text: /* Generic symbol-table support for the BFD library.
     Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
     Written by Cygnus Support.
  
  This file is part of BFD, the Binary File Descriptor library.
  
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.
  
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  
  */
  
  /*
  SECTION
  	Symbols
  
  	BFD trys to maintain as much symbol information as it can when
  	it moves information from file to file. BFD passes information
  	to applications though the <<asymbol>> structure. When the
  	application requests the symbol table, BFD reads the table in
  	the native form and translates parts of it into the internal
  	format. To maintain more than the infomation passed to
  	applications some targets keep some information `behind the
  	scenes', in a structure only the particular back end knows
  	about. For example, the coff back end keeps the original
  	symbol table structure as well as the canonical structure when
  	a BFD is read in. On output, the coff back end can reconstruct
  	the output symbol table so that no information is lost, even
  	information unique to coff which BFD doesn't know or
  	understand. If a coff symbol table was read, but was written
  	through an a.out back end, all the coff specific information
  	would be lost. The symbol table of a BFD
  	is not necessarily read in until a canonicalize request is
  	made. Then the BFD back end fills in a table provided by the
  	application with pointers to the canonical information.  To
  	output symbols, the application provides BFD with a table of
  	pointers to pointers to <<asymbol>>s. This allows applications
  	like the linker to output a symbol as read, since the `behind
  	the scenes' information will be still available. 
  @menu
  @* Reading Symbols::
  @* Writing Symbols::
  @* typedef asymbol::
  @* symbol handling functions::
  @end menu
  
  INODE
  Reading Symbols, Writing Symbols, Symbols, Symbols
  SUBSECTION
  	Reading Symbols
  
  	There are two stages to reading a symbol table from a BFD;
  	allocating storage, and the actual reading process. This is an
  	excerpt from an appliction which reads the symbol table:
  
  |	  unsigned int storage_needed;
  |	  asymbol **symbol_table;
  |	  unsigned int number_of_symbols;
  |	  unsigned int i;
  |	
  |	  storage_needed = get_symtab_upper_bound (abfd);
  |	
  |	  if (storage_needed == 0) {
  |	     return ;
  |	  }
  |	  symbol_table = (asymbol **) bfd_xmalloc (storage_needed);
  |	    ...
  |	  number_of_symbols = 
  |	     bfd_canonicalize_symtab (abfd, symbol_table); 
  |	
  |	  for (i = 0; i < number_of_symbols; i++) {
  |	     process_symbol (symbol_table[i]);
  |	  }
  
  	All storage for the symbols themselves is in an obstack
  	connected to the BFD, and is freed when the BFD is closed.
  
  
  INODE
  Writing Symbols, typedef asymbol, Reading Symbols, Symbols
  SUBSECTION
  	Writing Symbols
  
  	Writing of a symbol table is automatic when a BFD open for
  	writing is closed. The application attaches a vector of
  	pointers to pointers to symbols to the BFD being written, and
  	fills in the symbol count. The close and cleanup code reads
  	through the table provided and performs all the necessary
  	operations. The outputing code must always be provided with an
  	'owned' symbol; one which has come from another BFD, or one
  	which has been created using <<bfd_make_empty_symbol>>.   An
  	example showing the creation of a symbol table with only one element:
  
  |	#include "bfd.h"
  |	main() 
  |	{
  |	  bfd *abfd;
  |	  asymbol *ptrs[2];
  |	  asymbol *new;
  |	
  |	  abfd = bfd_openw("foo","a.out-sunos-big");
  |	  bfd_set_format(abfd, bfd_object);
  |	  new = bfd_make_empty_symbol(abfd);
  |	  new->name = "dummy_symbol";
  |	  new->section = bfd_make_section_old_way(abfd, ".text");
  |	  new->flags = BSF_GLOBAL;
  |	  new->value = 0x12345;
  |	
  |	  ptrs[0] = new;
  |	  ptrs[1] = (asymbol *)0;
  |	  
  |	  bfd_set_symtab(abfd, ptrs, 1);
  |	  bfd_close(abfd);
  |	}
  |	
  |	./makesym 
  |	nm foo
  |	00012345 A dummy_symbol
  
  	Many formats cannot represent arbitary symbol information; for
   	instance the <<a.out>> object format does not allow an
  	arbitary number of sections. A symbol pointing to a section
  	which is not one  of <<.text>>, <<.data>> or <<.bss>> cannot
  	be described. 
  
