archive.c

早期freebsd实现

/* BFD back-end for archive files (libraries).
   Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
   Written by Cygnus Support.  Mostly Gumby Henkel-Wallace's fault.

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.  */

/*
@setfilename archive-info
SECTION
	Archives

DESCRIPTION
	Archives are supported in BFD in <<archive.c>>.

	An archive (or library) is just another BFD.  It has a symbol
	table, although there's not much a user program will do with it.

	The big difference between an archive BFD and an ordinary BFD
	is that the archive doesn't have sections.  Instead it has a
	chain of BFDs considered its contents.  These BFDs can be
	manipulated just like any other.  The BFDs contained in an
	archive opened for reading will all be opened for reading; you
	may put either input or output BFDs into an archive opened for
	output; it will be handled correctly when the archive is closed.

	Use <<bfd_openr_next_archived_file>> to step through all
	the contents of an archive opened for input.  It's not
	required that you read the entire archive if you don't want
	to!  Read it until you find what you want.

	Archive contents of output BFDs are chained through the
	<<next>> pointer in a BFD.  The first one is findable through
	the <<archive_head>> slot of the archive.  Set it with
	<<set_archive_head>> (q.v.).  A given BFD may be in only one
	open output archive at a time.

	As expected, the BFD archive code is more general than the
	archive code of any given environment.  BFD archives may
	contain files of different formats (eg a.out and coff) and
	even different architectures.  You may even place archives
	recursively into archives!

	This can cause unexpected confusion, since some archive
	formats are more expressive than others.  For instance intel
	COFF archives can preserve long filenames; Sun a.out archives
	cannot.  If you move a file from the first to the second
	format and back again, the filename may be truncated.
	Likewise, different a.out environments have different
	conventions as to how they truncate filenames, whether they
	preserve directory names in filenames, etc.  When
	interoperating with native tools, be sure your files are
	homogeneous.

	Beware: most of these formats do not react well to the
	presence of spaces in filenames.  We do the best we can, but
	can't always handle this due to restrctions in the format of
	archives.  Many unix utilities are braindead in regards to
	spaces and such in filenames anyway, so this shouldn't be much
	of a restriction.
*/

/* Assumes:
   o - all archive elements start on an even boundary, newline padded;
   o - all arch headers are char *;
   o - all arch headers are the same size (across architectures).
*/

/* Some formats provide a way to cram a long filename into the short
   (16 chars) space provided by a bsd archive.  The trick is: make a
   special "file" in the front of the archive, sort of like the SYMDEF
   entry.  If the filename is too long to fit, put it in the extended
   name table, and use its index as the filename.  To prevent
   confusion prepend the index with a space.  This means you can't
   have filenames that start with a space, but then again, many unix
   utilities can't handle that anyway.

   This scheme unfortunately requires that you stand on your head in
   order to write an archive since you need to put a magic file at the
   front, and need to touch every entry to do so.  C'est la vie.
*/

#include "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
#include "aout/ar.h"
#include "aout/ranlib.h"
#include <errno.h>

#ifndef errno
extern int errno;
#endif

#ifdef GNU960
#define BFD_GNU960_ARMAG(abfd)	(BFD_COFF_FILE_P((abfd)) ? ARMAG : ARMAGB)
#endif

/* We keep a cache of archive filepointers to archive elements to
   speed up searching the archive by filepos.  We only add an entry to
   the cache when we actually read one.  We also don't sort the cache;
   it's generally short enough to search linearly.
   Note that the pointers here point to the front of the ar_hdr, not
   to the front of the contents!
*/
struct ar_cache {
  file_ptr ptr;
  bfd* arelt;
  struct ar_cache *next;
};

#define ar_padchar(abfd) ((abfd)->xvec->ar_pad_char)
#define ar_maxnamelen(abfd) ((abfd)->xvec->ar_max_namelen)

#define arch_hdr(bfd) ((struct ar_hdr *)   \
		       (((struct areltdata *)((bfd)->arelt_data))->arch_header))

boolean
_bfd_generic_mkarchive (abfd)
     bfd *abfd;
{
  abfd->tdata.aout_ar_data = (struct artdata *)bfd_zalloc(abfd, sizeof (struct artdata));

  if (bfd_ardata (abfd) == NULL) {
      bfd_error = no_memory;
      return false;
    }
  bfd_ardata(abfd)->cache = 0;
  return true;
}

/*
FUNCTION
	bfd_get_next_mapent

SYNOPSIS
	symindex bfd_get_next_mapent(bfd *, symindex previous, carsym ** sym);

DESCRIPTION
	This function steps through an archive's symbol table (if it
	has one).  Successively updates <<sym>> with the next symbol's
	information, returning that symbol's (internal) index into the
	symbol table.

	Supply BFD_NO_MORE_SYMBOLS as the <<previous>> entry to get
	the first one; returns BFD_NO_MORE_SYMBOLS when you're already
	got the last one.

