Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 1102 insertions, 0 deletions

diff --git a/vendor/gimli/src/read/abbrev.rs b/vendor/gimli/src/read/abbrev.rs
new file mode 100644
index 0000000..1162583
--- /dev/null
+++ b/vendor/gimli/src/read/abbrev.rs
@@ -0,0 +1,1102 @@
+//! Functions for parsing DWARF debugging abbreviations.
+
+use alloc::collections::btree_map;
+use alloc::sync::Arc;
+use alloc::vec::Vec;
+use core::convert::TryFrom;
+use core::fmt::{self, Debug};
+use core::iter::FromIterator;
+use core::ops::Deref;
+
+use crate::common::{DebugAbbrevOffset, Encoding, SectionId};
+use crate::constants;
+use crate::endianity::Endianity;
+use crate::read::{
+    DebugInfoUnitHeadersIter, EndianSlice, Error, Reader, ReaderOffset, Result, Section, UnitHeader,
+};
+
+/// The `DebugAbbrev` struct represents the abbreviations describing
+/// `DebuggingInformationEntry`s' attribute names and forms found in the
+/// `.debug_abbrev` section.
+#[derive(Debug, Default, Clone, Copy)]
+pub struct DebugAbbrev<R> {
+    debug_abbrev_section: R,
+}
+
+impl<'input, Endian> DebugAbbrev<EndianSlice<'input, Endian>>
+where
+    Endian: Endianity,
+{
+    /// Construct a new `DebugAbbrev` instance from the data in the `.debug_abbrev`
+    /// section.
+    ///
+    /// It is the caller's responsibility to read the `.debug_abbrev` section and
+    /// present it as a `&[u8]` slice. That means using some ELF loader on
+    /// Linux, a Mach-O loader on macOS, etc.
+    ///
+    /// ```
+    /// use gimli::{DebugAbbrev, LittleEndian};
+    ///
+    /// # let buf = [0x00, 0x01, 0x02, 0x03];
+    /// # let read_debug_abbrev_section_somehow = || &buf;
+    /// let debug_abbrev = DebugAbbrev::new(read_debug_abbrev_section_somehow(), LittleEndian);
+    /// ```
+    pub fn new(debug_abbrev_section: &'input [u8], endian: Endian) -> Self {
+        Self::from(EndianSlice::new(debug_abbrev_section, endian))
+    }
+}
+
+impl<R: Reader> DebugAbbrev<R> {
+    /// Parse the abbreviations at the given `offset` within this
+    /// `.debug_abbrev` section.
+    ///
+    /// The `offset` should generally be retrieved from a unit header.
+    pub fn abbreviations(
+        &self,
+        debug_abbrev_offset: DebugAbbrevOffset<R::Offset>,
+    ) -> Result<Abbreviations> {
+        let input = &mut self.debug_abbrev_section.clone();
+        input.skip(debug_abbrev_offset.0)?;
+        Abbreviations::parse(input)
+    }
+}
+
+impl<T> DebugAbbrev<T> {
+    /// Create a `DebugAbbrev` section that references the data in `self`.
+    ///
+    /// This is useful when `R` implements `Reader` but `T` does not.
+    ///
+    /// ## Example Usage
+    ///
+    /// ```rust,no_run
+    /// # let load_section = || unimplemented!();
+    /// // Read the DWARF section into a `Vec` with whatever object loader you're using.
+    /// let owned_section: gimli::DebugAbbrev<Vec<u8>> = load_section();
+    /// // Create a reference to the DWARF section.
+    /// let section = owned_section.borrow(|section| {
+    ///     gimli::EndianSlice::new(&section, gimli::LittleEndian)
+    /// });
+    /// ```
+    pub fn borrow<'a, F, R>(&'a self, mut borrow: F) -> DebugAbbrev<R>
+    where
+        F: FnMut(&'a T) -> R,
+    {
+        borrow(&self.debug_abbrev_section).into()
+    }
+}
+
+impl<R> Section<R> for DebugAbbrev<R> {
+    fn id() -> SectionId {
+        SectionId::DebugAbbrev
+    }
+
+    fn reader(&self) -> &R {
+        &self.debug_abbrev_section
+    }
+}
+
+impl<R> From<R> for DebugAbbrev<R> {
+    fn from(debug_abbrev_section: R) -> Self {
+        DebugAbbrev {
+            debug_abbrev_section,
+        }
+    }
+}
+
+/// The strategy to use for caching abbreviations.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[non_exhaustive]
+pub enum AbbreviationsCacheStrategy {
+    /// Cache abbreviations that are used more than once.
+    ///
+    /// This is useful if the units in the `.debug_info` section will be parsed only once.
+    Duplicates,
+    /// Cache all abbreviations.
+    ///
+    /// This is useful if the units in the `.debug_info` section will be parsed more than once.
+    All,
+}
+
+/// A cache of previously parsed `Abbreviations`.
+#[derive(Debug, Default)]
+pub struct AbbreviationsCache {
+    abbreviations: btree_map::BTreeMap<u64, Result<Arc<Abbreviations>>>,
+}
+
+impl AbbreviationsCache {
+    /// Create an empty abbreviations cache.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Parse abbreviations and store them in the cache.
