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/* linker.c -- BFD linker routines Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 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 3 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ #include "sysdep.h" #include "bfd.h" #include "libbfd.h" #include "bfdlink.h" #include "genlink.h" /* SECTION Linker Functions @cindex Linker The linker uses three special entry points in the BFD target vector. It is not necessary to write special routines for these entry points when creating a new BFD back end, since generic versions are provided. However, writing them can speed up linking and make it use significantly less runtime memory. The first routine creates a hash table used by the other routines. The second routine adds the symbols from an object file to the hash table. The third routine takes all the object files and links them together to create the output file. These routines are designed so that the linker proper does not need to know anything about the symbols in the object files that it is linking. The linker merely arranges the sections as directed by the linker script and lets BFD handle the details of symbols and relocs. The second routine and third routines are passed a pointer to a <<struct bfd_link_info>> structure (defined in <<bfdlink.h>>) which holds information relevant to the link, including the linker hash table (which was created by the first routine) and a set of callback functions to the linker proper. The generic linker routines are in <<linker.c>>, and use the header file <<genlink.h>>. As of this writing, the only back ends which have implemented versions of these routines are a.out (in <<aoutx.h>>) and ECOFF (in <<ecoff.c>>). The a.out routines are used as examples throughout this section. @menu @* Creating a Linker Hash Table:: @* Adding Symbols to the Hash Table:: @* Performing the Final Link:: @end menu INODE Creating a Linker Hash Table, Adding Symbols to the Hash Table, Linker Functions, Linker Functions SUBSECTION Creating a linker hash table @cindex _bfd_link_hash_table_create in target vector @cindex target vector (_bfd_link_hash_table_create) The linker routines must create a hash table, which must be derived from <<struct bfd_link_hash_table>> described in <<bfdlink.c>>. @xref{Hash Tables}, for information on how to create a derived hash table. This entry point is called using the target vector of the linker output file. The <<_bfd_link_hash_table_create>> entry point must allocate and initialize an instance of the desired hash table. If the back end does not require any additional information to be stored with the entries in the hash table, the entry point may simply create a <<struct bfd_link_hash_table>>. Most likely, however, some additional information will be needed. For example, with each entry in the hash table the a.out linker keeps the index the symbol has in the final output file (this index number is used so that when doing a relocatable link the symbol index used in the output file can be quickly filled in when copying over a reloc). The a.out linker code defines the required structures and functions for a hash table derived from <<struct bfd_link_hash_table>>. The a.out linker hash table is created by the function <<NAME(aout,link_hash_table_create)>>; it simply allocates space for the hash table, initializes it, and returns a pointer to it. When writing the linker routines for a new back end, you will generally not know exactly which fields will be required until you have finished. You should simply create a new hash table which defines no additional fields, and then simply add fields as they become necessary. INODE Adding Symbols to the Hash Table, Performing the Final Link, Creating a Linker Hash Table, Linker Functions SUBSECTION Adding symbols to the hash table @cindex _bfd_link_add_symbols in target vector @cindex target vector (_bfd_link_add_symbols) The linker proper will call the <<_bfd_link_add_symbols>> entry point for each object file or archive which is to be linked (typically these are the files named on the command line, but some may also come from the linker script). The entry point is responsible for examining the file. For an object file, BFD must add any relevant symbol information to the hash table. For an archive, BFD must determine which elements of the archive should be used and adding them to the link. The a.out version of this entry point is <<NAME(aout,link_add_symbols)>>. @menu @* Differing file formats:: @* Adding symbols from an object file:: @* Adding symbols from an archive:: @end menu INODE Differing file formats, Adding symbols from an object file, Adding Symbols to the Hash Table, Adding Symbols to the Hash Table SUBSUBSECTION Differing file formats Normally all the files involved in a link will be of the same format, but it is also possible to link together different format object files, and the back end must support that. The <<_bfd_link_add_symbols>> entry point is called via the target vector of the file to be added. This has an important consequence: the function may not assume that the hash table is the type created by the corresponding <<_bfd_link_hash_table_create>> vector. All the <<_bfd_link_add_symbols>> function can assume about the hash table is that it is derived from <<struct bfd_link_hash_table>>. Sometimes the <<_bfd_link_add_symbols>> function must store some information in the hash table entry to be used by the <<_bfd_final_link>> function. In such a case the output bfd xvec must be checked to make sure that the hash table was created by an object file of the same format. The <<_bfd_final_link>> routine must be prepared to handle a hash entry without any extra information added by the <<_bfd_link_add_symbols>> function. A hash entry without extra information will also occur when the linker script directs the linker to create a symbol. Note that, regardless of how a hash table entry is added, all the fields will be initialized to some sort of null value by the hash table entry initialization function. See <<ecoff_link_add_externals>> for an example of how to check the output bfd before saving information (in this case, the ECOFF external symbol debugging information) in a hash table entry. INODE Adding symbols from an object file, Adding symbols from an archive, Differing file formats, Adding Symbols to the Hash Table SUBSUBSECTION Adding symbols from an object file When the <<_bfd_link_add_symbols>> routine is passed an object file, it must add all externally visible symbols in that object file to the hash table. The actual work of adding the symbol to the hash table is normally handled by the function <<_bfd_generic_link_add_one_symbol>>. The <<_bfd_link_add_symbols>> routine is responsible for reading all the symbols from the object file and passing the correct information to <<_bfd_generic_link_add_one_symbol>>. The <<_bfd_link_add_symbols>> routine should not use <<bfd_canonicalize_symtab>> to read the symbols. The point of providing this routine is to avoid the overhead of converting the symbols into generic <<asymbol>> structures. @findex _bfd_generic_link_add_one_symbol <<_bfd_generic_link_add_one_symbol>> handles the details of combining common symbols, warning about multiple definitions, and so forth. It takes arguments which describe the symbol to add, notably symbol flags, a section, and an offset. The symbol flags include such things as <<BSF_WEAK>> or <<BSF_INDIRECT>>. The section is a section in the object file, or something like <<bfd_und_section_ptr>> for an undefined symbol or <<bfd_com_section_ptr>> for a common symbol. If the <<_bfd_final_link>> routine is also going to need to read the symbol information, the <<_bfd_link_add_symbols>> routine should save it somewhere attached to the object file BFD. However, the information should only be saved if the <<keep_memory>> field of the <<info>> argument is TRUE, so that the <<-no-keep-memory>> linker switch is effective. The a.out function which adds symbols from an object file is <<aout_link_add_object_symbols>>, and most of the interesting work is in <<aout_link_add_symbols>>. The latter saves pointers to the hash tables entries created by <<_bfd_generic_link_add_one_symbol>> indexed by symbol number, so that the <<_bfd_final_link>> routine does not have to call the hash table lookup routine to locate the entry. INODE Adding symbols from an archive, , Adding symbols from an object file, Adding Symbols to the Hash Table SUBSUBSECTION Adding symbols from an archive When the <<_bfd_link_add_symbols>> routine is passed an archive, it must look through the symbols defined by the archive and decide which elements of the archive should be included in the link. For each such element it must call the <<add_archive_element>> linker callback, and it must add the symbols from the object file to the linker hash table. @findex _bfd_generic_link_add_archive_symbols In most cases the work of looking through the symbols in the archive should be done by the <<_bfd_generic_link_add_archive_symbols>> function. This function builds a hash table from the archive symbol table and looks through the list of undefined symbols to see which elements should be included. <<_bfd_generic_link_add_archive_symbols>> is passed a function to call to make the final decision about adding an archive element to the link and to do the actual work of adding the symbols to the linker hash table. The function passed to <<_bfd_generic_link_add_archive_symbols>> must read the symbols of the archive element and decide whether the archive element should be included in the link. If the element is to be included, the <<add_archive_element>> linker callback routine must be called with the element as an argument, and the elements symbols must be added to the linker hash table just as though the element had itself been passed to the <<_bfd_link_add_symbols>> function. When the a.out <<_bfd_link_add_symbols>> function receives an archive, it calls <<_bfd_generic_link_add_archive_symbols>> passing <<aout_link_check_archive_element>> as the function argument. <<aout_link_check_archive_element>> calls <<aout_link_check_ar_symbols>>. If the latter decides to add the element (an element is only added if it provides a real, non-common, definition for a previously undefined or common symbol) it calls the <<add_archive_element>> callback and then <<aout_link_check_archive_element>> calls <<aout_link_add_symbols>> to actually add the symbols to the linker hash table. The ECOFF back end is unusual in that it does not normally call <<_bfd_generic_link_add_archive_symbols>>, because ECOFF archives already contain a hash table of symbols. The ECOFF back end searches the archive itself to avoid the overhead of creating a new hash table. INODE Performing the Final