  */
  
  
  
  /*
  DOCDD
  INODE
  typedef asymbol, symbol handling functions, Writing Symbols, Symbols
  
  */
  /*
  SUBSECTION
  	typedef asymbol
  
  	An <<asymbol>> has the form:
  
  */
  
  /*
  CODE_FRAGMENT
  
  .
  .typedef struct symbol_cache_entry 
  .{
  .	{* A pointer to the BFD which owns the symbol. This information
  .	   is necessary so that a back end can work out what additional
  .   	   information (invisible to the application writer) is carried
  .	   with the symbol.
  .
  .	   This field is *almost* redundant, since you can use section->owner
  .	   instead, except that some symbols point to the global sections
  .	   bfd_{abs,com,und}_section.  This could be fixed by making
  .	   these globals be per-bfd (or per-target-flavor).  FIXME. *}
  .
  .  struct _bfd *the_bfd; {* Use bfd_asymbol_bfd(sym) to access this field. *}
  .
  .	{* The text of the symbol. The name is left alone, and not copied - the
  .	   application may not alter it. *}
  .  CONST char *name;
  .
  .	{* The value of the symbol.  This really should be a union of a
  .          numeric value with a pointer, since some flags indicate that
  .          a pointer to another symbol is stored here.  *}
  .  symvalue value;
  .
  .	{* Attributes of a symbol: *}
  .
  .#define BSF_NO_FLAGS    0x00
  .
  .	{* The symbol has local scope; <<static>> in <<C>>. The value
  . 	   is the offset into the section of the data. *}
  .#define BSF_LOCAL	0x01
  .
  .	{* The symbol has global scope; initialized data in <<C>>. The
  .	   value is the offset into the section of the data. *}
  .#define BSF_GLOBAL	0x02
  .
  .	{* The symbol has global scope, and is exported. The value is
  .	   the offset into the section of the data. *}
  .#define BSF_EXPORT	BSF_GLOBAL {* no real difference *}
  .
  .	{* A normal C symbol would be one of:
  .	   <<BSF_LOCAL>>, <<BSF_FORT_COMM>>,  <<BSF_UNDEFINED>> or
  .	   <<BSF_GLOBAL>> *}
  .
  .	{* The symbol is a debugging record. The value has an arbitary
  .	   meaning. *}
  .#define BSF_DEBUGGING	0x08
  .
  .	{* The symbol denotes a function entry point.  Used in ELF,
  .	   perhaps others someday.  *}
  .#define BSF_FUNCTION    0x10
  .
  .	{* Used by the linker. *}
  .#define BSF_KEEP        0x20
  .#define BSF_KEEP_G      0x40
  .
  .	{* A weak global symbol, overridable without warnings by
  .	   a regular global symbol of the same name.  *}
  .#define BSF_WEAK        0x80
  .
  .       {* This symbol was created to point to a section, e.g. ELF's
  .	   STT_SECTION symbols.  *}
  .#define BSF_SECTION_SYM 0x100
  .
  .	{* The symbol used to be a common symbol, but now it is
  .	   allocated. *}
  .#define BSF_OLD_COMMON  0x200
  .
  .	{* The default value for common data. *}
  .#define BFD_FORT_COMM_DEFAULT_VALUE 0
  .
  .	{* In some files the type of a symbol sometimes alters its
  .	   location in an output file - ie in coff a <<ISFCN>> symbol
  .	   which is also <<C_EXT>> symbol appears where it was
  .	   declared and not at the end of a section.  This bit is set
  .  	   by the target BFD part to convey this information. *}
  .
  .#define BSF_NOT_AT_END    0x400
  .
  .	{* Signal that the symbol is the label of constructor section. *}
  .#define BSF_CONSTRUCTOR   0x800
  .
  .	{* Signal that the symbol is a warning symbol. If the symbol
  .	   is a warning symbol, then the value field (I know this is
  .	   tacky) will point to the asymbol which when referenced will
  .	   cause the warning. *}
  .#define BSF_WARNING       0x1000
  .
  .	{* Signal that the symbol is indirect. The value of the symbol
  .	   is a pointer to an undefined asymbol which contains the
  .	   name to use instead. *}
  .#define BSF_INDIRECT      0x2000
  .
  .	{* BSF_FILE marks symbols that contain a file name.  This is used
  .	   for ELF STT_FILE symbols.  *}
  .#define BSF_FILE          0x4000
  .
  .  flagword flags;
  .
  .	{* A pointer to the section to which this symbol is 
  .	   relative.  This will always be non NULL, there are special
  .          sections for undefined and absolute symbols *}
  .  struct sec *section;
  .
  .	{* Back end special data. This is being phased out in favour
  .	   of making this a union. *}
  .  PTR udata;
  .
  .} asymbol;
  */
  