	A <<carsym>> is a canonical archive symbol.  The only
	user-visible element is its name, a null-terminated string.
*/

symindex
DEFUN(bfd_get_next_mapent,(abfd, prev, entry),
     bfd *abfd AND
     symindex prev AND
     carsym **entry)
{
  if (!bfd_has_map (abfd)) {
    bfd_error = invalid_operation;
    return BFD_NO_MORE_SYMBOLS;
  }
  
  if (prev == BFD_NO_MORE_SYMBOLS) prev = 0;
  else if (++prev >= bfd_ardata (abfd)->symdef_count)
    return BFD_NO_MORE_SYMBOLS;

  *entry = (bfd_ardata (abfd)->symdefs + prev);
  return prev;
}

/* To be called by backends only */
bfd *
_bfd_create_empty_archive_element_shell (obfd)
     bfd *obfd;
{
  bfd *nbfd;

  nbfd = new_bfd_contained_in(obfd);
  if (nbfd == NULL) {
    bfd_error = no_memory;
    return NULL;
  }
  return nbfd;
}

/*
FUNCTION
	bfd_set_archive_head

SYNOPSIS
	boolean bfd_set_archive_head(bfd *output, bfd *new_head);

DESCRIPTION
	Used whilst processing archives. Sets the head of the chain of
	BFDs contained in an archive to @var{new_head}. 
*/

boolean
DEFUN(bfd_set_archive_head,(output_archive, new_head),
     bfd *output_archive AND 
     bfd *new_head)
{

  output_archive->archive_head = new_head;
  return true;
}

bfd *
look_for_bfd_in_cache (arch_bfd, filepos)
     bfd *arch_bfd;
     file_ptr filepos;
{
  struct ar_cache *current;

  for (current = bfd_ardata (arch_bfd)->cache; current != NULL;
       current = current->next)
    if (current->ptr == filepos) return current->arelt;

  return NULL;
}

/* Kind of stupid to call cons for each one, but we don't do too many */
boolean
add_bfd_to_cache (arch_bfd, filepos, new_elt)
     bfd *arch_bfd, *new_elt;
     file_ptr filepos;
{
  struct ar_cache *new_cache = (struct ar_cache *)
				bfd_zalloc(arch_bfd, sizeof (struct ar_cache));

  if (new_cache == NULL) {
    bfd_error = no_memory;
    return false;
  }

  new_cache->ptr = filepos;
  new_cache->arelt = new_elt;
  new_cache->next = (struct ar_cache *)NULL;
  if (bfd_ardata (arch_bfd)->cache == NULL)
    bfd_ardata (arch_bfd)->cache = new_cache;
  else {
    struct ar_cache *current = bfd_ardata (arch_bfd)->cache;

    for (; current->next != NULL; current = current->next);
    current->next = new_cache;
  }
    
  return true;
}



/* The name begins with space.  Hence the rest of the name is an index into
   the string table. */
char *
get_extended_arelt_filename (arch, name)
     bfd *arch;
     char *name;
{
  unsigned long index = 0;

  /* Should extract string so that I can guarantee not to overflow into
     the next region, but I"m too lazy. */
  errno = 0;
  index = strtol (name, NULL, 10);
  if (errno != 0) {
      bfd_error = malformed_archive;
      return NULL;
    }

  return bfd_ardata (arch)->extended_names + index;
}  

/* This functions reads an arch header and returns an areltdata pointer, or
   NULL on error.

   Presumes the file pointer is already in the right place (ie pointing
   to the ar_hdr in the file).   Moves the file pointer; on success it
   should be pointing to the front of the file contents; on failure it
   could have been moved arbitrarily.
*/

struct areltdata *
snarf_ar_hdr (abfd)
     bfd *abfd;
{
#ifndef errno
  extern int errno;
#endif

    struct ar_hdr hdr;
    char *hdrp = (char *) &hdr;
    unsigned int parsed_size;
    struct areltdata *ared;
    char *filename = NULL;
    unsigned int namelen = 0;
    unsigned int allocsize = sizeof (struct areltdata) + sizeof (struct ar_hdr);
    char *allocptr;

    if (bfd_read ((PTR)hdrp, 1, sizeof (struct ar_hdr), abfd)
	!= sizeof (struct ar_hdr)) {
	bfd_error = no_more_archived_files;
	return NULL;
    }
    if (strncmp ((hdr.ar_fmag), ARFMAG, 2)) {
	bfd_error = malformed_archive;
	return NULL;
    }

    errno = 0;
    parsed_size = strtol (hdr.ar_size, NULL, 10);
    if (errno != 0) {
	bfd_error = malformed_archive;
	return NULL;
    }

