data.go

     1  // Derived from Inferno utils/6l/obj.c and utils/6l/span.c
     2  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/obj.c
     3  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/span.c
     4  //
     5  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
     6  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
     7  //	Portions Copyright © 1997-1999 Vita Nuova Limited
     8  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
     9  //	Portions Copyright © 2004,2006 Bruce Ellis
    10  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
    11  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
    12  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
    13  //
    14  // Permission is hereby granted, free of charge, to any person obtaining a copy
    15  // of this software and associated documentation files (the "Software"), to deal
    16  // in the Software without restriction, including without limitation the rights
    17  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    18  // copies of the Software, and to permit persons to whom the Software is
    19  // furnished to do so, subject to the following conditions:
    20  //
    21  // The above copyright notice and this permission notice shall be included in
    22  // all copies or substantial portions of the Software.
    23  //
    24  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    25  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    26  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    27  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    28  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    29  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    30  // THE SOFTWARE.
    31  
    32  package obj
    33  
    34  import (
    35  	"cmd/internal/objabi"
    36  	"log"
    37  	"math"
    38  )
    39  
    40  // Grow increases the length of s.P to lsiz.
    41  func (s *LSym) Grow(lsiz int64) {
    42  	siz := int(lsiz)
    43  	if int64(siz) != lsiz {
    44  		log.Fatalf("LSym.Grow size %d too long", lsiz)
    45  	}
    46  	if len(s.P) >= siz {
    47  		return
    48  	}
    49  	s.P = append(s.P, make([]byte, siz-len(s.P))...)
    50  }
    51  
    52  // GrowCap increases the capacity of s.P to c.
    53  func (s *LSym) GrowCap(c int64) {
    54  	if int64(cap(s.P)) >= c {
    55  		return
    56  	}
    57  	if s.P == nil {
    58  		s.P = make([]byte, 0, c)
    59  		return
    60  	}
    61  	b := make([]byte, len(s.P), c)
    62  	copy(b, s.P)
    63  	s.P = b
    64  }
    65  
    66  // prepwrite prepares to write data of size siz into s at offset off.
    67  func (s *LSym) prepwrite(ctxt *Link, off int64, siz int) {
    68  	if off < 0 || siz < 0 || off >= 1<<30 {
    69  		ctxt.Diag("prepwrite: bad off=%d siz=%d s=%v", off, siz, s)
    70  	}
    71  	switch s.Type {
    72  	case objabi.Sxxx, objabi.SBSS:
    73  		s.Type = objabi.SDATA
    74  		s.setFIPSType(ctxt)
    75  	case objabi.SNOPTRBSS:
    76  		s.Type = objabi.SNOPTRDATA
    77  		s.setFIPSType(ctxt)
    78  	case objabi.STLSBSS:
    79  		ctxt.Diag("cannot supply data for %v var %v", s.Type, s.Name)
    80  	}
    81  	l := off + int64(siz)
    82  	s.Grow(l)
    83  	if l > s.Size {
    84  		s.Size = l
    85  	}
    86  }
    87  
    88  // WriteFloat32 writes f into s at offset off.
    89  func (s *LSym) WriteFloat32(ctxt *Link, off int64, f float32) {
    90  	s.prepwrite(ctxt, off, 4)
    91  	ctxt.Arch.ByteOrder.PutUint32(s.P[off:], math.Float32bits(f))
    92  }
    93  
    94  // WriteFloat64 writes f into s at offset off.
    95  func (s *LSym) WriteFloat64(ctxt *Link, off int64, f float64) {
    96  	s.prepwrite(ctxt, off, 8)
    97  	ctxt.Arch.ByteOrder.PutUint64(s.P[off:], math.Float64bits(f))
    98  }
    99  
   100  // WriteInt writes an integer i of size siz into s at offset off.
   101  func (s *LSym) WriteInt(ctxt *Link, off int64, siz int, i int64) {
   102  	s.prepwrite(ctxt, off, siz)
   103  	switch siz {
   104  	default:
   105  		ctxt.Diag("WriteInt: bad integer size: %d", siz)
   106  	case 1:
   107  		s.P[off] = byte(i)
   108  	case 2:
   109  		ctxt.Arch.ByteOrder.PutUint16(s.P[off:], uint16(i))
   110  	case 4:
   111  		ctxt.Arch.ByteOrder.PutUint32(s.P[off:], uint32(i))
   112  	case 8:
   113  		ctxt.Arch.ByteOrder.PutUint64(s.P[off:], uint64(i))
   114  	}
   115  }
   116  
   117  func (s *LSym) writeAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64, rtype objabi.RelocType) {
   118  	// Allow 4-byte addresses for DWARF.