+    ///
+    /// This will iterate over the given units to determine the abbreviations
+    /// offsets. Any existing cache entries are discarded.
+    ///
+    /// Errors during parsing abbreviations are also stored in the cache.
+    /// Errors during iterating over the units are ignored.
+    pub fn populate<R: Reader>(
+        &mut self,
+        strategy: AbbreviationsCacheStrategy,
+        debug_abbrev: &DebugAbbrev<R>,
+        mut units: DebugInfoUnitHeadersIter<R>,
+    ) {
+        let mut offsets = Vec::new();
+        match strategy {
+            AbbreviationsCacheStrategy::Duplicates => {
+                while let Ok(Some(unit)) = units.next() {
+                    offsets.push(unit.debug_abbrev_offset());
+                }
+                offsets.sort_unstable_by_key(|offset| offset.0);
+                let mut prev_offset = R::Offset::from_u8(0);
+                let mut count = 0;
+                offsets.retain(|offset| {
+                    if count == 0 || prev_offset != offset.0 {
+                        prev_offset = offset.0;
+                        count = 1;
+                    } else {
+                        count += 1;
+                    }
+                    count == 2
+                });
+            }
+            AbbreviationsCacheStrategy::All => {
+                while let Ok(Some(unit)) = units.next() {
+                    offsets.push(unit.debug_abbrev_offset());
+                }
+                offsets.sort_unstable_by_key(|offset| offset.0);
+                offsets.dedup();
+            }
+        }
+        self.abbreviations = offsets
+            .into_iter()
+            .map(|offset| {
+                (
+                    offset.0.into_u64(),
+                    debug_abbrev.abbreviations(offset).map(Arc::new),
+                )
+            })
+            .collect();
+    }
+
+    /// Set an entry in the abbreviations cache.
+    ///
+    /// This is only required if you want to manually populate the cache.
+    pub fn set<R: Reader>(
+        &mut self,
+        offset: DebugAbbrevOffset<R::Offset>,
+        abbreviations: Arc<Abbreviations>,
+    ) {
+        self.abbreviations
+            .insert(offset.0.into_u64(), Ok(abbreviations));
+    }
+
+    /// Parse the abbreviations at the given offset.
+    ///
+    /// This uses the cache if possible, but does not update it.
+    pub fn get<R: Reader>(
+        &self,
+        debug_abbrev: &DebugAbbrev<R>,
+        offset: DebugAbbrevOffset<R::Offset>,
+    ) -> Result<Arc<Abbreviations>> {
+        match self.abbreviations.get(&offset.0.into_u64()) {
+            Some(entry) => entry.clone(),
+            None => debug_abbrev.abbreviations(offset).map(Arc::new),
+        }
+    }
+}
+
+/// A set of type abbreviations.
+///
+/// Construct an `Abbreviations` instance with the
+/// [`abbreviations()`](struct.UnitHeader.html#method.abbreviations)
+/// method.
+#[derive(Debug, Default, Clone)]
+pub struct Abbreviations {
+    vec: Vec<Abbreviation>,
+    map: btree_map::BTreeMap<u64, Abbreviation>,
+}
+
+impl Abbreviations {
+    /// Construct a new, empty set of abbreviations.
+    fn empty() -> Abbreviations {
+        Abbreviations {
+            vec: Vec::new(),
+            map: btree_map::BTreeMap::new(),
+        }
+    }
+
+    /// Insert an abbreviation into the set.
+    ///
+    /// Returns `Ok` if it is the first abbreviation in the set with its code,
+    /// `Err` if the code is a duplicate and there already exists an
+    /// abbreviation in the set with the given abbreviation's code.
+    fn insert(&mut self, abbrev: Abbreviation) -> ::core::result::Result<(), ()> {
+        let code_usize = abbrev.code as usize;
+        if code_usize as u64 == abbrev.code {
+            // Optimize for sequential abbreviation codes by storing them
+            // in a Vec, as long as the map doesn't already contain them.
+            // A potential further optimization would be to allow some
+            // holes in the Vec, but there's no need for that yet.
+            if code_usize - 1 < self.vec.len() {
+                return Err(());
+            } else if code_usize - 1 == self.vec.len() {
+                if !self.map.is_empty() && self.map.contains_key(&abbrev.code) {
+                    return Err(());
+                } else {
+                    self.vec.push(abbrev);
+                    return Ok(());
+                }
+            }
+        }
+        match self.map.entry(abbrev.code) {
+            btree_map::Entry::Occupied(_) => Err(()),
+            btree_map::Entry::Vacant(entry) => {
+                entry.insert(abbrev);
+                Ok(())
+            }
+        }
+    }
+
+    /// Get the abbreviation associated with the given code.
+    #[inline]
+    pub fn get(&self, code: u64) -> Option<&Abbreviation> {
+        if let Ok(code) = usize::try_from(code) {
+            let index = code.checked_sub(1)?;
+            if index < self.vec.len() {
+                return Some(&self.vec[index]);
+            }
+        }
+
+        self.map.get(&code)
+    }
+
+    /// Parse a series of abbreviations, terminated by a null abbreviation.
