package dwarf

import "debug/dwarf"

Package dwarf provides access to DWARF debugging information loaded from executable files, as defined in the DWARF 2.0 Standard at


Package Files

buf.go class_string.go const.go entry.go line.go open.go type.go typeunit.go unit.go


var ErrUnknownPC = errors.New("ErrUnknownPC")

ErrUnknownPC is the error returned by LineReader.ScanPC when the seek PC is not covered by any entry in the line table.

type AddrType Uses

type AddrType struct {

An AddrType represents a machine address type.

type ArrayType Uses

type ArrayType struct {
    Type          Type
    StrideBitSize int64 // if > 0, number of bits to hold each element
    Count         int64 // if == -1, an incomplete array, like char x[].

An ArrayType represents a fixed size array type.

func (*ArrayType) Size Uses

func (t *ArrayType) Size() int64

func (*ArrayType) String Uses

func (t *ArrayType) String() string

type Attr Uses

type Attr uint32

An Attr identifies the attribute type in a DWARF Entry's Field.

const (
    AttrSibling        Attr = 0x01
    AttrLocation       Attr = 0x02
    AttrName           Attr = 0x03
    AttrOrdering       Attr = 0x09
    AttrByteSize       Attr = 0x0B
    AttrBitOffset      Attr = 0x0C
    AttrBitSize        Attr = 0x0D
    AttrStmtList       Attr = 0x10
    AttrLowpc          Attr = 0x11
    AttrHighpc         Attr = 0x12
    AttrLanguage       Attr = 0x13
    AttrDiscr          Attr = 0x15
    AttrDiscrValue     Attr = 0x16
    AttrVisibility     Attr = 0x17
    AttrImport         Attr = 0x18
    AttrStringLength   Attr = 0x19
    AttrCommonRef      Attr = 0x1A
    AttrCompDir        Attr = 0x1B
    AttrConstValue     Attr = 0x1C
    AttrContainingType Attr = 0x1D
    AttrDefaultValue   Attr = 0x1E
    AttrInline         Attr = 0x20
    AttrIsOptional     Attr = 0x21
    AttrLowerBound     Attr = 0x22
    AttrProducer       Attr = 0x25
    AttrPrototyped     Attr = 0x27
    AttrReturnAddr     Attr = 0x2A
    AttrStartScope     Attr = 0x2C
    AttrStrideSize     Attr = 0x2E
    AttrUpperBound     Attr = 0x2F
    AttrAbstractOrigin Attr = 0x31
    AttrAccessibility  Attr = 0x32
    AttrAddrClass      Attr = 0x33
    AttrArtificial     Attr = 0x34
    AttrBaseTypes      Attr = 0x35
    AttrCalling        Attr = 0x36
    AttrCount          Attr = 0x37
    AttrDataMemberLoc  Attr = 0x38
    AttrDeclColumn     Attr = 0x39
    AttrDeclFile       Attr = 0x3A
    AttrDeclLine       Attr = 0x3B
    AttrDeclaration    Attr = 0x3C
    AttrDiscrList      Attr = 0x3D
    AttrEncoding       Attr = 0x3E
    AttrExternal       Attr = 0x3F
    AttrFrameBase      Attr = 0x40
    AttrFriend         Attr = 0x41
    AttrIdentifierCase Attr = 0x42
    AttrMacroInfo      Attr = 0x43
    AttrNamelistItem   Attr = 0x44
    AttrPriority       Attr = 0x45
    AttrSegment        Attr = 0x46
    AttrSpecification  Attr = 0x47
    AttrStaticLink     Attr = 0x48
    AttrType           Attr = 0x49
    AttrUseLocation    Attr = 0x4A
    AttrVarParam       Attr = 0x4B
    AttrVirtuality     Attr = 0x4C
    AttrVtableElemLoc  Attr = 0x4D
    AttrAllocated      Attr = 0x4E
    AttrAssociated     Attr = 0x4F
    AttrDataLocation   Attr = 0x50
    AttrStride         Attr = 0x51
    AttrEntrypc        Attr = 0x52
    AttrUseUTF8        Attr = 0x53
    AttrExtension      Attr = 0x54
    AttrRanges         Attr = 0x55
    AttrTrampoline     Attr = 0x56
    AttrCallColumn     Attr = 0x57
    AttrCallFile       Attr = 0x58
    AttrCallLine       Attr = 0x59
    AttrDescription    Attr = 0x5A

