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
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 struct {
BasicType
}
An AddrType represents a machine address type.
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 (t *ArrayType) Size() int64
func (t *ArrayType) String() string
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 (a Attr) GoString() string
func (i Attr) String() string
type BasicType struct {
CommonType
BitSize int64
BitOffset int64
}
A BasicType holds fields common to all basic types.
func (b *BasicType) Basic() *BasicType
func (t *BasicType) String() string
type BoolType struct {
BasicType
}
A BoolType represents a boolean type.
type CharType struct {
BasicType
}
A CharType represents a signed character type.
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 (i Class) GoString() string
func (i Class) String() string
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 (c *CommonType) Common() *CommonType
func (c *CommonType) Size() int64
type ComplexType struct {
BasicType
}
A ComplexType represents a complex floating point type.
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(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 (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 (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 (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 (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 (d *Data) Type(off Offset) (Type, error)
Type reads the type at off in the DWARF ``info'' section.
type DecodeError struct {
Name string
Offset Offset
Err string
}
func (e DecodeError) Error() string
type DotDotDotType struct {
CommonType
}
A DotDotDotType represents the variadic ... function parameter.
func (t *DotDotDotType) String() string
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 (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 (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 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 (t *EnumType) String() string
type EnumValue struct {
Name string
Val int64
}
An EnumValue represents a single enumeration value.
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 struct {
BasicType
}
A FloatType represents a floating point type.
type FuncType struct {
CommonType
ReturnType Type
ParamType []Type
}
A FuncType represents a function type.
func (t *FuncType) String() string
type IntType struct {
BasicType
}
An IntType represents a signed integer type.
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 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 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 (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 (r *LineReader) Reset()
Reset repositions the line table reader at the beginning of the line table.
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 (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 (r *LineReader) Tell() LineReaderPos
Tell returns the current position in the line table.
type LineReaderPos struct {
// contains filtered or unexported fields
}
A LineReaderPos represents a position in a line table.
type Offset uint32
An Offset represents the location of an Entry within the DWARF info. (See Reader.Seek.)
type PtrType struct {
CommonType
Type Type
}
A PtrType represents a pointer type.
func (t *PtrType) String() string
type QualType struct {
CommonType
Qual string
Type Type
}
A QualType represents a type that has the C/C++ "const", "restrict", or "volatile" qualifier.
func (t *QualType) Size() int64
func (t *QualType) String() string
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 (r *Reader) AddressSize() int
AddressSize returns the size in bytes of addresses in the current compilation unit.
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 (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 (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 (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 struct {
Name string
Type Type
ByteOffset int64
ByteSize int64 // usually zero; use Type.Size() for normal fields
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 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 (t *StructType) Defn() string
func (t *StructType) String() string
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 (t Tag) GoString() string
func (i Tag) String() string
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 struct {
CommonType
Type Type
}
A TypedefType represents a named type.
func (t *TypedefType) Size() int64
func (t *TypedefType) String() string
type UcharType struct {
BasicType
}
A UcharType represents an unsigned character type.
type UintType struct {
BasicType
}
A UintType represents an unsigned integer type.
type UnspecifiedType struct {
BasicType
}
An UnspecifiedType represents an implicit, unknown, ambiguous or nonexistent type.
type UnsupportedType struct {
CommonType
Tag Tag
}
An UnsupportedType is a placeholder returned in situations where we encounter a type that isn't supported.
func (t *UnsupportedType) String() string
type VoidType struct {
CommonType
}
A VoidType represents the C void type.
func (t *VoidType) String() string