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/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  	case objabi.SNOPTRBSS:
    75  		s.Type = objabi.SNOPTRDATA
    76  	case objabi.STLSBSS:
    77  		ctxt.Diag("cannot supply data for %v var %v", s.Type, s.Name)
    78  	}
    79  	l := off + int64(siz)
    80  	s.Grow(l)
    81  	if l > s.Size {
    82  		s.Size = l
    83  	}
    84  }
    85  
    86  // WriteFloat32 writes f into s at offset off.
    87  func (s *LSym) WriteFloat32(ctxt *Link, off int64, f float32) {
    88  	s.prepwrite(ctxt, off, 4)
    89  	ctxt.Arch.ByteOrder.PutUint32(s.P[off:], math.Float32bits(f))
    90  }
    91  
    92  // WriteFloat64 writes f into s at offset off.
    93  func (s *LSym) WriteFloat64(ctxt *Link, off int64, f float64) {
    94  	s.prepwrite(ctxt, off, 8)
    95  	ctxt.Arch.ByteOrder.PutUint64(s.P[off:], math.Float64bits(f))
    96  }
    97  
    98  // WriteInt writes an integer i of size siz into s at offset off.
    99  func (s *LSym) WriteInt(ctxt *Link, off int64, siz int, i int64) {
   100  	s.prepwrite(ctxt, off, siz)
   101  	switch siz {
   102  	default:
   103  		ctxt.Diag("WriteInt: bad integer size: %d", siz)
   104  	case 1:
   105  		s.P[off] = byte(i)
   106  	case 2:
   107  		ctxt.Arch.ByteOrder.PutUint16(s.P[off:], uint16(i))
   108  	case 4:
   109  		ctxt.Arch.ByteOrder.PutUint32(s.P[off:], uint32(i))
   110  	case 8:
   111  		ctxt.Arch.ByteOrder.PutUint64(s.P[off:], uint64(i))
   112  	}
   113  }
   114  
   115  func (s *LSym) writeAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64, rtype objabi.RelocType) {
   116  	// Allow 4-byte addresses for DWARF.
   117  	if siz != ctxt.Arch.PtrSize && siz != 4 {
   118  		ctxt.Diag("WriteAddr: bad address size %d in %s", siz, s.Name)
   119  	}
   120  	s.prepwrite(ctxt, off, siz)
   121  	r := Addrel(s)
   122  	r.Off = int32(off)
   123  	if int64(r.Off) != off {
   124  		ctxt.Diag("WriteAddr: off overflow %d in %s", off, s.Name)
   125  	}
   126  	r.Siz = uint8(siz)
   127  	r.Sym = rsym
   128  	r.Type = rtype
   129  	r.Add = roff
   130  }
   131  
   132  // WriteAddr writes an address of size siz into s at offset off.
   133  // rsym and roff specify the relocation for the address.
   134  func (s *LSym) WriteAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64) {
   135  	s.writeAddr(ctxt, off, siz, rsym, roff, objabi.R_ADDR)
   136  }
   137  
   138  // WriteWeakAddr writes an address of size siz into s at offset off.
   139  // rsym and roff specify the relocation for the address.
   140  // This is a weak reference.
   141  func (s *LSym) WriteWeakAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64) {
   142  	s.writeAddr(ctxt, off, siz, rsym, roff, objabi.R_WEAKADDR)
   143  }
   144  
   145  // WriteCURelativeAddr writes a pointer-sized address into s at offset off.
   146  // rsym and roff specify the relocation for the address which will be
   147  // resolved by the linker to an offset from the DW_AT_low_pc attribute of
   148  // the DWARF Compile Unit of rsym.
   149  func (s *LSym) WriteCURelativeAddr(ctxt *Link, off int64, rsym *LSym, roff int64) {
   150  	s.writeAddr(ctxt, off, ctxt.Arch.PtrSize, rsym, roff, objabi.R_ADDRCUOFF)
   151  }
   152  
   153  // WriteOff writes a 4 byte offset to rsym+roff into s at offset off.
   154  // After linking the 4 bytes stored at s+off will be
   155  // rsym+roff-(start of section that s is in).
   156  func (s *LSym) WriteOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
   157  	s.prepwrite(ctxt, off, 4)
   158  	r := Addrel(s)
   159  	r.Off = int32(off)
   160  	if int64(r.Off) != off {
   161  		ctxt.Diag("WriteOff: off overflow %d in %s", off, s.Name)
   162  	}
   163  	r.Siz = 4
   164  	r.Sym = rsym
   165  	r.Type = objabi.R_ADDROFF
   166  	r.Add = roff
   167  }
   168  
   169  // WriteWeakOff writes a weak 4 byte offset to rsym+roff into s at offset off.
   170  // After linking the 4 bytes stored at s+off will be
   171  // rsym+roff-(start of section that s is in).
   172  func (s *LSym) WriteWeakOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
   173  	s.prepwrite(ctxt, off, 4)
   174  	r := Addrel(s)
   175  	r.Off = int32(off)
   176  	if int64(r.Off) != off {
   177  		ctxt.Diag("WriteOff: off overflow %d in %s", off, s.Name)
   178  	}
   179  	r.Siz = 4
   180  	r.Sym = rsym
   181  	r.Type = objabi.R_WEAKADDROFF
   182  	r.Add = roff
   183  }
   184  
   185  // WriteString writes a string of size siz into s at offset off.
   186  func (s *LSym) WriteString(ctxt *Link, off int64, siz int, str string) {
   187  	if siz < len(str) {
   188  		ctxt.Diag("WriteString: bad string size: %d < %d", siz, len(str))
   189  	}
   190  	s.prepwrite(ctxt, off, siz)
   191  	copy(s.P[off:off+int64(siz)], str)
   192  }
   193  
   194  // WriteBytes writes a slice of bytes into s at offset off.
   195  func (s *LSym) WriteBytes(ctxt *Link, off int64, b []byte) int64 {
   196  	s.prepwrite(ctxt, off, len(b))
   197  	copy(s.P[off:], b)
   198  	return off + int64(len(b))
   199  }
   200  
   201  func Addrel(s *LSym) *Reloc {
   202  	if s.R == nil {
   203  		s.R = make([]Reloc, 0, 4)
   204  	}
   205  	s.R = append(s.R, Reloc{})
   206  	return &s.R[len(s.R)-1]
   207  }
   208
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