Initial vendor packages

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

1 files changed, 1210 insertions, 0 deletions

diff --git a/vendor/gimli/src/read/dwarf.rs b/vendor/gimli/src/read/dwarf.rs
new file mode 100644
index 0000000..2f8dcb3
--- /dev/null
+++ b/vendor/gimli/src/read/dwarf.rs
@@ -0,0 +1,1210 @@
+use alloc::string::String;
+use alloc::sync::Arc;
+
+use crate::common::{
+    DebugAddrBase, DebugAddrIndex, DebugInfoOffset, DebugLineStrOffset, DebugLocListsBase,
+    DebugLocListsIndex, DebugRngListsBase, DebugRngListsIndex, DebugStrOffset, DebugStrOffsetsBase,
+    DebugStrOffsetsIndex, DebugTypeSignature, DebugTypesOffset, DwarfFileType, DwoId, Encoding,
+    LocationListsOffset, RangeListsOffset, RawRangeListsOffset, SectionId, UnitSectionOffset,
+};
+use crate::constants;
+use crate::read::{
+    Abbreviations, AbbreviationsCache, AbbreviationsCacheStrategy, AttributeValue, DebugAbbrev,
+    DebugAddr, DebugAranges, DebugCuIndex, DebugInfo, DebugInfoUnitHeadersIter, DebugLine,
+    DebugLineStr, DebugLoc, DebugLocLists, DebugRngLists, DebugStr, DebugStrOffsets, DebugTuIndex,
+    DebugTypes, DebugTypesUnitHeadersIter, DebuggingInformationEntry, EntriesCursor, EntriesRaw,
+    EntriesTree, Error, IncompleteLineProgram, LocListIter, LocationLists, Range, RangeLists,
+    RawLocListIter, RawRngListIter, Reader, ReaderOffset, ReaderOffsetId, Result, RngListIter,
+    Section, UnitHeader, UnitIndex, UnitIndexSectionIterator, UnitOffset, UnitType,
+};
+
+/// All of the commonly used DWARF sections, and other common information.
+#[derive(Debug, Default)]
+pub struct Dwarf<R> {
+    /// The `.debug_abbrev` section.
+    pub debug_abbrev: DebugAbbrev<R>,
+
+    /// The `.debug_addr` section.
+    pub debug_addr: DebugAddr<R>,
+
+    /// The `.debug_aranges` section.
+    pub debug_aranges: DebugAranges<R>,
+
+    /// The `.debug_info` section.
+    pub debug_info: DebugInfo<R>,
+
+    /// The `.debug_line` section.
+    pub debug_line: DebugLine<R>,
+
+    /// The `.debug_line_str` section.
+    pub debug_line_str: DebugLineStr<R>,
+
+    /// The `.debug_str` section.
+    pub debug_str: DebugStr<R>,
+
+    /// The `.debug_str_offsets` section.
+    pub debug_str_offsets: DebugStrOffsets<R>,
+
+    /// The `.debug_types` section.
+    pub debug_types: DebugTypes<R>,
+
+    /// The location lists in the `.debug_loc` and `.debug_loclists` sections.
+    pub locations: LocationLists<R>,
+
+    /// The range lists in the `.debug_ranges` and `.debug_rnglists` sections.
+    pub ranges: RangeLists<R>,
+
+    /// The type of this file.
+    pub file_type: DwarfFileType,
+
+    /// The DWARF sections for a supplementary object file.
+    pub sup: Option<Arc<Dwarf<R>>>,
+
+    /// A cache of previously parsed abbreviations for units in this file.
+    pub abbreviations_cache: AbbreviationsCache,
+}
+
+impl<T> Dwarf<T> {
+    /// Try to load the DWARF sections using the given loader function.
+    ///
+    /// `section` loads a DWARF section from the object file.
+    /// It should return an empty section if the section does not exist.
+    ///
+    /// `section` may either directly return a `Reader` instance (such as
+    /// `EndianSlice`), or it may return some other type and then convert
+    /// that type into a `Reader` using `Dwarf::borrow`.
+    ///
+    /// After loading, the user should set the `file_type` field and
+    /// call `load_sup` if required.
+    pub fn load<F, E>(mut section: F) -> core::result::Result<Self, E>
+    where
+        F: FnMut(SectionId) -> core::result::Result<T, E>,
+    {
+        // Section types are inferred.
+        let debug_loc = Section::load(&mut section)?;
+        let debug_loclists = Section::load(&mut section)?;
+        let debug_ranges = Section::load(&mut section)?;
+        let debug_rnglists = Section::load(&mut section)?;
+        Ok(Dwarf {
+            debug_abbrev: Section::load(&mut section)?,
+            debug_addr: Section::load(&mut section)?,
+            debug_aranges: Section::load(&mut section)?,
+            debug_info: Section::load(&mut section)?,
+            debug_line: Section::load(&mut section)?,
+            debug_line_str: Section::load(&mut section)?,
+            debug_str: Section::load(&mut section)?,
+            debug_str_offsets: Section::load(&mut section)?,
+            debug_types: Section::load(&mut section)?,
+            locations: LocationLists::new(debug_loc, debug_loclists),
+            ranges: RangeLists::new(debug_ranges, debug_rnglists),
+            file_type: DwarfFileType::Main,
+            sup: None,
+            abbreviations_cache: AbbreviationsCache::new(),
+        })
+    }
+
+    /// Load the DWARF sections from the supplementary object file.
+    ///
+    /// `section` operates the same as for `load`.
+    ///
+    /// Sets `self.sup`, replacing any previous value.
+    pub fn load_sup<F, E>(&mut self, section: F) -> core::result::Result<(), E>
+    where
+        F: FnMut(SectionId) -> core::result::Result<T, E>,
+    {
+        self.sup = Some(Arc::new(Self::load(section)?));
+        Ok(())
+    }
+
+    /// Create a `Dwarf` structure that references the data in `self`.
+    ///
+    /// This is useful when `R` implements `Reader` but `T` does not.
+    ///
+    /// ## Example Usage
+    ///
+    /// It can be useful to load DWARF sections into owned data structures,
+    /// such as `Vec`. However, we do not implement the `Reader` trait
+    /// for `Vec`, because it would be very inefficient, but this trait
+    /// is required for all of the methods that parse the DWARF data.
