/* bfdlink.h -- header file for BFD link routines Copyright 1993 Free Software Foundation, Inc. Written by Steve Chamberlain and Ian Lance Taylor, 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. */ #ifndef BFDLINK_H #define BFDLINK_H /* Which symbols to strip during a link. */ enum bfd_link_strip { strip_none, /* Don't strip any symbols. */ strip_debugger, /* Strip debugging symbols. */ strip_some, /* keep_hash is the list of symbols to keep. */ strip_all /* Strip all symbols. */ }; /* Which local symbols to discard during a link. This is irrelevant if strip_all is used. */ enum bfd_link_discard { discard_none, /* Don't discard any locals. */ discard_l, /* Discard locals with a certain prefix. */ discard_all /* Discard all locals. */ }; /* These are the possible types of an entry in the BFD link hash table. */ enum bfd_link_hash_type { bfd_link_hash_new, /* Symbol is new. */ bfd_link_hash_undefined, /* Symbol seen before, but undefined. */ bfd_link_hash_undefweak, /* Symbol is weak and undefined. */ bfd_link_hash_defined, /* Symbol is defined. */ bfd_link_hash_defweak, /* Symbol is weak and defined. */ bfd_link_hash_common, /* Symbol is common. */ bfd_link_hash_indirect, /* Symbol is an indirect link. */ bfd_link_hash_warning /* Like indirect, but warn if referenced. */ }; /* The linking routines use a hash table which uses this structure for its elements. */ struct bfd_link_hash_entry { /* Base hash table entry structure. */ struct bfd_hash_entry root; /* Type of this entry. */ enum bfd_link_hash_type type; /* Undefined and common symbols are kept in a linked list through this field. This field is not in the union because that would force us to remove entries from the list when we changed their type, which would force the list to be doubly linked, which would waste more memory. When an undefined or common symbol is created, it should be added to this list, the head of which is in the link hash table itself. As symbols are defined, they need not be removed from the list; anything which reads the list must doublecheck the symbol type. Weak symbols are not kept on this list. Defined and defweak symbols use this field as a reference marker. If the field is not NULL, or this structure is the tail of the undefined symbol list, the symbol has been referenced. If the symbol is undefined and becomes defined, this field will automatically be non-NULL since the symbol will have been on the undefined symbol list. */ struct bfd_link_hash_entry *next; /* A union of information depending upon the type. */ union { /* Nothing is kept for bfd_hash_new. */ /* bfd_link_hash_undefined, bfd_link_hash_undefweak. */ struct { bfd *abfd; /* BFD symbol was found in. */ } undef; /* bfd_link_hash_defined, bfd_link_hash_defweak. */ struct { bfd_vma value; /* Symbol value. */ asection *section; /* Symbol section. */ } def; /* bfd_link_hash_indirect, bfd_link_hash_warning. */ struct { struct bfd_link_hash_entry *link; /* Real symbol. */ const char *warning; /* Warning (bfd_link_hash_warning only). */ } i; /* bfd_link_hash_common. */ struct { /* The linker needs to know three things about common symbols: the size, the alignment, and the section in which the symbol should be placed. On the assumption that a single common symbol will not take up incredible amounts of memory, we pack the size and the alignment into the space of a single integer. The alignment is stored as a power of two. */ unsigned int alignment_power : 6; /* Alignment. */ unsigned int size : 26; /* Common symbol size. */ asection *section; /* Symbol section. */ } c; } u; }; /* This is the link hash table. It is a derived class of bfd_hash_table. */ struct bfd_link_hash_table { /* The hash table itself. */ struct bfd_hash_table table; /* The back end which created this hash table. This indicates the type of the entries in the hash table, which is sometimes important information when linking object files of different types together. */ const bfd_target *creator; /* A linked list of undefined and common symbols, linked through the next field in the bfd_link_hash_entry structure. */ struct bfd_link_hash_entry *undefs; /* Entries are added to the tail of the undefs list. */ struct bfd_link_hash_entry *undefs_tail; }; /* Look up an entry in a link hash table. If FOLLOW is true, this follows bfd_link_hash_indirect and bfd_link_hash_warning links to the real symbol. */ extern struct bfd_link_hash_entry *bfd_link_hash_lookup PARAMS ((struct bfd_link_hash_table *, const char *, boolean create, boolean copy, boolean follow)); /* Traverse a link hash table. */ extern void bfd_link_hash_traverse PARAMS ((struct bfd_link_hash_table *, boolean (*) (struct bfd_link_hash_entry *, PTR), PTR)); /* Add an entry to the undefs list. */ extern void bfd_link_add_undef PARAMS ((struct bfd_link_hash_table *, struct bfd_link_hash_entry *)); /* This structure holds all the information needed to communicate between BFD and the linker when doing