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433 lines
17 KiB
C
433 lines
17 KiB
C
/* bfdlink.h -- header file for BFD link routines
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Copyright 1993 Free Software Foundation, Inc.
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Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#ifndef BFDLINK_H
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#define BFDLINK_H
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/* Which symbols to strip during a link. */
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enum bfd_link_strip
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{
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strip_none, /* Don't strip any symbols. */
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strip_debugger, /* Strip debugging symbols. */
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strip_some, /* keep_hash is the list of symbols to keep. */
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strip_all /* Strip all symbols. */
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};
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/* Which local symbols to discard during a link. This is irrelevant
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if strip_all is used. */
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enum bfd_link_discard
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{
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discard_none, /* Don't discard any locals. */
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discard_l, /* Discard locals with a certain prefix. */
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discard_all /* Discard all locals. */
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};
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/* These are the possible types of an entry in the BFD link hash
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table. */
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enum bfd_link_hash_type
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{
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bfd_link_hash_new, /* Symbol is new. */
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bfd_link_hash_undefined, /* Symbol seen before, but undefined. */
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bfd_link_hash_undefweak, /* Symbol is weak and undefined. */
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bfd_link_hash_defined, /* Symbol is defined. */
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bfd_link_hash_defweak, /* Symbol is weak and defined. */
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bfd_link_hash_common, /* Symbol is common. */
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bfd_link_hash_indirect, /* Symbol is an indirect link. */
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bfd_link_hash_warning /* Like indirect, but warn if referenced. */
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};
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/* The linking routines use a hash table which uses this structure for
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its elements. */
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struct bfd_link_hash_entry
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{
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/* Base hash table entry structure. */
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struct bfd_hash_entry root;
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/* Type of this entry. */
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enum bfd_link_hash_type type;
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/* Undefined and common symbols are kept in a linked list through
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this field. This field is not in the union because that would
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force us to remove entries from the list when we changed their
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type, which would force the list to be doubly linked, which would
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waste more memory. When an undefined or common symbol is
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created, it should be added to this list, the head of which is in
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the link hash table itself. As symbols are defined, they need
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not be removed from the list; anything which reads the list must
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doublecheck the symbol type.
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Weak symbols are not kept on this list.
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Defined and defweak symbols use this field as a reference marker.
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If the field is not NULL, or this structure is the tail of the
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undefined symbol list, the symbol has been referenced. If the
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symbol is undefined and becomes defined, this field will
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automatically be non-NULL since the symbol will have been on the
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undefined symbol list. */
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struct bfd_link_hash_entry *next;
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/* A union of information depending upon the type. */
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union
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{
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/* Nothing is kept for bfd_hash_new. */
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/* bfd_link_hash_undefined, bfd_link_hash_undefweak. */
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struct
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{
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bfd *abfd; /* BFD symbol was found in. */
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} undef;
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/* bfd_link_hash_defined, bfd_link_hash_defweak. */
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struct
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{
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bfd_vma value; /* Symbol value. */
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asection *section; /* Symbol section. */
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} def;
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/* bfd_link_hash_indirect, bfd_link_hash_warning. */
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struct
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{
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struct bfd_link_hash_entry *link; /* Real symbol. */
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const char *warning; /* Warning (bfd_link_hash_warning only). */
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} i;
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/* bfd_link_hash_common. */
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struct
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{
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/* The linker needs to know three things about common
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symbols: the size, the alignment, and the section in
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which the symbol should be placed. We store the size
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here, and we allocate a small structure to hold the
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section and the alignment. The alignment is stored as a
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power of two. We don't store all the information
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directly because we don't want to increase the size of
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the union; this structure is a major space user in the
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linker. */
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bfd_size_type size; /* Common symbol size. */
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struct bfd_link_hash_common_entry
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{
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unsigned int alignment_power; /* Alignment. */
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asection *section; /* Symbol section. */
