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

Documentation: cmd/internal/obj

     1  // Derived from Inferno utils/6l/obj.c and utils/6l/span.c
     2  // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/obj.c
     3  // https://bitbucket.org/inferno-os/inferno-os/src/default/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  	// TODO(dfc) append cap-len at once, rather than
    50  	// one byte at a time.
    51  	for cap(s.P) < siz {
    52  		s.P = append(s.P[:cap(s.P)], 0)
    53  	}
    54  	s.P = s.P[:siz]
    55  }
    56  
    57  // GrowCap increases the capacity of s.P to c.
    58  func (s *LSym) GrowCap(c int64) {
    59  	if int64(cap(s.P)) >= c {
    60  		return
    61  	}
    62  	if s.P == nil {
    63  		s.P = make([]byte, 0, c)
    64  		return
    65  	}
    66  	b := make([]byte, len(s.P), c)
    67  	copy(b, s.P)
    68  	s.P = b
    69  }
    70  
    71  // prepwrite prepares to write data of size siz into s at offset off.
    72  func (s *LSym) prepwrite(ctxt *Link, off int64, siz int) {
    73  	if off < 0 || siz < 0 || off >= 1<<30 {
    74  		ctxt.Diag("prepwrite: bad off=%d siz=%d s=%v", off, siz, s)
    75  	}
    76  	switch s.Type {
    77  	case objabi.Sxxx, objabi.SBSS:
    78  		s.Type = objabi.SDATA
    79  	case objabi.SNOPTRBSS:
    80  		s.Type = objabi.SNOPTRDATA
    81  	case objabi.STLSBSS:
    82  		ctxt.Diag("cannot supply data for %v var %v", s.Type, s.Name)
    83  	}
    84  	l := off + int64(siz)
    85  	s.Grow(l)
    86  	if l > s.Size {
    87  		s.Size = l
    88  	}
    89  }
    90  
    91  // WriteFloat32 writes f into s at offset off.
    92  func (s *LSym) WriteFloat32(ctxt *Link, off int64, f float32) {
    93  	s.prepwrite(ctxt, off, 4)
    94  	ctxt.Arch.ByteOrder.PutUint32(s.P[off:], math.Float32bits(f))
    95  }
    96  
    97  // WriteFloat64 writes f into s at offset off.
    98  func (s *LSym) WriteFloat64(ctxt *Link, off int64, f float64) {
    99  	s.prepwrite(ctxt, off, 8)
   100  	ctxt.Arch.ByteOrder.PutUint64(s.P[off:], math.Float64bits(f))
   101  }
   102  
   103  // WriteInt writes an integer i of size siz into s at offset off.
   104  func (s *LSym) WriteInt(ctxt *Link, off int64, siz int, i int64) {
   105  	s.prepwrite(ctxt, off, siz)
   106  	switch siz {
   107  	default:
   108  		ctxt.Diag("WriteInt: bad integer size: %d", siz)
   109  	case 1:
   110  		s.P[off] = byte(i)
   111  	case 2:
   112  		ctxt.Arch.ByteOrder.PutUint16(s.P[off:], uint16(i))
   113  	case 4:
   114  		ctxt.Arch.ByteOrder.PutUint32(s.P[off:], uint32(i))
   115  	case 8:
   116  		ctxt.Arch.ByteOrder.PutUint64(s.P[off:], uint64(i))
   117  	}
   118  }
   119  
   120  func (s *LSym) writeAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64, rtype objabi.RelocType) {
   121  	// Allow 4-byte addresses for DWARF.
   122  	if siz != ctxt.Arch.PtrSize && siz != 4 {
   123  		ctxt.Diag("WriteAddr: bad address size %d in %s", siz, s.Name)
   124  	}
   125  	s.prepwrite(ctxt, off, siz)
   126  	r := Addrel(s)
   127  	r.Off = int32(off)
   128  	if int64(r.Off) != off {
   129  		ctxt.Diag("WriteAddr: off overflow %d in %s", off, s.Name)
   130  	}
   131  	r.Siz = uint8(siz)
   132  	r.Sym = rsym
   133  	r.Type = rtype
   134  	r.Add = roff
   135  }
   136  
   137  // WriteAddr writes an address of size siz into s at offset off.
   138  // rsym and roff specify the relocation for the address.
   139  func (s *LSym) WriteAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64) {
   140  	s.writeAddr(ctxt, off, siz, rsym, roff, objabi.R_ADDR)
   141  }
   142  
   143  // WriteCURelativeAddr writes a pointer-sized address into s at offset off.
   144  // rsym and roff specify the relocation for the address which will be
   145  // resolved by the linker to an offset from the DW_AT_low_pc attribute of
   146  // the DWARF Compile Unit of rsym.
   147  func (s *LSym) WriteCURelativeAddr(ctxt *Link, off int64, rsym *LSym, roff int64) {
   148  	s.writeAddr(ctxt, off, ctxt.Arch.PtrSize, rsym, roff, objabi.R_ADDRCUOFF)
   149  }
   150  
   151  // WriteOff writes a 4 byte offset to rsym+roff into s at offset off.
   152  // After linking the 4 bytes stored at s+off will be
   153  // rsym+roff-(start of section that s is in).
   154  func (s *LSym) WriteOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
   155  	s.prepwrite(ctxt, off, 4)
   156  	r := Addrel(s)
   157  	r.Off = int32(off)
   158  	if int64(r.Off) != off {
   159  		ctxt.Diag("WriteOff: off overflow %d in %s", off, s.Name)
   160  	}
   161  	r.Siz = 4
   162  	r.Sym = rsym
   163  	r.Type = objabi.R_ADDROFF
   164  	r.Add = roff
   165  }
   166  
   167  // WriteWeakOff writes a weak 4 byte offset to rsym+roff into s at offset off.
   168  // After linking the 4 bytes stored at s+off will be
   169  // rsym+roff-(start of section that s is in).
   170  func (s *LSym) WriteWeakOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
   171  	s.prepwrite(ctxt, off, 4)
   172  	r := Addrel(s)
   173  	r.Off = int32(off)
   174  	if int64(r.Off) != off {
   175  		ctxt.Diag("WriteOff: off overflow %d in %s", off, s.Name)
   176  	}
   177  	r.Siz = 4
   178  	r.Sym = rsym
   179  	r.Type = objabi.R_WEAKADDROFF
   180  	r.Add = roff
   181  }
   182  
   183  // WriteString writes a string of size siz into s at offset off.
   184  func (s *LSym) WriteString(ctxt *Link, off int64, siz int, str string) {
   185  	if siz < len(str) {
   186  		ctxt.Diag("WriteString: bad string size: %d < %d", siz, len(str))
   187  	}
   188  	s.prepwrite(ctxt, off, siz)
   189  	copy(s.P[off:off+int64(siz)], str)
   190  }
   191  
   192  // WriteBytes writes a slice of bytes into s at offset off.
   193  func (s *LSym) WriteBytes(ctxt *Link, off int64, b []byte) int64 {
   194  	s.prepwrite(ctxt, off, len(b))
   195  	copy(s.P[off:], b)
   196  	return off + int64(len(b))
   197  }
   198  
   199  func Addrel(s *LSym) *Reloc {
   200  	s.R = append(s.R, Reloc{})
   201  	return &s.R[len(s.R)-1]
   202  }
   203  

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