+    /// So we first load the DWARF sections into `Vec`s, and then use
+    /// `borrow` to create `Reader`s that reference the data.
+    ///
+    /// ```rust,no_run
+    /// # fn example() -> Result<(), gimli::Error> {
+    /// # let loader = |name| -> Result<_, gimli::Error> { unimplemented!() };
+    /// # let sup_loader = |name| -> Result<_, gimli::Error> { unimplemented!() };
+    /// // Read the DWARF sections into `Vec`s with whatever object loader you're using.
+    /// let mut owned_dwarf: gimli::Dwarf<Vec<u8>> = gimli::Dwarf::load(loader)?;
+    /// owned_dwarf.load_sup(sup_loader)?;
+    /// // Create references to the DWARF sections.
+    /// let dwarf = owned_dwarf.borrow(|section| {
+    ///     gimli::EndianSlice::new(&section, gimli::LittleEndian)
+    /// });
+    /// # unreachable!()
+    /// # }
+    /// ```
+    pub fn borrow<'a, F, R>(&'a self, mut borrow: F) -> Dwarf<R>
+    where
+        F: FnMut(&'a T) -> R,
+    {
+        Dwarf {
+            debug_abbrev: self.debug_abbrev.borrow(&mut borrow),
+            debug_addr: self.debug_addr.borrow(&mut borrow),
+            debug_aranges: self.debug_aranges.borrow(&mut borrow),
+            debug_info: self.debug_info.borrow(&mut borrow),
+            debug_line: self.debug_line.borrow(&mut borrow),
+            debug_line_str: self.debug_line_str.borrow(&mut borrow),
+            debug_str: self.debug_str.borrow(&mut borrow),
+            debug_str_offsets: self.debug_str_offsets.borrow(&mut borrow),
+            debug_types: self.debug_types.borrow(&mut borrow),
+            locations: self.locations.borrow(&mut borrow),
+            ranges: self.ranges.borrow(&mut borrow),
+            file_type: self.file_type,
+            sup: self.sup().map(|sup| Arc::new(sup.borrow(borrow))),
+            abbreviations_cache: AbbreviationsCache::new(),
+        }
+    }
+
+    /// Return a reference to the DWARF sections for supplementary object file.
+    pub fn sup(&self) -> Option<&Dwarf<T>> {
+        self.sup.as_ref().map(Arc::as_ref)
+    }
+}
+
+impl<R: Reader> Dwarf<R> {
+    /// Parse abbreviations and store them in the cache.
+    ///
+    /// This will iterate over the units in `self.debug_info` to determine the
+    /// abbreviations offsets.
+    ///
+    /// Errors during parsing abbreviations are also stored in the cache.
+    /// Errors during iterating over the units are ignored.
+    pub fn populate_abbreviations_cache(&mut self, strategy: AbbreviationsCacheStrategy) {
+        self.abbreviations_cache
+            .populate(strategy, &self.debug_abbrev, self.debug_info.units());
+    }
+
+    /// Iterate the unit headers in the `.debug_info` section.
+    ///
+    /// Can be [used with
+    /// `FallibleIterator`](./index.html#using-with-fallibleiterator).
+    #[inline]
+    pub fn units(&self) -> DebugInfoUnitHeadersIter<R> {
+        self.debug_info.units()
+    }
+
+    /// Construct a new `Unit` from the given unit header.
+    #[inline]
+    pub fn unit(&self, header: UnitHeader<R>) -> Result<Unit<R>> {
+        Unit::new(self, header)
+    }
+
+    /// Iterate the type-unit headers in the `.debug_types` section.
+    ///
+    /// Can be [used with
+    /// `FallibleIterator`](./index.html#using-with-fallibleiterator).
+    #[inline]
+    pub fn type_units(&self) -> DebugTypesUnitHeadersIter<R> {
+        self.debug_types.units()
+    }
+
+    /// Parse the abbreviations for a compilation unit.
+    #[inline]
+    pub fn abbreviations(&self, unit: &UnitHeader<R>) -> Result<Arc<Abbreviations>> {
+        self.abbreviations_cache
+            .get(&self.debug_abbrev, unit.debug_abbrev_offset())
+    }
+
+    /// Return the string offset at the given index.
+    #[inline]
+    pub fn string_offset(
+        &self,
+        unit: &Unit<R>,
+        index: DebugStrOffsetsIndex<R::Offset>,
+    ) -> Result<DebugStrOffset<R::Offset>> {
+        self.debug_str_offsets
+            .get_str_offset(unit.header.format(), unit.str_offsets_base, index)
+    }
+
+    /// Return the string at the given offset in `.debug_str`.
+    #[inline]
+    pub fn string(&self, offset: DebugStrOffset<R::Offset>) -> Result<R> {
+        self.debug_str.get_str(offset)
+    }
+
+    /// Return the string at the given offset in `.debug_line_str`.
+    #[inline]
+    pub fn line_string(&self, offset: DebugLineStrOffset<R::Offset>) -> Result<R> {
+        self.debug_line_str.get_str(offset)
+    }
+
+    /// Return an attribute value as a string slice.
+    ///
+    /// If the attribute value is one of:
+    ///
+    /// - an inline `DW_FORM_string` string
+    /// - a `DW_FORM_strp` reference to an offset into the `.debug_str` section
+    /// - a `DW_FORM_strp_sup` reference to an offset into a supplementary
+    /// object file
+    /// - a `DW_FORM_line_strp` reference to an offset into the `.debug_line_str`
+    /// section
+    /// - a `DW_FORM_strx` index into the `.debug_str_offsets` entries for the unit
+    ///
+    /// then return the attribute's string value. Returns an error if the attribute
+    /// value does not have a string form, or if a string form has an invalid value.