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} *p;
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} c;
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} u;
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};
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/* This is the link hash table. It is a derived class of
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bfd_hash_table. */
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struct bfd_link_hash_table
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{
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/* The hash table itself. */
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struct bfd_hash_table table;
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/* The back end which created this hash table. This indicates the
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type of the entries in the hash table, which is sometimes
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important information when linking object files of different
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types together. */
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const bfd_target *creator;
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/* A linked list of undefined and common symbols, linked through the
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next field in the bfd_link_hash_entry structure. */
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struct bfd_link_hash_entry *undefs;
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/* Entries are added to the tail of the undefs list. */
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struct bfd_link_hash_entry *undefs_tail;
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};
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/* Look up an entry in a link hash table. If FOLLOW is true, this
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follows bfd_link_hash_indirect and bfd_link_hash_warning links to
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the real symbol. */
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extern struct bfd_link_hash_entry *bfd_link_hash_lookup
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PARAMS ((struct bfd_link_hash_table *, const char *, boolean create,
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boolean copy, boolean follow));
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/* Traverse a link hash table. */
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extern void bfd_link_hash_traverse
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PARAMS ((struct bfd_link_hash_table *,
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boolean (*) (struct bfd_link_hash_entry *, PTR),
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PTR));
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/* Add an entry to the undefs list. */
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extern void bfd_link_add_undef
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PARAMS ((struct bfd_link_hash_table *, struct bfd_link_hash_entry *));
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/* This structure holds all the information needed to communicate
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between BFD and the linker when doing a link. */
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struct bfd_link_info
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{
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/* Function callbacks. */
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const struct bfd_link_callbacks *callbacks;
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/* true if BFD should generate a relocateable object file. */
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boolean relocateable;
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/* true if BFD should generate a shared object. */
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boolean shared;
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/* true if BFD should pre-bind symbols in a shared object. */
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boolean symbolic;
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/* Which symbols to strip. */
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enum bfd_link_strip strip;
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/* Which local symbols to discard. */
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enum bfd_link_discard discard;
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/* The local symbol prefix to discard if using discard_l. */
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unsigned int lprefix_len;
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const char *lprefix;
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/* true if symbols should be retained in memory, false if they
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should be freed and reread. */
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boolean keep_memory;
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/* The list of input BFD's involved in the link. These are chained
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together via the link_next field. */
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bfd *input_bfds;
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/* If a symbol should be created for each input BFD, this is section
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where those symbols should be placed. It must be a section in
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the output BFD. It may be NULL, in which case no such symbols
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will be created. This is to support CREATE_OBJECT_SYMBOLS in the
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linker command language. */
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asection *create_object_symbols_section;
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/* Hash table handled by BFD. */
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struct bfd_link_hash_table *hash;
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/* Hash table of symbols to keep. This is NULL unless strip is
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strip_some. */
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struct bfd_hash_table *keep_hash;
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/* Hash table of symbols to report back via notice_callback. If
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this is NULL no symbols are reported back. */
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struct bfd_hash_table *notice_hash;
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/* If a base output file is wanted, then this points to it */
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PTR base_file;
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};
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/* This structures holds a set of callback functions. These are
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called by the BFD linker routines. The first argument to each
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callback function is the bfd_link_info structure being used. Each
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function returns a boolean value. If the function returns false,
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then the BFD function which called it will return with a failure
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indication. */
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struct bfd_link_callbacks
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{
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/* A function which is called when an object is added from an
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archive. ABFD is the archive element being added. NAME is the
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name of the symbol which caused the archive element to be pulled
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in. */
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boolean (*add_archive_element) PARAMS ((struct bfd_link_info *,
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bfd *abfd,
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const char *name));
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/* A function which is called when a symbol is found with multiple
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definitions. NAME is the symbol which is defined multiple times.
