goobj

Documentation

Overview

Package goobj implements reading of Go object files and archives.

TODO(rsc): Decide where this package should live. (golang.org/issue/6932) TODO(rsc): Decide the appropriate integer types for various fields. TODO(rsc): Write tests. (File format still up in the air a little.)

Index

• type Data
• type Func
• type FuncData
• type Package
  • func Parse(r io.ReadSeeker, pkgpath string) (*Package, error)
• type Reloc
• type Sym
• type SymID
  • func (s SymID) String() string
• type SymKind
  • func (k SymKind) String() string
• type Var

Types

type Data

type Data struct {
	Offset int64
	Size   int64
}

A Data is a reference to data stored in an object file. It records the offset and size of the data, so that a client can read the data only if necessary.

type Func

type Func struct {
	Args     int        // size in bytes of of argument frame: inputs and outputs
	Frame    int        // size in bytes of local variable frame
	Var      []Var      // detail about local variables
	PCSP     Data       // PC → SP offset map
	PCFile   Data       // PC → file number map (index into File)
	PCLine   Data       // PC → line number map
	PCData   []Data     // PC → runtime support data map
	FuncData []FuncData // non-PC-specific runtime support data
	File     []string   // paths indexed by PCFile
}

Func contains additional per-symbol information specific to functions.

type FuncData

type FuncData struct {
	Sym    SymID // symbol holding data
	Offset int64 // offset into symbol for funcdata pointer
}

A FuncData is a single function-specific data value.

type Package

type Package struct {
	ImportPath string   // import path denoting this package
	Imports    []string // packages imported by this package
	Syms       []*Sym   // symbols defined by this package
	MaxVersion int      // maximum Version in any SymID in Syms
}

A Package is a parsed Go object file or archive defining a Go package.

func Parse

func Parse(r io.ReadSeeker, pkgpath string) (*Package, error)

Parse parses an object file or archive from r, assuming that its import path is pkgpath.

type Reloc

type Reloc struct {
	// The bytes at [Offset, Offset+Size) within the memory image
	// should be updated to refer to the address Add bytes after the start
	// of the symbol Sym.
	Offset int
	Size   int
	Sym    SymID
	Add    int

	// The Type records the form of address expected in the bytes
	// described by the previous fields: absolute, PC-relative, and so on.
	// TODO(rsc): The interpretation of Type is not exposed by this package.
	Type int
}

A Reloc describes a relocation applied to a memory image to refer to an address within a particular symbol.

type Sym

type Sym struct {
	SymID         // symbol identifier (name and version)
	Kind  SymKind // kind of symbol
	DupOK bool    // are duplicate definitions okay?
	Size  int     // size of corresponding data
	Type  SymID   // symbol for Go type information
	Data  Data    // memory image of symbol
	Reloc []Reloc // relocations to apply to Data
	Func  *Func   // additional data for functions
}

A Sym is a named symbol in an object file.

type SymID

type SymID struct {
	// Name is the name of a symbol.
	Name string

	// Version is zero for symbols with global visibility.
	// Symbols with only file visibility (such as file-level static
	// declarations in C) have a non-zero version distinguising
	// a symbol in one file from a symbol of the same name
	// in another file
	Version int
}

A SymID - the combination of Name and Version - uniquely identifies a symbol within a package.

func (SymID) String

func (s SymID) String() string

type SymKind

type SymKind int

A SymKind describes the kind of memory represented by a symbol.

const (

	// readonly, executable
	STEXT SymKind
	SELFRXSECT

	// readonly, non-executable
	STYPE
	SSTRING
	SGOSTRING
	SGOFUNC
	SRODATA
	SFUNCTAB
	STYPELINK
	SSYMTAB // TODO: move to unmapped section
	SPCLNTAB
	SELFROSECT

	// writable, non-executable
	SMACHOPLT
	SELFSECT
	SMACHO // Mach-O __nl_symbol_ptr
	SMACHOGOT
	SNOPTRDATA
	SINITARR
	SDATA
	SWINDOWS
	SBSS
	SNOPTRBSS
	STLSBSS

	// not mapped
	SXREF
	SMACHOSYMSTR
	SMACHOSYMTAB
	SMACHOINDIRECTPLT
	SMACHOINDIRECTGOT
	SFILE
	SFILEPATH
	SCONST
	SDYNIMPORT
	SHOSTOBJ
)

Defined SymKind values. TODO(rsc): Give idiomatic Go names. TODO(rsc): Reduce the number of symbol types in the object files.

func (SymKind) String

func (k SymKind) String() string

type Var

type Var struct {
	// The combination of Name, Kind, and Offset uniquely
	// identifies a variable in a function stack frame.
	// Using fewer of these - in particular, using only Name - does not.
	Name   string // Name of variable.
	Kind   int    // TODO(rsc): Define meaning.
	Offset int    // Frame offset. TODO(rsc): Define meaning.

	Type SymID // Go type for variable.
}

A Var describes a variable in a function stack frame: a declared local variable, an input argument, or an output result.