Home | History | Annotate | Download | only in ld 
      1 // Inferno utils/include/ar.h
      2 // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/include/ar.h
      3 //
      4 //	Copyright  1994-1999 Lucent Technologies Inc.  All rights reserved.
      5 //	Portions Copyright  1995-1997 C H Forsyth (forsyth (a] terzarima.net)
      6 //	Portions Copyright  1997-1999 Vita Nuova Limited
      7 //	Portions Copyright  2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
      8 //	Portions Copyright  2004,2006 Bruce Ellis
      9 //	Portions Copyright  2005-2007 C H Forsyth (forsyth (a] terzarima.net)
     10 //	Revisions Copyright  2000-2007 Lucent Technologies Inc. and others
     11 //	Portions Copyright  2009 The Go Authors. All rights reserved.
     12 //
     13 // Permission is hereby granted, free of charge, to any person obtaining a copy
     14 // of this software and associated documentation files (the "Software"), to deal
     15 // in the Software without restriction, including without limitation the rights
     16 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     17 // copies of the Software, and to permit persons to whom the Software is
     18 // furnished to do so, subject to the following conditions:
     19 //
     20 // The above copyright notice and this permission notice shall be included in
     21 // all copies or substantial portions of the Software.
     22 //
     23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     24 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     25 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
     26 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     27 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     28 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     29 // THE SOFTWARE.
     30 
     31 package ld
     32 
     33 import (
     34 	"cmd/internal/bio"
     35 	"cmd/internal/objabi"
     36 	"cmd/link/internal/sym"
     37 	"encoding/binary"
     38 	"fmt"
     39 	"io"
     40 	"os"
     41 )
     42 
     43 const (
     44 	SARMAG  = 8
     45 	SAR_HDR = 16 + 44
     46 )
     47 
     48 const (
     49 	ARMAG = "!<arch>\n"
     50 )
     51 
     52 type ArHdr struct {
     53 	name string
     54 	date string
     55 	uid  string
     56 	gid  string
     57 	mode string
     58 	size string
     59 	fmag string
     60 }
     61 
     62 // hostArchive reads an archive file holding host objects and links in
     63 // required objects. The general format is the same as a Go archive
     64 // file, but it has an armap listing symbols and the objects that
     65 // define them. This is used for the compiler support library
     66 // libgcc.a.
     67 func hostArchive(ctxt *Link, name string) {
     68 	f, err := bio.Open(name)
     69 	if err != nil {
     70 		if os.IsNotExist(err) {
     71 			// It's OK if we don't have a libgcc file at all.
     72 			if ctxt.Debugvlog != 0 {
     73 				ctxt.Logf("skipping libgcc file: %v\n", err)
     74 			}
     75 			return
     76 		}
     77 		Exitf("cannot open file %s: %v", name, err)
     78 	}
     79 	defer f.Close()
     80 
     81 	var magbuf [len(ARMAG)]byte
     82 	if _, err := io.ReadFull(f, magbuf[:]); err != nil {
     83 		Exitf("file %s too short", name)
     84 	}
     85 
     86 	if string(magbuf[:]) != ARMAG {
     87 		Exitf("%s is not an archive file", name)
     88 	}
     89 
     90 	var arhdr ArHdr
     91 	l := nextar(f, f.Offset(), &arhdr)
     92 	if l <= 0 {
     93 		Exitf("%s missing armap", name)
     94 	}
     95 
     96 	var armap archiveMap
     97 	if arhdr.name == "/" || arhdr.name == "/SYM64/" {
     98 		armap = readArmap(name, f, arhdr)
     99 	} else {
    100 		Exitf("%s missing armap", name)
    101 	}
    102 
    103 	loaded := make(map[uint64]bool)
    104 	any := true
    105 	for any {
    106 		var load []uint64
    107 		for _, s := range ctxt.Syms.Allsym {
    108 			for _, r := range s.R {
    109 				if r.Sym != nil && r.Sym.Type == sym.SXREF {
    110 					if off := armap[r.Sym.Name]; off != 0 && !loaded[off] {
    111 						load = append(load, off)
    112 						loaded[off] = true
    113 					}
    114 				}
    115 			}
    116 		}
    117 
    118 		for _, off := range load {
    119 			l := nextar(f, int64(off), &arhdr)
    120 			if l <= 0 {
    121 				Exitf("%s missing archive entry at offset %d", name, off)
    122 			}
    123 			pname := fmt.Sprintf("%s(%s)", name, arhdr.name)
    124 			l = atolwhex(arhdr.size)
    125 
    126 			libgcc := sym.Library{Pkg: "libgcc"}
    127 			h := ldobj(ctxt, f, &libgcc, l, pname, name, ArchiveObj)
    128 			f.Seek(h.off, 0)
    129 			h.ld(ctxt, f, h.pkg, h.length, h.pn)
    130 		}
    131 
    132 		any = len(load) > 0
    133 	}
    134 }
    135 
    136 // archiveMap is an archive symbol map: a mapping from symbol name to
    137 // offset within the archive file.
    138 type archiveMap map[string]uint64
    139 
    140 // readArmap reads the archive symbol map.
    141 func readArmap(filename string, f *bio.Reader, arhdr ArHdr) archiveMap {
    142 	is64 := arhdr.name == "/SYM64/"
    143 	wordSize := 4
    144 	if is64 {
    145 		wordSize = 8
    146 	}
    147 
    148 	contents := make([]byte, atolwhex(arhdr.size))
    149 	if _, err := io.ReadFull(f, contents); err != nil {
    150 		Exitf("short read from %s", filename)
    151 	}
    152 
    153 	var c uint64
    154 	if is64 {
    155 		c = binary.BigEndian.Uint64(contents)
    156 	} else {
    157 		c = uint64(binary.BigEndian.Uint32(contents))
    158 	}
    159 	contents = contents[wordSize:]
    160 
    161 	ret := make(archiveMap)
    162 
    163 	names := contents[c*uint64(wordSize):]
    164 	for i := uint64(0); i < c; i++ {
    165 		n := 0
    166 		for names[n] != 0 {
    167 			n++
    168 		}
    169 		name := string(names[:n])
    170 		names = names[n+1:]
    171 
    172 		// For Mach-O and PE/386 files we strip a leading
    173 		// underscore from the symbol name.
    174 		if objabi.GOOS == "darwin" || (objabi.GOOS == "windows" && objabi.GOARCH == "386") {
    175 			if name[0] == '_' && len(name) > 1 {
    176 				name = name[1:]
    177 			}
    178 		}
    179 
    180 		var off uint64
    181 		if is64 {
    182 			off = binary.BigEndian.Uint64(contents)
    183 		} else {
    184 			off = uint64(binary.BigEndian.Uint32(contents))
    185 		}
    186 		contents = contents[wordSize:]
    187 
    188 		ret[name] = off
    189 	}
    190 
    191 	return ret
    192 }
    193