a link. */ struct bfd_link_info { /* Function callbacks. */ const struct bfd_link_callbacks *callbacks; /* true if BFD should generate a relocateable object file. */ boolean relocateable; /* true if BFD should generate a shared object. */ boolean shared; /* Which symbols to strip. */ enum bfd_link_strip strip; /* Which local symbols to discard. */ enum bfd_link_discard discard; /* The local symbol prefix to discard if using discard_l. */ unsigned int lprefix_len; const char *lprefix; /* true if symbols should be retained in memory, false if they should be freed and reread. */ boolean keep_memory; /* The list of input BFD's involved in the link. These are chained together via the link_next field. */ bfd *input_bfds; /* If a symbol should be created for each input BFD, this is section where those symbols should be placed. It must be a section in the output BFD. It may be NULL, in which case no such symbols will be created. This is to support CREATE_OBJECT_SYMBOLS in the linker command language. */ asection *create_object_symbols_section; /* Hash table handled by BFD. */ struct bfd_link_hash_table *hash; /* Hash table of symbols to keep. This is NULL unless strip is strip_some. */ struct bfd_hash_table *keep_hash; /* Hash table of symbols to report back via notice_callback. If this is NULL no symbols are reported back. */ struct bfd_hash_table *notice_hash; }; /* This structures holds a set of callback functions. These are called by the BFD linker routines. The first argument to each callback function is the bfd_link_info structure being used. Each function returns a boolean value. If the function returns false, then the BFD function which called it will return with a failure indication. */ struct bfd_link_callbacks { /* A function which is called when an object is added from an archive. ABFD is the archive element being added. NAME is the name of the symbol which caused the archive element to be pulled in. */ boolean (*add_archive_element) PARAMS ((struct bfd_link_info *, bfd *abfd, const char *name)); /* A function which is called when a symbol is found with multiple definitions. NAME is the symbol which is defined multiple times. OBFD is the old BFD, OSEC is the old section, OVAL is the old value, NBFD is the new BFD, NSEC is the new section, and NVAL is the new value. OBFD may be NULL. OSEC and NSEC may be bfd_com_section or bfd_ind_section. */ boolean (*multiple_definition) PARAMS ((struct bfd_link_info *, const char *name, bfd *obfd, asection *osec, bfd_vma oval, bfd *nbfd, asection *nsec, bfd_vma nval)); /* A function which is called when a common symbol is defined multiple times. NAME is the symbol appearing multiple times. OBFD is the BFD of the existing symbol; it may be NULL if this is not known. OTYPE is the type of the existing symbol, which may be bfd_link_hash_defined, bfd_link_hash_defweak, bfd_link_hash_common, or bfd_link_hash_indirect. If OTYPE is bfd_link_hash_common, OSIZE is the size of the existing symbol. NBFD is the BFD of the new symbol. NTYPE is the type of the new symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE is the size of the new symbol. */ boolean (*multiple_common) PARAMS ((struct bfd_link_info *, const char *name, bfd *obfd, enum bfd_link_hash_type otype, bfd_vma osize, bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize)); /* A function which is called to add a symbol to a set. ENTRY is the link hash table entry for the set itself (e.g., __CTOR_LIST__). RELOC is the relocation to use for an entry in the set when generating a relocateable file, and is also used to get the size of the entry when generating an executable file. ABFD, SEC and VALUE identify the value to add to the set. */ boolean (*add_to_set) PARAMS ((struct bfd_link_info *, struct bfd_link_hash_entry *entry, bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value)); /* A function which is called when the name of a g++ constructor or destructor is found. This is only called by some object file formats. CONSTRUCTOR is true for a constructor, false for a destructor. This will use BFD_RELOC_CTOR when generating a relocateable file. NAME is the name of the symbol found. ABFD, SECTION and VALUE are the value of the symbol. */ boolean (*constructor) PARAMS ((struct bfd_link_info *, boolean constructor, const char *name, bfd *abfd, asection *sec, bfd_vma value)); /* A function which is called when there is a reference to a warning symbol. WARNING is the warning to be issued. */ boolean (*warning) PARAMS ((struct bfd_link_info *, const char *warning)); /* A function which is called when a relocation is attempted against an undefined symbol. NAME is the symbol which is undefined. ABFD, SECTION and ADDRESS identify the location from which the reference is made. In some cases SECTION may be NULL. */ boolean (*undefined_symbol) PARAMS ((struct bfd_link_info *, const char *name, bfd *abfd, asection *section, bfd_vma address)); /* A function which is