+    pub fn attr_string(&self, unit: &Unit<R>, attr: AttributeValue<R>) -> Result<R> {
+        match attr {
+            AttributeValue::String(string) => Ok(string),
+            AttributeValue::DebugStrRef(offset) => self.debug_str.get_str(offset),
+            AttributeValue::DebugStrRefSup(offset) => {
+                if let Some(sup) = self.sup() {
+                    sup.debug_str.get_str(offset)
+                } else {
+                    Err(Error::ExpectedStringAttributeValue)
+                }
+            }
+            AttributeValue::DebugLineStrRef(offset) => self.debug_line_str.get_str(offset),
+            AttributeValue::DebugStrOffsetsIndex(index) => {
+                let offset = self.debug_str_offsets.get_str_offset(
+                    unit.header.format(),
+                    unit.str_offsets_base,
+                    index,
+                )?;
+                self.debug_str.get_str(offset)
+            }
+            _ => Err(Error::ExpectedStringAttributeValue),
+        }
+    }
+
+    /// Return the address at the given index.
+    pub fn address(&self, unit: &Unit<R>, index: DebugAddrIndex<R::Offset>) -> Result<u64> {
+        self.debug_addr
+            .get_address(unit.encoding().address_size, unit.addr_base, index)
+    }
+
+    /// Try to return an attribute value as an address.
+    ///
+    /// If the attribute value is one of:
+    ///
+    /// - a `DW_FORM_addr`
+    /// - a `DW_FORM_addrx` index into the `.debug_addr` entries for the unit
+    ///
+    /// then return the address.
+    /// Returns `None` for other forms.
+    pub fn attr_address(&self, unit: &Unit<R>, attr: AttributeValue<R>) -> Result<Option<u64>> {
+        match attr {
+            AttributeValue::Addr(addr) => Ok(Some(addr)),
+            AttributeValue::DebugAddrIndex(index) => self.address(unit, index).map(Some),
+            _ => Ok(None),
+        }
+    }
+
+    /// Return the range list offset for the given raw offset.
+    ///
+    /// This handles adding `DW_AT_GNU_ranges_base` if required.
+    pub fn ranges_offset_from_raw(
+        &self,
+        unit: &Unit<R>,
+        offset: RawRangeListsOffset<R::Offset>,
+    ) -> RangeListsOffset<R::Offset> {
+        if self.file_type == DwarfFileType::Dwo && unit.header.version() < 5 {
+            RangeListsOffset(offset.0.wrapping_add(unit.rnglists_base.0))
+        } else {
+            RangeListsOffset(offset.0)
+        }
+    }
+
+    /// Return the range list offset at the given index.
+    pub fn ranges_offset(
+        &self,
+        unit: &Unit<R>,
+        index: DebugRngListsIndex<R::Offset>,
+    ) -> Result<RangeListsOffset<R::Offset>> {
+        self.ranges
+            .get_offset(unit.encoding(), unit.rnglists_base, index)
+    }
+
+    /// Iterate over the `RangeListEntry`s starting at the given offset.
+    pub fn ranges(
+        &self,
+        unit: &Unit<R>,
+        offset: RangeListsOffset<R::Offset>,
+    ) -> Result<RngListIter<R>> {
+        self.ranges.ranges(
+            offset,
+            unit.encoding(),
+            unit.low_pc,
+            &self.debug_addr,
+            unit.addr_base,
+        )
+    }
+
+    /// Iterate over the `RawRngListEntry`ies starting at the given offset.
+    pub fn raw_ranges(
+        &self,
+        unit: &Unit<R>,
+        offset: RangeListsOffset<R::Offset>,
+    ) -> Result<RawRngListIter<R>> {
+        self.ranges.raw_ranges(offset, unit.encoding())
+    }
+
+    /// Try to return an attribute value as a range list offset.
+    ///
+    /// If the attribute value is one of:
+    ///
+    /// - a `DW_FORM_sec_offset` reference to the `.debug_ranges` or `.debug_rnglists` sections
+    /// - a `DW_FORM_rnglistx` index into the `.debug_rnglists` entries for the unit
+    ///
+    /// then return the range list offset of the range list.
+    /// Returns `None` for other forms.
+    pub fn attr_ranges_offset(
+        &self,
+        unit: &Unit<R>,
+        attr: AttributeValue<R>,
+    ) -> Result<Option<RangeListsOffset<R::Offset>>> {
+        match attr {
+            AttributeValue::RangeListsRef(offset) => {
+                Ok(Some(self.ranges_offset_from_raw(unit, offset)))
+            }
+            AttributeValue::DebugRngListsIndex(index) => self.ranges_offset(unit, index).map(Some),
+            _ => Ok(None),
+        }
+    }
+
+    /// Try to return an attribute value as a range list entry iterator.
+    ///
+    /// If the attribute value is one of:
+    ///
+    /// - a `DW_FORM_sec_offset` reference to the `.debug_ranges` or `.debug_rnglists` sections
+    /// - a `DW_FORM_rnglistx` index into the `.debug_rnglists` entries for the unit
+    ///
+    /// then return an iterator over the entries in the range list.
+    /// Returns `None` for other forms.
+    pub fn attr_ranges(
+        &self,
+        unit: &Unit<R>,
+        attr: AttributeValue<R>,
+    ) -> Result<Option<RngListIter<R>>> {
+        match self.attr_ranges_offset(unit, attr)? {
+            Some(offset) => Ok(Some(self.ranges(unit, offset)?)),
+            None => Ok(None),
+        }
+    }
+
+    /// Return an iterator for the address ranges of a `DebuggingInformationEntry`.
+    ///
+    /// This uses `DW_AT_low_pc`, `DW_AT_high_pc` and `DW_AT_ranges`.
+    pub fn die_ranges(
+        &self,
+        unit: &Unit<R>,
+        entry: &DebuggingInformationEntry<R>,
+    ) -> Result<RangeIter<R>> {
+        let mut low_pc = None;
+        let mut high_pc = None;
+        let mut size = None;
+        let mut attrs = entry.attrs();
+        while let Some(attr) = attrs.next()? {
+            match attr.name() {
+                constants::DW_AT_low_pc => {
+                    low_pc = Some(
+                        self.attr_address(unit, attr.value())?
+                            .ok_or(Error::UnsupportedAttributeForm)?,
+                    );
+                }
+                constants::DW_AT_high_pc => match attr.value() {
+                    AttributeValue::Udata(val) => size = Some(val),
+                    attr => {
+                        high_pc = Some(
+                            self.attr_address(unit, attr)?