Link, , Adding Symbols to the Hash Table, Linker Functions SUBSECTION Performing the final link @cindex _bfd_link_final_link in target vector @cindex target vector (_bfd_final_link) When all the input files have been processed, the linker calls the <<_bfd_final_link>> entry point of the output BFD. This routine is responsible for producing the final output file, which has several aspects. It must relocate the contents of the input sections and copy the data into the output sections. It must build an output symbol table including any local symbols from the input files and the global symbols from the hash table. When producing relocatable output, it must modify the input relocs and write them into the output file. There may also be object format dependent work to be done. The linker will also call the <<write_object_contents>> entry point when the BFD is closed. The two entry points must work together in order to produce the correct output file. The details of how this works are inevitably dependent upon the specific object file format. The a.out <<_bfd_final_link>> routine is <<NAME(aout,final_link)>>. @menu @* Information provided by the linker:: @* Relocating the section contents:: @* Writing the symbol table:: @end menu INODE Information provided by the linker, Relocating the section contents, Performing the Final Link, Performing the Final Link SUBSUBSECTION Information provided by the linker Before the linker calls the <<_bfd_final_link>> entry point, it sets up some data structures for the function to use. The <<input_bfds>> field of the <<bfd_link_info>> structure will point to a list of all the input files included in the link. These files are linked through the <<link_next>> field of the <<bfd>> structure. Each section in the output file will have a list of <<link_order>> structures attached to the <<map_head.link_order>> field (the <<link_order>> structure is defined in <<bfdlink.h>>). These structures describe how to create the contents of the output section in terms of the contents of various input sections, fill constants, and, eventually, other types of information. They also describe relocs that must be created by the BFD backend, but do not correspond to any input file; this is used to support -Ur, which builds constructors while generating a relocatable object file. INODE Relocating the section contents, Writing the symbol table, Information provided by the linker, Performing the Final Link SUBSUBSECTION Relocating the section contents The <<_bfd_final_link>> function should look through the <<link_order>> structures attached to each section of the output file. Each <<link_order>> structure should either be handled specially, or it should be passed to the function <<_bfd_default_link_order>> which will do the right thing (<<_bfd_default_link_order>> is defined in <<linker.c>>). For efficiency, a <<link_order>> of type <<bfd_indirect_link_order>> whose associated section belongs to a BFD of the same format as the output BFD must be handled specially. This type of <<link_order>> describes part of an output section in terms of a section belonging to one of the input files. The <<_bfd_final_link>> function should read the contents of the section and any associated relocs, apply the relocs to the section contents, and write out the modified section contents. If performing a relocatable link, the relocs themselves must also be modified and written out. @findex _bfd_relocate_contents @findex _bfd_final_link_relocate The functions <<_bfd_relocate_contents>> and <<_bfd_final_link_relocate>> provide some general support for performing the actual relocations, notably overflow checking. Their arguments include information about the symbol the relocation is against and a <<reloc_howto_type>> argument which describes the relocation to perform. These functions are defined in <<reloc.c>>. The a.out function which handles reading, relocating, and writing section contents is <<aout_link_input_section>>. The actual relocation is done in <<aout_link_input_section_std>> and <<aout_link_input_section_ext>>. INODE Writing the symbol table, , Relocating the section contents, Performing the Final Link SUBSUBSECTION Writing the symbol table The <<_bfd_final_link>> function must gather all the symbols in the input files and write them out. It must also write out all the symbols in the global hash table. This must be controlled by the <<strip>> and <<discard>> fields of the <<bfd_link_info>> structure. The local symbols of the input files will not have been entered into the linker hash table. The <<_bfd_final_link>> routine must consider each input file and include the symbols in the output file. It may be convenient to do this when looking through the <<link_order>> structures, or it may be done by stepping through the <<input_bfds>> list. The <<_bfd_final_link>> routine must also traverse the global hash table to gather all the externally visible symbols. It is possible that most of the externally visible symbols may be written out when considering the symbols of each input file, but it is still necessary to traverse the hash table since the linker script may have defined some symbols that are not in any of the input files. The <<strip>> field of the <<bfd_link_info>> structure controls which symbols are written out. The possible values are listed in <<bfdlink.h>>. If the value is <<strip_some>>, then the <<keep_hash>> field of the <<bfd_link_info>> structure is a hash table of symbols to keep; each symbol should be looked up in this hash table, and only symbols which are present should be included in the output file. If the <<strip>> field of the <<bfd_link_info>> structure permits local symbols to be written out, the <<discard>> field is used to further controls which local symbols are included in the output file. If the value is <<discard_l>>, then all local symbols which begin with a certain prefix are discarded; this is controlled by the <<bfd_is_local_label_name>> entry point. The a.out backend handles symbols by calling <<aout_link_write_symbols>> on each input BFD and then traversing the global hash table with the function <<aout_link_write_other_symbol>>. It builds a string table while writing out the symbols, which is written to the output file at the end of <<NAME(aout,final_link)>>. */ static bfd_boolean generic_link_add_object_symbols (bfd *, struct bfd_link_info *, bfd_boolean collect); static bfd_boolean generic_link_add_symbols (bfd *, struct bfd_link_info *, bfd_boolean); static bfd_boolean generic_link_check_archive_element_no_collect (bfd *, struct bfd_link_info *, bfd_boolean *); static bfd_boolean generic_link_check_archive_element_collect (bfd *, struct bfd_link_info *, bfd_boolean *); static bfd_boolean generic_link_check_archive_element (bfd *, struct bfd_link_info *, bfd_boolean *, bfd_boolean); static bfd_boolean generic_link_add_symbol_list (bfd *, struct bfd_link_info *, bfd_size_type count, asymbol **, bfd_boolean); static bfd_boolean generic_add_output_symbol (bfd *, size_t *psymalloc, asymbol *); static bfd_boolean default_data_link_order (bfd *, struct bfd_link_info *, asection *, struct bfd_link_order *); static bfd_boolean default_indirect_link_order (bfd *, struct bfd_link_info *, asection *, struct bfd_link_order *, bfd_boolean); /* The link hash table structure is defined in bfdlink.h. It provides a base hash table which the backend specific hash tables are built upon. */ /* Routine to create an entry in the link hash table. */ struct bfd_hash_entry * _bfd_link_hash_newfunc (struct bfd_hash_entry *entry, struct bfd_hash_table *table, const char *string) { /* Allocate the structure if it has not already been allocated by a subclass. */ if (entry == NULL) { entry = bfd_hash_allocate (table, sizeof (struct bfd_link_hash_entry)); if (entry == NULL) return entry; } /* Call the allocation method of the superclass. */ entry = bfd_hash_newfunc (entry, table, string); if (entry) { struct bfd_link_hash_entry *h = (struct bfd_link_hash_entry *) entry; /* Initialize the local fields. */ h->type = bfd_link_hash_new; memset (&h->u.undef.next, 0, (sizeof (struct bfd_link_hash_entry) - offsetof (struct bfd_link_hash_entry, u.undef.next))); } return entry; } /* Initialize a link hash table. The BFD argument is the one responsible for creating this table. */ bfd_boolean _bfd_link_hash_table_init (struct bfd_link_hash_table *table, bfd *abfd ATTRIBUTE_UNUSED, struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *, struct bfd_hash_table *, const char *), unsigned int entsize) { table->undefs = NULL; table->undefs_tail = NULL; table->type = bfd_link_generic_hash_table; return bfd_hash_table_init (&table->table, newfunc, entsize); } /* Look up a symbol in a link hash table. If follow is TRUE, we follow bfd_link_hash_indirect and bfd_link_hash_warning links to the real symbol. */ struct bfd_link_hash_entry * bfd_link_hash_lookup (struct bfd_link_hash_table *table, const char *string, bfd_boolean create, bfd_boolean copy, bfd_boolean follow) { struct bfd_link_hash_entry *ret; ret = ((struct bfd_link_hash_entry *) bfd_hash_lookup (&table->table, string, create, copy)); if (follow && ret != NULL) { while (ret->type == bfd_link_hash_indirect || ret->type == bfd_link_hash_warning) ret = ret->u.i.link; } return ret; } /* Look up a symbol in the main linker hash table if the symbol might be wrapped. This should only be used for references to an undefined symbol, not for definitions of a symbol. */ struct bfd_link_hash_entry * bfd_wrapped_link_hash_lookup (bfd *abfd, struct bfd_link_info *info, const char *string, bfd_boolean create, bfd_boolean copy, bfd_boolean follow) { bfd_size_type amt; if (info->wrap_hash != NULL) { const char *l; char prefix = '\0'; l = string; if (*l == bfd_get_symbol_leading_char (abfd) || *l == info->wrap_char) { prefix = *l; ++l; } #undef WRAP #define WRAP "__wrap_" if (bfd_hash_lookup (info->wrap_hash, l, FALSE, FALSE) != NULL) { char *n; struct bfd_link_hash_entry *h; /* This symbol is being wrapped. We want to replace all references to SYM with references to __wrap_SYM. */ amt = strlen (l) + sizeof WRAP + 1; n = bfd_malloc (amt); if (n == NULL) return NULL; n[0] = prefix; n[1] = '\0'; strcat (n, WRAP); strcat (n, l); h = bfd_link_hash_lookup (info->hash, n, create, TRUE, follow); free (n); return h; } #undef WRAP #undef REAL #define REAL "__real_" if (*l == '_' && CONST_STRNEQ (l, REAL) && bfd_hash_lookup (info->wrap_hash, l + sizeof REAL - 1, FALSE, FALSE) != NULL) { char *n; struct bfd_link_hash_entry *h; /* This is a reference to __real_SYM, where SYM is being wrapped. We want to replace all references to __real_SYM with references to SYM. */ amt = strlen (l + sizeof REAL - 1) + 2; n = bfd_malloc (amt); if (n == NULL) return NULL; n[0] = prefix; n[1] = '\0'; strcat (n, l + sizeof