+    fn parse<R: Reader>(input: &mut R) -> Result<Abbreviations> {
+        let mut abbrevs = Abbreviations::empty();
+
+        while let Some(abbrev) = Abbreviation::parse(input)? {
+            if abbrevs.insert(abbrev).is_err() {
+                return Err(Error::DuplicateAbbreviationCode);
+            }
+        }
+
+        Ok(abbrevs)
+    }
+}
+
+/// An abbreviation describes the shape of a `DebuggingInformationEntry`'s type:
+/// its code, tag type, whether it has children, and its set of attributes.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Abbreviation {
+    code: u64,
+    tag: constants::DwTag,
+    has_children: constants::DwChildren,
+    attributes: Attributes,
+}
+
+impl Abbreviation {
+    /// Construct a new `Abbreviation`.
+    ///
+    /// ### Panics
+    ///
+    /// Panics if `code` is `0`.
+    pub(crate) fn new(
+        code: u64,
+        tag: constants::DwTag,
+        has_children: constants::DwChildren,
+        attributes: Attributes,
+    ) -> Abbreviation {
+        assert_ne!(code, 0);
+        Abbreviation {
+            code,
+            tag,
+            has_children,
+            attributes,
+        }
+    }
+
+    /// Get this abbreviation's code.
+    #[inline]
+    pub fn code(&self) -> u64 {
+        self.code
+    }
+
+    /// Get this abbreviation's tag.
+    #[inline]
+    pub fn tag(&self) -> constants::DwTag {
+        self.tag
+    }
+
+    /// Return true if this abbreviation's type has children, false otherwise.
+    #[inline]
+    pub fn has_children(&self) -> bool {
+        self.has_children == constants::DW_CHILDREN_yes
+    }
+
+    /// Get this abbreviation's attributes.
+    #[inline]
+    pub fn attributes(&self) -> &[AttributeSpecification] {
+        &self.attributes[..]
+    }
+
+    /// Parse an abbreviation's tag.
+    fn parse_tag<R: Reader>(input: &mut R) -> Result<constants::DwTag> {
+        let val = input.read_uleb128_u16()?;
+        if val == 0 {
+            Err(Error::AbbreviationTagZero)
+        } else {
+            Ok(constants::DwTag(val))
+        }
+    }
+
+    /// Parse an abbreviation's "does the type have children?" byte.
+    fn parse_has_children<R: Reader>(input: &mut R) -> Result<constants::DwChildren> {
+        let val = input.read_u8()?;
+        let val = constants::DwChildren(val);
+        if val == constants::DW_CHILDREN_no || val == constants::DW_CHILDREN_yes {
+            Ok(val)
+        } else {
+            Err(Error::BadHasChildren)
+        }
+    }
+
+    /// Parse a series of attribute specifications, terminated by a null attribute
+    /// specification.
+    fn parse_attributes<R: Reader>(input: &mut R) -> Result<Attributes> {
+        let mut attrs = Attributes::new();
+
+        while let Some(attr) = AttributeSpecification::parse(input)? {
+            attrs.push(attr);
+        }
+
+        Ok(attrs)
+    }
+
+    /// Parse an abbreviation. Return `None` for the null abbreviation, `Some`
+    /// for an actual abbreviation.
+    fn parse<R: Reader>(input: &mut R) -> Result<Option<Abbreviation>> {
+        let code = input.read_uleb128()?;
+        if code == 0 {
+            return Ok(None);
+        }
+
+        let tag = Self::parse_tag(input)?;
+        let has_children = Self::parse_has_children(input)?;
+        let attributes = Self::parse_attributes(input)?;
+        let abbrev = Abbreviation::new(code, tag, has_children, attributes);
+        Ok(Some(abbrev))
+    }
+}
+
+/// A list of attributes found in an `Abbreviation`
+#[derive(Clone)]
+pub(crate) enum Attributes {
+    Inline {
+        buf: [AttributeSpecification; MAX_ATTRIBUTES_INLINE],
+        len: usize,
+    },
+    Heap(Vec<AttributeSpecification>),
+}
+
+// Length of 5 based on benchmark results for both x86-64 and i686.
+const MAX_ATTRIBUTES_INLINE: usize = 5;
+
+impl Attributes {
+    /// Returns a new empty list of attributes
+    fn new() -> Attributes {
+        let default =
+            AttributeSpecification::new(constants::DW_AT_null, constants::DW_FORM_null, None);
+        Attributes::Inline {
+            buf: [default; 5],
+            len: 0,
+        }
+    }
+
+    /// Pushes a new value onto this list of attributes.