+                                .ok_or(Error::UnsupportedAttributeForm)?,
+                        );
+                    }
+                },
+                constants::DW_AT_ranges => {
+                    if let Some(list) = self.attr_ranges(unit, attr.value())? {
+                        return Ok(RangeIter(RangeIterInner::List(list)));
+                    }
+                }
+                _ => {}
+            }
+        }
+        let range = low_pc.and_then(|begin| {
+            let end = size.map(|size| begin + size).or(high_pc);
+            // TODO: perhaps return an error if `end` is `None`
+            end.map(|end| Range { begin, end })
+        });
+        Ok(RangeIter(RangeIterInner::Single(range)))
+    }
+
+    /// Return an iterator for the address ranges of a `Unit`.
+    ///
+    /// This uses `DW_AT_low_pc`, `DW_AT_high_pc` and `DW_AT_ranges` of the
+    /// root `DebuggingInformationEntry`.
+    pub fn unit_ranges(&self, unit: &Unit<R>) -> Result<RangeIter<R>> {
+        let mut cursor = unit.header.entries(&unit.abbreviations);
+        cursor.next_dfs()?;
+        let root = cursor.current().ok_or(Error::MissingUnitDie)?;
+        self.die_ranges(unit, root)
+    }
+
+    /// Return the location list offset at the given index.
+    pub fn locations_offset(
+        &self,
+        unit: &Unit<R>,
+        index: DebugLocListsIndex<R::Offset>,
+    ) -> Result<LocationListsOffset<R::Offset>> {
+        self.locations
+            .get_offset(unit.encoding(), unit.loclists_base, index)
+    }
+
+    /// Iterate over the `LocationListEntry`s starting at the given offset.
+    pub fn locations(
+        &self,
+        unit: &Unit<R>,
+        offset: LocationListsOffset<R::Offset>,
+    ) -> Result<LocListIter<R>> {
+        match self.file_type {
+            DwarfFileType::Main => self.locations.locations(
+                offset,
+                unit.encoding(),
+                unit.low_pc,
+                &self.debug_addr,
+                unit.addr_base,
+            ),
+            DwarfFileType::Dwo => self.locations.locations_dwo(
+                offset,
+                unit.encoding(),
+                unit.low_pc,
+                &self.debug_addr,
+                unit.addr_base,
+            ),
+        }
+    }
+
+    /// Iterate over the raw `LocationListEntry`s starting at the given offset.
+    pub fn raw_locations(
+        &self,
+        unit: &Unit<R>,
+        offset: LocationListsOffset<R::Offset>,
+    ) -> Result<RawLocListIter<R>> {
+        match self.file_type {
+            DwarfFileType::Main => self.locations.raw_locations(offset, unit.encoding()),
+            DwarfFileType::Dwo => self.locations.raw_locations_dwo(offset, unit.encoding()),
+        }
+    }
+
+    /// Try to return an attribute value as a location list offset.
+    ///
+    /// If the attribute value is one of:
+    ///
+    /// - a `DW_FORM_sec_offset` reference to the `.debug_loc` or `.debug_loclists` sections
+    /// - a `DW_FORM_loclistx` index into the `.debug_loclists` entries for the unit
+    ///
+    /// then return the location list offset of the location list.
+    /// Returns `None` for other forms.
+    pub fn attr_locations_offset(
+        &self,
+        unit: &Unit<R>,
+        attr: AttributeValue<R>,
+    ) -> Result<Option<LocationListsOffset<R::Offset>>> {
+        match attr {
+            AttributeValue::LocationListsRef(offset) => Ok(Some(offset)),
+            AttributeValue::DebugLocListsIndex(index) => {
+                self.locations_offset(unit, index).map(Some)
+            }
+            _ => Ok(None),
+        }
+    }
+
+    /// Try to return an attribute value as a location list entry iterator.
+    ///
+    /// If the attribute value is one of:
+    ///
+    /// - a `DW_FORM_sec_offset` reference to the `.debug_loc` or `.debug_loclists` sections
+    /// - a `DW_FORM_loclistx` index into the `.debug_loclists` entries for the unit
+    ///
+    /// then return an iterator over the entries in the location list.
+    /// Returns `None` for other forms.
+    pub fn attr_locations(
+        &self,
+        unit: &Unit<R>,
+        attr: AttributeValue<R>,
+    ) -> Result<Option<LocListIter<R>>> {
+        match self.attr_locations_offset(unit, attr)? {
+            Some(offset) => Ok(Some(self.locations(unit, offset)?)),
+            None => Ok(None),
+        }
+    }
+
+    /// Call `Reader::lookup_offset_id` for each section, and return the first match.
+    ///
+    /// The first element of the tuple is `true` for supplementary sections.
+    pub fn lookup_offset_id(&self, id: ReaderOffsetId) -> Option<(bool, SectionId, R::Offset)> {
+        None.or_else(|| self.debug_abbrev.lookup_offset_id(id))
+            .or_else(|| self.debug_addr.lookup_offset_id(id))
+            .or_else(|| self.debug_aranges.lookup_offset_id(id))
+            .or_else(|| self.debug_info.lookup_offset_id(id))
+            .or_else(|| self.debug_line.lookup_offset_id(id))
+            .or_else(|| self.debug_line_str.lookup_offset_id(id))
+            .or_else(|| self.debug_str.lookup_offset_id(id))
+            .or_else(|| self.debug_str_offsets.lookup_offset_id(id))
+            .or_else(|| self.debug_types.lookup_offset_id(id))
+            .or_else(|| self.locations.lookup_offset_id(id))
+            .or_else(|| self.ranges.lookup_offset_id(id))
+            .map(|(id, offset)| (false, id, offset))
+            .or_else(|| {
+                self.sup()
+                    .and_then(|sup| sup.lookup_offset_id(id))
+                    .map(|(_, id, offset)| (true, id, offset))
+            })
+    }
+
+    /// Returns a string representation of the given error.
+    ///
+    /// This uses information from the DWARF sections to provide more information in some cases.
