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Refactor location and range list parsing to take an enum specifying t…
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…he encoding, and add new _dwo methods on LocationsList that always use the new section and encoding regardless of the DWARF version to support the non-standard GNU split dwarf extension.
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@khuey
khuey committed Jul 14, 2020
1 parent 9d88443 commit 6d32a8e
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Showing 2 changed files with 190 additions and 112 deletions.
179 changes: 119 additions & 60 deletions src/read/loclists.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -196,6 +196,25 @@ impl<R: Reader> LocationLists<R> {
))
}

/// Similar to `locations`, but with special handling for .dwo files.
/// This should only been used when this `LocationLists` was loaded from a
/// .dwo file.
pub fn locations_dwo(
&self,
offset: LocationListsOffset<R::Offset>,
unit_encoding: Encoding,
base_address: u64,
debug_addr: &DebugAddr<R>,
debug_addr_base: DebugAddrBase<R::Offset>,
) -> Result<LocListIter<R>> {
Ok(LocListIter::new(
self.raw_locations_dwo(offset, unit_encoding)?,
base_address,
debug_addr.clone(),
debug_addr_base,
))
}

/// Iterate over the raw `LocationListEntry`s starting at the given offset.
///
/// The `unit_encoding` must match the compilation unit that the
Expand All @@ -210,14 +229,38 @@ impl<R: Reader> LocationLists<R> {
&self,
offset: LocationListsOffset<R::Offset>,
unit_encoding: Encoding,
) -> Result<RawLocListIter<R>> {
let (mut input, format) = if unit_encoding.version <= 4 {
(self.debug_loc.section.clone(), LocListsFormat::Bare)
} else {
(self.debug_loclists.section.clone(), LocListsFormat::LLE)
};
input.skip(offset.0)?;
Ok(RawLocListIter::new(input, unit_encoding, format))
}

/// Similar to `raw_locations`, but with special handling for .dwo files.
/// This should only been used when this `LocationLists` was loaded from a
/// .dwo file.
pub fn raw_locations_dwo(
&self,
offset: LocationListsOffset<R::Offset>,
unit_encoding: Encoding,
) -> Result<RawLocListIter<R>> {
let mut input = if unit_encoding.version <= 4 {
// In the GNU split dwarf extension the locations are present in the
// .debug_loc section but are encoded with the DW_LLE values used
// for the DWARF 5 .debug_loclists section.
self.debug_loc.section.clone()
} else {
self.debug_loclists.section.clone()
};
input.skip(offset.0)?;
Ok(RawLocListIter::new(input, unit_encoding))
Ok(RawLocListIter::new(
input,
unit_encoding,
LocListsFormat::LLE,
))
}

/// Returns the `.debug_loclists` offset at the given `base` and `index`.
Expand Down Expand Up @@ -251,6 +294,15 @@ impl<R: Reader> LocationLists<R> {
}
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum LocListsFormat {
/// The bare location list format used before DWARF 5.
Bare,
/// The DW_LLE encoded range list format used in DWARF 5 and the non-standard GNU
/// split dwarf extension.
LLE,
}

/// A raw iterator over a location list.
///
/// This iterator does not perform any processing of the location entries,
Expand All @@ -259,6 +311,7 @@ impl<R: Reader> LocationLists<R> {
pub struct RawLocListIter<R: Reader> {
input: R,
encoding: Encoding,
format: LocListsFormat,
}

/// A raw entry in .debug_loclists.
Expand Down Expand Up @@ -342,70 +395,76 @@ fn parse_data<R: Reader>(input: &mut R) -> Result<Expression<R>> {

