426 lines
13 KiB
C
426 lines
13 KiB
C
/* Read a symbol table in MIPS' format (Third-Eye).
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Copyright (C) 1986-2014 Free Software Foundation, Inc.
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Contributed by Alessandro Forin (af@cs.cmu.edu) at CMU. Major work
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by Per Bothner, John Gilmore and Ian Lance Taylor at Cygnus Support.
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This file is part of GDB.
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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 3 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, see <http://www.gnu.org/licenses/>. */
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/* Read symbols from an ECOFF file. Most of the work is done in
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mdebugread.c. */
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#include "defs.h"
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#include <string.h>
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#include "bfd.h"
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#include "symtab.h"
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#include "objfiles.h"
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#include "buildsym.h"
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#include "stabsread.h"
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#include "coff/sym.h"
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#include "coff/internal.h"
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#include "coff/ecoff.h"
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#include "libcoff.h" /* Private BFD COFF information. */
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#include "libecoff.h" /* Private BFD ECOFF information. */
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#include "elf/common.h"
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#include "elf/internal.h"
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#include "elf/mips.h"
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#include "psymtab.h"
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static void
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read_alphacoff_dynamic_symtab (struct section_offsets *,
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struct objfile *objfile);
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/* Initialize anything that needs initializing when a completely new
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symbol file is specified (not just adding some symbols from another
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file, e.g. a shared library). */
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static void
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mipscoff_new_init (struct objfile *ignore)
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{
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stabsread_new_init ();
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buildsym_new_init ();
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}
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/* Initialize to read a symbol file (nothing to do). */
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static void
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mipscoff_symfile_init (struct objfile *objfile)
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{
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}
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/* Read a symbol file from a file. */
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static void
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mipscoff_symfile_read (struct objfile *objfile, int symfile_flags)
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{
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bfd *abfd = objfile->obfd;
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struct cleanup *back_to;
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init_minimal_symbol_collection ();
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back_to = make_cleanup_discard_minimal_symbols ();
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/* Now that the executable file is positioned at symbol table,
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process it and define symbols accordingly. */
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if (!((*ecoff_backend (abfd)->debug_swap.read_debug_info)
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(abfd, (asection *) NULL, &ecoff_data (abfd)->debug_info)))
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error (_("Error reading symbol table: %s"), bfd_errmsg (bfd_get_error ()));
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mdebug_build_psymtabs (objfile, &ecoff_backend (abfd)->debug_swap,
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&ecoff_data (abfd)->debug_info);
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/* Add alpha coff dynamic symbols. */
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read_alphacoff_dynamic_symtab (objfile->section_offsets, objfile);
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/* Install any minimal symbols that have been collected as the current
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minimal symbols for this objfile. */
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install_minimal_symbols (objfile);
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do_cleanups (back_to);
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}
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/* Perform any local cleanups required when we are done with a
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particular objfile. */
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static void
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mipscoff_symfile_finish (struct objfile *objfile)
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{
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}
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/* Alpha OSF/1 encapsulates the dynamic symbols in ELF format in a
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standard COFF section. The ELF format for the symbols differs from
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the format defined in elf/external.h. It seems that a normal ELF
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32-bit format is used, and the representation only changes because
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longs are 64-bit on the alpha. In addition, the handling of
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text/data section indices for symbols is different from the ELF
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ABI. As the BFD linker currently does not support dynamic linking
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on the alpha, there seems to be no reason to pollute BFD with
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another mixture of object file formats for now. */
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/* Format of an alpha external ELF symbol. */
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typedef struct
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{
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unsigned char st_name[4]; /* Symbol name, index in string table. */
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unsigned char st_pad[4]; /* Pad to long word boundary. */
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unsigned char st_value[8]; /* Value of the symbol. */
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unsigned char st_size[4]; /* Associated symbol size. */
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unsigned char st_info[1]; /* Type and binding attributes. */
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unsigned char st_other[1]; /* No defined meaning, 0. */
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unsigned char st_shndx[2]; /* Associated section index. */
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} Elfalpha_External_Sym;
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/* Format of an alpha external ELF dynamic info structure. */
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typedef struct
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{
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unsigned char d_tag[4]; /* Tag. */
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unsigned char d_pad[4]; /* Pad to long word boundary. */
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union
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{
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unsigned char d_ptr[8]; /* Pointer value. */
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unsigned char d_val[4]; /* Integer value. */
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}
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d_un;
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} Elfalpha_External_Dyn;
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/* Struct to obtain the section pointers for alpha dynamic symbol info. */
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struct alphacoff_dynsecinfo
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{
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asection *sym_sect; /* Section pointer for .dynsym section. */
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asection *str_sect; /* Section pointer for .dynstr section. */
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asection *dyninfo_sect; /* Section pointer for .dynamic section. */
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asection *got_sect; /* Section pointer for .got section. */
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};
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/* We are called once per section from read_alphacoff_dynamic_symtab.