+    pub fn format_error(&self, err: Error) -> String {
+        #[allow(clippy::single_match)]
+        match err {
+            Error::UnexpectedEof(id) => match self.lookup_offset_id(id) {
+                Some((sup, section, offset)) => {
+                    return format!(
+                        "{} at {}{}+0x{:x}",
+                        err,
+                        section.name(),
+                        if sup { "(sup)" } else { "" },
+                        offset.into_u64(),
+                    );
+                }
+                None => {}
+            },
+            _ => {}
+        }
+        err.description().into()
+    }
+}
+
+impl<R: Clone> Dwarf<R> {
+    /// Assuming `self` was loaded from a .dwo, take the appropriate
+    /// sections from `parent` (which contains the skeleton unit for this
+    /// dwo) such as `.debug_addr` and merge them into this `Dwarf`.
+    pub fn make_dwo(&mut self, parent: &Dwarf<R>) {
+        self.file_type = DwarfFileType::Dwo;
+        // These sections are always taken from the parent file and not the dwo.
+        self.debug_addr = parent.debug_addr.clone();
+        // .debug_rnglists comes from the DWO, .debug_ranges comes from the
+        // parent file.
+        self.ranges
+            .set_debug_ranges(parent.ranges.debug_ranges().clone());
+        self.sup = parent.sup.clone();
+    }
+}
+
+/// The sections from a `.dwp` file.
+#[derive(Debug)]
+pub struct DwarfPackage<R: Reader> {
+    /// The compilation unit index in the `.debug_cu_index` section.
+    pub cu_index: UnitIndex<R>,
+
+    /// The type unit index in the `.debug_tu_index` section.
+    pub tu_index: UnitIndex<R>,
+
+    /// The `.debug_abbrev.dwo` section.
+    pub debug_abbrev: DebugAbbrev<R>,
+
+    /// The `.debug_info.dwo` section.
+    pub debug_info: DebugInfo<R>,
+
+    /// The `.debug_line.dwo` section.
+    pub debug_line: DebugLine<R>,
+
+    /// The `.debug_str.dwo` section.
+    pub debug_str: DebugStr<R>,
+
+    /// The `.debug_str_offsets.dwo` section.
+    pub debug_str_offsets: DebugStrOffsets<R>,
+
+    /// The `.debug_loc.dwo` section.
+    ///
+    /// Only present when using GNU split-dwarf extension to DWARF 4.
+    pub debug_loc: DebugLoc<R>,
+
+    /// The `.debug_loclists.dwo` section.
+    pub debug_loclists: DebugLocLists<R>,
+
+    /// The `.debug_rnglists.dwo` section.
+    pub debug_rnglists: DebugRngLists<R>,
+
+    /// The `.debug_types.dwo` section.
+    ///
+    /// Only present when using GNU split-dwarf extension to DWARF 4.
+    pub debug_types: DebugTypes<R>,
+
+    /// An empty section.
+    ///
+    /// Used when creating `Dwarf<R>`.
+    pub empty: R,
+}
+
+impl<R: Reader> DwarfPackage<R> {
+    /// Try to load the `.dwp` sections using the given loader function.
+    ///
+    /// `section` loads a DWARF section from the object file.
+    /// It should return an empty section if the section does not exist.
+    pub fn load<F, E>(mut section: F, empty: R) -> core::result::Result<Self, E>
+    where
+        F: FnMut(SectionId) -> core::result::Result<R, E>,
+        E: From<Error>,
+    {
+        Ok(DwarfPackage {
+            cu_index: DebugCuIndex::load(&mut section)?.index()?,
+            tu_index: DebugTuIndex::load(&mut section)?.index()?,
+            // Section types are inferred.
+            debug_abbrev: Section::load(&mut section)?,
+            debug_info: Section::load(&mut section)?,
+            debug_line: Section::load(&mut section)?,
+            debug_str: Section::load(&mut section)?,
+            debug_str_offsets: Section::load(&mut section)?,
+            debug_loc: Section::load(&mut section)?,
+            debug_loclists: Section::load(&mut section)?,
+            debug_rnglists: Section::load(&mut section)?,
+            debug_types: Section::load(&mut section)?,
+            empty,
+        })
+    }
+
+    /// Find the compilation unit with the given DWO identifier and return its section
+    /// contributions.
+    pub fn find_cu(&self, id: DwoId, parent: &Dwarf<R>) -> Result<Option<Dwarf<R>>> {
+        let row = match self.cu_index.find(id.0) {
+            Some(row) => row,
+            None => return Ok(None),
+        };
+        self.cu_sections(row, parent).map(Some)
+    }
+
+    /// Find the type unit with the given type signature and return its section
+    /// contributions.
+    pub fn find_tu(
+        &self,
+        signature: DebugTypeSignature,
+        parent: &Dwarf<R>,
+    ) -> Result<Option<Dwarf<R>>> {
+        let row = match self.tu_index.find(signature.0) {
+            Some(row) => row,
+            None => return Ok(None),
+        };
+        self.tu_sections(row, parent).map(Some)
+    }
+
+    /// Return the section contributions of the compilation unit at the given index.
+    ///
+    /// The index must be in the range `1..cu_index.unit_count`.
+    ///
+    /// This function should only be needed by low level parsers.
+    pub fn cu_sections(&self, index: u32, parent: &Dwarf<R>) -> Result<Dwarf<R>> {
+        self.sections(self.cu_index.sections(index)?, parent)
+    }
+
+    /// Return the section contributions of the compilation unit at the given index.
+    ///
+    /// The index must be in the range `1..tu_index.unit_count`.
+    ///
+    /// This function should only be needed by low level parsers.
+    pub fn tu_sections(&self, index: u32, parent: &Dwarf<R>) -> Result<Dwarf<R>> {
+        self.sections(self.tu_index.sections(index)?, parent)
+    }
+
+    /// Return the section contributions of a unit.
+    ///
+    /// This function should only be needed by low level parsers.