  #include "bfd.h"
  #include "sysdep.h"
  
  #include "libbfd.h"
  #include "aout/stab_gnu.h"
   
  /*
  DOCDD
  INODE
  symbol handling functions,  , typedef asymbol, Symbols
  SUBSECTION
  	Symbol Handling Functions
  */
  
  /*
  FUNCTION
  	get_symtab_upper_bound
  
  DESCRIPTION
  	Returns the number of bytes required in a vector of pointers
  	to <<asymbols>> for all the symbols in the supplied BFD,
  	including a terminal NULL pointer. If there are no symbols in
  	the BFD, then 0 is returned.
  
  .#define get_symtab_upper_bound(abfd) \
  .     BFD_SEND (abfd, _get_symtab_upper_bound, (abfd))
  
  */
  
  /*
  FUNCTION
  	bfd_canonicalize_symtab
  
  DESCRIPTION
  	Supplied a BFD and a pointer to an uninitialized vector of
  	pointers. This reads in the symbols from the BFD, and fills in
  	the table with pointers to the symbols, and a trailing NULL.
  	The routine returns the actual number of symbol pointers not
  	including the NULL.
  
  
  .#define bfd_canonicalize_symtab(abfd, location) \
  .     BFD_SEND (abfd, _bfd_canonicalize_symtab,\
  .                  (abfd, location))
  
  */
  
  
  /*
  FUNCTION
  	bfd_set_symtab
  
  DESCRIPTION
  	Provided a table of pointers to symbols and a count, writes to
  	the output BFD the symbols when closed.
  
  SYNOPSIS
  	boolean bfd_set_symtab (bfd *, asymbol **, unsigned int );
  */
  
  boolean
  bfd_set_symtab (abfd, location, symcount)
       bfd *abfd;
       asymbol **location;
       unsigned int symcount;
  {
    if ((abfd->format != bfd_object) || (bfd_read_p (abfd))) {
      bfd_error = invalid_operation;
      return false;
    }
  
    bfd_get_outsymbols (abfd) = location;
    bfd_get_symcount (abfd) = symcount;
    return true;
  }
  
  /*
  FUNCTION
  	bfd_print_symbol_vandf
  
  DESCRIPTION
  	Prints the value and flags of the symbol supplied to the stream file.
  
  SYNOPSIS
  	void bfd_print_symbol_vandf(PTR file, asymbol *symbol);
  */
  void
  DEFUN(bfd_print_symbol_vandf,(file, symbol),
  PTR file AND
  asymbol *symbol)
  {
    flagword type = symbol->flags;
    if (symbol->section != (asection *)NULL)
        {
  	fprintf_vma(file, symbol->value+symbol->section->vma);
        }
    else 
        {
  	fprintf_vma(file, symbol->value);
        }
    fprintf(file," %c%c%c%c%c%c%c",
  	  (type & BSF_LOCAL)  ? 'l':' ',
  	  (type & BSF_GLOBAL) ? 'g' : ' ',
  	  (type & BSF_WEAK) ? 'w' : ' ',
  	  (type & BSF_CONSTRUCTOR) ? 'C' : ' ',
  	  (type & BSF_WARNING) ? 'W' : ' ',
  	  (type & BSF_INDIRECT) ? 'I' : ' ',
  	  (type & BSF_DEBUGGING) ? 'd' :' ');
  
  }
  
  
  /*
  FUNCTION
  	bfd_make_empty_symbol
  
  DESCRIPTION
  	This function creates a new <<asymbol>> structure for the BFD,
  	and returns a pointer to it.
  
