673 lines
16 KiB
C
673 lines
16 KiB
C
/* All symbol handling for the linker
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Copyright (C) 1991 Free Software Foundation, Inc.
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Written by Steve Chamberlain steve@cygnus.com
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This file is part of GLD, the Gnu Linker.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/*
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We keep a hash table of global symbols. Each entry in a hash table
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is called an ldsym_type. Each has three chains; a pointer to a
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chain of definitions for the symbol (hopefully one long), a pointer
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to a chain of references to the symbol, and a pointer to a chain of
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common symbols. Each pointer points into the canonical symbol table
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provided by bfd, each one of which points to an asymbol. During
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linkage, the linker uses the udata field to point to the next entry
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in a canonical table....
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ld_sym
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| |
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+----------+ +----------+
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| defs | a canonical symbol table
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+----------+ +----------+
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| refs | -----> | one entry| -----> asymbol
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+----------+ +----------+ | |
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| coms | | | +---------+
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+----------+ +----------+ | udata |-----> another canonical
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+---------+ symbol
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It is very simple to make all the symbol pointers point to the same
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definition - just run down the chain and make the asymbols pointers
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within the canonical table point to the asymbol attacthed to the
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definition of the symbol.
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*/
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#include "bfd.h"
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#include "sysdep.h"
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#include "ld.h"
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#include "ldsym.h"
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#include "ldmisc.h"
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#include "ldlang.h"
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/* IMPORT */
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extern int symbol_truncate;
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extern bfd *output_bfd;
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extern strip_symbols_type strip_symbols;
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extern discard_locals_type discard_locals;
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/* Head and tail of global symbol table chronological list */
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ldsym_type *symbol_head = (ldsym_type *) NULL;
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ldsym_type **symbol_tail_ptr = &symbol_head;
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CONST char *keepsyms_file;
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int kept_syms;
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extern ld_config_type config;
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struct obstack global_sym_obstack;
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#define obstack_chunk_alloc ldmalloc
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#define obstack_chunk_free free
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/*
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incremented for each symbol in the ldsym_type table
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no matter what flavour it is
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*/
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unsigned int global_symbol_count;
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/* IMPORTS */
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/* LOCALS */
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#define TABSIZE 1009
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static ldsym_type *global_symbol_hash_table[TABSIZE];
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/* Compute the hash code for symbol name KEY. */
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static
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#ifdef __GNUC__
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__inline
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#endif
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int
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hash_string (key)
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CONST char *key;
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{
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register CONST char *cp;
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register int k;
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register int l = 0;
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cp = key;
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k = 0;
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while (*cp && l < symbol_truncate)
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{
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k = (((k << 1) + (k >> 14)) ^ (*cp++)) & 0x3fff;
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l++;
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}
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return k;
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}
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static
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#ifdef __GNUC__
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__inline
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#endif
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ldsym_type *
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search (key, hashval)
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CONST char *key;
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int hashval;
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{
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ldsym_type *bp;
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for (bp = global_symbol_hash_table[hashval]; bp; bp = bp->link)
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if (!strncmp (key, bp->name, symbol_truncate))
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{
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if (bp->flags & SYM_INDIRECT)
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{
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/* Use the symbol we're aliased to instead */
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return (ldsym_type *) (bp->sdefs_chain);
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}
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return bp;
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}
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return 0;
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}
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/* Get the symbol table entry for the global symbol named KEY.