+    fn push(&mut self, attr: AttributeSpecification) {
+        match self {
+            Attributes::Heap(list) => list.push(attr),
+            Attributes::Inline {
+                buf,
+                len: MAX_ATTRIBUTES_INLINE,
+            } => {
+                let mut list = buf.to_vec();
+                list.push(attr);
+                *self = Attributes::Heap(list);
+            }
+            Attributes::Inline { buf, len } => {
+                buf[*len] = attr;
+                *len += 1;
+            }
+        }
+    }
+}
+
+impl Debug for Attributes {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        (**self).fmt(f)
+    }
+}
+
+impl PartialEq for Attributes {
+    fn eq(&self, other: &Attributes) -> bool {
+        **self == **other
+    }
+}
+
+impl Eq for Attributes {}
+
+impl Deref for Attributes {
+    type Target = [AttributeSpecification];
+    fn deref(&self) -> &[AttributeSpecification] {
+        match self {
+            Attributes::Inline { buf, len } => &buf[..*len],
+            Attributes::Heap(list) => list,
+        }
+    }
+}
+
+impl FromIterator<AttributeSpecification> for Attributes {
+    fn from_iter<I>(iter: I) -> Attributes
+    where
+        I: IntoIterator<Item = AttributeSpecification>,
+    {
+        let mut list = Attributes::new();
+        for item in iter {
+            list.push(item);
+        }
+        list
+    }
+}
+
+impl From<Vec<AttributeSpecification>> for Attributes {
+    fn from(list: Vec<AttributeSpecification>) -> Attributes {
+        Attributes::Heap(list)
+    }
+}
+
+/// The description of an attribute in an abbreviated type. It is a pair of name
+/// and form.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct AttributeSpecification {
+    name: constants::DwAt,
+    form: constants::DwForm,
+    implicit_const_value: i64,
+}
+
+impl AttributeSpecification {
+    /// Construct a new `AttributeSpecification` from the given name and form
+    /// and implicit const value.
+    #[inline]
+    pub fn new(
+        name: constants::DwAt,
+        form: constants::DwForm,
+        implicit_const_value: Option<i64>,
+    ) -> AttributeSpecification {
+        debug_assert!(
+            (form == constants::DW_FORM_implicit_const && implicit_const_value.is_some())
+                || (form != constants::DW_FORM_implicit_const && implicit_const_value.is_none())
+        );
+        AttributeSpecification {
+            name,
+            form,
+            implicit_const_value: implicit_const_value.unwrap_or(0),
+        }
+    }
+
+    /// Get the attribute's name.
+    #[inline]
+    pub fn name(&self) -> constants::DwAt {
+        self.name
+    }
+
+    /// Get the attribute's form.
+    #[inline]
+    pub fn form(&self) -> constants::DwForm {
+        self.form
+    }
+
+    /// Get the attribute's implicit const value.
+    #[inline]
+    pub fn implicit_const_value(&self) -> Option<i64> {
+        if self.form == constants::DW_FORM_implicit_const {
+            Some(self.implicit_const_value)
+        } else {
+            None
+        }
+    }
+
+    /// Return the size of the attribute, in bytes.
+    ///
+    /// Note that because some attributes are variably sized, the size cannot
+    /// always be known without parsing, in which case we return `None`.
+    pub fn size<R: Reader>(&self, header: &UnitHeader<R>) -> Option<usize> {
+        get_attribute_size(self.form, header.encoding()).map(usize::from)
+    }
+
+    /// Parse an attribute's form.
+    fn parse_form<R: Reader>(input: &mut R) -> Result<constants::DwForm> {
+        let val = input.read_uleb128_u16()?;
+        if val == 0 {
+            Err(Error::AttributeFormZero)
+        } else {
+            Ok(constants::DwForm(val))
+        }
+    }
+
+    /// Parse an attribute specification. Returns `None` for the null attribute
+    /// specification, `Some` for an actual attribute specification.
+    fn parse<R: Reader>(input: &mut R) -> Result<Option<AttributeSpecification>> {
+        let name = input.read_uleb128_u16()?;
+        if name == 0 {
+            // Parse the null attribute specification.
+            let form = input.read_uleb128_u16()?;
+            return if form == 0 {
+                Ok(None)
+            } else {
+                Err(Error::ExpectedZero)
+            };
+        }
+
+        let name = constants::DwAt(name);
+        let form = Self::parse_form(input)?;
+        let implicit_const_value = if form == constants::DW_FORM_implicit_const {
+            Some(input.read_sleb128()?)