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OBFD is the old BFD, OSEC is the old section, OVAL is the old
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value, NBFD is the new BFD, NSEC is the new section, and NVAL is
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the new value. OBFD may be NULL. OSEC and NSEC may be
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bfd_com_section or bfd_ind_section. */
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boolean (*multiple_definition) PARAMS ((struct bfd_link_info *,
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const char *name,
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bfd *obfd,
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asection *osec,
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bfd_vma oval,
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bfd *nbfd,
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asection *nsec,
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bfd_vma nval));
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/* A function which is called when a common symbol is defined
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multiple times. NAME is the symbol appearing multiple times.
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OBFD is the BFD of the existing symbol; it may be NULL if this is
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not known. OTYPE is the type of the existing symbol, which may
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be bfd_link_hash_defined, bfd_link_hash_defweak,
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bfd_link_hash_common, or bfd_link_hash_indirect. If OTYPE is
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bfd_link_hash_common, OSIZE is the size of the existing symbol.
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NBFD is the BFD of the new symbol. NTYPE is the type of the new
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symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
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bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE
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is the size of the new symbol. */
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boolean (*multiple_common) PARAMS ((struct bfd_link_info *,
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const char *name,
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bfd *obfd,
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enum bfd_link_hash_type otype,
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bfd_vma osize,
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bfd *nbfd,
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enum bfd_link_hash_type ntype,
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bfd_vma nsize));
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/* A function which is called to add a symbol to a set. ENTRY is
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the link hash table entry for the set itself (e.g.,
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__CTOR_LIST__). RELOC is the relocation to use for an entry in
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the set when generating a relocateable file, and is also used to
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get the size of the entry when generating an executable file.
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ABFD, SEC and VALUE identify the value to add to the set. */
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boolean (*add_to_set) PARAMS ((struct bfd_link_info *,
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struct bfd_link_hash_entry *entry,
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bfd_reloc_code_real_type reloc,
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bfd *abfd, asection *sec, bfd_vma value));
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/* A function which is called when the name of a g++ constructor or
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destructor is found. This is only called by some object file
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formats. CONSTRUCTOR is true for a constructor, false for a
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destructor. This will use BFD_RELOC_CTOR when generating a
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relocateable file. NAME is the name of the symbol found. ABFD,
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SECTION and VALUE are the value of the symbol. */
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boolean (*constructor) PARAMS ((struct bfd_link_info *,
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boolean constructor,
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const char *name, bfd *abfd, asection *sec,
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bfd_vma value));
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/* A function which is called when there is a reference to a warning
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symbol. WARNING is the warning to be issued. */
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boolean (*warning) PARAMS ((struct bfd_link_info *,
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const char *warning));
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/* A function which is called when a relocation is attempted against
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an undefined symbol. NAME is the symbol which is undefined.
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ABFD, SECTION and ADDRESS identify the location from which the
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reference is made. In some cases SECTION may be NULL. */
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boolean (*undefined_symbol) PARAMS ((struct bfd_link_info *,
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const char *name, bfd *abfd,
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asection *section, bfd_vma address));
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/* A function which is called when a reloc overflow occurs. NAME is
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the name of the symbol or section the reloc is against,
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RELOC_NAME is the name of the relocation, and ADDEND is any
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addend that is used. ABFD, SECTION and ADDRESS identify the
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location at which the overflow occurs; if this is the result of a
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bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
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ABFD will be NULL. */
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boolean (*reloc_overflow) PARAMS ((struct bfd_link_info *,
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const char *name,
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const char *reloc_name, bfd_vma addend,
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bfd *abfd, asection *section,
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bfd_vma address));
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/* A function which is called when a dangerous reloc is performed.
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The canonical example is an a29k IHCONST reloc which does not
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follow an IHIHALF reloc. MESSAGE is an appropriate message.