+    pub fn sections(
+        &self,
+        sections: UnitIndexSectionIterator<R>,
+        parent: &Dwarf<R>,
+    ) -> Result<Dwarf<R>> {
+        let mut abbrev_offset = 0;
+        let mut abbrev_size = 0;
+        let mut info_offset = 0;
+        let mut info_size = 0;
+        let mut line_offset = 0;
+        let mut line_size = 0;
+        let mut loc_offset = 0;
+        let mut loc_size = 0;
+        let mut loclists_offset = 0;
+        let mut loclists_size = 0;
+        let mut str_offsets_offset = 0;
+        let mut str_offsets_size = 0;
+        let mut rnglists_offset = 0;
+        let mut rnglists_size = 0;
+        let mut types_offset = 0;
+        let mut types_size = 0;
+        for section in sections {
+            match section.section {
+                SectionId::DebugAbbrev => {
+                    abbrev_offset = section.offset;
+                    abbrev_size = section.size;
+                }
+                SectionId::DebugInfo => {
+                    info_offset = section.offset;
+                    info_size = section.size;
+                }
+                SectionId::DebugLine => {
+                    line_offset = section.offset;
+                    line_size = section.size;
+                }
+                SectionId::DebugLoc => {
+                    loc_offset = section.offset;
+                    loc_size = section.size;
+                }
+                SectionId::DebugLocLists => {
+                    loclists_offset = section.offset;
+                    loclists_size = section.size;
+                }
+                SectionId::DebugStrOffsets => {
+                    str_offsets_offset = section.offset;
+                    str_offsets_size = section.size;
+                }
+                SectionId::DebugRngLists => {
+                    rnglists_offset = section.offset;
+                    rnglists_size = section.size;
+                }
+                SectionId::DebugTypes => {
+                    types_offset = section.offset;
+                    types_size = section.size;
+                }
+                SectionId::DebugMacro | SectionId::DebugMacinfo => {
+                    // These are valid but we can't parse these yet.
+                }
+                _ => return Err(Error::UnknownIndexSection),
+            }
+        }
+
+        let debug_abbrev = self.debug_abbrev.dwp_range(abbrev_offset, abbrev_size)?;
+        let debug_info = self.debug_info.dwp_range(info_offset, info_size)?;
+        let debug_line = self.debug_line.dwp_range(line_offset, line_size)?;
+        let debug_loc = self.debug_loc.dwp_range(loc_offset, loc_size)?;
+        let debug_loclists = self
+            .debug_loclists
+            .dwp_range(loclists_offset, loclists_size)?;
+        let debug_str_offsets = self
+            .debug_str_offsets
+            .dwp_range(str_offsets_offset, str_offsets_size)?;
+        let debug_rnglists = self
+            .debug_rnglists
+            .dwp_range(rnglists_offset, rnglists_size)?;
+        let debug_types = self.debug_types.dwp_range(types_offset, types_size)?;
+
+        let debug_str = self.debug_str.clone();
+
+        let debug_addr = parent.debug_addr.clone();
+        let debug_ranges = parent.ranges.debug_ranges().clone();
+
+        let debug_aranges = self.empty.clone().into();
+        let debug_line_str = self.empty.clone().into();
+
+        Ok(Dwarf {
+            debug_abbrev,
+            debug_addr,
+            debug_aranges,
+            debug_info,
+            debug_line,
+            debug_line_str,
+            debug_str,
+            debug_str_offsets,
+            debug_types,
+            locations: LocationLists::new(debug_loc, debug_loclists),
+            ranges: RangeLists::new(debug_ranges, debug_rnglists),
+            file_type: DwarfFileType::Dwo,
+            sup: parent.sup.clone(),
+            abbreviations_cache: AbbreviationsCache::new(),
+        })
+    }
+}
+
+/// All of the commonly used information for a unit in the `.debug_info` or `.debug_types`
+/// sections.
+#[derive(Debug)]
+pub struct Unit<R, Offset = <R as Reader>::Offset>
+where
+    R: Reader<Offset = Offset>,
+    Offset: ReaderOffset,
+{
+    /// The header of the unit.
+    pub header: UnitHeader<R, Offset>,
+
+    /// The parsed abbreviations for the unit.
+    pub abbreviations: Arc<Abbreviations>,
+
+    /// The `DW_AT_name` attribute of the unit.
+    pub name: Option<R>,
+
+    /// The `DW_AT_comp_dir` attribute of the unit.
+    pub comp_dir: Option<R>,
+
+    /// The `DW_AT_low_pc` attribute of the unit. Defaults to 0.
+    pub low_pc: u64,
+
+    /// The `DW_AT_str_offsets_base` attribute of the unit. Defaults to 0.
+    pub str_offsets_base: DebugStrOffsetsBase<Offset>,
+
+    /// The `DW_AT_addr_base` attribute of the unit. Defaults to 0.
+    pub addr_base: DebugAddrBase<Offset>,
+
+    /// The `DW_AT_loclists_base` attribute of the unit. Defaults to 0.
+    pub loclists_base: DebugLocListsBase<Offset>,
+
+    /// The `DW_AT_rnglists_base` attribute of the unit. Defaults to 0.
+    pub rnglists_base: DebugRngListsBase<Offset>,
+
+    /// The line number program of the unit.
+    pub line_program: Option<IncompleteLineProgram<R, Offset>>,
+
+    /// The DWO ID of a skeleton unit or split compilation unit.
+    pub dwo_id: Option<DwoId>,
+}
+
+impl<R: Reader> Unit<R> {
+    /// Construct a new `Unit` from the given unit header.
+    #[inline]
+    pub fn new(dwarf: &Dwarf<R>, header: UnitHeader<R>) -> Result<Self> {
+        let abbreviations = dwarf.abbreviations(&header)?;
+        Self::new_with_abbreviations(dwarf, header, abbreviations)
+    }
+
+    /// Construct a new `Unit` from the given unit header and abbreviations.
+    ///
+    /// The abbreviations for this call can be obtained using `dwarf.abbreviations(&header)`.
+    /// The caller may implement caching to reuse the `Abbreviations` across units with the
+    /// same `header.debug_abbrev_offset()` value.
