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 http://dwarfstd.org/doc/dwarf-2.0.0.pdf

Index Variables type AddrType type ArrayType func (t *ArrayType) Size() int64 func (t *ArrayType) String() string type Attr func (a Attr) GoString() string func (a Attr) String() string type BasicType func (b *BasicType) Basic() *BasicType func (t *BasicType) String() string type BoolType type CharType type Class func (i Class) GoString() string func (i Class) String() string type CommonType func (c *CommonType) Common() *CommonType func (c *CommonType) Size() int64 type ComplexType type Data func New(abbrev, aranges, frame, info, line, pubnames, ranges, str []byte) (*Data, error) func (d *Data) AddTypes(name string, types []byte) error func (d *Data) LineReader(cu *Entry) (*LineReader, error) func (d *Data) Ranges(e *Entry) ([][2]uint64, error) func (d *Data) Reader() *Reader func (d *Data) Type(off Offset) (Type, error) type DecodeError func (e DecodeError) Error() string type DotDotDotType func (t *DotDotDotType) String() string type Entry func (e *Entry) AttrField(a Attr) *Field func (e *Entry) Val(a Attr) interface{} type EnumType func (t *EnumType) String() string type EnumValue type Field type FloatType type FuncType func (t *FuncType) String() string type IntType type LineEntry type LineFile type LineReader func (r *LineReader) Next(entry *LineEntry) error func (r *LineReader) Reset() func (r *LineReader) Seek(pos LineReaderPos) func (r *LineReader) SeekPC(pc uint64, entry *LineEntry) error func (r *LineReader) Tell() LineReaderPos type LineReaderPos type Offset type PtrType func (t *PtrType) String() string type QualType func (t *QualType) Size() int64 func (t *QualType) String() string type Reader func (r *Reader) AddressSize() int func (r *Reader) Next() (*Entry, error) func (r *Reader) Seek(off Offset) func (r *Reader) SeekPC(pc uint64) (*Entry, error) func (r *Reader) SkipChildren() type StructField type StructType func (t *StructType) Defn() string func (t *StructType) String() string type Tag func (t Tag) GoString() string func (t Tag) String() string type Type type TypedefType func (t *TypedefType) Size() int64 func (t *TypedefType) String() string type UcharType type UintType type UnspecifiedType type VoidType func (t *VoidType) String() string Package Files

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

Variables ❖ 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 ❖ type AddrType struct { BasicType } An AddrType represents a machine address type.

type ArrayType ❖ type ArrayType struct { CommonType 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

❖ func (t *ArrayType) Size() int64 func (*ArrayType) String

❖ func (t *ArrayType) String() string type Attr ❖ 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

❖ func (a Attr) GoString() string func (Attr) String

❖ func (a Attr) String() string type BasicType ❖ type BasicType struct { CommonType BitSize int64 BitOffset int64 } A BasicType holds fields common to all basic types.

func (*BasicType) Basic

❖ func (b *BasicType) Basic() *BasicType func (*BasicType) String

❖ func (t *BasicType) String() string type BoolType ❖ type BoolType struct { BasicType } A BoolType represents a boolean type.

type CharType ❖ type CharType struct { BasicType } A CharType represents a signed character type.

type Class ❖ 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.
ClassAddress

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

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

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

// ClassFlag represents values of type bool.
ClassFlag

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

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

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

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

// 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".
ClassReference

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

// 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.
ClassString

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

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

) func (Class) GoString

❖ func (i Class) GoString() string func (Class) String

❖ func (i Class) String() string type CommonType ❖ 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

❖ func (c *CommonType) Common() *CommonType func (*CommonType) Size

❖ func (c *CommonType) Size() int64 type ComplexType ❖ type ComplexType struct { BasicType } A ComplexType represents a complex floating point type.

type Data ❖ 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

❖ 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

❖ 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

❖ 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

❖ 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

❖ 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

❖ func (d *Data) Type(off Offset) (Type, error) Type reads the type at off in the DWARF “info” section.

type DecodeError ❖ type DecodeError struct { Name string Offset Offset Err string } func (DecodeError) Error

❖ func (e DecodeError) Error() string type DotDotDotType ❖ type DotDotDotType struct { CommonType } A DotDotDotType represents the variadic … function parameter.

func (*DotDotDotType) String

❖ func (t *DotDotDotType) String() string type Entry ❖ 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

❖ 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

❖ 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 ❖ type EnumType struct { CommonType 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

❖ func (t *EnumType) String() string type EnumValue ❖ type EnumValue struct { Name string Val int64 } An EnumValue represents a single enumeration value.

type Field ❖ 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 reference 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 ❖ type FloatType struct { BasicType } A FloatType represents a floating point type.

type FuncType ❖ type FuncType struct { CommonType ReturnType Type ParamType []Type } A FuncType represents a function type.

func (*FuncType) String

❖ func (t *FuncType) String() string type IntType ❖ type IntType struct { BasicType } An IntType represents a signed integer type.

type LineEntry ❖ 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 ❖ 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 ❖ 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

❖ 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

❖ func (r *LineReader) Reset() Reset repositions the line table reader at the beginning of the line table.

func (*LineReader) Seek

❖ 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

❖ 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

❖ func (r *LineReader) Tell() LineReaderPos Tell returns the current position in the line table.

type LineReaderPos ❖ type LineReaderPos struct { // contains filtered or unexported fields } A LineReaderPos represents a position in a line table.

type Offset ❖ type Offset uint32 An Offset represents the location of an Entry within the DWARF info. (See Reader.Seek.)

type PtrType ❖ type PtrType struct { CommonType Type Type } A PtrType represents a pointer type.

func (*PtrType) String

❖ func (t *PtrType) String() string type QualType ❖ type QualType struct { CommonType Qual string Type Type } A QualType represents a type that has the C/C++ “const”, “restrict”, or “volatile” qualifier.

func (*QualType) Size

❖ func (t *QualType) Size() int64 func (*QualType) String

❖ func (t *QualType) String() string type Reader ❖ 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

❖ func (r *Reader) AddressSize() int AddressSize returns the size in bytes of addresses in the current compilation unit.

func (*Reader) Next

❖ 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

❖ 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

❖ 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

❖ 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 ❖ 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 ❖ type StructType struct { CommonType 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

❖ func (t *StructType) Defn() string func (*StructType) String

❖ func (t *StructType) String() string type Tag ❖ 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

❖ func (t Tag) GoString() string func (Tag) String

❖ func (t Tag) String() string type Type ❖ 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 ❖ type TypedefType struct { CommonType Type Type } A TypedefType represents a named type.

func (*TypedefType) Size

❖ func (t *TypedefType) Size() int64 func (*TypedefType) String

❖ func (t *TypedefType) String() string type UcharType ❖ type UcharType struct { BasicType } A UcharType represents an unsigned character type.

type UintType ❖ type UintType struct { BasicType } A UintType represents an unsigned integer type.

type UnspecifiedType ❖ type UnspecifiedType struct { BasicType } An UnspecifiedType represents an implicit, unknown, ambiguous or nonexistent type.

type VoidType ❖ type VoidType struct { CommonType } A VoidType represents the C void type.

func (*VoidType) String

❖ func (t *VoidType) String() string