Module gimli::read

Expand description

Read DWARF debugging information.

Example Usage
API Structure
Using with FallibleIterator

Example Usage

Print out all of the functions in the debuggee program:

// Read the DWARF sections with whatever object loader you're using.
// These closures should return a `Reader` instance (e.g. `EndianSlice`).
let loader = |section: gimli::SectionId| { get_file_section_reader(section.name()) };
let sup_loader = |section: gimli::SectionId| { get_sup_file_section_reader(section.name()) };
let mut dwarf = gimli::Dwarf::load(loader)?;
dwarf.load_sup(sup_loader)?;

// Iterate over all compilation units.
let mut iter = dwarf.units();
while let Some(header) = iter.next()? {
    // Parse the abbreviations and other information for this compilation unit.
    let unit = dwarf.unit(header)?;

    // Iterate over all of this compilation unit's entries.
    let mut entries = unit.entries();
    while let Some((_, entry)) = entries.next_dfs()? {
        // If we find an entry for a function, print it.
        if entry.tag() == gimli::DW_TAG_subprogram {
            println!("Found a function: {:?}", entry);
        }
    }
}

Full example programs:

A simple parser
A dwarfdump clone
An addr2line clone
ddbug, a utility giving insight into code generation by making debugging information readable
dwprod, a tiny utility to list the compilers used to create each compilation unit within a shared library or executable (via DW_AT_producer)
dwarf-validate, a program to validate the integrity of some DWARF and its references between sections and compilation units.

API Structure

Basic familiarity with DWARF is assumed.
The Dwarf type contains the commonly used DWARF sections. It has methods that simplify access to debugging data that spans multiple sections. Use of this type is optional, but recommended.
Each section gets its own type. Consider these types the entry points to the library:
- DebugAbbrev: The .debug_abbrev section.
- DebugAddr: The .debug_addr section.
- DebugAranges: The .debug_aranges section.
- DebugFrame: The .debug_frame section.
- DebugInfo: The .debug_info section.
- DebugLine: The .debug_line section.
- DebugLineStr: The .debug_line_str section.
- DebugLoc: The .debug_loc section.
- DebugLocLists: The .debug_loclists section.
- DebugPubNames: The .debug_pubnames section.
- DebugPubTypes: The .debug_pubtypes section.
- DebugRanges: The .debug_ranges section.
- DebugRngLists: The .debug_rnglists section.
- DebugStr: The .debug_str section.
- DebugStrOffsets: The .debug_str_offsets section.
- DebugTypes: The .debug_types section.
- DebugCuIndex: The .debug_cu_index section.
- DebugTuIndex: The .debug_tu_index section.
- EhFrame: The .eh_frame section.
- EhFrameHdr: The .eh_frame_hdr section.
Each section type exposes methods for accessing the debugging data encoded in that section. For example, the DebugInfo struct has the units method for iterating over the compilation units defined within it.
Offsets into a section are strongly typed: an offset into .debug_info is the DebugInfoOffset type. It cannot be used to index into the DebugLine type because DebugLine represents the .debug_line section. There are similar types for offsets relative to a compilation unit rather than a section.

The standard library’s Iterator trait and related APIs do not play well with iterators where the next operation is fallible. One can make the Iterator’s associated Item type be a Result<T, E>, however the provided methods cannot gracefully handle the case when an Err is returned.

This situation led to the fallible-iterator crate’s existence. You can read more of the rationale for its existence in its docs. The crate provides the helpers you have come to expect (eg map, filter, etc) for iterators that can fail.

gimli’s many lazy parsing iterators are a perfect match for the fallible-iterator crate’s FallibleIterator trait because parsing is not done eagerly. Parse errors later in the input might only be discovered after having iterated through many items.

To use gimli iterators with FallibleIterator, import the crate and trait into your code:

// Use the `FallibleIterator` trait so its methods are in scope!
use fallible_iterator::FallibleIterator;
use gimli::{DebugAranges, EndianSlice, LittleEndian};

fn find_sum_of_address_range_lengths(aranges: DebugAranges<EndianSlice<LittleEndian>>)
    -> gimli::Result<u64>
{
    // `DebugAranges::headers` returns a `FallibleIterator`!
    aranges.headers()
        // `flat_map` is provided by `FallibleIterator`!
        .flat_map(|header| Ok(header.entries()))
        // `map` is provided by `FallibleIterator`!
        .map(|arange| Ok(arange.length()))
        // `fold` is provided by `FallibleIterator`!
        .fold(0, |sum, len| Ok(sum + len))
}

Structs

Abbreviation

An abbreviation describes the shape of a DebuggingInformationEntry’s type: its code, tag type, whether it has children, and its set of attributes.