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Create one if there is none. */
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ldsym_type *
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ldsym_get (key)
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CONST char *key;
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{
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register int hashval;
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register ldsym_type *bp;
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/* Determine the proper bucket. */
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hashval = hash_string (key) % TABSIZE;
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/* Search the bucket. */
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bp = search (key, hashval);
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if (bp)
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{
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return bp;
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}
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/* Nothing was found; create a new symbol table entry. */
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bp = (ldsym_type *) obstack_alloc (&global_sym_obstack, (bfd_size_type) (sizeof (ldsym_type)));
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bp->srefs_chain = (asymbol **) NULL;
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bp->sdefs_chain = (asymbol **) NULL;
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bp->scoms_chain = (asymbol **) NULL;
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bp->name = obstack_copy (&global_sym_obstack, key, strlen (key) + 1);
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bp->flags = 0;
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/* Add the entry to the bucket. */
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bp->link = global_symbol_hash_table[hashval];
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global_symbol_hash_table[hashval] = bp;
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/* Keep the chronological list up to date too */
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*symbol_tail_ptr = bp;
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symbol_tail_ptr = &bp->next;
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bp->next = 0;
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global_symbol_count++;
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return bp;
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}
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/* Like `ldsym_get' but return 0 if the symbol is not already known. */
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ldsym_type *
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ldsym_get_soft (key)
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CONST char *key;
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{
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register int hashval;
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/* Determine which bucket. */
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hashval = hash_string (key) % TABSIZE;
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/* Search the bucket. */
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return search (key, hashval);
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}
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static asymbol **
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process_keepsyms (table, size)
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asymbol **table;
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int size;
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{
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struct obstack obstack;
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char *start_of_obstack;
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FILE *ks_file = 0;
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asymbol **out = table;
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asymbol **end = table + size;
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asymbol **sym;
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if (!keepsyms_file || size == 0)
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return end;
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obstack_init (&obstack);
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obstack_alloc (&obstack, 1);
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obstack_finish (&obstack);
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start_of_obstack = obstack_alloc (&obstack, 1);
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ks_file = fopen (keepsyms_file, "r");
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if (!ks_file)
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{
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info ("%X%P: can't open keep-symbols file `%s'\n", keepsyms_file);
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goto egress;
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}
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errno = 0;
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#define KEEP(S) \
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do { asymbol **p = (S), *tmp = *out; *out = *p; *p = tmp; out++; } while (0)
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while (!feof (ks_file) && !ferror (ks_file))
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{
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int c;
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char *ptr;
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int found = 0;
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obstack_free (&obstack, start_of_obstack);
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do
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{
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c = getc (ks_file);
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if (c == '\n')
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c = 0;
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obstack_1grow (&obstack, c);
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}
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while (c > 0);
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if (c == EOF)
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{
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if (!feof (ks_file))
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/* error occurred */
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{
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info ("%X%P: error reading keep-symbols file `%s': %E\n",
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keepsyms_file);
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out = end;
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goto egress;
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}
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if (obstack_next_free (&obstack) != obstack_base (&obstack) + 1)
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/* eof in middle of symbol */
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{
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info ("%X%P: eof reached mid-line while reading keep-symbols file `%s'\n",
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keepsyms_file);
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out = end;
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goto egress;
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}
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/* All okay -- no incomplete lines, EOF reached. */
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break;
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}
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ptr = obstack_next_free (&obstack) - 2;
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/* discard trailing trash */
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while (*ptr == ' '
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|| *ptr == '\t')
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*ptr-- = 0;
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ptr = obstack_base (&obstack);
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for (sym = out; sym < end; sym++)
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if (!strncmp ((*sym)->name, ptr, symbol_truncate))
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{
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KEEP (sym);
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found = 1;
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}
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if (!found)
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info ("%P: symbol `%s' (requested to be kept) not found\n", ptr);
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}
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/* It'd be slightly faster to move this pass above the previous one,
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but that'd mean any symbols preserved in this pass would generate
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warnings if they were also listed in the keepsyms file. */
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for (sym = out; sym < end; sym++)
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{
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asymbol *s = *sym;
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if (s->section == &bfd_und_section
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|| bfd_is_com_section (s->section)
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|| s->flags & BSF_KEEP_G)
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KEEP (sym);
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}
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egress:
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obstack_free (&obstack, start_of_obstack);
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if (ks_file)
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fclose (ks_file);
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return out;
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}
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static void
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list_file_locals (entry)