func (Attr) GoString Uses

func (a Attr) GoString() string

func (Attr) String Uses

func (a Attr) String() string

type BasicType Uses

type BasicType struct {
    BitSize   int64
    BitOffset int64

A BasicType holds fields common to all basic types.

func (*BasicType) Basic Uses

func (b *BasicType) Basic() *BasicType

func (*BasicType) String Uses

func (t *BasicType) String() string

type BoolType Uses

type BoolType struct {

A BoolType represents a boolean type.

type CharType Uses

type CharType struct {

A CharType represents a signed character type.

type Class Uses

type Class int

A Class is the DWARF 4 class of an attribute value.

In general, a given attribute's value may take on one of several possible classes defined by DWARF, each of which leads to a slightly different interpretation of the attribute.

DWARF version 4 distinguishes attribute value classes more finely than previous versions of DWARF. The reader will disambiguate coarser classes from earlier versions of DWARF into the appropriate DWARF 4 class. For example, DWARF 2 uses "constant" for constants as well as all types of section offsets, but the reader will canonicalize attributes in DWARF 2 files that refer to section offsets to one of the Class*Ptr classes, even though these classes were only defined in DWARF 3.

const (
    // ClassUnknown represents values of unknown DWARF class.
    ClassUnknown Class = iota

    // ClassAddress represents values of type uint64 that are
    // addresses on the target machine.

    // ClassBlock represents values of type []byte whose
    // interpretation depends on the attribute.

    // ClassConstant represents values of type int64 that are
    // constants. The interpretation of this constant depends on
    // the attribute.

    // ClassExprLoc represents values of type []byte that contain
    // an encoded DWARF expression or location description.

    // ClassFlag represents values of type bool.

    // ClassLinePtr represents values that are an int64 offset
    // into the "line" section.

    // ClassLocListPtr represents values that are an int64 offset
    // into the "loclist" section.

    // ClassMacPtr represents values that are an int64 offset into
    // the "mac" section.

    // ClassMacPtr represents values that are an int64 offset into
    // the "rangelist" section.

    // ClassReference represents values that are an Offset offset
    // of an Entry in the info section (for use with Reader.Seek).
    // The DWARF specification combines ClassReference and
    // ClassReferenceSig into class "reference".

    // ClassReferenceSig represents values that are a uint64 type
    // signature referencing a type Entry.

    // ClassString represents values that are strings. If the
    // compilation unit specifies the AttrUseUTF8 flag (strongly
    // recommended), the string value will be encoded in UTF-8.
    // Otherwise, the encoding is unspecified.

    // ClassReferenceAlt represents values of type int64 that are
    // an offset into the DWARF "info" section of an alternate
    // object file.

    // ClassStringAlt represents values of type int64 that are an
    // offset into the DWARF string section of an alternate object
    // file.

func (Class) GoString Uses

func (i Class) GoString() string

func (Class) String Uses

func (i Class) String() string

type CommonType Uses

type CommonType struct {
    ByteSize int64  // size of value of this type, in bytes
    Name     string // name that can be used to refer to type

A CommonType holds fields common to multiple types. If a field is not known or not applicable for a given type, the zero value is used.

func (*CommonType) Common Uses

func (c *CommonType) Common() *CommonType

func (*CommonType) Size Uses

func (c *CommonType) Size() int64

type ComplexType Uses

type ComplexType struct {

A ComplexType represents a complex floating point type.

type Data Uses

type Data struct {
    // contains filtered or unexported fields

Data represents the DWARF debugging information loaded from an executable file (for example, an ELF or Mach-O executable).

func New Uses

func New(abbrev, aranges, frame, info, line, pubnames, ranges, str []byte) (*Data, error)

New returns a new Data object initialized from the given parameters. Rather than calling this function directly, clients should typically use the DWARF method of the File type of the appropriate package debug/elf, debug/macho, or debug/pe.

