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Source file src/cmd/internal/obj/data.go

Documentation: cmd/internal/obj

  // Derived from Inferno utils/6l/obj.c and utils/6l/span.c
  // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/obj.c
  // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/span.c
  //
  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
  //	Portions Copyright © 1997-1999 Vita Nuova Limited
  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
  //	Portions Copyright © 2004,2006 Bruce Ellis
  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  
  package obj
  
  import (
  	"cmd/internal/objabi"
  	"log"
  	"math"
  )
  
  // Grow increases the length of s.P to lsiz.
  func (s *LSym) Grow(lsiz int64) {
  	siz := int(lsiz)
  	if int64(siz) != lsiz {
  		log.Fatalf("LSym.Grow size %d too long", lsiz)
  	}
  	if len(s.P) >= siz {
  		return
  	}
  	// TODO(dfc) append cap-len at once, rather than
  	// one byte at a time.
  	for cap(s.P) < siz {
  		s.P = append(s.P[:cap(s.P)], 0)
  	}
  	s.P = s.P[:siz]
  }
  
  // GrowCap increases the capacity of s.P to c.
  func (s *LSym) GrowCap(c int64) {
  	if int64(cap(s.P)) >= c {
  		return
  	}
  	if s.P == nil {
  		s.P = make([]byte, 0, c)
  		return
  	}
  	b := make([]byte, len(s.P), c)
  	copy(b, s.P)
  	s.P = b
  }
  
  // prepwrite prepares to write data of size siz into s at offset off.
  func (s *LSym) prepwrite(ctxt *Link, off int64, siz int) {
  	if off < 0 || siz < 0 || off >= 1<<30 {
  		ctxt.Diag("prepwrite: bad off=%d siz=%d s=%v", off, siz, s)
  	}
  	switch s.Type {
  	case objabi.Sxxx, objabi.SBSS:
  		s.Type = objabi.SDATA
  	case objabi.SNOPTRBSS:
  		s.Type = objabi.SNOPTRDATA
  	case objabi.STLSBSS:
  		ctxt.Diag("cannot supply data for %v var %v", s.Type, s.Name)
  	}
  	l := off + int64(siz)
  	s.Grow(l)
  	if l > s.Size {
  		s.Size = l
  	}
  }
  
  // WriteFloat32 writes f into s at offset off.
  func (s *LSym) WriteFloat32(ctxt *Link, off int64, f float32) {
  	s.prepwrite(ctxt, off, 4)
  	ctxt.Arch.ByteOrder.PutUint32(s.P[off:], math.Float32bits(f))
  }
  
  // WriteFloat64 writes f into s at offset off.
  func (s *LSym) WriteFloat64(ctxt *Link, off int64, f float64) {
  	s.prepwrite(ctxt, off, 8)
  	ctxt.Arch.ByteOrder.PutUint64(s.P[off:], math.Float64bits(f))
  }
  
  // WriteInt writes an integer i of size siz into s at offset off.
  func (s *LSym) WriteInt(ctxt *Link, off int64, siz int, i int64) {
  	s.prepwrite(ctxt, off, siz)
  	switch siz {
  	default:
  		ctxt.Diag("WriteInt: bad integer size: %d", siz)
  	case 1:
  		s.P[off] = byte(i)
  	case 2:
  		ctxt.Arch.ByteOrder.PutUint16(s.P[off:], uint16(i))
  	case 4:
  		ctxt.Arch.ByteOrder.PutUint32(s.P[off:], uint32(i))
  	case 8:
  		ctxt.Arch.ByteOrder.PutUint64(s.P[off:], uint64(i))
  	}
  }
  
  // WriteAddr writes an address of size siz into s at offset off.
  // rsym and roff specify the relocation for the address.
  func (s *LSym) WriteAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64) {
  	// Allow 4-byte addresses for DWARF.
  	if siz != ctxt.Arch.PtrSize && siz != 4 {
  		ctxt.Diag("WriteAddr: bad address size %d in %s", siz, s.Name)
  	}
  	s.prepwrite(ctxt, off, siz)
  	r := Addrel(s)
  	r.Off = int32(off)
  	if int64(r.Off) != off {
  		ctxt.Diag("WriteAddr: off overflow %d in %s", off, s.Name)
  	}
  	r.Siz = uint8(siz)
  	r.Sym = rsym
  	r.Type = objabi.R_ADDR
  	r.Add = roff
  }
  
  // WriteOff writes a 4 byte offset to rsym+roff into s at offset off.
  // After linking the 4 bytes stored at s+off will be
  // rsym+roff-(start of section that s is in).
  func (s *LSym) WriteOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
  	s.prepwrite(ctxt, off, 4)
  	r := Addrel(s)
  	r.Off = int32(off)
  	if int64(r.Off) != off {
  		ctxt.Diag("WriteOff: off overflow %d in %s", off, s.Name)
  	}
  	r.Siz = 4
  	r.Sym = rsym
  	r.Type = objabi.R_ADDROFF
  	r.Add = roff
  }
  
  // WriteWeakOff writes a weak 4 byte offset to rsym+roff into s at offset off.
  // After linking the 4 bytes stored at s+off will be
  // rsym+roff-(start of section that s is in).
  func (s *LSym) WriteWeakOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
  	s.prepwrite(ctxt, off, 4)
  	r := Addrel(s)
  	r.Off = int32(off)
  	if int64(r.Off) != off {
  		ctxt.Diag("WriteOff: off overflow %d in %s", off, s.Name)
  	}
  	r.Siz = 4
  	r.Sym = rsym
  	r.Type = objabi.R_WEAKADDROFF
  	r.Add = roff
  }
  
  // WriteString writes a string of size siz into s at offset off.
  func (s *LSym) WriteString(ctxt *Link, off int64, siz int, str string) {
  	if siz < len(str) {
  		ctxt.Diag("WriteString: bad string size: %d < %d", siz, len(str))
  	}
  	s.prepwrite(ctxt, off, siz)
  	copy(s.P[off:off+int64(siz)], str)
  }
  
  // WriteBytes writes a slice of bytes into s at offset off.
  func (s *LSym) WriteBytes(ctxt *Link, off int64, b []byte) int64 {
  	s.prepwrite(ctxt, off, len(b))
  	copy(s.P[off:], b)
  	return off + int64(len(b))
  }
  
  func Addrel(s *LSym) *Reloc {
  	s.R = append(s.R, Reloc{})
  	return &s.R[len(s.R)-1]
  }
  

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