diff options
Diffstat (limited to 'vendor/github.com/google/gops/internal/goobj/read.go')
| -rw-r--r-- | vendor/github.com/google/gops/internal/goobj/read.go | 714 |
1 files changed, 0 insertions, 714 deletions
diff --git a/vendor/github.com/google/gops/internal/goobj/read.go b/vendor/github.com/google/gops/internal/goobj/read.go deleted file mode 100644 index 8a6f13bc..00000000 --- a/vendor/github.com/google/gops/internal/goobj/read.go +++ /dev/null @@ -1,714 +0,0 @@ -// Copyright 2013 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// 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.) -package goobj - -import ( - "bufio" - "bytes" - "errors" - "fmt" - "io" - "strconv" - "strings" - - "github.com/google/gops/internal/obj" -) - -// A SymKind describes the kind of memory represented by a symbol. -type SymKind int - -// This list is taken from include/link.h. - -// Defined SymKind values. -// TODO(rsc): Give idiomatic Go names. -// TODO(rsc): Reduce the number of symbol types in the object files. -const ( - // readonly, executable - STEXT = SymKind(obj.STEXT) - SELFRXSECT = SymKind(obj.SELFRXSECT) - - // readonly, non-executable - STYPE = SymKind(obj.STYPE) - SSTRING = SymKind(obj.SSTRING) - SGOSTRING = SymKind(obj.SGOSTRING) - SGOFUNC = SymKind(obj.SGOFUNC) - SRODATA = SymKind(obj.SRODATA) - SFUNCTAB = SymKind(obj.SFUNCTAB) - STYPELINK = SymKind(obj.STYPELINK) - SITABLINK = SymKind(obj.SITABLINK) - SSYMTAB = SymKind(obj.SSYMTAB) // TODO: move to unmapped section - SPCLNTAB = SymKind(obj.SPCLNTAB) - SELFROSECT = SymKind(obj.SELFROSECT) - - // writable, non-executable - SMACHOPLT = SymKind(obj.SMACHOPLT) - SELFSECT = SymKind(obj.SELFSECT) - SMACHO = SymKind(obj.SMACHO) // Mach-O __nl_symbol_ptr - SMACHOGOT = SymKind(obj.SMACHOGOT) - SWINDOWS = SymKind(obj.SWINDOWS) - SELFGOT = SymKind(obj.SELFGOT) - SNOPTRDATA = SymKind(obj.SNOPTRDATA) - SINITARR = SymKind(obj.SINITARR) - SDATA = SymKind(obj.SDATA) - SBSS = SymKind(obj.SBSS) - SNOPTRBSS = SymKind(obj.SNOPTRBSS) - STLSBSS = SymKind(obj.STLSBSS) - - // not mapped - SXREF = SymKind(obj.SXREF) - SMACHOSYMSTR = SymKind(obj.SMACHOSYMSTR) - SMACHOSYMTAB = SymKind(obj.SMACHOSYMTAB) - SMACHOINDIRECTPLT = SymKind(obj.SMACHOINDIRECTPLT) - SMACHOINDIRECTGOT = SymKind(obj.SMACHOINDIRECTGOT) - SFILE = SymKind(obj.SFILE) - SFILEPATH = SymKind(obj.SFILEPATH) - SCONST = SymKind(obj.SCONST) - SDYNIMPORT = SymKind(obj.SDYNIMPORT) - SHOSTOBJ = SymKind(obj.SHOSTOBJ) -) - -var symKindStrings = []string{ - SBSS: "SBSS", - SCONST: "SCONST", - SDATA: "SDATA", - SDYNIMPORT: "SDYNIMPORT", - SELFROSECT: "SELFROSECT", - SELFRXSECT: "SELFRXSECT", - SELFSECT: "SELFSECT", - SFILE: "SFILE", - SFILEPATH: "SFILEPATH", - SFUNCTAB: "SFUNCTAB", - SGOFUNC: "SGOFUNC", - SGOSTRING: "SGOSTRING", - SHOSTOBJ: "SHOSTOBJ", - SINITARR: "SINITARR", - SMACHO: "SMACHO", - SMACHOGOT: "SMACHOGOT", - SMACHOINDIRECTGOT: "SMACHOINDIRECTGOT", - SMACHOINDIRECTPLT: "SMACHOINDIRECTPLT", - SMACHOPLT: "SMACHOPLT", - SMACHOSYMSTR: "SMACHOSYMSTR", - SMACHOSYMTAB: "SMACHOSYMTAB", - SNOPTRBSS: "SNOPTRBSS", - SNOPTRDATA: "SNOPTRDATA", - SPCLNTAB: "SPCLNTAB", - SRODATA: "SRODATA", - SSTRING: "SSTRING", - SSYMTAB: "SSYMTAB", - STEXT: "STEXT", - STLSBSS: "STLSBSS", - STYPE: "STYPE", - STYPELINK: "STYPELINK", - SITABLINK: "SITABLINK", - SWINDOWS: "SWINDOWS", - SXREF: "SXREF", -} - -func (k SymKind) String() string { - if k < 0 || int(k) >= len(symKindStrings) { - return fmt.Sprintf("SymKind(%d)", k) - } - return symKindStrings[k] -} - -// A Sym is a named symbol in an object file. -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 