Module gimli::read

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 dwarf = gimli::Dwarf::load(loader, 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.

  • 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.

Using with FallibleIterator

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::items` returns a `FallibleIterator`!
    aranges.items()
        // `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.
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.
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.
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.
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 or .debug_rnglists 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.
UninitializedUnwindContext	Common context needed when evaluating the call frame unwinding information.
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.
UnitOffset	An offset into the current compilation or type unit.
UnwindContext	An unwinding context.
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

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:
UnwindOffset	An offset into an UnwindSection.
UnwindSection	A section holding unwind information: either .debug_frame or .eh_frame. See DebugFrame and EhFrame respectively.

Type Definitions

CompleteLineNumberProgram	Deprecated Deprecated. CompleteLineNumberProgram has been renamed to CompleteLineProgram.
EndianBuf	Deprecated EndianBuf has been renamed to EndianSlice. For ease of upgrading across gimli versions, we export this type alias.
IncompleteLineNumberProgram	Deprecated Deprecated. IncompleteLineNumberProgram has been renamed to IncompleteLineProgram.
LineNumberProgram	Deprecated Deprecated. LineNumberProgram has been renamed to LineProgram.
LineNumberProgramHeader	Deprecated Deprecated. LineNumberProgramHeader has been renamed to LineProgramHeader.
LineNumberRow	Deprecated Deprecated. LineNumberRow has been renamed to LineRow.
LineNumberSequence	Deprecated Deprecated. LineNumberSequence has been renamed to LineSequence.
Opcode	Deprecated Deprecated. Opcode has been renamed to LineInstruction.
OpcodesIter	Deprecated Deprecated. OpcodesIter has been renamed to LineInstructions.
Result	The result of a parse.
StateMachine	Deprecated Deprecated. StateMachine has been renamed to LineRows.