REAL - 1); h = bfd_link_hash_lookup (info->hash, n, create, TRUE, follow); free (n); return h; } #undef REAL } return bfd_link_hash_lookup (info->hash, string, create, copy, follow); } /* Traverse a generic link hash table. The only reason this is not a macro is to do better type checking. This code presumes that an argument passed as a struct bfd_hash_entry * may be caught as a struct bfd_link_hash_entry * with no explicit cast required on the call. */ void bfd_link_hash_traverse (struct bfd_link_hash_table *table, bfd_boolean (*func) (struct bfd_link_hash_entry *, void *), void *info) { bfd_hash_traverse (&table->table, (bfd_boolean (*) (struct bfd_hash_entry *, void *)) func, info); } /* Add a symbol to the linker hash table undefs list. */ void bfd_link_add_undef (struct bfd_link_hash_table *table, struct bfd_link_hash_entry *h) { BFD_ASSERT (h->u.undef.next == NULL); if (table->undefs_tail != NULL) table->undefs_tail->u.undef.next = h; if (table->undefs == NULL) table->undefs = h; table->undefs_tail = h; } /* The undefs list was designed so that in normal use we don't need to remove entries. However, if symbols on the list are changed from bfd_link_hash_undefined to either bfd_link_hash_undefweak or bfd_link_hash_new for some reason, then they must be removed from the list. Failure to do so might result in the linker attempting to add the symbol to the list again at a later stage. */ void bfd_link_repair_undef_list (struct bfd_link_hash_table *table) { struct bfd_link_hash_entry **pun; pun = &table->undefs; while (*pun != NULL) { struct bfd_link_hash_entry *h = *pun; if (h->type == bfd_link_hash_new || h->type == bfd_link_hash_undefweak) { *pun = h->u.undef.next; h->u.undef.next = NULL; if (h == table->undefs_tail) { if (pun == &table->undefs) table->undefs_tail = NULL; else /* pun points at an u.undef.next field. Go back to the start of the link_hash_entry. */ table->undefs_tail = (struct bfd_link_hash_entry *) ((char *) pun - ((char *) &h->u.undef.next - (char *) h)); break; } } else pun = &h->u.undef.next; } } /* Routine to create an entry in a generic link hash table. */ struct bfd_hash_entry * _bfd_generic_link_hash_newfunc (struct bfd_hash_entry *entry, struct bfd_hash_table *table, const char *string) { /* Allocate the structure if it has not already been allocated by a subclass. */ if (entry == NULL) { entry = bfd_hash_allocate (table, sizeof (struct generic_link_hash_entry)); if (entry == NULL) return entry; } /* Call the allocation method of the superclass. */ entry = _bfd_link_hash_newfunc (entry, table, string); if (entry) { struct generic_link_hash_entry *ret; /* Set local fields. */ ret = (struct generic_link_hash_entry *) entry; ret->written = FALSE; ret->sym = NULL; } return entry; } /* Create a generic link hash table. */ struct bfd_link_hash_table * _bfd_generic_link_hash_table_create (bfd *abfd) { struct generic_link_hash_table *ret; bfd_size_type amt = sizeof (struct generic_link_hash_table); ret = bfd_malloc (amt); if (ret == NULL) return NULL; if (! _bfd_link_hash_table_init (&ret->root, abfd, _bfd_generic_link_hash_newfunc, sizeof (struct generic_link_hash_entry))) { free (ret); return NULL; } return &ret->root; } void _bfd_generic_link_hash_table_free (struct bfd_link_hash_table *hash) { struct generic_link_hash_table *ret = (struct generic_link_hash_table *) hash; bfd_hash_table_free (&ret->root.table); free (ret); } /* Grab the symbols for an object file when doing a generic link. We store the symbols in the outsymbols field. We need to keep them around for the entire link to ensure that we only read them once. If we read them multiple times, we might wind up with relocs and the hash table pointing to different instances of the symbol structure. */ static bfd_boolean generic_link_read_symbols (bfd *abfd) { if (bfd_get_outsymbols (abfd) == NULL) { long symsize; long symcount; symsize = bfd_get_symtab_upper_bound (abfd); if (symsize < 0) return FALSE; bfd_get_outsymbols (abfd) = bfd_alloc (abfd, symsize); if (bfd_get_outsymbols (abfd) == NULL && symsize != 0) return FALSE; symcount = bfd_canonicalize_symtab (abfd, bfd_get_outsymbols (abfd)); if (symcount < 0) return FALSE; bfd_get_symcount (abfd) = symcount; } return TRUE; } /* Generic function to add symbols to from an object file to the global hash table. This version does not automatically collect constructors by name. */ bfd_boolean _bfd_generic_link_add_symbols (bfd *abfd, struct bfd_link_info *info) { return generic_link_add_symbols (abfd, info, FALSE); } /* Generic function to add symbols from an object file to the global hash table. This version automatically collects constructors by name, as the collect2 program does. It should be used for any target which does not provide some other mechanism for setting up constructors and destructors; these are approximately those targets for which gcc uses collect2 and do not support stabs. */ bfd_boolean _bfd_generic_link_add_symbols_collect (bfd *abfd, struct bfd_link_info *info) { return generic_link_add_symbols (abfd, info, TRUE); } /* Indicate that we are only retrieving symbol values from this section. We want the symbols to act as though the values in the file are absolute. */ void _bfd_generic_link_just_syms (asection *sec, struct bfd_link_info *info ATTRIBUTE_UNUSED) { sec->output_section = bfd_abs_section_ptr; sec->output_offset = sec->vma; } /* Add symbols from an object file to the global hash table. */ static bfd_boolean generic_link_add_symbols (bfd *abfd, struct bfd_link_info *info, bfd_boolean collect) { bfd_boolean ret; switch (bfd_get_format (abfd)) { case bfd_object: ret = generic_link_add_object_symbols (abfd, info, collect); break; case bfd_archive: ret = (_bfd_generic_link_add_archive_symbols (abfd, info, (collect ? generic_link_check_archive_element_collect : generic_link_check_archive_element_no_collect))); break; default: bfd_set_error (bfd_error_wrong_format); ret = FALSE; } return ret; } /* Add symbols from an object file to the global hash table. */ static bfd_boolean generic_link_add_object_symbols (bfd *abfd, struct bfd_link_info *info, bfd_boolean collect) { bfd_size_type symcount; struct bfd_symbol **outsyms; if (! generic_link_read_symbols (abfd)) return FALSE; symcount = _bfd_generic_link_get_symcount (abfd); outsyms = _bfd_generic_link_get_symbols (abfd); return generic_link_add_symbol_list (abfd, info, symcount, outsyms, collect); } /* We build a hash table of all symbols defined in an archive. */ /* An archive symbol may be defined by multiple archive elements. This linked list is used to hold the elements. */ struct archive_list { struct archive_list *next; unsigned int indx; }; /* An entry in an archive hash table. */ struct archive_hash_entry { struct bfd_hash_entry root; /* Where the symbol is defined. */ struct archive_list *defs; }; /* An archive hash table itself. */ struct archive_hash_table { struct bfd_hash_table table; }; /* Create a new entry for an archive hash table. */ static struct bfd_hash_entry * archive_hash_newfunc (struct bfd_hash_entry *entry, struct bfd_hash_table *table, const char *string) { struct archive_hash_entry *ret = (struct archive_hash_entry *) entry; /* Allocate the structure if it has not already been allocated by a subclass. */ if (ret == NULL) ret = bfd_hash_allocate (table, sizeof (struct archive_hash_entry)); if (ret == NULL) return NULL; /* Call the allocation method of the superclass. */ ret = ((struct archive_hash_entry *) bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string)); if (ret) { /* Initialize the local fields. */ ret->defs = NULL; } return &ret->root; } /* Initialize an archive hash table. */ static bfd_boolean archive_hash_table_init (struct archive_hash_table *table, struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *, struct bfd_hash_table *, const char *), unsigned int entsize) { return bfd_hash_table_init (&table->table, newfunc, entsize); } /* Look up an entry in an archive hash table. */ #define archive_hash_lookup(t, string, create, copy) \ ((struct archive_hash_entry *) \ bfd_hash_lookup (&(t)->table, (string), (create), (copy))) /* Allocate space in an archive hash table. */ #define archive_hash_allocate(t, size) bfd_hash_allocate (&(t)->table, (size)) /* Free an archive hash table. */ #define archive_hash_table_free(t) bfd_hash_table_free (&(t)->table) /* Generic function to add symbols from an archive file to the global hash file. This function presumes that the archive symbol table has already been read in (this is normally done by the bfd_check_format entry point). It looks through the undefined and common symbols and searches the archive symbol table for them. If it finds an entry, it includes the associated object file in the link. The old linker looked through the archive symbol table for undefined symbols. We do it the other way around, looking through undefined symbols for symbols defined in the archive. The advantage of the newer scheme is that we only have to look through the list of undefined symbols once, whereas the old method had to re-search the symbol table each time a new object file was added. The CHECKFN argument is used to see if an object file should be included. CHECKFN should set *PNEEDED to TRUE if the object file should be included, and must also call the bfd_link_info add_archive_element callback function and handle adding the symbols to the global hash table. CHECKFN should only return FALSE if some sort of error occurs. For some formats, such as a.out, it is possible to look through an object file but not actually include it in the link. The archive_pass field in a BFD is used to avoid checking the symbols of an object files too many times. When an object is included in the link, archive_pass is set to -1. If an object is scanned but not included, archive_pass is set to the pass number. The pass number is incremented each time a new object file is included. The pass number is used because when a new object file is included it may create new undefined symbols which cause a previously examined object file to be included. */ bfd_boolean _bfd_generic_link_add_archive_symbols (bfd *abfd, struct bfd_link_info *info, bfd_boolean (*checkfn) (bfd *, struct bfd_link_info *, bfd_boolean *)) { carsym *arsyms; carsym *arsym_end; register carsym *arsym; int pass; struct archive_hash_table arsym_hash; unsigned int indx; struct bfd_link_hash_entry **pundef; if (! bfd_has_map (abfd)) { /* An empty archive is a special case. */ if (bfd_openr_next_archived_file (abfd, NULL) == NULL) return TRUE; bfd_set_error (bfd_error_no_armap); return FALSE; } arsyms = bfd_ardata (abfd)->symdefs; arsym_end = arsyms + bfd_ardata (abfd)->symdef_count; /* In order to quickly determine whether an symbol is defined in this archive, we build a hash table of the symbols. */ if (! archive_hash_table_init (&arsym_hash, archive_hash_newfunc, sizeof (struct archive_hash_entry))) return FALSE; for (arsym = arsyms, indx = 0; arsym < arsym_end; arsym++, indx++) { struct archive_hash_entry *arh; struct archive_list *l, **pp; arh = archive_hash_lookup (&arsym_hash, arsym->name, TRUE, FALSE); if (arh == NULL) goto error_return; l = ((struct archive_list *) archive_hash_allocate (&arsym_hash, sizeof (struct archive_list))); if (l == NULL) goto error_return; l->indx = indx; for (pp = &arh->defs; *pp != NULL; pp = &(*pp)->next) ; *pp = l; l->next = NULL; } /* The archive_pass field in the archive itself is used to initialize PASS, sine we may search the same archive multiple times. */ pass = abfd->archive_pass + 1; /* New undefined symbols are added to the end of the list, so we only need to look through it once. */ pundef = &info->hash->undefs; while (*pundef != NULL) { struct bfd_link_hash_entry *h; struct archive_hash_entry *arh; struct archive_list *l; h = *pundef; /* When a symbol is defined, it is not necessarily removed from the list. */ if (h->type != bfd_link_hash_undefined && h->type != bfd_link_hash_common) { /* Remove this entry from the list, for general cleanliness and because we are going to look through the list again if we search any more libraries. We can't remove the entry if it is the tail, because that would lose any entries we add to the list later on (it would also cause us to lose track of whether the symbol has been referenced). */ if (*pundef != info->hash->undefs_tail) *pundef = (*pundef)->u.undef.next; else pundef = &(*pundef)->u.undef.next; continue; } /* Look for this symbol in the archive symbol map. */ arh = archive_hash_lookup (&arsym_hash, h->root.string, FALSE, FALSE); if (arh == NULL) { /* If we haven't found the exact symbol we're looking for, let's look for its import thunk */ if (info->pei386_auto_import) { bfd_size_type amt = strlen (h->root.string) + 10; char *buf = bfd_malloc (amt); if (buf == NULL) return FALSE; sprintf (buf, "__imp_%s", h->root.string); arh = archive_hash_lookup (&arsym_hash, buf, FALSE, FALSE); free(buf); } if (arh == NULL) { pundef = &(*pundef)->u.undef.next; continue; } } /* Look at all the objects which define this symbol. */ for (l = arh->defs; l != NULL; l = l->next) { bfd *element; bfd_boolean needed; /* If the symbol has gotten defined along the way, quit. */ if (h->type != bfd_link_hash_undefined && h->type != bfd_link_hash_common) break; element = bfd_get_elt_at_index (abfd, l->indx); if (element == NULL) goto error_return; /* If we've already included this element, or if we've already checked it on this pass, continue. */ if (element->archive_pass == -1 || element->archive_pass == pass) continue; /* If we can't figure this element out, just ignore it. */ if (! bfd_check_format (element, bfd_object)) { element->archive_pass = -1; continue; } /* CHECKFN will see if this element should be included, and go ahead and include it if appropriate. */ if (! (*checkfn) (element, info, &needed)) goto error_return; if (! needed) element->archive_pass = pass; else { element->archive_pass = -1; /* Increment the pass count to show that we may need to recheck object files which were already checked. */ ++pass; } } pundef = &(*pundef)->u.undef.next; } archive_hash_table_free (&arsym_hash); /* Save PASS in case we are called again. */ abfd->archive_pass = pass; return TRUE; error_return: archive_hash_table_free (&arsym_hash); return FALSE; } /* See if we should include an archive element. This version is used when we do not want to automatically collect constructors based on the symbol name, presumably because we have some other mechanism for finding them. */ static bfd_boolean generic_link_check_archive_element_no_collect ( bfd *abfd, struct bfd_link_info *info, bfd_boolean *pneeded) { return generic_link_check_archive_element (abfd, info, pneeded, FALSE); } /* See if we should include an archive element. This version is used when we want to automatically collect constructors based on the symbol name, as collect2 does. */ static bfd_boolean generic_link_check_archive_element_collect (bfd *abfd, struct bfd_link_info *info, bfd_boolean *pneeded) { return generic_link_check_archive_element (abfd, info, pneeded, TRUE); } /* See if we should include an archive element. Optionally collect constructors. */ static bfd_boolean generic_link_check_archive_element (bfd *abfd, struct bfd_link_info *info, bfd_boolean *pneeded, bfd_boolean collect) { asymbol **pp, **ppend; *pneeded = FALSE; if (! generic_link_read_symbols (abfd)) return FALSE; pp = _bfd_generic_link_get_symbols (abfd); ppend = pp + _bfd_generic_link_get_symcount (abfd); for (; pp < ppend; pp++) { asymbol *p; struct bfd_link_hash_entry *h; p = *pp; /* We are only interested in globally visible symbols. */ if (! bfd_is_com_section (p->section) && (p->flags & (BSF_GLOBAL | BSF_INDIRECT | BSF_WEAK)) == 0) continue; /* We are only interested if we know something about this symbol, and it is undefined or common. An undefined weak symbol (type bfd_link_hash_undefweak) is not considered to be a reference when pulling files out of an archive. See the SVR4 ABI, p. 4-27. */ h = bfd_link_hash_lookup (info->hash, bfd_asymbol_name (p), FALSE, FALSE, TRUE); if (h == NULL || (h->type != bfd_link_hash_undefined && h->type != bfd_link_hash_common)) continue; /* P is a symbol we are looking for. */ if (! bfd_is_com_section (p->section)) { bfd_size_type symcount; asymbol **symbols; /* This object file defines this symbol, so pull it in. */ if (! (*info->callbacks->add_archive_element) (info, abfd, bfd_asymbol_name (p))) return FALSE; symcount = _bfd_generic_link_get_symcount (abfd); symbols = _bfd_generic_link_get_symbols (abfd); if (! generic_link_add_symbol_list (abfd, info, symcount, symbols, collect)) return FALSE; *pneeded = TRUE; return TRUE; } /* P is a common symbol. */ if (h->type == bfd_link_hash_undefined) { bfd *symbfd; bfd_vma size; unsigned int power; symbfd = h->u.undef.abfd; if (symbfd == NULL) { /* This symbol was created as undefined from outside BFD. We assume that we should link in the object file. This is for the -u option in the linker. */ if (! (*info->callbacks->add_archive_element) (info, abfd, bfd_asymbol_name (p))) return FALSE; *pneeded = TRUE; return TRUE; } /* Turn the symbol into a common symbol but do not link in the object file. This is how a.out works. Object formats that require different semantics must implement this function differently. This symbol is already on the undefs list. We add the section to a common section attached to symbfd to ensure that it is in a BFD which will be linked in. */ h->type = bfd_link_hash_common; h->u.c.p = bfd_hash_allocate (&info->hash->table, sizeof (struct bfd_link_hash_common_entry)); if (h->u.c.p == NULL) return FALSE; size = bfd_asymbol_value (p); h->u.c.size = size; power = bfd_log2 (size); if (power > 4) power = 4; h->u.c.p->alignment_power = power; if (p->section == bfd_com_section_ptr) h->u.c.p->section = bfd_make_section_old_way (symbfd, "COMMON"); else h->u.c.p->section = bfd_make_section_old_way (symbfd, p->section->name); h->u.c.p->section->flags = SEC_ALLOC; } else { /* Adjust the size of the common symbol if necessary. This is how a.out works. Object formats that require different semantics must implement this function differently. */ if (bfd_asymbol_value (p) > h->u.c.size) h->u.c.size = bfd_asymbol_value (p); } } /* This archive element is not needed. */ return TRUE; } /* Add the symbols from an object file to the global hash table. ABFD is the object file. INFO is the linker information. SYMBOL_COUNT is the number of symbols. SYMBOLS is the list of symbols. COLLECT is TRUE if constructors should be automatically collected by name as is done by collect2. */ static bfd_boolean generic_link_add_symbol_list (bfd *abfd, struct bfd_link_info *info, bfd_size_type symbol_count, asymbol **symbols, bfd_boolean collect) { asymbol **pp, **ppend; pp = symbols; ppend = symbols + symbol_count; for (; pp < ppend; pp++) { asymbol *p; p = *pp; if ((p->flags & (BSF_INDIRECT | BSF_WARNING | BSF_GLOBAL | BSF_CONSTRUCTOR | BSF_WEAK)) != 0 || bfd_is_und_section (bfd_get_section (p)) || bfd_is_com_section (bfd_get_section (p)) || bfd_is_ind_section (bfd_get_section (p))) { const char *name; const char *string; struct generic_link_hash_entry *h; struct bfd_link_hash_entry *bh; string = name = bfd_asymbol_name (p); if (((p->flags & BSF_INDIRECT) != 0 || bfd_is_ind_section (p->section)) && pp + 1 < ppend) { pp++; string = bfd_asymbol_name (*pp); } else if ((p->flags & BSF_WARNING) != 0 && pp + 1 < ppend) { /* The name of P is actually the warning string, and the next symbol is the one to warn about. */ pp++; name = bfd_asymbol_name (*pp); } bh = NULL; if (! (_bfd_generic_link_add_one_symbol (info, abfd, name, p->flags, bfd_get_section (p), p->value, string, FALSE, collect, &bh))) return FALSE; h = (struct generic_link_hash_entry *) bh; /* If this is a constructor symbol, and the linker didn't do anything with it, then we want to just pass the symbol through to the output file. This will happen when linking with -r. */ if ((p->flags & BSF_CONSTRUCTOR) != 0 && (h == NULL || h->root.type == bfd_link_hash_new)) { p->udata.p = NULL; continue; } /* Save the BFD symbol so that we don't lose any backend specific information that may be attached to it. We only want this one if it gives more information than the existing one; we don't want to replace a defined symbol with an undefined one. This routine may be called with a hash table other than the generic hash table, so we only do this if we are certain that the hash table is a generic one. */ if (info->output_bfd->xvec == abfd->xvec) { if (h->sym == NULL || (! bfd_is_und_section (bfd_get_section (p)) && (! bfd_is_com_section (bfd_get_section (p)) || bfd_is_und_section (bfd_get_section (h->sym))))) { h->sym = p; /* BSF_OLD_COMMON is a hack to support COFF reloc reading, and it should go away when the COFF linker is switched to the new version. */ if (bfd_is_com_section (bfd_get_section (p))) p->flags |= BSF_OLD_COMMON; } } /* Store a back pointer from the symbol to the hash table entry for the benefit of relaxation code until it gets rewritten to not use asymbol structures. Setting this is also used to check whether these symbols were set up by the generic linker. */ p->udata.p = h; } } return TRUE; } /* We use a state table to deal with adding symbols from an object file. The first index into the state table describes the symbol from the object file. The second index into the state table is the type of the symbol in the hash table. */ /* The symbol from the object file is turned into one of these row values. */ enum link_row { UNDEF_ROW, /* Undefined. */ UNDEFW_ROW, /* Weak undefined. */ DEF_ROW, /* Defined. */ DEFW_ROW, /* Weak