dwarf

package
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 Go to latest Published: Aug 17, 2022 License: BSD-3-Clause Imports: 7 Imported by: 0

Documentation

Overview

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

Constants

This section is empty.

Variables

View Source 
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.

Functions

This section is empty.

Types

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 attibute 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) 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) 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

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