Abbreviations

A set of type abbreviations.

ArangeEntry

A single parsed arange.

ArangeEntryIter

An iterator over the aranges from a .debug_aranges section.

ArangeHeader

A header for a set of entries in the .debug_arange section.

ArangeHeaderIter

An iterator over the headers of a .debug_aranges section.

Attribute

An attribute in a DebuggingInformationEntry, consisting of a name and associated value.

AttributeSpecification

The description of an attribute in an abbreviated type. It is a pair of name and form.

AttrsIter

An iterator over a particular entry’s attributes.

Augmentation

We support the z-style augmentation defined by .eh_frame.

BaseAddresses

Optional base addresses for the relative DW_EH_PE_* encoded pointers.

CallFrameInstructionIter

A lazy iterator parsing call frame instructions.

CfiEntriesIter

An iterator over CIE and FDE entries in a .debug_frame or .eh_frame section.

CommonInformationEntry

A Common Information Entry holds information that is shared among many Frame Description Entries. There is at least one CIE in every non-empty .debug_frame section.

CompleteLineProgram

A line number program that has previously been run to completion.

DebugAbbrev

The DebugAbbrev struct represents the abbreviations describing DebuggingInformationEntrys’ attribute names and forms found in the .debug_abbrev section.

DebugAddr

The raw contents of the .debug_addr section.

DebugAranges

The DebugAranges struct represents the DWARF address range information found in the .debug_aranges section.

DebugCuIndex

The data in the .debug_cu_index section of a .dwp file.

DebugFrame

DebugFrame contains the .debug_frame section’s frame unwinding information required to unwind to and recover registers from older frames on the stack. For example, this is useful for a debugger that wants to print locals in a backtrace.

DebugInfo

The DebugInfo struct represents the DWARF debugging information found in the .debug_info section.

DebugInfoUnitHeadersIter

An iterator over the units of a .debug_info section.

DebugLine

The DebugLine struct contains the source location to instruction mapping found in the .debug_line section.

DebugLineStr

The DebugLineStr struct represents the DWARF strings found in the .debug_line_str section.

DebugLoc

The raw contents of the .debug_loc section.

DebugLocLists

The DebugLocLists struct represents the DWARF data found in the .debug_loclists section.

DebugPubNames

The DebugPubNames struct represents the DWARF public names information found in the .debug_pubnames section.

DebugPubTypes

The DebugPubTypes struct represents the DWARF public types information found in the .debug_info section.

DebugRanges

The raw contents of the .debug_ranges section.

DebugRngLists

The DebugRngLists struct represents the contents of the .debug_rnglists section.

DebugStr

The DebugStr struct represents the DWARF strings found in the .debug_str section.

DebugStrOffsets

The raw contents of the .debug_str_offsets section.

DebugTuIndex

The data in the .debug_tu_index section of a .dwp file.

DebugTypes

The DebugTypes struct represents the DWARF type information found in the .debug_types section.

DebugTypesUnitHeadersIter

An iterator over the type-units of this .debug_types section.

DebuggingInformationEntry

A Debugging Information Entry (DIE).

Dwarf

All of the commonly used DWARF sections, and other common information.

DwarfPackage

The sections from a .dwp file.

EhFrame

EhFrame contains the frame unwinding information needed during exception handling found in the .eh_frame section.

EhFrameHdr

EhFrameHdr contains the information about the .eh_frame_hdr section.

EhHdrTable

The CFI binary search table that is an optional part of the .eh_frame_hdr section.

EndianSlice

A &[u8] slice with endianity metadata.

EntriesCursor

A cursor into the Debugging Information Entries tree for a compilation unit.

EntriesRaw

A raw reader of the data that defines the Debugging Information Entries.

EntriesTree

The state information for a tree view of the Debugging Information Entries.

EntriesTreeIter

An iterator that allows traversal of the children of an EntriesTreeNode.

EntriesTreeNode

A node in the Debugging Information Entry tree.

Evaluation

A DWARF expression evaluator.

Expression

The bytecode for a DWARF expression or location description.

FileEntry

An entry in the LineProgramHeader’s file_names set.

FileEntryFormat

The format of a component of an include directory or file name entry.

FrameDescriptionEntry

A FrameDescriptionEntry is a set of CFA instructions for an address range.

IncompleteLineProgram

A line number program that has not been run to completion.

LineInstructions

An iterator yielding parsed instructions.

LineProgramHeader

A header for a line number program in the .debug_line section, as defined in section 6.2.4 of the standard.