called when a reloc overflow occurs. NAME is the name of the symbol or section the reloc is against, RELOC_NAME is the name of the relocation, and ADDEND is any addend that is used. ABFD, SECTION and ADDRESS identify the location at which the overflow occurs; if this is the result of a bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then ABFD will be NULL. */ boolean (*reloc_overflow) PARAMS ((struct bfd_link_info *, const char *name, const char *reloc_name, bfd_vma addend, bfd *abfd, asection *section, bfd_vma address)); /* A function which is called when a dangerous reloc is performed. The canonical example is an a29k IHCONST reloc which does not follow an IHIHALF reloc. MESSAGE is an appropriate message. ABFD, SECTION and ADDRESS identify the location at which the problem occurred; if this is the result of a bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then ABFD will be NULL. */ boolean (*reloc_dangerous) PARAMS ((struct bfd_link_info *, const char *message, bfd *abfd, asection *section, bfd_vma address)); /* A function which is called when a reloc is found to be attached to a symbol which is not being written out. NAME is the name of the symbol. ABFD, SECTION and ADDRESS identify the location of the reloc; if this is the result of a bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then ABFD will be NULL. */ boolean (*unattached_reloc) PARAMS ((struct bfd_link_info *, const char *name, bfd *abfd, asection *section, bfd_vma address)); /* A function which is called when a symbol in notice_hash is defined or referenced. NAME is the symbol. ABFD, SECTION and ADDRESS are the value of the symbol. If SECTION is bfd_und_section, this is a reference. */ boolean (*notice) PARAMS ((struct bfd_link_info *, const char *name, bfd *abfd, asection *section, bfd_vma address)); }; /* The linker builds link_order structures which tell the code how to include input data in the output file. */ /* These are the types of link_order structures. */ enum bfd_link_order_type { bfd_undefined_link_order, /* Undefined. */ bfd_indirect_link_order, /* Built from a section. */ bfd_fill_link_order, /* Fill with a 16 bit constant. */ bfd_data_link_order, /* Set to explicit data. */ bfd_section_reloc_link_order, /* Relocate against a section. */ bfd_symbol_reloc_link_order /* Relocate against a symbol. */ }; /* This is the link_order structure itself. These form a chain attached to the section whose contents they are describing. */ struct bfd_link_order { /* Next link_order in chain. */ struct bfd_link_order *next; /* Type of link_order. */ enum bfd_link_order_type type; /* Offset within output section. */ bfd_vma offset; /* Size within output section. */ bfd_size_type size; /* Type specific information. */ union { struct { /* Section to include. If this is used, then section->output_section must be the section the link_order is attached to, section->output_offset must equal the link_order offset field, and section->_raw_size must equal the link_order size field. Maybe these restrictions should be relaxed someday. */ asection *section; } indirect; struct { /* Value to fill with. */ unsigned int value; } fill; struct { /* Data to put into file. The size field gives the number of bytes which this field points to. */ bfd_byte *contents; } data; struct { /* Description of reloc to generate. Used for bfd_section_reloc_link_order and bfd_symbol_reloc_link_order. */ struct bfd_link_order_reloc *p; } reloc; } u; }; /* A linker order of type bfd_section_reloc_link_order or bfd_symbol_reloc_link_order means to create a reloc against a section or symbol, respectively. This is used to implement -Ur to generate relocs for the constructor tables. The bfd_link_order_reloc structure describes the reloc that BFD should create. It is similar to a arelent, but I didn't use arelent because the linker does not know anything about most symbols, and any asymbol structure it creates will be partially meaningless. This information could logically be in the bfd_link_order struct, but I didn't want to waste the space since these types of relocs are relatively rare. */ struct bfd_link_order_reloc { /* Reloc type. */ bfd_reloc_code_real_type reloc; union { /* For type bfd_section_reloc_link_order, this is the section the reloc should be against. This must be a section in the output BFD, not any of the input BFDs. */ asection *section; /* For type bfd_symbol_reloc_link_order, this is the name of the symbol the reloc should be against. */ const char *name; } u; /* Addend to use. The object file should contain zero. The BFD backend is responsible for filling in the contents of the object file correctly. For some object file formats (e.g., COFF) the addend must be stored into in the object file, and for some (e.g., SPARC a.out) it is kept in the reloc. */ bfd_vma addend; }; /* Allocate a new link_order for a section. */ extern struct bfd_link_order *bfd_new_link_order PARAMS ((bfd *, asection *)); #endif