SymID - the combination of Name and Version - uniquely identifies -// a symbol within a package. -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 distinguishing - // a symbol in one file from a symbol of the same name - // in another file - Version int -} - -func (s SymID) String() string { - if s.Version == 0 { - return s.Name - } - return fmt.Sprintf("%s<%d>", s.Name, s.Version) -} - -// 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 Data struct { - Offset int64 - Size int64 -} - -// A Reloc describes a relocation applied to a memory image to refer -// to an address within a particular symbol. -type Reloc struct { - // The bytes at [Offset, Offset+Size) within the containing Sym - // 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 obj.RelocType -} - -// A Var describes a variable in a function stack frame: a declared -// local variable, an input argument, or an output result. -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. -} - -// Func contains additional per-symbol information specific to functions. -type Func struct { - Args int // size in bytes of argument frame: inputs and outputs - Frame int // size in bytes of local variable frame - Leaf bool // function omits save of link register (ARM) - NoSplit bool // function omits stack split prologue - 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 -} - -// TODO: Add PCData []byte and PCDataIter (similar to liblink). - -// A FuncData is a single function-specific data value. -type FuncData struct { - Sym SymID // symbol holding data - Offset int64 // offset into symbol for funcdata pointer -} - -// A Package is a parsed Go object file or archive defining a Go package. -type Package struct { - ImportPath string // import path denoting this package - Imports []string // packages imported by this package - SymRefs []SymID // list of symbol names and versions referred to by this pack - Syms []*Sym // symbols defined by this package - MaxVersion int // maximum Version in any SymID in Syms - Arch string // architecture -} - -var ( - archiveHeader = []byte("!<arch>\n") - archiveMagic = []byte("`\n") - goobjHeader = []byte("go objec") // truncated to size of archiveHeader - - errCorruptArchive = errors.New("corrupt archive") - errTruncatedArchive = errors.New("truncated archive") - errCorruptObject = errors.New("corrupt object file") - errNotObject = errors.New("unrecognized object file format") -) - -// An objReader is an object file reader. -type objReader struct { - p *Package - b *bufio.Reader - f io.ReadSeeker - err error - offset int64 - dataOffset int64 - limit int64 - tmp [256]byte - pkgprefix string -} - -// importPathToPrefix returns the prefix that will be used in the -// final symbol table for the given import path. -// We escape '%', '"', all control characters and non-ASCII bytes, -// and any '.' after the final slash. -// -// See ../../../cmd/ld/lib.c:/^pathtoprefix and -// ../../../cmd/gc/subr.c:/^pathtoprefix. -func importPathToPrefix(s string) string { - // find index of last slash, if any, or else -1. - // used for determining whether an index is after the last slash. - slash := strings.LastIndex(s, "/") - - // check for chars that need escaping - n := 0 - for r := 0; r < len(s); r++ { - if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F { - n++ - } - } - - // quick exit - if n == 0 { - return s - } - - // escape - const hex = "0123456789abcdef" - p := make([]byte, 0, len(s)+2*n) - for r := 0; r < len(s); r++ { - if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F { - p = append(p, '%', hex[c>>4], hex[c&0xF]) - } else { - p = append(p, c) - } - } - - return string(p) -} - -// init initializes r to read package p from f. -func (r *objReader) init(f io.ReadSeeker, p *Package) { - r.f = f - r.p = p - r.offset, _ = f.Seek(0, io.SeekCurrent) - r.limit, _ = f.Seek(0, io.SeekEnd) - f.Seek(r.offset, io.SeekStart) - r.b = bufio.NewReader(f) - r.pkgprefix = importPathToPrefix(p.ImportPath) + "." -} - -// error records that an error occurred. -// It returns only the first error, so that an error -// caused by an earlier error does not discard information -// about the earlier error. -func (r *objReader) error(err error) error { - if r.err == nil { - if err == io.EOF { - err = io.ErrUnexpectedEOF - } - r.err = err - } - // panic("corrupt") // useful for debugging - return r.err -} - -// readByte reads and returns a byte from the input file. -// On I/O error or EOF, it records the error but returns byte 0. -// A sequence of 0 bytes will eventually terminate any -// parsing state in the object file. In particular, it ends the -// reading of a varint. -func (r *objReader) readByte() byte { - if r.err != nil { - return 0 - } - if r.offset >= r.limit { - r.error(io.ErrUnexpectedEOF) - return 0 - } - b, err := r.b.ReadByte() - if err != nil { - if err == io.EOF { - err = io.ErrUnexpectedEOF - } - r.error(err) - b = 0 - } else { - r.offset++ - } - return b -} - -// read reads exactly len(b) bytes from the input file. -// If an error occurs, read returns the error but also -// records it, so it is safe for callers to ignore the result -// as long as delaying the report is not a problem. -func (r *objReader) readFull(b []byte) error { - if r.err != nil { - return r.err - } - if r.offset+int64(len(b)) > r.limit { - return r.error(io.ErrUnexpectedEOF) - } - n, err := io.ReadFull(r.b, b) - r.offset += int64(n) - if err != nil { - return r.error(err) - } - return nil -} - -// readInt reads a zigzag varint from the input file. -func (r *objReader) readInt() int { - var u uint64 - - for shift := uint(0); ; shift += 7 { - if shift >= 64 { - r.error(errCorruptObject) - return 0 - } - c := r.readByte() - u |= uint64(c&0x7F) << shift - if c&0x80 == 0 { - break - } - } - - v := int64(u>>1) ^ (int64(u) << 63 >> 63) - if int64(int(v)) != v { - r.error(errCorruptObject) // TODO - return 0 - } - return int(v) -} - -// readString reads a length-delimited string from the input file. -func (r *objReader) readString() string { - n := r.readInt() - buf := make([]byte, n) - r.readFull(buf) - return string(buf) -} - -// readSymID reads a SymID from the input file. -func (r *objReader) readSymID() SymID { - i := r.readInt() - return r.p.SymRefs[i] -} - -func (r *objReader) readRef() { - name, vers := r.readString(), r.readInt() - - // In a symbol name in an object file, "". denotes the - // prefix for the package in which the object file has been found. - // Expand it. - name = strings.Replace(name, `"".`, r.pkgprefix, -1) - - // An individual object file only records version 0 (extern) or 1 (static). - // To make static symbols unique across all files being read, we - // replace version 1 with the version corresponding to the current - // file number. The number is incremented on each call to parseObject. - if vers != 0 { - vers = r.p.MaxVersion - } - r.p.SymRefs = append(r.p.SymRefs, SymID{name, vers}) -} - -// readData reads a data reference from the input file. -func (r *objReader) readData() Data { - n := r.readInt() - d := Data{Offset: r.dataOffset, Size: int64(n)} - r.dataOffset += int64(n) - return d -} - -// skip