+        } else {
+            None
+        };
+        let spec = AttributeSpecification::new(name, form, implicit_const_value);
+        Ok(Some(spec))
+    }
+}
+
+#[inline]
+pub(crate) fn get_attribute_size(form: constants::DwForm, encoding: Encoding) -> Option<u8> {
+    match form {
+        constants::DW_FORM_addr => Some(encoding.address_size),
+
+        constants::DW_FORM_implicit_const | constants::DW_FORM_flag_present => Some(0),
+
+        constants::DW_FORM_data1
+        | constants::DW_FORM_flag
+        | constants::DW_FORM_strx1
+        | constants::DW_FORM_ref1
+        | constants::DW_FORM_addrx1 => Some(1),
+
+        constants::DW_FORM_data2
+        | constants::DW_FORM_ref2
+        | constants::DW_FORM_addrx2
+        | constants::DW_FORM_strx2 => Some(2),
+
+        constants::DW_FORM_addrx3 | constants::DW_FORM_strx3 => Some(3),
+
+        constants::DW_FORM_data4
+        | constants::DW_FORM_ref_sup4
+        | constants::DW_FORM_ref4
+        | constants::DW_FORM_strx4
+        | constants::DW_FORM_addrx4 => Some(4),
+
+        constants::DW_FORM_data8
+        | constants::DW_FORM_ref8
+        | constants::DW_FORM_ref_sig8
+        | constants::DW_FORM_ref_sup8 => Some(8),
+
+        constants::DW_FORM_data16 => Some(16),
+
+        constants::DW_FORM_sec_offset
+        | constants::DW_FORM_GNU_ref_alt
+        | constants::DW_FORM_strp
+        | constants::DW_FORM_strp_sup
+        | constants::DW_FORM_GNU_strp_alt
+        | constants::DW_FORM_line_strp => Some(encoding.format.word_size()),
+
+        constants::DW_FORM_ref_addr => {
+            // This is an offset, but DWARF version 2 specifies that DW_FORM_ref_addr
+            // has the same size as an address on the target system.  This was changed
+            // in DWARF version 3.
+            Some(if encoding.version == 2 {
+                encoding.address_size
+            } else {
+                encoding.format.word_size()
+            })
+        }
+
+        // Variably sized forms.
+        constants::DW_FORM_block
+        | constants::DW_FORM_block1
+        | constants::DW_FORM_block2
+        | constants::DW_FORM_block4
+        | constants::DW_FORM_exprloc
+        | constants::DW_FORM_ref_udata
+        | constants::DW_FORM_string
+        | constants::DW_FORM_sdata
+        | constants::DW_FORM_udata
+        | constants::DW_FORM_indirect => None,
+
+        // We don't know the size of unknown forms.
+        _ => None,
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+    use crate::constants;
+    use crate::endianity::LittleEndian;
+    use crate::read::{EndianSlice, Error};
+    use crate::test_util::GimliSectionMethods;
+    #[cfg(target_pointer_width = "32")]
+    use core::u32;
+    use test_assembler::Section;
+
+    pub trait AbbrevSectionMethods {
+        fn abbrev(self, code: u64, tag: constants::DwTag, children: constants::DwChildren) -> Self;
+        fn abbrev_null(self) -> Self;
+        fn abbrev_attr(self, name: constants::DwAt, form: constants::DwForm) -> Self;
+        fn abbrev_attr_implicit_const(self, name: constants::DwAt, value: i64) -> Self;
+        fn abbrev_attr_null(self) -> Self;
+    }
+
+    impl AbbrevSectionMethods for Section {
+        fn abbrev(self, code: u64, tag: constants::DwTag, children: constants::DwChildren) -> Self {
+            self.uleb(code).uleb(tag.0.into()).D8(children.0)
+        }
+
+        fn abbrev_null(self) -> Self {
+            self.D8(0)
+        }
+
+        fn abbrev_attr(self, name: constants::DwAt, form: constants::DwForm) -> Self {
+            self.uleb(name.0.into()).uleb(form.0.into())
+        }
+
+        fn abbrev_attr_implicit_const(self, name: constants::DwAt, value: i64) -> Self {
+            self.uleb(name.0.into())
+                .uleb(constants::DW_FORM_implicit_const.0.into())
+                .sleb(value)
+        }
+
+        fn abbrev_attr_null(self) -> Self {
+            self.D8(0).D8(0)
+        }
+    }
+
+    #[test]
+    fn test_debug_abbrev_ok() {
+        let extra_start = [1, 2, 3, 4];
+        let expected_rest = [5, 6, 7, 8];
+        #[rustfmt::skip]
+        let buf = Section::new()
+            .append_bytes(&extra_start)
+            .abbrev(2, constants::DW_TAG_subprogram, constants::DW_CHILDREN_no)
+                .abbrev_attr(constants::DW_AT_name, constants::DW_FORM_string)
+                .abbrev_attr_null()
+            .abbrev(1, constants::DW_TAG_compile_unit, constants::DW_CHILDREN_yes)
+                .abbrev_attr(constants::DW_AT_producer, constants::DW_FORM_strp)
+                .abbrev_attr(constants::DW_AT_language, constants::DW_FORM_data2)
+                .abbrev_attr_null()
+            .abbrev_null()
+            .append_bytes(&expected_rest)
+            .get_contents()
+            .unwrap();
+
+        let abbrev1 = Abbreviation::new(
+            1,
+            constants::DW_TAG_compile_unit,
+            constants::DW_CHILDREN_yes,
+            vec![
+                AttributeSpecification::new(
+                    constants::DW_AT_producer,
+                    constants::DW_FORM_strp,
+                    None,
+                ),
+                AttributeSpecification::new(
+                    constants::DW_AT_language,
+                    constants::DW_FORM_data2,
+                    None,
+                ),
+            ]
+            .into(),
+        );
+
+        let abbrev2 = Abbreviation::new(
+            2,
+            constants::DW_TAG_subprogram,
+            constants::DW_CHILDREN_no,
+            vec![AttributeSpecification::new(
+                constants::DW_AT_name,
+                constants::DW_FORM_string,
+                None,
+            )]
+            .into(),
+        );
+
+        let debug_abbrev = DebugAbbrev::new(&buf, LittleEndian);
+        let debug_abbrev_offset = DebugAbbrevOffset(extra_start.len());
+        let abbrevs = debug_abbrev
+            .abbreviations(debug_abbrev_offset)
+            .expect("Should parse abbreviations");
+        assert_eq!(abbrevs.get(1), Some(&abbrev1));
+        assert_eq!(abbrevs.get(2), Some(&abbrev2));
+    }
+
+    #[test]
+    fn test_abbreviations_insert() {
+        fn abbrev(code: u16) -> Abbreviation {
+            Abbreviation::new(
+                code.into(),
+                constants::DwTag(code),
+                constants::DW_CHILDREN_no,
+                vec![].into(),
+            )
+        }
+
+        fn assert_abbrev(abbrevs: &Abbreviations, code: u16) {
+            let abbrev = abbrevs.get(code.into()).unwrap();
+            assert_eq!(abbrev.tag(), constants::DwTag(code));
+        }
+
+        // Sequential insert.