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lang_input_statement_type *entry;
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{
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asymbol **q;
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fprintf (config.map_file, "\nLocal symbols of ");
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minfo ("%I", entry);
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fprintf (config.map_file, ":\n\n");
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if (entry->asymbols)
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{
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for (q = entry->asymbols; *q; q++)
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{
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asymbol *p = *q;
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/* If this is a definition,
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update it if necessary by this file's start address. */
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if (p->flags & BSF_LOCAL)
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info (" %V %s\n", p->value, p->name);
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}
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}
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}
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static void
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print_file_stuff (f)
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lang_input_statement_type * f;
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{
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fprintf (config.map_file, " %s\n", f->filename);
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if (f->just_syms_flag)
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{
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fprintf (config.map_file, " symbols only\n");
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}
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else
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{
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asection *s;
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if (true)
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{
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for (s = f->the_bfd->sections;
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s != (asection *) NULL;
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s = s->next)
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{
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print_address (s->output_offset);
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if (s->reloc_done)
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{
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fprintf (config.map_file, " %08x 2**%2ud %s\n",
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(unsigned) bfd_get_section_size_after_reloc (s),
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s->alignment_power, s->name);
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}
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else
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{
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fprintf (config.map_file, " %08x 2**%2ud %s\n",
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(unsigned) bfd_get_section_size_before_reloc (s),
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s->alignment_power, s->name);
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}
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}
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}
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else
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{
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for (s = f->the_bfd->sections;
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s != (asection *) NULL;
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s = s->next)
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{
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fprintf (config.map_file, "%s ", s->name);
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print_address (s->output_offset);
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fprintf (config.map_file, "(%x)", (unsigned) bfd_get_section_size_after_reloc (s));
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}
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fprintf (config.map_file, "hex \n");
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}
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}
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fprintf (config.map_file, "\n");
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}
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void
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ldsym_print_symbol_table ()
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{
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fprintf (config.map_file, "**FILES**\n\n");
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lang_for_each_file (print_file_stuff);
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fprintf (config.map_file, "**GLOBAL SYMBOLS**\n\n");
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fprintf (config.map_file, "offset section offset symbol\n");
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{
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register ldsym_type *sp;
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for (sp = symbol_head; sp; sp = sp->next)
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{
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if (sp->flags & SYM_INDIRECT)
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{
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fprintf (config.map_file, "indirect %s to %s\n",
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sp->name, (((ldsym_type *) (sp->sdefs_chain))->name));
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}
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else
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{
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if (sp->sdefs_chain)
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{
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asymbol *defsym = *(sp->sdefs_chain);
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asection *defsec = bfd_get_section (defsym);
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print_address (defsym->value);
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if (defsec)
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{
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fprintf (config.map_file, " %-10s",
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bfd_section_name (output_bfd,
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defsec));
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print_space ();
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print_address (defsym->value + defsec->vma);
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}
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else
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{
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fprintf (config.map_file, " .......");
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}
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}
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if (sp->scoms_chain)
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{
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fprintf (config.map_file, "common ");
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print_address ((*(sp->scoms_chain))->value);
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fprintf (config.map_file, " %s ", sp->name);
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}
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else if (sp->sdefs_chain)
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{
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fprintf (config.map_file, " %s ", sp->name);
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}
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else
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{
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fprintf (config.map_file, "undefined ");
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fprintf (config.map_file, "%s ", sp->name);
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}
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}
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print_nl ();
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}
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}
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}
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extern lang_output_section_statement_type *create_object_symbols;
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extern char lprefix;
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static asymbol **
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write_file_locals (output_buffer)
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asymbol **output_buffer;
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{
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LANG_FOR_EACH_INPUT_STATEMENT (entry)
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{
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/* Run trough the symbols and work out what to do with them */
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unsigned int i;
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/* Add one for the filename symbol if needed */
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if (create_object_symbols
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!= (lang_output_section_statement_type *) NULL)
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{
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asection *s;
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for (s = entry->the_bfd->sections;
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s != (asection *) NULL;
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s = s->next)
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{
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if (s->output_section == create_object_symbols->bfd_section)