+    #[inline]
+    pub fn new_with_abbreviations(
+        dwarf: &Dwarf<R>,
+        header: UnitHeader<R>,
+        abbreviations: Arc<Abbreviations>,
+    ) -> Result<Self> {
+        let mut unit = Unit {
+            abbreviations,
+            name: None,
+            comp_dir: None,
+            low_pc: 0,
+            str_offsets_base: DebugStrOffsetsBase::default_for_encoding_and_file(
+                header.encoding(),
+                dwarf.file_type,
+            ),
+            // NB: Because the .debug_addr section never lives in a .dwo, we can assume its base is always 0 or provided.
+            addr_base: DebugAddrBase(R::Offset::from_u8(0)),
+            loclists_base: DebugLocListsBase::default_for_encoding_and_file(
+                header.encoding(),
+                dwarf.file_type,
+            ),
+            rnglists_base: DebugRngListsBase::default_for_encoding_and_file(
+                header.encoding(),
+                dwarf.file_type,
+            ),
+            line_program: None,
+            dwo_id: match header.type_() {
+                UnitType::Skeleton(dwo_id) | UnitType::SplitCompilation(dwo_id) => Some(dwo_id),
+                _ => None,
+            },
+            header,
+        };
+        let mut name = None;
+        let mut comp_dir = None;
+        let mut line_program_offset = None;
+        let mut low_pc_attr = None;
+
+        {
+            let mut cursor = unit.header.entries(&unit.abbreviations);
+            cursor.next_dfs()?;
+            let root = cursor.current().ok_or(Error::MissingUnitDie)?;
+            let mut attrs = root.attrs();
+            while let Some(attr) = attrs.next()? {
+                match attr.name() {
+                    constants::DW_AT_name => {
+                        name = Some(attr.value());
+                    }
+                    constants::DW_AT_comp_dir => {
+                        comp_dir = Some(attr.value());
+                    }
+                    constants::DW_AT_low_pc => {
+                        low_pc_attr = Some(attr.value());
+                    }
+                    constants::DW_AT_stmt_list => {
+                        if let AttributeValue::DebugLineRef(offset) = attr.value() {
+                            line_program_offset = Some(offset);
+                        }
+                    }
+                    constants::DW_AT_str_offsets_base => {
+                        if let AttributeValue::DebugStrOffsetsBase(base) = attr.value() {
+                            unit.str_offsets_base = base;
+                        }
+                    }
+                    constants::DW_AT_addr_base | constants::DW_AT_GNU_addr_base => {
+                        if let AttributeValue::DebugAddrBase(base) = attr.value() {
+                            unit.addr_base = base;
+                        }
+                    }
+                    constants::DW_AT_loclists_base => {
+                        if let AttributeValue::DebugLocListsBase(base) = attr.value() {
+                            unit.loclists_base = base;
+                        }
+                    }
+                    constants::DW_AT_rnglists_base | constants::DW_AT_GNU_ranges_base => {
+                        if let AttributeValue::DebugRngListsBase(base) = attr.value() {
+                            unit.rnglists_base = base;
+                        }
+                    }
+                    constants::DW_AT_GNU_dwo_id => {
+                        if unit.dwo_id.is_none() {
+                            if let AttributeValue::DwoId(dwo_id) = attr.value() {
+                                unit.dwo_id = Some(dwo_id);
+                            }
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+
+        unit.name = match name {
+            Some(val) => dwarf.attr_string(&unit, val).ok(),
+            None => None,
+        };
+        unit.comp_dir = match comp_dir {
+            Some(val) => dwarf.attr_string(&unit, val).ok(),
+            None => None,
+        };
+        unit.line_program = match line_program_offset {
+            Some(offset) => Some(dwarf.debug_line.program(
+                offset,
+                unit.header.address_size(),
+                unit.comp_dir.clone(),
+                unit.name.clone(),
+            )?),
+            None => None,
+        };
+        if let Some(low_pc_attr) = low_pc_attr {
+            if let Some(addr) = dwarf.attr_address(&unit, low_pc_attr)? {
+                unit.low_pc = addr;
+            }
+        }
+        Ok(unit)
+    }
+
+    /// Return the encoding parameters for this unit.
+    #[inline]
+    pub fn encoding(&self) -> Encoding {
+        self.header.encoding()
+    }
+
+    /// Read the `DebuggingInformationEntry` at the given offset.
+    pub fn entry(&self, offset: UnitOffset<R::Offset>) -> Result<DebuggingInformationEntry<R>> {
+        self.header.entry(&self.abbreviations, offset)
+    }
+
+    /// Navigate this unit's `DebuggingInformationEntry`s.
+    #[inline]
+    pub fn entries(&self) -> EntriesCursor<R> {
+        self.header.entries(&self.abbreviations)
+    }
+
+    /// Navigate this unit's `DebuggingInformationEntry`s
+    /// starting at the given offset.
+    #[inline]
+    pub fn entries_at_offset(&self, offset: UnitOffset<R::Offset>) -> Result<EntriesCursor<R>> {
+        self.header.entries_at_offset(&self.abbreviations, offset)
+    }
+
+    /// Navigate this unit's `DebuggingInformationEntry`s as a tree
+    /// starting at the given offset.
+    #[inline]
+    pub fn entries_tree(&self, offset: Option<UnitOffset<R::Offset>>) -> Result<EntriesTree<R>> {
+        self.header.entries_tree(&self.abbreviations, offset)
+    }
+
+    /// Read the raw data that defines the Debugging Information Entries.
+    #[inline]
+    pub fn entries_raw(&self, offset: Option<UnitOffset<R::Offset>>) -> Result<EntriesRaw<R>> {
+        self.header.entries_raw(&self.abbreviations, offset)
+    }
+
+    /// Copy attributes that are subject to relocation from another unit. This is intended
+    /// to be used to copy attributes from a skeleton compilation unit to the corresponding
+    /// split compilation unit.
+    pub fn copy_relocated_attributes(&mut self, other: &Unit<R>) {
+        self.low_pc = other.low_pc;
+        self.addr_base = other.addr_base;
+        if self.header.version() < 5 {
+            self.rnglists_base = other.rnglists_base;
+        }
+    }
+
+    /// Find the dwo name (if any) for this unit, automatically handling the differences
+    /// between the standardized DWARF 5 split DWARF format and the pre-DWARF 5 GNU
+    /// extension.