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs.insert(abbrev(1)).unwrap();
+        abbrevs.insert(abbrev(2)).unwrap();
+        assert_eq!(abbrevs.vec.len(), 2);
+        assert!(abbrevs.map.is_empty());
+        assert_abbrev(&abbrevs, 1);
+        assert_abbrev(&abbrevs, 2);
+
+        // Out of order insert.
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs.insert(abbrev(2)).unwrap();
+        abbrevs.insert(abbrev(3)).unwrap();
+        assert!(abbrevs.vec.is_empty());
+        assert_abbrev(&abbrevs, 2);
+        assert_abbrev(&abbrevs, 3);
+
+        // Mixed order insert.
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs.insert(abbrev(1)).unwrap();
+        abbrevs.insert(abbrev(3)).unwrap();
+        abbrevs.insert(abbrev(2)).unwrap();
+        assert_eq!(abbrevs.vec.len(), 2);
+        assert_abbrev(&abbrevs, 1);
+        assert_abbrev(&abbrevs, 2);
+        assert_abbrev(&abbrevs, 3);
+
+        // Duplicate code in vec.
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs.insert(abbrev(1)).unwrap();
+        abbrevs.insert(abbrev(2)).unwrap();
+        assert_eq!(abbrevs.insert(abbrev(1)), Err(()));
+        assert_eq!(abbrevs.insert(abbrev(2)), Err(()));
+
+        // Duplicate code in map when adding to map.
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs.insert(abbrev(2)).unwrap();
+        assert_eq!(abbrevs.insert(abbrev(2)), Err(()));
+
+        // Duplicate code in map when adding to vec.
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs.insert(abbrev(2)).unwrap();
+        abbrevs.insert(abbrev(1)).unwrap();
+        assert_eq!(abbrevs.insert(abbrev(2)), Err(()));
+
+        // 32-bit usize conversions.
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs.insert(abbrev(2)).unwrap();
+    }
+
+    #[test]
+    #[cfg(target_pointer_width = "32")]
+    fn test_abbreviations_insert_32() {
+        fn abbrev(code: u64) -> Abbreviation {
+            Abbreviation::new(
+                code,
+                constants::DwTag(code as u16),
+                constants::DW_CHILDREN_no,
+                vec![].into(),
+            )
+        }
+
+        fn assert_abbrev(abbrevs: &Abbreviations, code: u64) {
+            let abbrev = abbrevs.get(code).unwrap();
+            assert_eq!(abbrev.tag(), constants::DwTag(code as u16));
+        }
+
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs.insert(abbrev(1)).unwrap();
+
+        let wrap_code = (u32::MAX as u64 + 1) + 1;
+        // `get` should not treat the wrapped code as `1`.
+        assert_eq!(abbrevs.get(wrap_code), None);
+        // `insert` should not treat the wrapped code as `1`.