LineRow

A row in the line number program’s resulting matrix.

LineRows

Executes a LineProgram to iterate over the rows in the matrix of line number information.

LineSequence

A sequence within a line number program. A sequence, as defined in section 6.2.5 of the standard, is a linear subset of a line number program within which addresses are monotonically increasing.

LocListIter

An iterator over a location list.

LocationListEntry

A location list entry from the .debug_loc or .debug_loclists sections.

LocationLists

The DWARF data found in .debug_loc and .debug_loclists sections.

OperationIter

An iterator for the operations in an expression.

ParsedEhFrameHdr

ParsedEhFrameHdr contains the parsed information from the .eh_frame_hdr section.

PartialFrameDescriptionEntry

A partially parsed FrameDescriptionEntry.

Piece

The description of a single piece of the result of a DWARF expression.

PubNamesEntry

A single parsed pubname.

PubNamesEntryIter

An iterator over the pubnames from a .debug_pubnames section.

PubTypesEntry

A single parsed pubtype.

PubTypesEntryIter

An iterator over the pubtypes from a .debug_pubtypes section.

Range

An address range from the .debug_ranges, .debug_rnglists, or .debug_aranges sections.

RangeIter

An iterator for the address ranges of a DebuggingInformationEntry.

RangeLists

The DWARF data found in .debug_ranges and .debug_rnglists sections.

RawLocListIter

A raw iterator over a location list.

RawRngListIter

A raw iterator over an address range list.

ReaderOffsetId

An identifier for an offset within a section reader.

RegisterRuleIter

An unordered iterator for register rules.

RngListIter

An iterator over an address range list.

SectionBaseAddresses

Optional base addresses for the relative DW_EH_PE_* encoded pointers in a particular section.

StoreOnHeap

Indicates that storage should be allocated on heap.

Unit

All of the commonly used information for a unit in the .debug_info or .debug_types sections.

UnitHeader

The common fields for the headers of compilation units and type units.

UnitIndex

The partially parsed index from a DebugCuIndex or DebugTuIndex.

UnitIndexSection

Information about a unit’s contribution to a section in a .dwp file.

UnitIndexSectionIterator

An iterator over the section offsets and sizes for a row in a UnitIndex.

UnitOffset

An offset into the current compilation or type unit.

UnwindContext

Common context needed when evaluating the call frame unwinding information.

UnwindTable

The UnwindTable iteratively evaluates a FrameDescriptionEntry’s CallFrameInstruction program, yielding the each row one at a time.

UnwindTableRow

A row in the virtual unwind table that describes how to find the values of the registers in the previous frame for a range of PC addresses.

Enums

AttributeValue

The value of an attribute in a DebuggingInformationEntry.

CallFrameInstruction

A parsed call frame instruction.

CfaRule

The canonical frame address (CFA) recovery rules.

CieOrFde

Either a CommonInformationEntry (CIE) or a FrameDescriptionEntry (FDE).

ColumnType

The type of column that a row is referring to.

DieReference

A reference to a DIE, either relative to the current CU or relative to the section.

Error

An error that occurred when parsing.

EvaluationResult

The state of an Evaluation after evaluating a DWARF expression. The evaluation is either Complete, or it requires more data to continue, as described by the variant.

LineInstruction

A parsed line number program instruction.

Location

A single location of a piece of the result of a DWARF expression.

Operation

A single decoded DWARF expression operation.

Pointer

A decoded pointer.

RawLocListEntry

A raw entry in .debug_loclists.

RawRngListEntry

A raw entry in .debug_rnglists

RegisterRule

An entry in the abstract CFI table that describes how to find the value of a register.

UnitType

This enum specifies the type of the unit and any type specific data carried in the header (e.g. the type signature/type offset of a type unit).

Value

The value of an entry on the DWARF stack.

ValueType

The type of an entry on the DWARF stack.

Traits

ArrayLike

Marker trait for types that can be used as backing storage when a growable array type is needed.

EvaluationStorage

Specification of what storage should be used for Evaluation.

LineProgram

A LineProgram provides access to a LineProgramHeader and a way to add files to the files table if necessary. Gimli consumers should never need to use or see this trait.

Reader

A trait for reading the data from a DWARF section.

ReaderOffset

A trait for offsets with a DWARF section.

Section

A convenience trait for loading DWARF sections from object files. To be used like:

UnwindContextStorage

Specification of what storage should be used for UnwindContext.

UnwindOffset

An offset into an UnwindSection.

UnwindSection

A section holding unwind information: either .debug_frame or .eh_frame. See DebugFrame and EhFrame respectively.