  	This routine is necessary, since each back end has private
  	information surrounding the <<asymbol>>. Building your own
  	<<asymbol>> and pointing to it will not create the private
  	information, and will cause problems later on.
  
  .#define bfd_make_empty_symbol(abfd) \
  .     BFD_SEND (abfd, _bfd_make_empty_symbol, (abfd))
  */
  
  /*
  FUNCTION
  	bfd_make_debug_symbol
  
  DESCRIPTION
  	This function creates a new <<asymbol>> structure for the BFD,
  	to be used as a debugging symbol.  Further details of its use have
  	yet to be worked out.
  
  .#define bfd_make_debug_symbol(abfd,ptr,size) \
  .        BFD_SEND (abfd, _bfd_make_debug_symbol, (abfd, ptr, size))
  */
  
  struct section_to_type
  {
    CONST char *section;
    char type;
  };
  
  /* Map COFF section names to POSIX/BSD single-character symbol types.
     This table is probably incomplete.  It is sorted for convenience of
     adding entries.  Since it is so short, a linear search is used.  */
  static CONST struct section_to_type stt[] = {
    {"*DEBUG*", 'N'},
    {".bss", 'b'},
    {".data", 'd'},
    {".sbss", 's'},		/* Small BSS (uninitialized data) */
    {".scommon", 'c'},		/* Small common */
    {".sdata", 'g'},		/* Small initialized data */
    {".text", 't'},
    {0, 0}
  };
  
  /* Return the single-character symbol type corresponding to
     COFF section S, or '?' for an unknown COFF section.  */
  
  static char
  coff_section_type (s)
       char *s;
  {
    CONST struct section_to_type *t;
  
    for (t = &stt[0]; t->section; t++)
      if (!strcmp (s, t->section))
        return t->type;
    return '?';
  }
  
  #ifndef islower
  #define islower(c) ((c) >= 'a' && (c) <= 'z')
  #endif
  #ifndef toupper
  #define toupper(c) (islower(c) ? ((c) & ~0x20) : (c))
  #endif
  
  /*
  FUNCTION
  	bfd_decode_symclass
  
  DESCRIPTION
  	Return a character corresponding to the symbol
  	class of symbol, or '?' for an unknown class.
  
  SYNOPSIS
  	int bfd_decode_symclass(asymbol *symbol);
  */
  int
  DEFUN(bfd_decode_symclass,(symbol),
  asymbol *symbol)
  {
    char c;
  
    if (bfd_is_com_section (symbol->section))
      return 'C';
    if (symbol->section == &bfd_und_section)
      return 'U';
    if (symbol->section == &bfd_ind_section)
      return 'I';
    if (!(symbol->flags & (BSF_GLOBAL|BSF_LOCAL)))
      return '?';
  
    if (symbol->section == &bfd_abs_section)
      c = 'a';
    else if (symbol->section)
      c = coff_section_type (symbol->section->name);
    else
      return '?';
    if (symbol->flags & BSF_GLOBAL)
      c = toupper (c);
    return c;
  
    /* We don't have to handle these cases just yet, but we will soon:
       N_SETV: 'v'; 
       N_SETA: 'l'; 
       N_SETT: 'x';
       N_SETD: 'z';
       N_SETB: 's';
       N_INDR: 'i';
       */
  }
  
  /*
  FUNCTION
  	bfd_symbol_info
  
  DESCRIPTION
  	Fill in the basic info about symbol that nm needs.
  	Additional info may be added by the back-ends after
  	calling this function.
  
  SYNOPSIS
  	void bfd_symbol_info(asymbol *symbol, symbol_info *ret);
  */
  
  void
  DEFUN(bfd_symbol_info,(symbol, ret),
        asymbol *symbol AND
        symbol_info *ret)
  {
    ret->type = bfd_decode_symclass (symbol);
    if (ret->type != 'U')
      ret->value = symbol->value+symbol->section->vma;
    else
      ret->value = 0;
    ret->name = symbol->name;
  }
  
  void
  bfd_symbol_is_absolute()
  {
    abort();
  }
  
  