+        abbrevs.insert(abbrev(wrap_code)).unwrap();
+        assert_abbrev(&abbrevs, 1);
+        assert_abbrev(&abbrevs, wrap_code);
+    }
+
+    #[test]
+    fn test_parse_abbreviations_ok() {
+        let expected_rest = [1, 2, 3, 4];
+        #[rustfmt::skip]
+        let buf = Section::new()
+            .abbrev(2, constants::DW_TAG_subprogram, constants::DW_CHILDREN_no)
+                .abbrev_attr(constants::DW_AT_name, constants::DW_FORM_string)
+                .abbrev_attr_null()
+            .abbrev(1, constants::DW_TAG_compile_unit, constants::DW_CHILDREN_yes)
+                .abbrev_attr(constants::DW_AT_producer, constants::DW_FORM_strp)
+                .abbrev_attr(constants::DW_AT_language, constants::DW_FORM_data2)
+                .abbrev_attr_null()
+            .abbrev_null()
+            .append_bytes(&expected_rest)
+            .get_contents()
+            .unwrap();
+        let rest = &mut EndianSlice::new(&*buf, LittleEndian);
+
+        let abbrev1 = Abbreviation::new(
+            1,
+            constants::DW_TAG_compile_unit,
+            constants::DW_CHILDREN_yes,
+            vec![
+                AttributeSpecification::new(
+                    constants::DW_AT_producer,
+                    constants::DW_FORM_strp,
+                    None,
+                ),
+                AttributeSpecification::new(
+                    constants::DW_AT_language,
+                    constants::DW_FORM_data2,
+                    None,
+                ),
+            ]
+            .into(),
+        );
+
+        let abbrev2 = Abbreviation::new(
+            2,
+            constants::DW_TAG_subprogram,
+            constants::DW_CHILDREN_no,
+            vec![AttributeSpecification::new(
+                constants::DW_AT_name,
+                constants::DW_FORM_string,
+                None,
+            )]
+            .into(),
+        );
+
+        let abbrevs = Abbreviations::parse(rest).expect("Should parse abbreviations");
+        assert_eq!(abbrevs.get(1), Some(&abbrev1));
+        assert_eq!(abbrevs.get(2), Some(&abbrev2));
+        assert_eq!(*rest, EndianSlice::new(&expected_rest, LittleEndian));
+    }
+
+    #[test]
+    fn test_parse_abbreviations_duplicate() {
+        let expected_rest = [1, 2, 3, 4];
+        #[rustfmt::skip]
+        let buf = Section::new()
+            .abbrev(1, constants::DW_TAG_subprogram, constants::DW_CHILDREN_no)
+                .abbrev_attr(constants::DW_AT_name, constants::DW_FORM_string)
+                .abbrev_attr_null()
+            .abbrev(1, constants::DW_TAG_compile_unit, constants::DW_CHILDREN_yes)
+                .abbrev_attr(constants::DW_AT_producer, constants::DW_FORM_strp)
+                .abbrev_attr(constants::DW_AT_language, constants::DW_FORM_data2)
+                .abbrev_attr_null()
+            .abbrev_null()
+            .append_bytes(&expected_rest)
+            .get_contents()
+            .unwrap();
+        let buf = &mut EndianSlice::new(&*buf, LittleEndian);
+
+        match Abbreviations::parse(buf) {
+            Err(Error::DuplicateAbbreviationCode) => {}
+            otherwise => panic!("Unexpected result: {:?}", otherwise),
+        };
+    }
+
+    #[test]
+    fn test_parse_abbreviation_tag_ok() {
+        let buf = [0x01, 0x02];
+        let rest = &mut EndianSlice::new(&buf, LittleEndian);
+        let tag = Abbreviation::parse_tag(rest).expect("Should parse tag");
+        assert_eq!(tag, constants::DW_TAG_array_type);
+        assert_eq!(*rest, EndianSlice::new(&buf[1..], LittleEndian));
+    }
+
+    #[test]
+    fn test_parse_abbreviation_tag_zero() {
+        let buf = [0x00];
+        let buf = &mut EndianSlice::new(&buf, LittleEndian);
+        match Abbreviation::parse_tag(buf) {
+            Err(Error::AbbreviationTagZero) => {}
+            otherwise => panic!("Unexpected result: {:?}", otherwise),
+        };
+    }
+
+    #[test]
+    fn test_parse_abbreviation_has_children() {
+        let buf = [0x00, 0x01, 0x02];
+        let rest = &mut EndianSlice::new(&buf, LittleEndian);
+        let val = Abbreviation::parse_has_children(rest).expect("Should parse children");
+        assert_eq!(val, constants::DW_CHILDREN_no);
+        let val = Abbreviation::parse_has_children(rest).expect("Should parse children");
+        assert_eq!(val, constants::DW_CHILDREN_yes);
+        match Abbreviation::parse_has_children(rest) {
+            Err(Error::BadHasChildren) => {}
+            otherwise => panic!("Unexpected result: {:?}", otherwise),
+        };
+    }
+
+    #[test]
+    fn test_parse_abbreviation_ok() {
+        let expected_rest = [0x01, 0x02, 0x03, 0x04];
+        let buf = Section::new()
+            .abbrev(1, constants::DW_TAG_subprogram, constants::DW_CHILDREN_no)
+            .abbrev_attr(constants::DW_AT_name, constants::DW_FORM_string)
+            .abbrev_attr_null()
+            .append_bytes(&expected_rest)
+            .get_contents()
+            .unwrap();