    /* extract the filename from the archive - there are two ways to
       specify an extendend name table, either the first char of the
       name is a space, or it's a slash  */
    if ((hdr.ar_name[0] == '/' || hdr.ar_name[0] == ' ') 
	&& bfd_ardata (abfd)->extended_names != NULL) {
	filename = get_extended_arelt_filename (abfd, hdr.ar_name);
	if (filename == NULL) {
	    bfd_error = malformed_archive;
	    return NULL;
	}
    } 
    else 
	{
	    /* We judge the end of the name by looking for a space or a
	       padchar */

	    namelen = 0;

	    while (namelen < (unsigned)ar_maxnamelen(abfd) &&
		   ( hdr.ar_name[namelen] != 0 &&
		    hdr.ar_name[namelen] != ' ' &&
		    hdr.ar_name[namelen] != ar_padchar(abfd))) {
		namelen++;
	    }

	    allocsize += namelen + 1;
	}

    allocptr = bfd_zalloc(abfd, allocsize);
    if (allocptr == NULL) {
	bfd_error = no_memory;
	return NULL;
    }

    ared = (struct areltdata *) allocptr;

    ared->arch_header = allocptr + sizeof (struct areltdata);
    memcpy ((char *) ared->arch_header, (char *) &hdr, sizeof (struct ar_hdr));
    ared->parsed_size = parsed_size;

    if (filename != NULL) ared->filename = filename;
    else {
	ared->filename = allocptr + (sizeof (struct areltdata) +
				     sizeof (struct ar_hdr));
	if (namelen)
	    memcpy (ared->filename, hdr.ar_name, namelen);
	ared->filename[namelen] = '\0';
    }
  
    return ared;
}

/* This is an internal function; it's mainly used when indexing
   through the archive symbol table, but also used to get the next
   element, since it handles the bookkeeping so nicely for us.
*/

bfd *
get_elt_at_filepos (archive, filepos)
     bfd *archive;
     file_ptr filepos;
{
  struct areltdata *new_areldata;
  bfd *n_nfd;

  n_nfd = look_for_bfd_in_cache (archive, filepos);
  if (n_nfd) return n_nfd;

  if (0 > bfd_seek (archive, filepos, SEEK_SET)) {
    bfd_error = system_call_error;
    return NULL;
  }

  if ((new_areldata = snarf_ar_hdr (archive)) == NULL) return NULL;
  
  n_nfd = _bfd_create_empty_archive_element_shell (archive);
  if (n_nfd == NULL) {
    bfd_release (archive, (PTR)new_areldata);
    return NULL;
  }
  n_nfd->origin = bfd_tell (archive);
  n_nfd->arelt_data = (PTR) new_areldata;
  n_nfd->filename = new_areldata->filename;

  if (add_bfd_to_cache (archive, filepos, n_nfd))
    return n_nfd;

  /* huh? */
  bfd_release (archive, (PTR)n_nfd);
  bfd_release (archive, (PTR)new_areldata);
  return NULL;
}

/*
FUNCTION
	bfd_get_elt_at_index

SYNOPSIS
	bfd *bfd_get_elt_at_index(bfd * archive, int index);

DESCRIPTION
	Return the bfd which is referenced by the symbol indexed by <<index>>.
	<<index>> should have been returned by <<bfd_get_next_mapent>> (q.v.).

*/
bfd *
DEFUN(bfd_get_elt_at_index,(abfd, index),
     bfd *abfd AND
     int index)
{
  bfd *result =
    get_elt_at_filepos
      (abfd, (bfd_ardata (abfd)->symdefs + index)->file_offset);
  return result;
}

/*
FUNCTION
	bfd_openr_next_archived_file

SYNOPSIS
	bfd* bfd_openr_next_archived_file(bfd *archive, bfd *previous);

DESCRIPTION
	Initially provided a BFD containing an archive and NULL, opens
	an inpout BFD on the first contained element and returns that.
	Subsequent calls to bfd_openr_next_archived_file should pass
	the archive and the previous return value to return a created
	BFD to the next contained element. NULL is returned when there
	are no more.

*/

bfd *
DEFUN(bfd_openr_next_archived_file,(archive, last_file),
     bfd *archive AND  
      bfd*last_file)
{

    if ((bfd_get_format (archive) != bfd_archive) ||
	(archive->direction == write_direction)) {
	    bfd_error = invalid_operation;
	    return NULL;
	}


    return BFD_SEND (archive,
		     openr_next_archived_file,
		     (archive,
		      last_file));

}

bfd *bfd_generic_openr_next_archived_file(archive, last_file)
     bfd *archive;
     bfd *last_file;
{
  file_ptr filestart;

  if (!last_file)
    filestart = bfd_ardata (archive)->first_file_filepos;
  else {
    unsigned int size = arelt_size(last_file);
    /* Pad to an even boundary... */
    filestart = last_file->origin + size + size%2;
  }

  return get_elt_at_filepos (archive, filestart);
}


bfd_target *
bfd_generic_archive_p (abfd)
     bfd *abfd;
{