The []byte arguments are the data from the corresponding debug section in the object file; for example, for an ELF object, abbrev is the contents of the ".debug_abbrev" section.

func (*Data) AddTypes Uses

func (d *Data) AddTypes(name string, types []byte) error

AddTypes will add one .debug_types section to the DWARF data. A typical object with DWARF version 4 debug info will have multiple .debug_types sections. The name is used for error reporting only, and serves to distinguish one .debug_types section from another.

func (*Data) LineReader Uses

func (d *Data) LineReader(cu *Entry) (*LineReader, error)

LineReader returns a new reader for the line table of compilation unit cu, which must be an Entry with tag TagCompileUnit.

If this compilation unit has no line table, it returns nil, nil.

func (*Data) Ranges Uses

func (d *Data) Ranges(e *Entry) ([][2]uint64, error)

Ranges returns the PC ranges covered by e, a slice of [low,high) pairs. Only some entry types, such as TagCompileUnit or TagSubprogram, have PC ranges; for others, this will return nil with no error.

func (*Data) Reader Uses

func (d *Data) Reader() *Reader

Reader returns a new Reader for Data. The reader is positioned at byte offset 0 in the DWARF “info” section.

func (*Data) Type Uses

func (d *Data) Type(off Offset) (Type, error)

Type reads the type at off in the DWARF “info” section.

type DecodeError Uses

type DecodeError struct {
    Name   string
    Offset Offset
    Err    string

func (DecodeError) Error Uses

func (e DecodeError) Error() string

type DotDotDotType Uses

type DotDotDotType struct {

A DotDotDotType represents the variadic ... function parameter.

func (*DotDotDotType) String Uses

func (t *DotDotDotType) String() string

type Entry Uses

type Entry struct {
    Offset   Offset // offset of Entry in DWARF info
    Tag      Tag    // tag (kind of Entry)
    Children bool   // whether Entry is followed by children
    Field    []Field

An entry is a sequence of attribute/value pairs.

func (*Entry) AttrField Uses

func (e *Entry) AttrField(a Attr) *Field

AttrField returns the Field associated with attribute Attr in Entry, or nil if there is no such attribute.

func (*Entry) Val Uses

func (e *Entry) Val(a Attr) interface{}

Val returns the value associated with attribute Attr in Entry, or nil if there is no such attribute.

A common idiom is to merge the check for nil return with the check that the value has the expected dynamic type, as in:

v, ok := e.Val(AttrSibling).(int64)

type EnumType Uses

type EnumType struct {
    EnumName string
    Val      []*EnumValue

An EnumType represents an enumerated type. The only indication of its native integer type is its ByteSize (inside CommonType).

func (*EnumType) String Uses

func (t *EnumType) String() string

type EnumValue Uses

type EnumValue struct {
    Name string
    Val  int64

An EnumValue represents a single enumeration value.

type Field Uses

type Field struct {
    Attr  Attr
    Val   interface{}
    Class Class

A Field is a single attribute/value pair in an Entry.

A value can be one of several "attribute classes" defined by DWARF. The Go types corresponding to each class are:

DWARF class       Go type        Class
-----------       -------        -----
address           uint64         ClassAddress
block             []byte         ClassBlock
constant          int64          ClassConstant
flag              bool           ClassFlag
  to info         dwarf.Offset   ClassReference
  to type unit    uint64         ClassReferenceSig
string            string         ClassString
exprloc           []byte         ClassExprLoc
lineptr           int64          ClassLinePtr
loclistptr        int64          ClassLocListPtr
macptr            int64          ClassMacPtr
rangelistptr      int64          ClassRangeListPtr

For unrecognized or vendor-defined attributes, Class may be ClassUnknown.