+        let rest = &mut EndianSlice::new(&*buf, LittleEndian);
+
+        let expect = Some(Abbreviation::new(
+            1,
+            constants::DW_TAG_subprogram,
+            constants::DW_CHILDREN_no,
+            vec![AttributeSpecification::new(
+                constants::DW_AT_name,
+                constants::DW_FORM_string,
+                None,
+            )]
+            .into(),
+        ));
+
+        let abbrev = Abbreviation::parse(rest).expect("Should parse abbreviation");
+        assert_eq!(abbrev, expect);
+        assert_eq!(*rest, EndianSlice::new(&expected_rest, LittleEndian));
+    }
+
+    #[test]
+    fn test_parse_abbreviation_implicit_const_ok() {
+        let expected_rest = [0x01, 0x02, 0x03, 0x04];
+        let buf = Section::new()
+            .abbrev(1, constants::DW_TAG_subprogram, constants::DW_CHILDREN_no)
+            .abbrev_attr_implicit_const(constants::DW_AT_name, -42)
+            .abbrev_attr_null()
+            .append_bytes(&expected_rest)
+            .get_contents()
+            .unwrap();
+        let rest = &mut EndianSlice::new(&*buf, LittleEndian);
+
+        let expect = Some(Abbreviation::new(
+            1,
+            constants::DW_TAG_subprogram,
+            constants::DW_CHILDREN_no,
+            vec![AttributeSpecification::new(
+                constants::DW_AT_name,
+                constants::DW_FORM_implicit_const,
+                Some(-42),
+            )]
+            .into(),
+        ));
+
+        let abbrev = Abbreviation::parse(rest).expect("Should parse abbreviation");
+        assert_eq!(abbrev, expect);
+        assert_eq!(*rest, EndianSlice::new(&expected_rest, LittleEndian));
+    }
+
+    #[test]
+    fn test_parse_abbreviation_implicit_const_no_const() {
+        let buf = Section::new()
+            .abbrev(1, constants::DW_TAG_subprogram, constants::DW_CHILDREN_no)
+            .abbrev_attr(constants::DW_AT_name, constants::DW_FORM_implicit_const)
+            .get_contents()
+            .unwrap();
+        let buf = &mut EndianSlice::new(&*buf, LittleEndian);
+
+        match Abbreviation::parse(buf) {
+            Err(Error::UnexpectedEof(_)) => {}
+            otherwise => panic!("Unexpected result: {:?}", otherwise),
+        }
+    }
+
+    #[test]
+    fn test_parse_null_abbreviation_ok() {
+        let expected_rest = [0x01, 0x02, 0x03, 0x04];
+        let buf = Section::new()
+            .abbrev_null()
+            .append_bytes(&expected_rest)
+            .get_contents()
+            .unwrap();
+        let rest = &mut EndianSlice::new(&*buf, LittleEndian);
+
+        let abbrev = Abbreviation::parse(rest).expect("Should parse null abbreviation");
+        assert!(abbrev.is_none());
+        assert_eq!(*rest, EndianSlice::new(&expected_rest, LittleEndian));
+    }
+
+    #[test]
+    fn test_parse_attribute_form_ok() {
+        let buf = [0x01, 0x02];
+        let rest = &mut EndianSlice::new(&buf, LittleEndian);
+        let tag = AttributeSpecification::parse_form(rest).expect("Should parse form");
+        assert_eq!(tag, constants::DW_FORM_addr);
+        assert_eq!(*rest, EndianSlice::new(&buf[1..], LittleEndian));
+    }
+
+    #[test]
+    fn test_parse_attribute_form_zero() {
+        let buf = [0x00];
+        let buf = &mut EndianSlice::new(&buf, LittleEndian);
+        match AttributeSpecification::parse_form(buf) {
+            Err(Error::AttributeFormZero) => {}
+            otherwise => panic!("Unexpected result: {:?}", otherwise),
+        };
+    }
+
+    #[test]
+    fn test_parse_null_attribute_specification_ok() {
+        let buf = [0x00, 0x00, 0x01];
+        let rest = &mut EndianSlice::new(&buf, LittleEndian);
+        let attr =
+            AttributeSpecification::parse(rest).expect("Should parse null attribute specification");
+        assert!(attr.is_none());
+        assert_eq!(*rest, EndianSlice::new(&buf[2..], LittleEndian));
+    }
+
+    #[test]
+    fn test_parse_attribute_specifications_name_zero() {
+        let buf = [0x00, 0x01, 0x00, 0x00];
+        let buf = &mut EndianSlice::new(&buf, LittleEndian);
+        match AttributeSpecification::parse(buf) {
+            Err(Error::ExpectedZero) => {}
+            otherwise => panic!("Unexpected result: {:?}", otherwise),
+        };
+    }
+
+    #[test]
+    fn test_parse_attribute_specifications_form_zero() {
+        let buf = [0x01, 0x00, 0x00, 0x00];
+        let buf = &mut EndianSlice::new(&buf, LittleEndian);
+        match AttributeSpecification::parse(buf) {
+            Err(Error::AttributeFormZero) => {}
+            otherwise => panic!("Unexpected result: {:?}", otherwise),
+        };
+    }
+
+    #[test]
+    fn test_get_abbrev_zero() {
+        let mut abbrevs = Abbreviations::empty();
+        abbrevs
+            .insert(Abbreviation::new(
+                1,
+                constants::DwTag(1),
+                constants::DW_CHILDREN_no,
+                vec![].into(),
+            ))
+            .unwrap();
+        assert!(abbrevs.get(0).is_none());
+    }
+}