
+    type Endian: endian::Endian;
+
+    fn n_namesz(&self, endian: Self::Endian) -> u32;
+    fn n_descsz(&self, endian: Self::Endian) -> u32;
+    fn n_type(&self, endian: Self::Endian) -> u32;
+}
+
+impl<Endian: endian::Endian> NoteHeader for elf::NoteHeader32<Endian> {
+    type Endian = Endian;
+
+    #[inline]
+    fn n_namesz(&self, endian: Self::Endian) -> u32 {
+        self.n_namesz.get(endian)
+    }
+
+    #[inline]
+    fn n_descsz(&self, endian: Self::Endian) -> u32 {
+        self.n_descsz.get(endian)
+    }
+
+    #[inline]
+    fn n_type(&self, endian: Self::Endian) -> u32 {
+        self.n_type.get(endian)
+    }
+}
+
+impl<Endian: endian::Endian> NoteHeader for elf::NoteHeader64<Endian> {
+    type Endian = Endian;
+
+    #[inline]
+    fn n_namesz(&self, endian: Self::Endian) -> u32 {
+        self.n_namesz.get(endian)
+    }
+
+    #[inline]
+    fn n_descsz(&self, endian: Self::Endian) -> u32 {
+        self.n_descsz.get(endian)
+    }
+
+    #[inline]
+    fn n_type(&self, endian: Self::Endian) -> u32 {
+        self.n_type.get(endian)
+    }
+}
+
+/// An iterator for the properties in a [`elf::NT_GNU_PROPERTY_TYPE_0`] note.
+///
+/// Returned by [`Note::gnu_properties`].
+#[derive(Debug)]
+pub struct GnuPropertyIterator<'data, Endian: endian::Endian> {
+    endian: Endian,
+    align: usize,
+    data: Bytes<'data>,
+}
+
+impl<'data, Endian: endian::Endian> GnuPropertyIterator<'data, Endian> {
+    /// Returns the next property.
+    pub fn next(&mut self) -> read::Result<Option<GnuProperty<'data>>> {
+        let mut data = self.data;
+        if data.is_empty() {
+            return Ok(None);
+        }
+
+        (|| -> Result<_, ()> {
+            let pr_type = data.read_at::<U32<Endian>>(0)?.get(self.endian);
+            let pr_datasz = data.read_at::<U32<Endian>>(4)?.get(self.endian) as usize;
+            let pr_data = data.read_bytes_at(8, pr_datasz)?.0;
+            data.skip(util::align(8 + pr_datasz, self.align))?;
+            self.data = data;
+            Ok(Some(GnuProperty { pr_type, pr_data }))
+        })()
+        .read_error("Invalid ELF GNU property")
+    }
+}
+
+/// A property in a [`elf::NT_GNU_PROPERTY_TYPE_0`] note.
+#[derive(Debug)]
+pub struct GnuProperty<'data> {
+    pr_type: u32,
+    pr_data: &'data [u8],
+}
+
+impl<'data> GnuProperty<'data> {
+    /// Return the property type.
+    ///
+    /// This is one of the `GNU_PROPERTY_*` constants.
+    pub fn pr_type(&self) -> u32 {
+        self.pr_type
+    }
+
+    /// Return the property data.
+    pub fn pr_data(&self) -> &'data [u8] {
+        self.pr_data
+    }
+
+    /// Parse the property data as an unsigned 32-bit integer.
+    pub fn data_u32<E: endian::Endian>(&self, endian: E) -> read::Result<u32> {
+        Bytes(self.pr_data)
+            .read_at::<U32<E>>(0)
+            .read_error("Invalid ELF GNU property data")
+            .map(|val| val.get(endian))
+    }
+}