type FloatType Uses

type FloatType struct {

A FloatType represents a floating point type.

type FuncType Uses

type FuncType struct {
    ReturnType Type
    ParamType  []Type

A FuncType represents a function type.

func (*FuncType) String Uses

func (t *FuncType) String() string

type IntType Uses

type IntType struct {

An IntType represents a signed integer type.

type LineEntry Uses

type LineEntry struct {
    // Address is the program-counter value of a machine
    // instruction generated by the compiler. This LineEntry
    // applies to each instruction from Address to just before the
    // Address of the next LineEntry.
    Address uint64

    // OpIndex is the index of an operation within a VLIW
    // instruction. The index of the first operation is 0. For
    // non-VLIW architectures, it will always be 0. Address and
    // OpIndex together form an operation pointer that can
    // reference any individual operation within the instruction
    // stream.
    OpIndex int

    // File is the source file corresponding to these
    // instructions.
    File *LineFile

    // Line is the source code line number corresponding to these
    // instructions. Lines are numbered beginning at 1. It may be
    // 0 if these instructions cannot be attributed to any source
    // line.
    Line int

    // Column is the column number within the source line of these
    // instructions. Columns are numbered beginning at 1. It may
    // be 0 to indicate the "left edge" of the line.
    Column int

    // IsStmt indicates that Address is a recommended breakpoint
    // location, such as the beginning of a line, statement, or a
    // distinct subpart of a statement.
    IsStmt bool

    // BasicBlock indicates that Address is the beginning of a
    // basic block.
    BasicBlock bool

    // PrologueEnd indicates that Address is one (of possibly
    // many) PCs where execution should be suspended for a
    // breakpoint on entry to the containing function.
    // Added in DWARF 3.
    PrologueEnd bool

    // EpilogueBegin indicates that Address is one (of possibly
    // many) PCs where execution should be suspended for a
    // breakpoint on exit from this function.
    // Added in DWARF 3.
    EpilogueBegin bool

    // ISA is the instruction set architecture for these
    // instructions. Possible ISA values should be defined by the
    // applicable ABI specification.
    // Added in DWARF 3.
    ISA int

    // Discriminator is an arbitrary integer indicating the block
    // to which these instructions belong. It serves to
    // distinguish among multiple blocks that may all have with
    // the same source file, line, and column. Where only one
    // block exists for a given source position, it should be 0.
    // Added in DWARF 3.
    Discriminator int

    // EndSequence indicates that Address is the first byte after
    // the end of a sequence of target machine instructions. If it
    // is set, only this and the Address field are meaningful. A
    // line number table may contain information for multiple
    // potentially disjoint instruction sequences. The last entry
    // in a line table should always have EndSequence set.
    EndSequence bool

A LineEntry is a row in a DWARF line table.

type LineFile Uses

type LineFile struct {
    Name   string
    Mtime  uint64 // Implementation defined modification time, or 0 if unknown
    Length int    // File length, or 0 if unknown

A LineFile is a source file referenced by a DWARF line table entry.

type LineReader Uses

type LineReader struct {
    // contains filtered or unexported fields

A LineReader reads a sequence of LineEntry structures from a DWARF "line" section for a single compilation unit. LineEntries occur in order of increasing PC and each LineEntry gives metadata for the instructions from that LineEntry's PC to just before the next LineEntry's PC. The last entry will have its EndSequence field set.

func (*LineReader) Next Uses

func (r *LineReader) Next(entry *LineEntry) error

Next sets *entry to the next row in this line table and moves to the next row. If there are no more entries and the line table is properly terminated, it returns io.EOF.

Rows are always in order of increasing entry.Address, but entry.Line may go forward or backward.

func (*LineReader) Reset Uses

func (r *LineReader) Reset()

Reset repositions the line table reader at the beginning of the line table.

func (*LineReader) Seek Uses

func (r *LineReader) Seek(pos LineReaderPos)

Seek restores the line table reader to a position returned by Tell.