skips n bytes in the input. -func (r *objReader) skip(n int64) { - if n < 0 { - r.error(fmt.Errorf("debug/goobj: internal error: misuse of skip")) - } - if n < int64(len(r.tmp)) { - // Since the data is so small, a just reading from the buffered - // reader is better than flushing the buffer and seeking. - r.readFull(r.tmp[:n]) - } else if n <= int64(r.b.Buffered()) { - // Even though the data is not small, it has already been read. - // Advance the buffer instead of seeking. - for n > int64(len(r.tmp)) { - r.readFull(r.tmp[:]) - n -= int64(len(r.tmp)) - } - r.readFull(r.tmp[:n]) - } else { - // Seek, giving up buffered data. - _, err := r.f.Seek(r.offset+n, io.SeekStart) - if err != nil { - r.error(err) - } - r.offset += n - r.b.Reset(r.f) - } -} - -// Parse parses an object file or archive from r, -// assuming that its import path is pkgpath. -func Parse(r io.ReadSeeker, pkgpath string) (*Package, error) { - if pkgpath == "" { - pkgpath = `""` - } - p := new(Package) - p.ImportPath = pkgpath - - var rd objReader - rd.init(r, p) - err := rd.readFull(rd.tmp[:8]) - if err != nil { - if err == io.EOF { - err = io.ErrUnexpectedEOF - } - return nil, err - } - - switch { - default: - return nil, errNotObject - - case bytes.Equal(rd.tmp[:8], archiveHeader): - if err := rd.parseArchive(); err != nil { - return nil, err - } - case bytes.Equal(rd.tmp[:8], goobjHeader): - if err := rd.parseObject(goobjHeader); err != nil { - return nil, err - } - } - - return p, nil -} - -// trimSpace removes trailing spaces from b and returns the corresponding string. -// This effectively parses the form used in archive headers. -func trimSpace(b []byte) string { - return string(bytes.TrimRight(b, " ")) -} - -// parseArchive parses a Unix archive of Go object files. -// TODO(rsc): Need to skip non-Go object files. -// TODO(rsc): Maybe record table of contents in r.p so that -// linker can avoid having code to parse archives too. -func (r *objReader) parseArchive() error { - for r.offset < r.limit { - if err := r.readFull(r.tmp[:60]); err != nil { - return err - } - data := r.tmp[:60] - - // Each file is preceded by this text header (slice indices in first column): - // 0:16 name - // 16:28 date - // 28:34 uid - // 34:40 gid - // 40:48 mode - // 48:58 size - // 58:60 magic - `\n - // We only care about name, size, and magic. - // The fields are space-padded on the right. - // The size is in decimal. - // The file data - size bytes - follows the header. - // Headers are 2-byte aligned, so if size is odd, an extra padding - // byte sits between the file data and the next header. - // The file data that follows is padded to an even number of bytes: - // if size is odd, an extra padding byte is inserted betw the next header. - if len(data) < 60 { - return errTruncatedArchive - } - if !bytes.Equal(data[58:60], archiveMagic) { - return errCorruptArchive - } - name := trimSpace(data[0:16]) - size, err := strconv.ParseInt(trimSpace(data[48:58]), 10, 64) - if err != nil { - return errCorruptArchive - } - data = data[60:] - fsize := size + size&1 - if fsize < 0 || fsize < size { - return errCorruptArchive - } - switch name { - case "__.PKGDEF": - r.skip(size) - default: - oldLimit := r.limit - r.limit = r.offset + size - if err := r.parseObject(nil); err != nil { - return fmt.Errorf("parsing archive member %q: %v", name, err) - } - r.skip(r.limit - r.offset) - r.limit = oldLimit - } - if size&1 != 0 { - r.skip(1) - } - } - return nil -} - -// parseObject parses a single Go object file. -// The prefix is the bytes already read from the file, -// typically in order to detect that this is an object file. -// The object file consists of a textual header ending in "\n!