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{
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/* Add symbol to this section */
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asymbol *newsym =
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(asymbol *) bfd_make_empty_symbol (entry->the_bfd);
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newsym->name = entry->local_sym_name;
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/* The symbol belongs to the output file's text section */
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/* The value is the start of this section in the output file*/
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newsym->value = 0;
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/* FIXME: Usurping BSF_KEEP_G flag, since it's defined as
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"used by the linker" and I can't find any other code that
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uses it. Should be a cleaner way of doing this (like an
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"application flags" field in the symbol structure?). */
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newsym->flags = BSF_LOCAL | BSF_KEEP_G;
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newsym->section = s;
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*output_buffer++ = newsym;
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break;
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}
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}
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}
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for (i = 0; i < entry->symbol_count; i++)
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{
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asymbol *p = entry->asymbols[i];
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/* FIXME, temporary hack, since not all of ld knows about the new abs section convention */
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if (p->section == 0)
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p->section = &bfd_abs_section;
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if (flag_is_global (p->flags))
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{
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/* We are only interested in outputting
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globals at this stage in special circumstances */
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if (bfd_asymbol_bfd (p) == entry->the_bfd
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&& flag_is_not_at_end (p->flags))
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{
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/* And this is one of them */
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*(output_buffer++) = p;
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p->flags |= BSF_KEEP;
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}
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}
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else
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{
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if (p->section == &bfd_ind_section)
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{
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/* Dont think about indirect symbols */
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}
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else if (flag_is_debugger (p->flags))
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{
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/* Only keep the debugger symbols if no stripping required */
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if (strip_symbols == STRIP_NONE)
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{
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*output_buffer++ = p;
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}
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}
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else if (p->section == &bfd_und_section
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|| bfd_is_com_section (p->section))
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{
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/* These must be global. */
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}
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else if (flag_is_ordinary_local (p->flags))
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{
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if (discard_locals == DISCARD_ALL)
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{
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}
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else if (discard_locals == DISCARD_L &&
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(p->name[0] == lprefix))
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{
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}
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else if (p->flags == BSF_WARNING)
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{
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}
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else
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{
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*output_buffer++ = p;
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}
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}
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else if (p->flags & BSF_CONSTRUCTOR)
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{
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if (strip_symbols != STRIP_ALL)
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{
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*output_buffer++ = p;
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}
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}
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else
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{
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FAIL ();
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}
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}
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}
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}
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return output_buffer;
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}
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static asymbol **
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write_file_globals (symbol_table)
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asymbol **symbol_table;
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{
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FOR_EACH_LDSYM (sp)
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{
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if (sp->flags & SYM_INDIRECT)
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{
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asymbol *bufp = (*(sp->srefs_chain));
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ldsym_type *aliased_to = (ldsym_type *) (sp->sdefs_chain);
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if (aliased_to->sdefs_chain)
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{
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asymbol *p = aliased_to->sdefs_chain[0];
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bufp->value = p->value;
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bufp->section = p->section;
|
|
bufp->flags = p->flags;
|
|
}
|
|
else
|
|
{
|
|
bufp->value = 0;
|
|
bufp->flags = 0;
|
|
bufp->section = &bfd_und_section;
|
|
}
|
|
*symbol_table++ = bufp;
|
|
}
|
|
else if ((sp->flags & SYM_INDIRECT) == 0 && sp->sdefs_chain != (asymbol **) NULL)
|
|
{
|
|
asymbol *bufp = (*(sp->sdefs_chain));
|
|
|
|
if ((bufp->flags & BSF_KEEP) == 0)
|
|
{
|
|
ASSERT (bufp != (asymbol *) NULL);
|
|
|
|
bufp->name = sp->name;
|
|
|
|
if (sp->scoms_chain != (asymbol **) NULL)
|
|
|
|
{
|
|
/*
|
|
defined as common but not allocated, this happens
|
|
only with -r and not -d, write out a common
|
|
definition
|
|
*/
|
|
bufp = *(sp->scoms_chain);
|
|
}
|
|
*symbol_table++ = bufp;
|
|
}
|
|
}
|
|
else if (sp->scoms_chain != (asymbol **) NULL)
|
|
{
|
|
/* This symbol is a common - just output */
|
|
asymbol *bufp = (*(sp->scoms_chain));
|
|
*symbol_table++ = bufp;
|
|
}
|
|
else if (sp->srefs_chain != (asymbol **) NULL)
|
|
{
|
|
/* This symbol is undefined but has a reference */
|
|
asymbol *bufp = (*(sp->srefs_chain));
|
|
*symbol_table++ = bufp;
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
This symbol has neither defs nor refs, it must have come
|
|
from the command line, since noone has used it it has no
|
|
data attatched, so we'll ignore it
|
|
*/
|
|
}
|
|
}
|
|
return symbol_table;
|
|
}
|
|
|
|
void
|
|
ldsym_write ()
|
|
{
|
|
if (keepsyms_file != 0
|
|
&& strip_symbols != STRIP_SOME)
|
|
{
|
|
info ("%P `-retain-symbols-file' overrides `-s' and `-S'\n");
|
|
strip_symbols = STRIP_SOME;
|
|
}
|
|
if (strip_symbols != STRIP_ALL)
|
|
{
|
|
/* We know the maximum size of the symbol table -
|
|
it's the size of all the global symbols ever seen +
|
|
the size of all the symbols from all the files +
|
|
the number of files (for the per file symbols)
|
|
+1 (for the null at the end)
|
|
*/
|
|
extern unsigned int total_files_seen;
|
|
extern unsigned int total_symbols_seen;
|
|
|
|
asymbol **symbol_table = (asymbol **)
|
|
ldmalloc ((bfd_size_type) (global_symbol_count +
|
|
total_files_seen +
|
|
total_symbols_seen + 1) * sizeof (asymbol *));
|
|
asymbol **tablep = write_file_locals (symbol_table);
|
|
|
|
tablep = write_file_globals (tablep);
|
|
tablep = process_keepsyms (symbol_table, tablep - symbol_table);
|
|
|
|
*tablep = (asymbol *) NULL;
|
|
bfd_set_symtab (output_bfd, symbol_table, (unsigned) (tablep - symbol_table));
|
|
}
|
|
}
|
|
|
|
/*
|
|
return true if the supplied symbol name is not in the
|
|
linker symbol table
|
|
*/
|
|
boolean
|
|
ldsym_undefined (sym)
|
|
CONST char *sym;
|
|
{
|
|
ldsym_type *from_table = ldsym_get_soft (sym);
|
|
if (from_table != (ldsym_type *) NULL)
|
|
{
|
|
if (from_table->sdefs_chain != (asymbol **) NULL)
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
void
|
|
ldsym_init ()
|
|
{
|
|
obstack_begin (&global_sym_obstack, 20000);
|
|
}
|