   119  	if siz != ctxt.Arch.PtrSize && siz != 4 {
   120  		ctxt.Diag("WriteAddr: bad address size %d in %s", siz, s.Name)
   121  	}
   122  	s.prepwrite(ctxt, off, siz)
   123  	if int64(int32(off)) != off {
   124  		ctxt.Diag("WriteAddr: off overflow %d in %s", off, s.Name)
   125  	}
   126  	s.AddRel(ctxt, Reloc{
   127  		Type: rtype,
   128  		Off:  int32(off),
   129  		Siz:  uint8(siz),
   130  		Sym:  rsym,
   131  		Add:  roff,
   132  	})
   133  }
   134  
   135  // WriteAddr writes an address of size siz into s at offset off.
   136  // rsym and roff specify the relocation for the address.
   137  func (s *LSym) WriteAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64) {
   138  	s.writeAddr(ctxt, off, siz, rsym, roff, objabi.R_ADDR)
   139  }
   140  
   141  // WriteWeakAddr writes an address of size siz into s at offset off.
   142  // rsym and roff specify the relocation for the address.
   143  // This is a weak reference.
   144  func (s *LSym) WriteWeakAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64) {
   145  	s.writeAddr(ctxt, off, siz, rsym, roff, objabi.R_WEAKADDR)
   146  }
   147  
   148  // WriteCURelativeAddr writes a pointer-sized address into s at offset off.
   149  // rsym and roff specify the relocation for the address which will be
   150  // resolved by the linker to an offset from the DW_AT_low_pc attribute of
   151  // the DWARF Compile Unit of rsym.
   152  func (s *LSym) WriteCURelativeAddr(ctxt *Link, off int64, rsym *LSym, roff int64) {
   153  	s.writeAddr(ctxt, off, ctxt.Arch.PtrSize, rsym, roff, objabi.R_ADDRCUOFF)
   154  }
   155  
   156  // WriteOff writes a 4 byte offset to rsym+roff into s at offset off.
   157  // After linking the 4 bytes stored at s+off will be
   158  // rsym+roff-(start of section that s is in).
   159  func (s *LSym) WriteOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
   160  	s.prepwrite(ctxt, off, 4)
   161  	if int64(int32(off)) != off {
   162  		ctxt.Diag("WriteOff: off overflow %d in %s", off, s.Name)
   163  	}
   164  	s.AddRel(ctxt, Reloc{
   165  		Type: objabi.R_ADDROFF,
   166  		Off:  int32(off),
   167  		Siz:  4,
   168  		Sym:  rsym,
   169  		Add:  roff,
   170  	})
   171  }
   172  
   173  // WriteWeakOff writes a weak 4 byte offset to rsym+roff into s at offset off.
   174  // After linking the 4 bytes stored at s+off will be
   175  // rsym+roff-(start of section that s is in).
   176  func (s *LSym) WriteWeakOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
   177  	s.prepwrite(ctxt, off, 4)
   178  	if int64(int32(off)) != off {
   179  		ctxt.Diag("WriteWeakOff: off overflow %d in %s", off, s.Name)
   180  	}
   181  	s.AddRel(ctxt, Reloc{
   182  		Type: objabi.R_WEAKADDROFF,
   183  		Off:  int32(off),
   184  		Siz:  4,
   185  		Sym:  rsym,
   186  		Add:  roff,
   187  	})
   188  }
   189  
   190  // WriteString writes a string of size siz into s at offset off.
   191  func (s *LSym) WriteString(ctxt *Link, off int64, siz int, str string) {
   192  	if siz < len(str) {
   193  		ctxt.Diag("WriteString: bad string size: %d < %d", siz, len(str))
   194  	}
   195  	s.prepwrite(ctxt, off, siz)
   196  	copy(s.P[off:off+int64(siz)], str)
   197  }
   198  
   199  // WriteBytes writes a slice of bytes into s at offset off.
   200  func (s *LSym) WriteBytes(ctxt *Link, off int64, b []byte) int64 {
   201  	s.prepwrite(ctxt, off, len(b))
   202  	copy(s.P[off:], b)
   203  	return off + int64(len(b))
   204  }
   205  
   206  // AddRel adds the relocation rel to s.
   207  func (s *LSym) AddRel(ctxt *Link, rel Reloc) {
   208  	if s.Type.IsFIPS() {
   209  		s.checkFIPSReloc(ctxt, rel)
   210  	}
   211  	s.R = append(s.R, rel)
   212  }
   213
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