\n" -// and then the part we want to parse begins. -// The format of that part is defined in a comment at the top -// of src/liblink/objfile.c. -func (r *objReader) parseObject(prefix []byte) error { - r.p.MaxVersion++ - h := make([]byte, 0, 256) - h = append(h, prefix...) - var c1, c2, c3 byte - for { - c1, c2, c3 = c2, c3, r.readByte() - h = append(h, c3) - // The new export format can contain 0 bytes. - // Don't consider them errors, only look for r.err != nil. - if r.err != nil { - return errCorruptObject - } - if c1 == '\n' && c2 == '!' && c3 == '\n' { - break - } - } - - hs := strings.Fields(string(h)) - if len(hs) >= 4 { - r.p.Arch = hs[3] - } - // TODO: extract OS + build ID if/when we need it - - r.readFull(r.tmp[:8]) - if !bytes.Equal(r.tmp[:8], []byte("\x00\x00go17ld")) { - return r.error(errCorruptObject) - } - - b := r.readByte() - if b != 1 { - return r.error(errCorruptObject) - } - - // Direct package dependencies. - for { - s := r.readString() - if s == "" { - break - } - r.p.Imports = append(r.p.Imports, s) - } - - r.p.SymRefs = []SymID{{"", 0}} - for { - if b := r.readByte(); b != 0xfe { - if b != 0xff { - return r.error(errCorruptObject) - } - break - } - - r.readRef() - } - - dataLength := r.readInt() - r.readInt() // n relocations - ignore - r.readInt() // n pcdata - ignore - r.readInt() // n autom - ignore - r.readInt() // n funcdata - ignore - r.readInt() // n files - ignore - - r.dataOffset = r.offset - r.skip(int64(dataLength)) - - // Symbols. - for { - if b := r.readByte(); b != 0xfe { - if b != 0xff { - return r.error(errCorruptObject) - } - break - } - - typ := r.readInt() - s := &Sym{SymID: r.readSymID()} - r.p.Syms = append(r.p.Syms, s) - s.Kind = SymKind(typ) - flags := r.readInt() - s.DupOK = flags&1 != 0 - s.Size = r.readInt() - s.Type = r.readSymID() - s.Data = r.readData() - s.Reloc = make([]Reloc, r.readInt()) - for i := range s.Reloc { - rel := &s.Reloc[i] - rel.Offset = r.readInt() - rel.Size = r.readInt() - rel.Type = obj.RelocType(r.readInt()) - rel.Add = r.readInt() - rel.Sym = r.readSymID() - } - - if s.Kind == STEXT { - f := new(Func) - s.Func = f - f.Args = r.readInt() - f.Frame = r.readInt() - flags := r.readInt() - f.Leaf = flags&1 != 0 - f.NoSplit = r.readInt() != 0 - f.Var = make([]Var, r.readInt()) - for i := range f.Var { - v := &f.Var[i] - v.Name = r.readSymID().Name - v.Offset = r.readInt() - v.Kind = r.readInt() - v.Type = r.readSymID() - } - - f.PCSP = r.readData() - f.PCFile = r.readData() - f.PCLine = r.readData() - f.PCData = make([]Data, r.readInt()) - for i := range f.PCData { - f.PCData[i] = r.readData() - } - f.FuncData = make([]FuncData, r.readInt()) - for i := range f.FuncData { - f.FuncData[i].Sym = r.readSymID() - } - for i := range f.FuncData { - f.FuncData[i].Offset = int64(r.readInt()) // TODO - } - f.File = make([]string, r.readInt()) - for i := range f.File { - f.File[i] = r.readSymID().Name - } - } - } - - r.readFull(r.tmp[:7]) - if !bytes.Equal(r.tmp[:7], []byte("\xffgo17ld")) { - return r.error(errCorruptObject) - } - - return nil -} - -func (r *Reloc) String(insnOffset uint64) string { - delta := r.Offset - int(insnOffset) - s := fmt.Sprintf("[%d:%d]%s", delta, delta+r.Size, r.Type) - if r.Sym.Name != "" { - if r.Add != 0 { - return fmt.Sprintf("%s:%s+%d", s, r.Sym.Name, r.Add) - } - return fmt.Sprintf("%s:%s", s, r.Sym.Name) - } - if r.Add != 0 { - return fmt.Sprintf("%s:%d", s, r.Add) - } - return s -} |