The argument pos must have been returned by a call to Tell on this line table.

func (*LineReader) SeekPC Uses

func (r *LineReader) SeekPC(pc uint64, entry *LineEntry) error

SeekPC sets *entry to the LineEntry that includes pc and positions the reader on the next entry in the line table. If necessary, this will seek backwards to find pc.

If pc is not covered by any entry in this line table, SeekPC returns ErrUnknownPC. In this case, *entry and the final seek position are unspecified.

Note that DWARF line tables only permit sequential, forward scans. Hence, in the worst case, this takes time linear in the size of the line table. If the caller wishes to do repeated fast PC lookups, it should build an appropriate index of the line table.

func (*LineReader) Tell Uses

func (r *LineReader) Tell() LineReaderPos

Tell returns the current position in the line table.

type LineReaderPos Uses

type LineReaderPos struct {
    // contains filtered or unexported fields

A LineReaderPos represents a position in a line table.

type Offset Uses

type Offset uint32

An Offset represents the location of an Entry within the DWARF info. (See Reader.Seek.)

type PtrType Uses

type PtrType struct {
    Type Type

A PtrType represents a pointer type.

func (*PtrType) String Uses

func (t *PtrType) String() string

type QualType Uses

type QualType struct {
    Qual string
    Type Type

A QualType represents a type that has the C/C++ "const", "restrict", or "volatile" qualifier.

func (*QualType) Size Uses

func (t *QualType) Size() int64

func (*QualType) String Uses

func (t *QualType) String() string

type Reader Uses

type Reader struct {
    // contains filtered or unexported fields

A Reader allows reading Entry structures from a DWARF “info” section. The Entry structures are arranged in a tree. The Reader's Next function return successive entries from a pre-order traversal of the tree. If an entry has children, its Children field will be true, and the children follow, terminated by an Entry with Tag 0.

func (*Reader) AddressSize Uses

func (r *Reader) AddressSize() int

AddressSize returns the size in bytes of addresses in the current compilation unit.

func (*Reader) Next Uses

func (r *Reader) Next() (*Entry, error)

Next reads the next entry from the encoded entry stream. It returns nil, nil when it reaches the end of the section. It returns an error if the current offset is invalid or the data at the offset cannot be decoded as a valid Entry.

func (*Reader) Seek Uses

func (r *Reader) Seek(off Offset)

Seek positions the Reader at offset off in the encoded entry stream. Offset 0 can be used to denote the first entry.

func (*Reader) SeekPC Uses

func (r *Reader) SeekPC(pc uint64) (*Entry, error)

SeekPC returns the Entry for the compilation unit that includes pc, and positions the reader to read the children of that unit. If pc is not covered by any unit, SeekPC returns ErrUnknownPC and the position of the reader is undefined.

Because compilation units can describe multiple regions of the executable, in the worst case SeekPC must search through all the ranges in all the compilation units. Each call to SeekPC starts the search at the compilation unit of the last call, so in general looking up a series of PCs will be faster if they are sorted. If the caller wishes to do repeated fast PC lookups, it should build an appropriate index using the Ranges method.

func (*Reader) SkipChildren Uses

func (r *Reader) SkipChildren()

SkipChildren skips over the child entries associated with the last Entry returned by Next. If that Entry did not have children or Next has not been called, SkipChildren is a no-op.

type StructField Uses

type StructField struct {
    Name       string
    Type       Type
    ByteOffset int64
    ByteSize   int64
    BitOffset  int64 // within the ByteSize bytes at ByteOffset
    BitSize    int64 // zero if not a bit field

A StructField represents a field in a struct, union, or C++ class type.

type StructType Uses

type StructType struct {
    StructName string
    Kind       string // "struct", "union", or "class".
    Field      []*StructField
    Incomplete bool // if true, struct, union, class is declared but not defined

A StructType represents a struct, union, or C++ class type.

func (*StructType) Defn Uses

func (t *StructType) Defn() string

func (*StructType) String Uses

func (t *StructType) String() string

type Tag Uses

type Tag uint32

A Tag is the classification (the type) of an Entry.