defined. */ COMMON_ROW, /* Common. */ INDR_ROW, /* Indirect. */ WARN_ROW, /* Warning. */ SET_ROW /* Member of set. */ }; /* apparently needed for Hitachi 3050R(HI-UX/WE2)? */ #undef FAIL /* The actions to take in the state table. */ enum link_action { FAIL, /* Abort. */ UND, /* Mark symbol undefined. */ WEAK, /* Mark symbol weak undefined. */ DEF, /* Mark symbol defined. */ DEFW, /* Mark symbol weak defined. */ COM, /* Mark symbol common. */ REF, /* Mark defined symbol referenced. */ CREF, /* Possibly warn about common reference to defined symbol. */ CDEF, /* Define existing common symbol. */ NOACT, /* No action. */ BIG, /* Mark symbol common using largest size. */ MDEF, /* Multiple definition error. */ MIND, /* Multiple indirect symbols. */ IND, /* Make indirect symbol. */ CIND, /* Make indirect symbol from existing common symbol. */ SET, /* Add value to set. */ MWARN, /* Make warning symbol. */ WARN, /* Issue warning. */ CWARN, /* Warn if referenced, else MWARN. */ CYCLE, /* Repeat with symbol pointed to. */ REFC, /* Mark indirect symbol referenced and then CYCLE. */ WARNC /* Issue warning and then CYCLE. */ }; /* The state table itself. The first index is a link_row and the second index is a bfd_link_hash_type. */ static const enum link_action link_action[8][8] = { /* current\prev new undef undefw def defw com indr warn */ /* UNDEF_ROW */ {UND, NOACT, UND, REF, REF, NOACT, REFC, WARNC }, /* UNDEFW_ROW */ {WEAK, NOACT, NOACT, REF, REF, NOACT, REFC, WARNC }, /* DEF_ROW */ {DEF, DEF, DEF, MDEF, DEF, CDEF, MDEF, CYCLE }, /* DEFW_ROW */ {DEFW, DEFW, DEFW, NOACT, NOACT, NOACT, NOACT, CYCLE }, /* COMMON_ROW */ {COM, COM, COM, CREF, COM, BIG, REFC, WARNC }, /* INDR_ROW */ {IND, IND, IND, MDEF, IND, CIND, MIND, CYCLE }, /* WARN_ROW */ {MWARN, WARN, WARN, CWARN, CWARN, WARN, CWARN, NOACT }, /* SET_ROW */ {SET, SET, SET, SET, SET, SET, CYCLE, CYCLE } }; /* Most of the entries in the LINK_ACTION table are straightforward, but a few are somewhat subtle. A reference to an indirect symbol (UNDEF_ROW/indr or UNDEFW_ROW/indr) is counted as a reference both to the indirect symbol and to the symbol the indirect symbol points to. A reference to a warning symbol (UNDEF_ROW/warn or UNDEFW_ROW/warn) causes the warning to be issued. A common definition of an indirect symbol (COMMON_ROW/indr) is treated as a multiple definition error. Likewise for an indirect definition of a common symbol (INDR_ROW/com). An indirect definition of a warning (INDR_ROW/warn) does not cause the warning to be issued. If a warning is created for an indirect symbol (WARN_ROW/indr) no warning is created for the symbol the indirect symbol points to. Adding an entry to a set does not count as a reference to a set, and no warning is issued (SET_ROW/warn). */ /* Return the BFD in which a hash entry has been defined, if known. */ static bfd * hash_entry_bfd (struct bfd_link_hash_entry *h) { while (h->type == bfd_link_hash_warning) h = h->u.i.link; switch (h->type) { default: return NULL; case bfd_link_hash_undefined: case bfd_link_hash_undefweak: return h->u.undef.abfd; case bfd_link_hash_defined: case bfd_link_hash_defweak: return h->u.def.section->owner; case bfd_link_hash_common: return h->u.c.p->section->owner; } /*NOTREACHED*/ } /* Add a symbol to the global hash table. ABFD is the BFD the symbol comes from. NAME is the name of the symbol. FLAGS is the BSF_* bits associated with the symbol. SECTION is the section in which the symbol is defined; this may be bfd_und_section_ptr or bfd_com_section_ptr. VALUE is the value of the symbol, relative to the section. STRING is used for either an indirect symbol, in which case it is the name of the symbol to indirect to, or a warning symbol, in which case it is the warning string. COPY is TRUE if NAME or STRING must be copied into locally allocated memory if they need to be saved. COLLECT is TRUE if we should automatically collect gcc constructor or destructor names as collect2 does. HASHP, if not NULL, is a place to store the created hash table entry; if *HASHP is not NULL, the caller has already looked up the hash table entry, and stored it in *HASHP. */ bfd_boolean _bfd_generic_link_add_one_symbol (struct bfd_link_info *info, bfd *abfd, const char *name, flagword flags, asection *section, bfd_vma value, const char *string, bfd_boolean copy, bfd_boolean collect, struct bfd_link_hash_entry **hashp) { enum link_row row; struct bfd_link_hash_entry *h; bfd_boolean cycle; if (bfd_is_ind_section (section) || (flags & BSF_INDIRECT) != 0) row = INDR_ROW; else if ((flags & BSF_WARNING) != 0) row = WARN_ROW; else if ((flags & BSF_CONSTRUCTOR) != 0) row = SET_ROW; else if (bfd_is_und_section (section)) { if ((flags & BSF_WEAK) != 0) row = UNDEFW_ROW; else row = UNDEF_ROW; } else if ((flags & BSF_WEAK) != 0) row = DEFW_ROW; else if (bfd_is_com_section (section)) row = COMMON_ROW; else row = DEF_ROW; if (hashp != NULL && *hashp != NULL) h = *hashp; else { if (row == UNDEF_ROW || row == UNDEFW_ROW) h = bfd_wrapped_link_hash_lookup (abfd, info, name, TRUE, copy, FALSE); else h = bfd_link_hash_lookup (info->hash, name, TRUE, copy, FALSE); if (h == NULL) { if (hashp != NULL) *hashp = NULL; return FALSE; } } if (info->notice_all || (info->notice_hash != NULL && bfd_hash_lookup (info->notice_hash, name, FALSE, FALSE) != NULL)) { if (! (*info->callbacks->notice) (info, h->root.string, abfd, section, value)) return FALSE; } if (hashp != NULL) *hashp = h; do { enum link_action action; cycle = FALSE; action = link_action[(int) row][(int) h->type]; switch (action) { case FAIL: abort (); case NOACT: /* Do nothing. */ break; case UND: /* Make a new undefined symbol. */ h->type = bfd_link_hash_undefined; h->u.undef.abfd = abfd; bfd_link_add_undef (info->hash, h); break; case WEAK: /* Make a new weak undefined symbol. */ h->type = bfd_link_hash_undefweak; h->u.undef.abfd = abfd; h->u.undef.weak = abfd; break; case CDEF: /* We have found a definition for a symbol which was previously common. */ BFD_ASSERT (h->type == bfd_link_hash_common); if (! ((*info->callbacks->multiple_common) (info, h->root.string, h->u.c.p->section->owner, bfd_link_hash_common, h->u.c.size, abfd, bfd_link_hash_defined, 0))) return FALSE; /* Fall through. */ case DEF: case DEFW: { enum bfd_link_hash_type oldtype; /* Define a symbol. */ oldtype = h->type; if (action == DEFW) h->type = bfd_link_hash_defweak; else h->type = bfd_link_hash_defined; h->u.def.section = section; h->u.def.value = value; /* If we have been asked to, we act like collect2 and identify all functions that might be global constructors and destructors and pass them up in a callback. We only do this for certain object file types, since many object file types can handle this automatically. */ if (collect && name[0] == '_') { const char *s; /* A constructor or destructor name starts like this: _+GLOBAL_[_.$][ID][_.$] where the first [_.$] and the second are the same character (we accept any character there, in case a new object file format comes along with even worse naming restrictions). */ #define CONS_PREFIX "GLOBAL_" #define CONS_PREFIX_LEN (sizeof CONS_PREFIX - 1) s = name + 1; while (*s == '_') ++s; if (s[0] == 'G' && CONST_STRNEQ (s, CONS_PREFIX)) { char c; c = s[CONS_PREFIX_LEN + 1]; if ((c == 'I' || c == 'D') && s[CONS_PREFIX_LEN] == s[CONS_PREFIX_LEN + 2]) { /* If this is a definition of a symbol which was previously weakly defined, we are in trouble. We have already added a constructor entry for the weak defined symbol, and now we are trying to add one for the new symbol. Fortunately, this case should never arise in practice. */ if (oldtype == bfd_link_hash_defweak) abort (); if (! ((*info->callbacks->constructor) (info, c == 'I', h->root.string, abfd, section, value))) return FALSE; } } } } break; case COM: /* We have found a common definition for a symbol. */ if (h->type == bfd_link_hash_new) bfd_link_add_undef (info->hash, h); h->type = bfd_link_hash_common; h->u.c.p = bfd_hash_allocate (&info->hash->table, sizeof (struct bfd_link_hash_common_entry)); if (h->u.c.p == NULL) return FALSE; h->u.c.size = value; /* Select a default alignment based on the size. This may be overridden by the caller. */ { unsigned int power; power = bfd_log2 (value); if (power > 4) power = 4; h->u.c.p->alignment_power = power; } /* The section of a common symbol is only used if the common symbol is actually allocated. It basically provides a hook for the linker script to decide which output section the common symbols should be put in. In most cases, the section of a common symbol will be bfd_com_section_ptr, the code here will choose a common symbol section named "COMMON", and the linker script will contain *(COMMON) in the appropriate place. A few targets use separate common sections for small symbols, and they require special handling. */ if (section == bfd_com_section_ptr) { h->u.c.p->section = bfd_make_section_old_way (abfd, "COMMON"); h->u.c.p->section->flags = SEC_ALLOC; } else if (section->owner != abfd) { h->u.c.p->section = bfd_make_section_old_way (abfd, section->name); h->u.c.p->section->flags = SEC_ALLOC; } else h->u.c.p->section = section; break; case REF: /* A reference to a defined symbol. */ if (h->u.undef.next == NULL && info->hash->undefs_tail != h) h->u.undef.next = h; break; case BIG: /* We have found a common definition for a symbol which already had a common definition. Use the maximum of the two sizes, and use the section required by the larger symbol. */ BFD_ASSERT (h->type == bfd_link_hash_common); if (! ((*info->callbacks->multiple_common) (info, h->root.string, h->u.c.p->section->owner, bfd_link_hash_common, h->u.c.size, abfd, bfd_link_hash_common, value))) return FALSE; if (value > h->u.c.size) { unsigned int power; h->u.c.size = value; /* Select a default alignment based on the size. This may be overridden by the caller. */ power = bfd_log2 (value); if (power > 4) power = 4; h->u.c.p->alignment_power = power; /* Some systems have special treatment for small commons, hence we want to select the section used by the larger symbol. This makes sure the symbol does not go in a small common section if it is now too large. */ if (section == bfd_com_section_ptr) { h->u.c.p->section = bfd_make_section_old_way (abfd, "COMMON"); h->u.c.p->section->flags = SEC_ALLOC; } else if (section->owner != abfd) { h->u.c.p->section = bfd_make_section_old_way (abfd, section->name); h->u.c.p->section->flags = SEC_ALLOC; } else h->u.c.p->section = section; } break; case CREF: { bfd *obfd; /* We have found a common definition for a symbol which was already defined. FIXME: It would nice if we could report the BFD which defined an indirect symbol, but we don't have anywhere to store the information. */ if (h->type == bfd_link_hash_defined || h->type == bfd_link_hash_defweak) obfd = h->u.def.section->owner; else obfd = NULL; if (! ((*info->callbacks->multiple_common) (info, h->root.string, obfd, h->type, 0, abfd, bfd_link_hash_common, value))) return FALSE; } break; case MIND: /* Multiple indirect symbols. This is OK if they both point to the same symbol. */ if (strcmp (h->u.i.link->root.string, string) == 0) break; /* Fall through. */ case MDEF: /* Handle a multiple definition. */ if (!info->allow_multiple_definition) { asection *msec = NULL; bfd_vma mval = 0; switch (h->type) { case bfd_link_hash_defined: msec = h->u.def.section; mval = h->u.def.value; break; case bfd_link_hash_indirect: msec = bfd_ind_section_ptr; mval = 0; break; default: abort (); } /* Ignore a redefinition of an absolute symbol to the same value; it's harmless. */ if (h->type == bfd_link_hash_defined && bfd_is_abs_section (msec) && bfd_is_abs_section (section) && value == mval) break; if (! ((*info->callbacks->multiple_definition) (info, h->root.string, msec->owner, msec, mval, abfd, section, value))) return FALSE; } break; case CIND: /* Create an indirect symbol from an existing common symbol. */ BFD_ASSERT (h->type == bfd_link_hash_common); if (! ((*info->callbacks->multiple_common) (info, h->root.string, h->u.c.p->section->owner, bfd_link_hash_common, h->u.c.size, abfd, bfd_link_hash_indirect, 0))) return FALSE; /* Fall through. */ case IND: /* Create an indirect symbol. */ { struct bfd_link_hash_entry *inh; /* STRING is the name of the symbol we want to indirect to. */ inh = bfd_wrapped_link_hash_lookup (abfd, info, string, TRUE, copy, FALSE); if (inh == NULL) return FALSE; if (inh->type == bfd_link_hash_indirect && inh->u.i.link == h) { (*_bfd_error_handler) (_("%B: indirect symbol `%s' to `%s' is a loop"), abfd, name, string); bfd_set_error (bfd_error_invalid_operation); return FALSE; } if (inh->type == bfd_link_hash_new) { inh->type = bfd_link_hash_undefined; inh->u.undef.abfd = abfd; bfd_link_add_undef (info->hash, inh); } /* If the indirect symbol has been referenced, we need to push the reference down to the symbol we are referencing. */ if (h->type != bfd_link_hash_new) { row = UNDEF_ROW; cycle = TRUE; } h->type = bfd_link_hash_indirect; h->u.i.link = inh; } break; case SET: /* Add an entry to a set. */ if (! (*info->callbacks->add_to_set) (info, h, BFD_RELOC_CTOR, abfd, section, value)) return FALSE; break; case WARNC: /* Issue a warning and cycle. */ if (h->u.i.warning != NULL) { if (! (*info->callbacks->warning) (info, h->u.i.warning, h->root.string, abfd, NULL, 0)) return FALSE; /* Only issue a warning once. */ h->u.i.warning = NULL; } /* Fall through. */ case CYCLE: /* Try again with the referenced symbol. */ h = h->u.i.link; cycle = TRUE; break; case REFC: /* A reference to an indirect symbol. */ if (h->u.undef.next == NULL && info->hash->undefs_tail != h) h->u.undef.next = h; h = h->u.i.link; cycle = TRUE; break; case WARN: /* Issue a warning. */ if (! (*info->callbacks->warning) (info, string, h->root.string, hash_entry_bfd (h), NULL, 0)) return FALSE; break; case CWARN: /* Warn if this symbol has been referenced already, otherwise add a warning. A symbol has been referenced if the u.undef.next field is not NULL, or it is the tail of the undefined symbol list. The REF case above helps to ensure this. */ if (h->u.undef.next != NULL || info->hash->undefs_tail == h) { if (! (*info->callbacks->warning) (info, string, h->root.string, hash_entry_bfd (h), NULL, 0)) return FALSE; break; } /* Fall through. */ case MWARN: /* Make a warning symbol. */ { struct bfd_link_hash_entry *sub; /* STRING is the warning to give. */ sub = ((struct bfd_link_hash_entry *) ((*info->hash->table.newfunc) (NULL, &info->hash->table, h->root.string))); if (sub == NULL) return FALSE; *sub = *h; sub->type = bfd_link_hash_warning; sub->u.i.link = h; if (! copy) sub->u.i.warning = string; else { char *w; size_t len = strlen (string) + 1; w = bfd_hash_allocate (&info->hash->table, len); if (w == NULL) return FALSE; memcpy (w, string, len); sub->u.i.warning = w; } bfd_hash_replace (&info->hash->table, (struct bfd_hash_entry *) h, (struct bfd_hash_entry *) sub); if (hashp != NULL) *hashp = sub; } break; } } while (cycle); return TRUE; } /* Generic final link routine. */ bfd_boolean _bfd_generic_final_link (bfd *abfd, struct bfd_link_info *info) { bfd *sub; asection *o; struct bfd_link_order *p; size_t outsymalloc; struct generic_write_global_symbol_info wginfo; bfd_get_outsymbols (abfd) = NULL; bfd_get_symcount (abfd) = 0; outsymalloc = 0; /* Mark all sections which will be included in the output file. */ for (o = abfd->sections; o != NULL; o = o->next) for (p = o->map_head.link_order; p != NULL; p = p->next) if (p->type == bfd_indirect_link_order) p->u.indirect.section->linker_mark = TRUE; /* Build the output symbol table. */ for (sub = info->input_bfds; sub != NULL; sub = sub->link_next) if (! _bfd_generic_link_output_symbols (abfd, sub, info, &outsymalloc)) return FALSE; /* Accumulate the global symbols. */ wginfo.info = info; wginfo.output_bfd = abfd; wginfo.psymalloc = &outsymalloc; _bfd_generic_link_hash_traverse (_bfd_generic_hash_table (info), _bfd_generic_link_write_global_symbol, &wginfo); /* Make sure we have a trailing NULL pointer on OUTSYMBOLS. We shouldn't really need one, since we have SYMCOUNT, but some old code still expects one. */ if (! generic_add_output_symbol (abfd, &outsymalloc, NULL)) return FALSE; if (info->relocatable) { /* Allocate space for the output relocs for each section. */ for (o = abfd->sections; o != NULL; o = o->next) { o->reloc_count = 0; for (p = o->map_head.link_order; p != NULL; p = p->next) { if (p->type == bfd_section_reloc_link_order || p->type == bfd_symbol_reloc_link_order) ++o->reloc_count; else if (p->type == bfd_indirect_link_order) { asection *input_section; bfd *input_bfd; long relsize; arelent **relocs; asymbol **symbols; long reloc_count; input_section = p->u.indirect.section; input_bfd = input_section->owner; relsize = bfd_get_reloc_upper_bound (input_bfd, input_section); if (relsize < 0) return FALSE; relocs = bfd_malloc (relsize); if (!relocs && relsize != 0) return FALSE; symbols = _bfd_generic_link_get_symbols (input_bfd); reloc_count = bfd_canonicalize_reloc (input_bfd, input_section, relocs, symbols); free (relocs); if (reloc_count < 0) return FALSE; BFD_ASSERT ((unsigned long) reloc_count == input_section->reloc_count); o->reloc_count += reloc_count; } } if (o->reloc_count > 0) { bfd_size_type amt; amt = o->reloc_count; amt *= sizeof (arelent *); o->orelocation = bfd_alloc (abfd, amt); if (!o->orelocation) return FALSE; o->flags |= SEC_RELOC; /* Reset the count so that it can be used as an index when putting in the output relocs. */ o->reloc_count = 0; } } } /* Handle all the link order information for the sections. */ for (o = abfd->sections; o != NULL; o = o->next) { for (p = o->map_head.link_order; p != NULL; p = p->next) { switch (p->type) { case bfd_section_reloc_link_order: case bfd_symbol_reloc_link_order: if (! _bfd_generic_reloc_link_order (abfd, info, o, p)) return FALSE; break; case bfd_indirect_link_order: if (! default_indirect_link_order (abfd, info, o, p, TRUE)) return FALSE; break; default: if (! _bfd_default_link_order (abfd, info, o, p)) return FALSE; break; } } } return TRUE; } /* Add an output symbol to the output BFD. */ static bfd_boolean generic_add_output_symbol (bfd *output_bfd, size_t *psymalloc, asymbol *sym) { if (bfd_get_symcount (output_bfd) >= *psymalloc) { asymbol **newsyms; bfd_size_type amt; if (*psymalloc == 0) *psymalloc = 124; else *psymalloc *= 2; amt = *psymalloc; amt *= sizeof (asymbol *); newsyms = bfd_realloc (bfd_get_outsymbols (output_bfd), amt); if (newsyms == NULL) return FALSE; bfd_get_outsymbols (output_bfd) = newsyms; } bfd_get_outsymbols (output_bfd) [bfd_get_symcount (output_bfd)] = sym; if (sym != NULL) ++ bfd_get_symcount (output_bfd); return TRUE; } /* Handle the symbols for an input BFD. */ bfd_boolean _bfd_generic_link_output_symbols (bfd *output_bfd, bfd *input_bfd, struct bfd_link_info *info, size_t *psymalloc) { asymbol **sym_ptr; asymbol **sym_end; if (! generic_link_read_symbols (input_bfd)) return FALSE; /* Create a filename symbol if we are supposed to. */ if (info->create_object_symbols_section != NULL) { asection *sec; for (sec = input_bfd->sections; sec != NULL; sec = sec->next) { if (sec->output_section == info->create_object_symbols_section) { asymbol *newsym; newsym = bfd_make_empty_symbol (input_bfd); if (!newsym) return FALSE; newsym->name = input_bfd->filename; newsym->value = 0; newsym->flags = BSF_LOCAL | BSF_FILE; newsym->section = sec; if (! generic_add_output_symbol (output_bfd, psymalloc, newsym)) return FALSE; break; } } } /* Adjust the values of the globally visible symbols, and write out local symbols. */ sym_ptr = _bfd_generic_link_get_symbols (input_bfd); sym_end = sym_ptr + _bfd_generic_link_get_symcount (input_bfd); for (; sym_ptr < sym_end; sym_ptr++) { asymbol *sym; struct generic_link_hash_entry *h; bfd_boolean output; h = NULL; sym = *sym_ptr; if ((sym->flags & (BSF_INDIRECT | BSF_WARNING | BSF_GLOBAL | BSF_CONSTRUCTOR | BSF_WEAK)) != 0 || bfd_is_und_section (bfd_get_section (sym)) || bfd_is_com_section (bfd_get_section (sym)) || bfd_is_ind_section (bfd_get_section (sym))) { if (sym->udata.p != NULL) h = sym->udata.p; else if ((sym->flags & BSF_CONSTRUCTOR) != 0) { /* This case normally means that the main linker code deliberately ignored this constructor symbol. We should just pass it through. This will screw up if the constructor symbol is from a different, non-generic, object file format, but the case will only arise when linking with -r, which will probably fail anyhow, since there will be no way to represent the relocs in the output format being used. */ h = NULL; } else if (bfd_is_und_section (bfd_get_section (sym))) h = ((struct generic_link_hash_entry *) bfd_wrapped_link_hash_lookup (output_bfd, info, bfd_asymbol_name (sym), FALSE, FALSE, TRUE)); else h = _bfd_generic_link_hash_lookup (_bfd_generic_hash_table (info), bfd_asymbol_name (sym), FALSE, FALSE, TRUE); if (h != NULL) { /* Force all references to this symbol to point to the same area in memory. It is possible that this routine will be called with a hash table other than a generic hash table, so we double check that. */ if (info->output_bfd->xvec == input_bfd->xvec) { if (h->sym != NULL) *sym_ptr = sym = h->sym; } switch (h->root.type) { default: case bfd_link_hash_new: abort (); case bfd_link_hash_undefined: break; case bfd_link_hash_undefweak: sym->flags |= BSF_WEAK; break; case bfd_link_hash_indirect: h = (struct generic_link_hash_entry *) h->root.u.i.link; /* fall through */ case bfd_link_hash_defined: sym->flags |= BSF_GLOBAL; sym->flags &=~ BSF_CONSTRUCTOR; sym->value = h->root.u.def.value; sym->section = h->root.u.def.section; break; case bfd_link_hash_defweak: sym->flags |= BSF_WEAK; sym->flags &=~ BSF_CONSTRUCTOR; sym->value = h->root.u.def.value; sym->section = h->root.u.def.section; break; case bfd_link_hash_common: sym->value = h->root.u.c.size; sym->flags |= BSF_GLOBAL; if (! bfd_is_com_section (sym->section)) { BFD_ASSERT (bfd_is_und_section (sym->section)); sym->section = bfd_com_section_ptr; } /* We do not set the section of the symbol to h->root.u.c.p->section. That value was saved so that we would know where to allocate the symbol if it was defined. In this case the type is still bfd_link_hash_common, so we did not define it, so we do not want to use that section. */ break; } } } /* This switch is straight from the old code in write_file_locals in ldsym.c. */ if (info->strip == strip_all || (info->strip == strip_some && bfd_hash_lookup (info->keep_hash, bfd_asymbol_name (sym), FALSE, FALSE) == NULL)) output = FALSE; else if ((sym->flags & (BSF_GLOBAL | BSF_WEAK)) != 0) { /* If this symbol is marked as occurring now, rather than at the end, output it now. This is used for COFF C_EXT FCN symbols. FIXME: There must be a better way. */ if (bfd_asymbol_bfd (sym) == input_bfd && (sym->flags & BSF_NOT_AT_END) != 0) output = TRUE; else output = FALSE; } else if (bfd_is_ind_section (sym->section)) output = FALSE; else if ((sym->flags & BSF_DEBUGGING) != 0) { if (info->strip == strip_none) output = TRUE; else output = FALSE; } else if (bfd_is_und_section (sym->section) || bfd_is_com_section (sym->section)) output = FALSE; else if ((sym->flags & BSF_LOCAL) != 0) { if ((sym->flags & BSF_WARNING) != 0) output = FALSE; else { switch (info->discard) { default: case discard_all: output = FALSE; break; case discard_sec_merge: output = TRUE; if (info->relocatable || ! (sym->section->flags & SEC_MERGE)) break; /* FALLTHROUGH */ case discard_l: if (bfd_is_local_label (input_bfd, sym)) output = FALSE; else output = TRUE; break; case discard_none: output = TRUE; break; } } } else if ((sym->flags & BSF_CONSTRUCTOR)) { if (info->strip != strip_all) output = TRUE; else output = FALSE; } else abort (); /* If this symbol is in a section which is not being included in the output file, then we don't want to output the symbol. */ if (!bfd_is_abs_section (sym->section) && bfd_section_removed_from_list (output_bfd, sym->section->output_section)) output = FALSE; if (output) { if (! generic_add_output_symbol (output_bfd, psymalloc, sym)) return FALSE; if (h != NULL) h->written = TRUE; } } return TRUE; } /* Set the section and value of a generic BFD symbol based on a linker hash table entry. */ static void set_symbol_from_hash (asymbol *sym, struct bfd_link_hash_entry *h) { switch (h->type) { default: abort (); break; case bfd_link_hash_new: /* This can happen when a constructor symbol is seen but we are not building constructors. */ if (sym->section != NULL) { BFD_ASSERT ((sym->flags & BSF_CONSTRUCTOR) != 0); } else { sym->flags |= BSF_CONSTRUCTOR; sym->section = bfd_abs_section_ptr; sym->value = 0; } break; case bfd_link_hash_undefined: sym->section = bfd_und_section_ptr; sym->value = 0; break; case bfd_link_hash_undefweak: sym->section = bfd_und_section_ptr; sym->value = 0; sym->flags |= BSF_WEAK; break; case bfd_link_hash_defined: sym->section = h->u.def.section; sym->value = h->u.def.value; break; case bfd_link_hash_defweak: sym->flags |= BSF_WEAK; sym->section = h->u.def.section; sym->value = h->u.def.value; break; case bfd_link_hash_common: sym->value = h->u.c.size; if (sym->section == NULL) sym->section = bfd_com_section_ptr; else if (! bfd_is_com_section (sym->section)) { BFD_ASSERT (bfd_is_und_section (sym->section)); sym->section = bfd_com_section_ptr; } /* Do not set the section; see _bfd_generic_link_output_symbols. */ break; case bfd_link_hash_indirect: case bfd_link_hash_warning: /* FIXME: What should we do here? */ break; } } /* Write out a global symbol, if it hasn't already been written out. This is called for each symbol in the hash table. */ bfd_boolean _bfd_generic_link_write_global_symbol (struct generic_link_hash_entry *h, void *data) { struct generic_write_global_symbol_info *wginfo = data; asymbol *sym; if (h->root.type == bfd_link_hash_warning) h = (struct generic_link_hash_entry *) h->root.u.i.link; if (h->written) return TRUE; h->written = TRUE; if (wginfo->info->strip == strip_all || (wginfo->info->strip == strip_some && bfd_hash_lookup (wginfo->info->keep_hash, h->root.root.string, FALSE, FALSE) == NULL)) return TRUE; if (h->sym != NULL) sym = h->sym; else { sym = bfd_make_empty_symbol (wginfo->output_bfd); if (!sym) return FALSE; sym->name = h->root.root.string; sym->flags = 0; } set_symbol_from_hash (sym, &h->root); sym->flags |= BSF_GLOBAL; if (! generic_add_output_symbol (wginfo->output_bfd, wginfo->psymalloc, sym)) { /* FIXME: No way to return failure. */ abort (); } return TRUE; } /* Create a relocation. */ bfd_boolean _bfd_generic_reloc_link_order (bfd *abfd, struct bfd_link_info *info, asection *sec, struct bfd_link_order *link_order) { arelent *r; if (! info->relocatable) abort (); if (sec->orelocation == NULL) abort (); r = bfd_alloc (abfd, sizeof (arelent)); if (r == NULL) return FALSE; r->address = link_order->offset; r->howto = bfd_reloc_type_lookup (abfd, link_order->u.reloc.p->reloc); if (r->howto == 0) { bfd_set_error (bfd_error_bad_value); return FALSE; } /* Get the symbol to use for the relocation. */ if (link_order->type == bfd_section_reloc_link_order) r->sym_ptr_ptr = link_order->u.reloc.p->u.section->symbol_ptr_ptr; else { struct generic_link_hash_entry *h; h = ((struct generic_link_hash_entry *) bfd_wrapped_link_hash_lookup (abfd, info, link_order->u.reloc.p->u.name, FALSE, FALSE, TRUE)); if (h == NULL || ! h->written) { if (! ((*info->callbacks->unattached_reloc) (info, link_order->u.reloc.p->u.name, NULL, NULL, 0))) return FALSE; bfd_set_error (bfd_error_bad_value); return FALSE; } r->sym_ptr_ptr = &h->sym; } /* If this is an inplace reloc, write the addend to the object file. Otherwise, store it in the reloc addend. */ if (! r->howto->partial_inplace) r->addend = link_order->u.reloc.p->addend; else { bfd_size_type size; bfd_reloc_status_type rstat; bfd_byte *buf; bfd_boolean ok; file_ptr loc; size = bfd_get_reloc_size (r->howto); buf = bfd_zmalloc (size); if (buf == NULL) return FALSE; rstat = _bfd_relocate_contents (r->howto, abfd, (bfd_vma) link_order->u.reloc.p->addend, buf); switch (rstat) { case bfd_reloc_ok: break; default: case bfd_reloc_outofrange: abort (); case bfd_reloc_overflow: if (! ((*info->callbacks->reloc_overflow) (info, NULL, (link_order->type == bfd_section_reloc_link_order ? bfd_section_name (abfd, link_order->u.reloc.p->u.section) : link_order->u.reloc.p->u.name), r->howto->name, link_order->u.reloc.p->addend, NULL, NULL, 0))) { free (buf); return FALSE; } break; } loc = link_order->offset * bfd_octets_per_byte (abfd); ok = bfd_set_section_contents (abfd, sec, buf, loc, size); free (buf); if (! ok) return FALSE; r->addend = 0; } sec->orelocation[sec->reloc_count] = r; ++sec->reloc_count; return TRUE; } /* Allocate a new link_order for a section. */ struct bfd_link_order * bfd_new_link_order (bfd *abfd, asection *section) { bfd_size_type amt = sizeof (struct bfd_link_order); struct bfd_link_order *new; new = bfd_zalloc (abfd, amt); if (!new) return NULL; new->type = bfd_undefined_link_order; if (section->map_tail.link_order != NULL) section->map_tail.link_order->next = new; else section->map_head.link_order = new; section->map_tail.link_order = new; return new; } /* Default link order processing routine. Note that we can not handle the reloc_link_order types here, since they depend upon the details of how the particular backends generates relocs. */ bfd_boolean _bfd_default_link_order (bfd *abfd, struct bfd_link_info *info, asection *sec, struct bfd_link_order *link_order) { switch (link_order->type) { case bfd_undefined_link_order: case bfd_section_reloc_link_order: case bfd_symbol_reloc_link_order: default: abort (); case bfd_indirect_link_order: return default_indirect_link_order (abfd, info, sec, link_order, FALSE); case bfd_data_link_order: return default_data_link_order (abfd, info, sec, link_order); } } /* Default routine to handle a bfd_data_link_order. */ static bfd_boolean default_data_link_order (bfd *abfd, struct bfd_link_info *info ATTRIBUTE_UNUSED, asection *sec, struct bfd_link_order *link_order) { bfd_size_type size; size_t fill_size; bfd_byte *fill; file_ptr loc; bfd_boolean result; BFD_ASSERT ((sec->flags & SEC_HAS_CONTENTS) != 0); size = link_order->size; if (size == 0) return TRUE; fill = link_order->u.data.contents; fill_size = link_order->u.data.size; if (fill_size != 0 && fill_size < size) { bfd_byte *p; fill = bfd_malloc (size); if (fill == NULL) return FALSE; p = fill; if (fill_size == 1) memset (p, (int) link_order->u.data.contents[0], (size_t) size); else { do { memcpy (p, link_order->u.data.contents, fill_size); p += fill_size; size -= fill_size; } while (size >= fill_size); if (size != 0) memcpy (p, link_order->u.data.contents, (size_t) size); size = link_order->size; } } loc = link_order->offset * bfd_octets_per_byte (abfd); result = bfd_set_section_contents (abfd, sec, fill, loc, size); if (fill != link_order->u.data.contents) free (fill); return result; } /* Default routine to handle a bfd_indirect_link_order. */ static bfd_boolean default_indirect_link_order (bfd *output_bfd, struct bfd_link_info *info, asection *output_section, struct bfd_link_order *link_order, bfd_boolean generic_linker) { asection *input_section; bfd *input_bfd; bfd_byte *contents = NULL; bfd_byte *new_contents; bfd_size_type sec_size; file_ptr loc; BFD_ASSERT ((output_section->flags & SEC_HAS_CONTENTS) != 0); input_section = link_order->u.indirect.section; input_bfd = input_section->owner; if (input_section->size == 0) return TRUE; BFD_ASSERT (input_section->output_section == output_section); BFD_ASSERT (input_section->output_offset == link_order->offset); BFD_ASSERT (input_section->size == link_order->size); if (info->relocatable && input_section->reloc_count > 0 && output_section->orelocation == NULL) { /* Space has not been allocated for the output relocations. This can happen when we are called by a specific backend because somebody is attempting to link together different types of object files. Handling this case correctly is difficult, and sometimes impossible. */ (*_bfd_error_handler) (_("Attempt to do relocatable link with %s input and %s output"), bfd_get_target (input_bfd), bfd_get_target (output_bfd)); bfd_set_error (bfd_error_wrong_format); return FALSE; } if (! generic_linker) { asymbol **sympp; asymbol **symppend; /* Get the canonical symbols. The generic linker will always have retrieved them by this point, but we are being called by a specific linker, presumably because we are linking different types of