+    ///
+    /// The returned value is relative to this unit's `comp_dir`.
+    pub fn dwo_name(&self) -> Result<Option<AttributeValue<R>>> {
+        let mut entries = self.entries();
+        if let None = entries.next_entry()? {
+            return Ok(None);
+        }
+
+        let entry = entries.current().unwrap();
+        if self.header.version() < 5 {
+            entry.attr_value(constants::DW_AT_GNU_dwo_name)
+        } else {
+            entry.attr_value(constants::DW_AT_dwo_name)
+        }
+    }
+}
+
+impl<T: ReaderOffset> UnitSectionOffset<T> {
+    /// Convert an offset to be relative to the start of the given unit,
+    /// instead of relative to the start of the section.
+    /// Returns `None` if the offset is not within the unit entries.
+    pub fn to_unit_offset<R>(&self, unit: &Unit<R>) -> Option<UnitOffset<T>>
+    where
+        R: Reader<Offset = T>,
+    {
+        let (offset, unit_offset) = match (self, unit.header.offset()) {
+            (
+                UnitSectionOffset::DebugInfoOffset(offset),
+                UnitSectionOffset::DebugInfoOffset(unit_offset),
+            ) => (offset.0, unit_offset.0),
+            (
+                UnitSectionOffset::DebugTypesOffset(offset),
+                UnitSectionOffset::DebugTypesOffset(unit_offset),
+            ) => (offset.0, unit_offset.0),
+            _ => return None,
+        };
+        let offset = match offset.checked_sub(unit_offset) {
+            Some(offset) => UnitOffset(offset),
+            None => return None,
+        };
+        if !unit.header.is_valid_offset(offset) {
+            return None;
+        }
+        Some(offset)
+    }
+}
+
+impl<T: ReaderOffset> UnitOffset<T> {
+    /// Convert an offset to be relative to the start of the .debug_info section,
+    /// instead of relative to the start of the given compilation unit.
+    ///
+    /// Does not check that the offset is valid.
+    pub fn to_unit_section_offset<R>(&self, unit: &Unit<R>) -> UnitSectionOffset<T>
+    where
+        R: Reader<Offset = T>,
+    {
+        match unit.header.offset() {
+            UnitSectionOffset::DebugInfoOffset(unit_offset) => {
+                DebugInfoOffset(unit_offset.0 + self.0).into()
+            }
+            UnitSectionOffset::DebugTypesOffset(unit_offset) => {
+                DebugTypesOffset(unit_offset.0 + self.0).into()
+            }
+        }
+    }
+}
+
+/// An iterator for the address ranges of a `DebuggingInformationEntry`.
+///
+/// Returned by `Dwarf::die_ranges` and `Dwarf::unit_ranges`.
+#[derive(Debug)]
+pub struct RangeIter<R: Reader>(RangeIterInner<R>);
+
+#[derive(Debug)]
+enum RangeIterInner<R: Reader> {
+    Single(Option<Range>),
+    List(RngListIter<R>),
+}
+
+impl<R: Reader> Default for RangeIter<R> {
+    fn default() -> Self {
+        RangeIter(RangeIterInner::Single(None))
+    }
+}
+
+impl<R: Reader> RangeIter<R> {
+    /// Advance the iterator to the next range.
+    pub fn next(&mut self) -> Result<Option<Range>> {
+        match self.0 {
+            RangeIterInner::Single(ref mut range) => Ok(range.take()),
+            RangeIterInner::List(ref mut list) => list.next(),
+        }
+    }
+}
+
+#[cfg(feature = "fallible-iterator")]
+impl<R: Reader> fallible_iterator::FallibleIterator for RangeIter<R> {
+    type Item = Range;
+    type Error = Error;
+
+    #[inline]
+    fn next(&mut self) -> ::core::result::Result<Option<Self::Item>, Self::Error> {
+        RangeIter::next(self)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::read::EndianSlice;
+    use crate::{Endianity, LittleEndian};
+
+    /// Ensure that `Dwarf<R>` is covariant wrt R.
+    #[test]
+    fn test_dwarf_variance() {
+        /// This only needs to compile.
+        fn _f<'a: 'b, 'b, E: Endianity>(x: Dwarf<EndianSlice<'a, E>>) -> Dwarf<EndianSlice<'b, E>> {
+            x
+        }
+    }
+
+    /// Ensure that `Unit<R>` is covariant wrt R.
+    #[test]
+    fn test_dwarf_unit_variance() {
+        /// This only needs to compile.
+        fn _f<'a: 'b, 'b, E: Endianity>(x: Unit<EndianSlice<'a, E>>) -> Unit<EndianSlice<'b, E>> {
+            x
+        }
+    }
+
+    #[test]
+    fn test_send() {
+        fn assert_is_send<T: Send>() {}
+        assert_is_send::<Dwarf<EndianSlice<LittleEndian>>>();
+        assert_is_send::<Unit<EndianSlice<LittleEndian>>>();
+    }
+
+    #[test]
+    fn test_format_error() {
+        let mut owned_dwarf = Dwarf::load(|_| -> Result<_> { Ok(vec![1, 2]) }).unwrap();
+        owned_dwarf
+            .load_sup(|_| -> Result<_> { Ok(vec![1, 2]) })
+            .unwrap();
+        let dwarf = owned_dwarf.borrow(|section| EndianSlice::new(&section, LittleEndian));
+
+        match dwarf.debug_str.get_str(DebugStrOffset(1)) {
+            Ok(r) => panic!("Unexpected str {:?}", r),
+            Err(e) => {
+                assert_eq!(
+                    dwarf.format_error(e),
+                    "Hit the end of input before it was expected at .debug_str+0x1"
+                );
+            }
+        }
+        match dwarf.sup().unwrap().debug_str.get_str(DebugStrOffset(1)) {
+            Ok(r) => panic!("Unexpected str {:?}", r),
+            Err(e) => {
+                assert_eq!(
+                    dwarf.format_error(e),
+                    "Hit the end of input before it was expected at .debug_str(sup)+0x1"
+                );
+            }
+        }
+        assert_eq!(dwarf.format_error(Error::Io), Error::Io.description());
+    }
+}