const (
    TagArrayType              Tag = 0x01
    TagClassType              Tag = 0x02
    TagEntryPoint             Tag = 0x03
    TagEnumerationType        Tag = 0x04
    TagFormalParameter        Tag = 0x05
    TagImportedDeclaration    Tag = 0x08
    TagLabel                  Tag = 0x0A
    TagLexDwarfBlock          Tag = 0x0B
    TagMember                 Tag = 0x0D
    TagPointerType            Tag = 0x0F
    TagReferenceType          Tag = 0x10
    TagCompileUnit            Tag = 0x11
    TagStringType             Tag = 0x12
    TagStructType             Tag = 0x13
    TagSubroutineType         Tag = 0x15
    TagTypedef                Tag = 0x16
    TagUnionType              Tag = 0x17
    TagUnspecifiedParameters  Tag = 0x18
    TagVariant                Tag = 0x19
    TagCommonDwarfBlock       Tag = 0x1A
    TagCommonInclusion        Tag = 0x1B
    TagInheritance            Tag = 0x1C
    TagInlinedSubroutine      Tag = 0x1D
    TagModule                 Tag = 0x1E
    TagPtrToMemberType        Tag = 0x1F
    TagSetType                Tag = 0x20
    TagSubrangeType           Tag = 0x21
    TagWithStmt               Tag = 0x22
    TagAccessDeclaration      Tag = 0x23
    TagBaseType               Tag = 0x24
    TagCatchDwarfBlock        Tag = 0x25
    TagConstType              Tag = 0x26
    TagConstant               Tag = 0x27
    TagEnumerator             Tag = 0x28
    TagFileType               Tag = 0x29
    TagFriend                 Tag = 0x2A
    TagNamelist               Tag = 0x2B
    TagNamelistItem           Tag = 0x2C
    TagPackedType             Tag = 0x2D
    TagSubprogram             Tag = 0x2E
    TagTemplateTypeParameter  Tag = 0x2F
    TagTemplateValueParameter Tag = 0x30
    TagThrownType             Tag = 0x31
    TagTryDwarfBlock          Tag = 0x32
    TagVariantPart            Tag = 0x33
    TagVariable               Tag = 0x34
    TagVolatileType           Tag = 0x35
    // The following are new in DWARF 3.
    TagDwarfProcedure  Tag = 0x36
    TagRestrictType    Tag = 0x37
    TagInterfaceType   Tag = 0x38
    TagNamespace       Tag = 0x39
    TagImportedModule  Tag = 0x3A
    TagUnspecifiedType Tag = 0x3B
    TagPartialUnit     Tag = 0x3C
    TagImportedUnit    Tag = 0x3D
    TagMutableType     Tag = 0x3E // Later removed from DWARF.
    TagCondition       Tag = 0x3F
    TagSharedType      Tag = 0x40
    // The following are new in DWARF 4.
    TagTypeUnit            Tag = 0x41
    TagRvalueReferenceType Tag = 0x42
    TagTemplateAlias       Tag = 0x43

func (Tag) GoString Uses

func (t Tag) GoString() string

func (Tag) String Uses

func (t Tag) String() string

type Type Uses

type Type interface {
    Common() *CommonType
    String() string
    Size() int64

A Type conventionally represents a pointer to any of the specific Type structures (CharType, StructType, etc.).

type TypedefType Uses

type TypedefType struct {
    Type Type

A TypedefType represents a named type.

func (*TypedefType) Size Uses

func (t *TypedefType) Size() int64

func (*TypedefType) String Uses

func (t *TypedefType) String() string

type UcharType Uses

type UcharType struct {

A UcharType represents an unsigned character type.

type UintType Uses

type UintType struct {

A UintType represents an unsigned integer type.

type UnspecifiedType Uses

type UnspecifiedType struct {

An UnspecifiedType represents an implicit, unknown, ambiguous or nonexistent type.

type VoidType Uses

type VoidType struct {

A VoidType represents the C void type.

func (*VoidType) String Uses

func (t *VoidType) String() string