impl<R: Reader> RawLocListEntry<R> {
/// Parse a location list entry from `.debug_loclists`
fn parse(input: &mut R, encoding: Encoding) -> Result<Option<Self>> {
if encoding.version < 5 {
let range = RawRange::parse(input, encoding.address_size)?;
return Ok(if range.is_end() {
None
} else if range.is_base_address(encoding.address_size) {
Some(RawLocListEntry::BaseAddress { addr: range.end })
} else {
let len = R::Offset::from_u16(input.read_u16()?);
let data = Expression(input.split(len)?);
Some(RawLocListEntry::AddressOrOffsetPair {
begin: range.begin,
end: range.end,
data,
})
});
}
Ok(match constants::DwLle(input.read_u8()?) {
constants::DW_LLE_end_of_list => None,
constants::DW_LLE_base_addressx => Some(RawLocListEntry::BaseAddressx {
addr: DebugAddrIndex(input.read_uleb128().and_then(R::Offset::from_u64)?),
}),
constants::DW_LLE_startx_endx => Some(RawLocListEntry::StartxEndx {
begin: DebugAddrIndex(input.read_uleb128().and_then(R::Offset::from_u64)?),
end: DebugAddrIndex(input.read_uleb128().and_then(R::Offset::from_u64)?),
data: parse_data(input)?,
}),
constants::DW_LLE_startx_length => Some(RawLocListEntry::StartxLength {
begin: DebugAddrIndex(input.read_uleb128().and_then(R::Offset::from_u64)?),
length: input.read_uleb128()?,
data: parse_data(input)?,
}),
constants::DW_LLE_offset_pair => Some(RawLocListEntry::OffsetPair {
begin: input.read_uleb128()?,
end: input.read_uleb128()?,
data: parse_data(input)?,
}),
constants::DW_LLE_default_location => Some(RawLocListEntry::DefaultLocation {
data: parse_data(input)?,
}),
constants::DW_LLE_base_address => Some(RawLocListEntry::BaseAddress {
addr: input.read_address(encoding.address_size)?,
}),
constants::DW_LLE_start_end => Some(RawLocListEntry::StartEnd {
begin: input.read_address(encoding.address_size)?,
end: input.read_address(encoding.address_size)?,
data: parse_data(input)?,
}),
constants::DW_LLE_start_length => Some(RawLocListEntry::StartLength {
begin: input.read_address(encoding.address_size)?,
length: input.read_uleb128()?,
data: parse_data(input)?,
}),
_ => {
return Err(Error::InvalidAddressRange);
fn parse(input: &mut R, encoding: Encoding, format: LocListsFormat) -> Result<Option<Self>> {
match format {
LocListsFormat::Bare => {
let range = RawRange::parse(input, encoding.address_size)?;
return Ok(if range.is_end() {
None
} else if range.is_base_address(encoding.address_size) {
Some(RawLocListEntry::BaseAddress { addr: range.end })
} else {
let len = R::Offset::from_u16(input.read_u16()?);
let data = Expression(input.split(len)?);
Some(RawLocListEntry::AddressOrOffsetPair {
begin: range.begin,
end: range.end,
data,
})
});
}
})
LocListsFormat::LLE => Ok(match constants::DwLle(input.read_u8()?) {
constants::DW_LLE_end_of_list => None,
constants::DW_LLE_base_addressx => Some(RawLocListEntry::BaseAddressx {
addr: DebugAddrIndex(input.read_uleb128().and_then(R::Offset::from_u64)?),
}),
constants::DW_LLE_startx_endx => Some(RawLocListEntry::StartxEndx {
begin: DebugAddrIndex(input.read_uleb128().and_then(R::Offset::from_u64)?),
end: DebugAddrIndex(input.read_uleb128().and_then(R::Offset::from_u64)?),
data: parse_data(input)?,
}),
constants::DW_LLE_startx_length => Some(RawLocListEntry::StartxLength {
begin: DebugAddrIndex(input.read_uleb128().and_then(R::Offset::from_u64)?),
length: input.read_uleb128()?,
data: parse_data(input)?,
}),
constants::DW_LLE_offset_pair => Some(RawLocListEntry::OffsetPair {
begin: input.read_uleb128()?,
end: input.read_uleb128()?,
data: parse_data(input)?,
}),
constants::DW_LLE_default_location => Some(RawLocListEntry::DefaultLocation {
data: parse_data(input)?,
}),
constants::DW_LLE_base_address => Some(RawLocListEntry::BaseAddress {
addr: input.read_address(encoding.address_size)?,
}),
constants::DW_LLE_start_end => Some(RawLocListEntry::StartEnd {
begin: input.read_address(encoding.address_size)?,
end: input.read_address(encoding.address_size)?,
data: parse_data(input)?,
}),
constants::DW_LLE_start_length => Some(RawLocListEntry::StartLength {
begin: input.read_address(encoding.address_size)?,
length: input.read_uleb128()?,
data: parse_data(input)?,
}),
_ => {
return Err(Error::InvalidAddressRange);
}
}),
}
}
}

impl<R: Reader> RawLocListIter<R> {
/// Construct a `RawLocListIter`.
pub fn new(input: R, encoding: Encoding) -> RawLocListIter<R> {
RawLocListIter { input, encoding }
fn new(input: R, encoding: Encoding, format: LocListsFormat) -> RawLocListIter<R> {
RawLocListIter {
input,
encoding,
format,
}
}

/// Advance the iterator to the next location.
Expand All @@ -414,7 +473,7 @@ impl<R: Reader> RawLocListIter<R> {
return Ok(None);
}

match RawLocListEntry::parse(&mut self.input, self.encoding) {
match RawLocListEntry::parse(&mut self.input, self.encoding, self.format) {
Ok(entry) => {
if entry.is_none() {
self.input.empty();
Expand Down
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