include/aout/encap.h

   1 /* Yet Another Try at encapsulating bfd object files in coff.
   2    Copyright (C) 1988-2021 Free Software Foundation, Inc.
   3    Written by Pace Willisson 12/9/88
   4
   5    This file is obsolete.  It needs to be converted to just define a bunch
   6    of stuff that BFD can use to do coff-encapsulated files.  --gnu@cygnus.com
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21    MA 02110-1301, USA.  */
  22
  23 /*
  24  * We only use the coff headers to tell the kernel
  25  * how to exec the file.  Therefore, the only fields that need to
  26  * be filled in are the scnptr and vaddr for the text and data
  27  * sections, and the vaddr for the bss.  As far as coff is concerned,
  28  * there is no symbol table, relocation, or line numbers.
  29  *
  30  * A normal bsd header (struct exec) is placed after the coff headers,
  31  * and before the real text.  I defined a the new fields 'a_machtype'
  32  * and a_flags.  If a_machtype is M_386, and a_flags & A_ENCAP is
  33  * true, then the bsd header is preceeded by a coff header.  Macros
  34  * like N_TXTOFF and N_TXTADDR use this field to find the bsd header.
  35  *
  36  * The only problem is to track down the bsd exec header.  The
  37  * macros HEADER_OFFSET, etc do this.
  38  */
  39
  40 #define N_FLAGS_COFF_ENCAPSULATE 0x20 /* coff header precedes bsd header */
  41
  42 /* Describe the COFF header used for encapsulation.  */
  43
  44 struct coffheader
  45 {
  46   /* filehdr */
  47   unsigned short f_magic;
  48   unsigned short f_nscns;
  49   long f_timdat;
  50   long f_symptr;
  51   long f_nsyms;
  52   unsigned short f_opthdr;
  53   unsigned short f_flags;
  54   /* aouthdr */
  55   short magic;
  56   short vstamp;
  57   long tsize;
  58   long dsize;
  59   long bsize;
  60   long entry;
  61   long text_start;
  62   long data_start;
  63   struct coffscn
  64     {
  65       char s_name[8];
  66       long s_paddr;
  67       long s_vaddr;
  68       long s_size;
  69       long s_scnptr;
  70       long s_relptr;
  71       long s_lnnoptr;
  72       unsigned short s_nreloc;
  73       unsigned short s_nlnno;
  74       long s_flags;
  75     } scns[3];
  76 };
  77 \f
  78 /* Describe some of the parameters of the encapsulation,
  79    including how to find the encapsulated BSD header.  */
  80
  81 /* FIXME, this is dumb.  The same tools can't handle a.outs for different
  82    architectures, just because COFF_MAGIC is different; so you need a
  83    separate GNU nm for every architecture!!?  Unfortunately, it needs to
  84    be this way, since the COFF_MAGIC value is determined by the kernel
  85    we're trying to fool here.  */
  86
  87 #define COFF_MAGIC_I386 0514 /* I386MAGIC */
  88 #define COFF_MAGIC_M68K 0520 /* MC68MAGIC */
  89
  90 #ifdef COFF_MAGIC
  91 short __header_offset_temp;
  92 #define HEADER_OFFSET(f) \
  93         (__header_offset_temp = 0, \
  94          fread ((char *)&__header_offset_temp, sizeof (short), 1, (f)), \
  95          fseek ((f), -sizeof (short), 1), \
  96          __header_offset_temp==COFF_MAGIC ? sizeof(struct coffheader) : 0)
  97 #else
  98 #define HEADER_OFFSET(f) 0
  99 #endif
 100
 101 #define HEADER_SEEK(f) (fseek ((f), HEADER_OFFSET((f)), 1))
 102 \f
 103 /* Describe the characteristics of the BSD header
 104    that appears inside the encapsulation.  */
 105
 106 /* Encapsulated coff files that are linked ZMAGIC have a text segment
 107    offset just past the header (and a matching TXTADDR), excluding
 108    the headers from the text segment proper but keeping the physical
 109    layout and the virtual memory layout page-aligned.
 110
 111    Non-encapsulated a.out files that are linked ZMAGIC have a text
 112    segment that starts at 0 and an N_TXTADR similarly offset to 0.
 113    They too are page-aligned with each other, but they include the
 114    a.out header as part of the text.
 115
 116    The _N_HDROFF gets sizeof struct exec added to it, so we have
 117    to compensate here.  See <a.out.gnu.h>.  */
 118
 119 #undef _N_HDROFF
 120 #undef N_TXTADDR
 121 #undef N_DATADDR
 122
 123 #define _N_HDROFF(x) ((N_FLAGS(x) & N_FLAGS_COFF_ENCAPSULATE) ? \
 124                       sizeof (struct coffheader) : 0)
 125
 126 /* Address of text segment in memory after it is loaded.  */
 127 #define N_TXTADDR(x) \
 128         ((N_FLAGS(x) & N_FLAGS_COFF_ENCAPSULATE) ? \
 129          sizeof (struct coffheader) + sizeof (struct exec) : 0)
 130 #define SEGMENT_SIZE 0x400000
 131
 132 #define N_DATADDR(x) \
 133         ((N_FLAGS(x) & N_FLAGS_COFF_ENCAPSULATE) ? \
 134          (SEGMENT_SIZE + ((N_TXTADDR(x)+(x)->a_text-1) & ~(SEGMENT_SIZE-1))) : \
 135          (N_TXTADDR(x)+(x)->a_text))