object files together. */ if (! generic_link_read_symbols (input_bfd)) return FALSE; /* Since we have been called by a specific linker, rather than the generic linker, the values of the symbols will not be right. They will be the values as seen in the input file, not the values of the final link. We need to fix them up before we can relocate the section. */ sympp = _bfd_generic_link_get_symbols (input_bfd); symppend = sympp + _bfd_generic_link_get_symcount (input_bfd); for (; sympp < symppend; sympp++) { asymbol *sym; struct bfd_link_hash_entry *h; sym = *sympp; if ((sym->flags & (BSF_INDIRECT | BSF_WARNING | BSF_GLOBAL | BSF_CONSTRUCTOR | BSF_WEAK)) != 0 || bfd_is_und_section (bfd_get_section (sym)) || bfd_is_com_section (bfd_get_section (sym)) || bfd_is_ind_section (bfd_get_section (sym))) { /* sym->udata may have been set by generic_link_add_symbol_list. */ if (sym->udata.p != NULL) h = sym->udata.p; else if (bfd_is_und_section (bfd_get_section (sym))) h = bfd_wrapped_link_hash_lookup (output_bfd, info, bfd_asymbol_name (sym), FALSE, FALSE, TRUE); else h = bfd_link_hash_lookup (info->hash, bfd_asymbol_name (sym), FALSE, FALSE, TRUE); if (h != NULL) set_symbol_from_hash (sym, h); } } } /* Get and relocate the section contents. */ sec_size = (input_section->rawsize > input_section->size ? input_section->rawsize : input_section->size); contents = bfd_malloc (sec_size); if (contents == NULL && sec_size != 0) goto error_return; new_contents = (bfd_get_relocated_section_contents (output_bfd, info, link_order, contents, info->relocatable, _bfd_generic_link_get_symbols (input_bfd))); if (!new_contents) goto error_return; /* Output the section contents. */ loc = input_section->output_offset * bfd_octets_per_byte (output_bfd); if (! bfd_set_section_contents (output_bfd, output_section, new_contents, loc, input_section->size)) goto error_return; if (contents != NULL) free (contents); return TRUE; error_return: if (contents != NULL) free (contents); return FALSE; } /* A little routine to count the number of relocs in a link_order list. */ unsigned int _bfd_count_link_order_relocs (struct bfd_link_order *link_order) { register unsigned int c; register struct bfd_link_order *l; c = 0; for (l = link_order; l != NULL; l = l->next) { if (l->type == bfd_section_reloc_link_order || l->type == bfd_symbol_reloc_link_order) ++c; } return c; } /* FUNCTION bfd_link_split_section SYNOPSIS bfd_boolean bfd_link_split_section (bfd *abfd, asection *sec); DESCRIPTION Return nonzero if @var{sec} should be split during a reloceatable or final link. .#define bfd_link_split_section(abfd, sec) \ . BFD_SEND (abfd, _bfd_link_split_section, (abfd, sec)) . */ bfd_boolean _bfd_generic_link_split_section (bfd *abfd ATTRIBUTE_UNUSED, asection *sec ATTRIBUTE_UNUSED) { return FALSE; } /* FUNCTION bfd_section_already_linked SYNOPSIS void bfd_section_already_linked (bfd *abfd, asection *sec, struct bfd_link_info *info); DESCRIPTION Check if @var{sec} has been already linked during a reloceatable or final link. .#define bfd_section_already_linked(abfd, sec, info) \ . BFD_SEND (abfd, _section_already_linked, (abfd, sec, info)) . */ /* Sections marked with the SEC_LINK_ONCE flag should only be linked once into the output. This routine checks each section, and arrange to discard it if a section of the same name has already been linked. This code assumes that all relevant sections have the SEC_LINK_ONCE flag set; that is, it does not depend solely upon the section name. bfd_section_already_linked is called via bfd_map_over_sections. */ /* The hash table. */ static struct bfd_hash_table _bfd_section_already_linked_table; /* Support routines for the hash table used by section_already_linked, initialize the table, traverse, lookup, fill in an entry and remove the table. */ void bfd_section_already_linked_table_traverse (bfd_boolean (*func) (struct bfd_section_already_linked_hash_entry *, void *), void *info) { bfd_hash_traverse (&_bfd_section_already_linked_table, (bfd_boolean (*) (struct bfd_hash_entry *, void *)) func, info); } struct bfd_section_already_linked_hash_entry * bfd_section_already_linked_table_lookup (const char *name) { return ((struct bfd_section_already_linked_hash_entry *) bfd_hash_lookup (&_bfd_section_already_linked_table, name, TRUE, FALSE)); } bfd_boolean bfd_section_already_linked_table_insert (struct bfd_section_already_linked_hash_entry *already_linked_list, asection *sec) { struct bfd_section_already_linked *l; /* Allocate the memory from the same obstack as the hash table is kept in. */ l = bfd_hash_allocate (&_bfd_section_already_linked_table, sizeof *l); if (l == NULL) return FALSE; l->sec = sec; l->next = already_linked_list->entry; already_linked_list->entry = l; return TRUE; } static struct bfd_hash_entry * already_linked_newfunc (struct bfd_hash_entry *entry ATTRIBUTE_UNUSED, struct bfd_hash_table *table, const char *string ATTRIBUTE_UNUSED) { struct bfd_section_already_linked_hash_entry *ret = bfd_hash_allocate (table, sizeof *ret); if (ret == NULL) return NULL; ret->entry = NULL; return &ret->root; } bfd_boolean bfd_section_already_linked_table_init (void) { return bfd_hash_table_init_n (&_bfd_section_already_linked_table, already_linked_newfunc, sizeof (struct bfd_section_already_linked_hash_entry), 42); } void bfd_section_already_linked_table_free (void) { bfd_hash_table_free (&_bfd_section_already_linked_table); } /* This is used on non-ELF inputs. */ void _bfd_generic_section_already_linked (bfd *abfd, asection *sec, struct bfd_link_info *info) { flagword flags; const char *name; struct bfd_section_already_linked *l; struct bfd_section_already_linked_hash_entry *already_linked_list; flags = sec->flags; if ((flags & SEC_LINK_ONCE) == 0) return; /* FIXME: When doing a relocatable link, we may have trouble copying relocations in other sections that refer to local symbols in the section being discarded. Those relocations will have to be converted somehow; as of this writing I'm not sure that any of the backends handle that correctly. It is tempting to instead not discard link once sections when doing a relocatable link (technically, they should be discarded whenever we are building constructors). However, that fails, because the linker winds up combining all the link once sections into a single large link once section, which defeats the purpose of having link once sections in the first place. */ name = bfd_get_section_name (abfd, sec); already_linked_list = bfd_section_already_linked_table_lookup (name); for (l = already_linked_list->entry; l != NULL; l = l->next) { bfd_boolean skip = FALSE; struct coff_comdat_info *s_comdat = bfd_coff_get_comdat_section (abfd, sec); struct coff_comdat_info *l_comdat = bfd_coff_get_comdat_section (l->sec->owner, l->sec); /* We may have 3 different sections on the list: group section, comdat section and linkonce section. SEC may be a linkonce or comdat section. We always ignore group section. For non-COFF inputs, we also ignore comdat section. FIXME: Is that safe to match a linkonce section with a comdat section for COFF inputs? */ if ((l->sec->flags & SEC_GROUP) != 0) skip = TRUE; else if (bfd_get_flavour (abfd) == bfd_target_coff_flavour) { if (s_comdat != NULL && l_comdat != NULL && strcmp (s_comdat->name, l_comdat->name) != 0) skip = TRUE; } else if (l_comdat != NULL) skip = TRUE; if (!skip) { /* The section has already been linked. See if we should issue a warning. */ switch (flags & SEC_LINK_DUPLICATES) { default: abort (); case SEC_LINK_DUPLICATES_DISCARD: break; case SEC_LINK_DUPLICATES_ONE_ONLY: (*_bfd_error_handler) (_("%B: warning: ignoring duplicate section `%A'\n"), abfd, sec); break; case SEC_LINK_DUPLICATES_SAME_CONTENTS: /* FIXME: We should really dig out the contents of both sections and memcmp them. The COFF/PE spec says that the Microsoft linker does not implement this correctly, so I'm not going to bother doing it either. */ /* Fall through. */ case SEC_LINK_DUPLICATES_SAME_SIZE: if (sec->size != l->sec->size) (*_bfd_error_handler) (_("%B: warning: duplicate section `%A' has different size\n"), abfd, sec); break; } /* Set the output_section field so that lang_add_section does not create a lang_input_section structure for this section. Since there might be a symbol in the section being discarded, we must retain a pointer to the section which we are really going to use. */ sec->output_section = bfd_abs_section_ptr; sec->kept_section = l->sec; return; } } /* This is the first section with this name. Record it. */ if (! bfd_section_already_linked_table_insert (already_linked_list, sec)) info->callbacks->einfo (_("%F%P: already_linked_table: %E")); } /* Convert symbols in excluded output sections to use a kept section. */ static bfd_boolean fix_syms (struct bfd_link_hash_entry *h, void *data) { bfd *obfd = (bfd *) data; if (h->type == bfd_link_hash_warning) h = h->u.i.link; if (h->type == bfd_link_hash_defined || h->type == bfd_link_hash_defweak) { asection *s = h->u.def.section; if (s != NULL && s->output_section != NULL && (s->output_section->flags & SEC_EXCLUDE) != 0 && bfd_section_removed_from_list (obfd, s->output_section)) { asection *op, *op1; h->u.def.value += s->output_offset + s->output_section->vma; /* Find preceding kept section. */ for (op1 = s->output_section->prev; op1 != NULL; op1 = op1->prev) if ((op1->flags & SEC_EXCLUDE) == 0 && !bfd_section_removed_from_list (obfd, op1)) break; /* Find following kept section. Start at prev->next because other sections may have been added after S was removed. */ if (s->output_section->prev != NULL) op = s->output_section->prev->next; else op = s->output_section->owner->sections; for (; op != NULL; op = op->next) if ((op->flags & SEC_EXCLUDE) == 0 && !bfd_section_removed_from_list (obfd, op)) break; /* Choose better of two sections, based on flags. The idea is to choose a section that will be in the same segment as S would have been if it was kept. */ if (op1 == NULL) { if (op == NULL) op = bfd_abs_section_ptr; } else if (op == NULL) op = op1; else if (((op1->flags ^ op->flags) & (SEC_ALLOC | SEC_THREAD_LOCAL)) != 0) { if (((op->flags ^ s->flags) & (SEC_ALLOC | SEC_THREAD_LOCAL)) != 0) op = op1; } else if (((op1->flags ^ op->flags) & SEC_READONLY) != 0) { if (((op->flags ^ s->flags) & SEC_READONLY) != 0) op = op1; } else if (((op1->flags ^ op->flags) & SEC_CODE) != 0) { if (((op->flags ^ s->flags) & SEC_CODE) != 0) op = op1; } else { /* Flags we care about are the same. Prefer the following section if that will result in a positive valued sym. */ if (h->u.def.value < op->vma) op = op1; } h->u.def.value -= op->vma; h->u.def.section = op; } } return TRUE; } void _bfd_fix_excluded_sec_syms (bfd *obfd, struct bfd_link_info *info) { bfd_link_hash_traverse (info->hash, fix_syms, obfd); }
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