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ABFD, SECTION and ADDRESS identify the location at which the
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problem occurred; if this is the result of a
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bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
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ABFD will be NULL. */
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boolean (*reloc_dangerous) PARAMS ((struct bfd_link_info *,
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const char *message,
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bfd *abfd, asection *section,
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bfd_vma address));
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/* A function which is called when a reloc is found to be attached
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to a symbol which is not being written out. NAME is the name of
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the symbol. ABFD, SECTION and ADDRESS identify the location of
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the reloc; if this is the result of a
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bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
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ABFD will be NULL. */
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boolean (*unattached_reloc) PARAMS ((struct bfd_link_info *,
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const char *name,
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bfd *abfd, asection *section,
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bfd_vma address));
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/* A function which is called when a symbol in notice_hash is
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defined or referenced. NAME is the symbol. ABFD, SECTION and
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ADDRESS are the value of the symbol. If SECTION is
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bfd_und_section, this is a reference. */
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boolean (*notice) PARAMS ((struct bfd_link_info *, const char *name,
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bfd *abfd, asection *section, bfd_vma address));
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};
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/* The linker builds link_order structures which tell the code how to
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include input data in the output file. */
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/* These are the types of link_order structures. */
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enum bfd_link_order_type
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{
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bfd_undefined_link_order, /* Undefined. */
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bfd_indirect_link_order, /* Built from a section. */
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bfd_fill_link_order, /* Fill with a 16 bit constant. */
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bfd_data_link_order, /* Set to explicit data. */
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bfd_section_reloc_link_order, /* Relocate against a section. */
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bfd_symbol_reloc_link_order /* Relocate against a symbol. */
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};
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/* This is the link_order structure itself. These form a chain
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attached to the section whose contents they are describing. */
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struct bfd_link_order
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{
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/* Next link_order in chain. */
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struct bfd_link_order *next;
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/* Type of link_order. */
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enum bfd_link_order_type type;
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/* Offset within output section. */
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bfd_vma offset;
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/* Size within output section. */
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bfd_size_type size;
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/* Type specific information. */
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union
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{
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struct
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{
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/* Section to include. If this is used, then
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section->output_section must be the section the
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link_order is attached to, section->output_offset must
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equal the link_order offset field, and section->_raw_size
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must equal the link_order size field. Maybe these
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restrictions should be relaxed someday. */
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asection *section;
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} indirect;
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struct
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{
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/* Value to fill with. */
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unsigned int value;
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} fill;
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struct
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{
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/* Data to put into file. The size field gives the number
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of bytes which this field points to. */
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bfd_byte *contents;
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} data;
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struct
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{
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/* Description of reloc to generate. Used for
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bfd_section_reloc_link_order and
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bfd_symbol_reloc_link_order. */
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struct bfd_link_order_reloc *p;
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} reloc;
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} u;
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};
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/* A linker order of type bfd_section_reloc_link_order or
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bfd_symbol_reloc_link_order means to create a reloc against a
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section or symbol, respectively. This is used to implement -Ur to
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generate relocs for the constructor tables. The
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bfd_link_order_reloc structure describes the reloc that BFD should
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create. It is similar to a arelent, but I didn't use arelent
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because the linker does not know anything about most symbols, and
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any asymbol structure it creates will be partially meaningless.
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This information could logically be in the bfd_link_order struct,
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but I didn't want to waste the space since these types of relocs
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are relatively rare. */
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struct bfd_link_order_reloc
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{
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/* Reloc type. */
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bfd_reloc_code_real_type reloc;
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union
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{
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/* For type bfd_section_reloc_link_order, this is the section
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the reloc should be against. This must be a section in the
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output BFD, not any of the input BFDs. */
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asection *section;
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/* For type bfd_symbol_reloc_link_order, this is the name of the
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symbol the reloc should be against. */
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const char *name;
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} u;
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/* Addend to use. The object file should contain zero. The BFD
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backend is responsible for filling in the contents of the object
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file correctly. For some object file formats (e.g., COFF) the
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addend must be stored into in the object file, and for some
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(e.g., SPARC a.out) it is kept in the reloc. */
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bfd_vma addend;
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};
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/* Allocate a new link_order for a section. */
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extern struct bfd_link_order *bfd_new_link_order PARAMS ((bfd *, asection *));
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#endif
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