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We need to examine each section we are passed, check to see if it
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is something we are interested in processing, and if so, stash away
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some access information for the section. */
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static void
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alphacoff_locate_sections (bfd *ignore_abfd, asection *sectp, void *sip)
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{
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struct alphacoff_dynsecinfo *si;
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si = (struct alphacoff_dynsecinfo *) sip;
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if (strcmp (sectp->name, ".dynsym") == 0)
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si->sym_sect = sectp;
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else if (strcmp (sectp->name, ".dynstr") == 0)
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si->str_sect = sectp;
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else if (strcmp (sectp->name, ".dynamic") == 0)
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si->dyninfo_sect = sectp;
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else if (strcmp (sectp->name, ".got") == 0)
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si->got_sect = sectp;
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}
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/* Scan an alpha dynamic symbol table for symbols of interest and add
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them to the minimal symbol table. */
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static void
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read_alphacoff_dynamic_symtab (struct section_offsets *section_offsets,
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struct objfile *objfile)
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{
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bfd *abfd = objfile->obfd;
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struct alphacoff_dynsecinfo si;
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char *sym_secptr;
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char *str_secptr;
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char *dyninfo_secptr;
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char *got_secptr;
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bfd_size_type sym_secsize;
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bfd_size_type str_secsize;
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bfd_size_type dyninfo_secsize;
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bfd_size_type got_secsize;
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int sym_count;
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int i;
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int stripped;
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Elfalpha_External_Sym *x_symp;
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char *dyninfo_p;
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char *dyninfo_end;
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int got_entry_size = 8;
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int dt_mips_local_gotno = -1;
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int dt_mips_gotsym = -1;
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struct cleanup *cleanups;
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/* We currently only know how to handle alpha dynamic symbols. */
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if (bfd_get_arch (abfd) != bfd_arch_alpha)
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return;
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/* Locate the dynamic symbols sections and read them in. */
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memset ((char *) &si, 0, sizeof (si));
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bfd_map_over_sections (abfd, alphacoff_locate_sections, (void *) & si);
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if (si.sym_sect == NULL || si.str_sect == NULL
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|| si.dyninfo_sect == NULL || si.got_sect == NULL)
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return;
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sym_secsize = bfd_get_section_size (si.sym_sect);
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str_secsize = bfd_get_section_size (si.str_sect);
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dyninfo_secsize = bfd_get_section_size (si.dyninfo_sect);
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got_secsize = bfd_get_section_size (si.got_sect);
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sym_secptr = xmalloc (sym_secsize);
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cleanups = make_cleanup (xfree, sym_secptr);
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str_secptr = xmalloc (str_secsize);
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make_cleanup (xfree, str_secptr);
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dyninfo_secptr = xmalloc (dyninfo_secsize);
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make_cleanup (xfree, dyninfo_secptr);
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got_secptr = xmalloc (got_secsize);
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make_cleanup (xfree, got_secptr);
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if (!bfd_get_section_contents (abfd, si.sym_sect, sym_secptr,
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(file_ptr) 0, sym_secsize))
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{
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do_cleanups (cleanups);
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return;
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}
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if (!bfd_get_section_contents (abfd, si.str_sect, str_secptr,
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(file_ptr) 0, str_secsize))
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{
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do_cleanups (cleanups);
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return;
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}
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if (!bfd_get_section_contents (abfd, si.dyninfo_sect, dyninfo_secptr,
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(file_ptr) 0, dyninfo_secsize))
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{
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do_cleanups (cleanups);
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return;
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}
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if (!bfd_get_section_contents (abfd, si.got_sect, got_secptr,
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(file_ptr) 0, got_secsize))
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{
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do_cleanups (cleanups);
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return;
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}
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/* Find the number of local GOT entries and the index for the
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first dynamic symbol in the GOT. */
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for (dyninfo_p = dyninfo_secptr, dyninfo_end = dyninfo_p + dyninfo_secsize;
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dyninfo_p < dyninfo_end;
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dyninfo_p += sizeof (Elfalpha_External_Dyn))
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{
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Elfalpha_External_Dyn *x_dynp = (Elfalpha_External_Dyn *) dyninfo_p;
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long dyn_tag;
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dyn_tag = bfd_h_get_32 (abfd, (bfd_byte *) x_dynp->d_tag);
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if (dyn_tag == DT_NULL)
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break;
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else if (dyn_tag == DT_MIPS_LOCAL_GOTNO)
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{
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if (dt_mips_local_gotno < 0)
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dt_mips_local_gotno
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= bfd_h_get_32 (abfd, (bfd_byte *) x_dynp->d_un.d_val);
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}
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else if (dyn_tag == DT_MIPS_GOTSYM)
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{
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if (dt_mips_gotsym < 0)
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dt_mips_gotsym
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= bfd_h_get_32 (abfd, (bfd_byte *) x_dynp->d_un.d_val);
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}
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}
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if (dt_mips_local_gotno < 0 || dt_mips_gotsym < 0)
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{
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do_cleanups (cleanups);
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return;
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}
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/* Scan all dynamic symbols and enter them into the minimal symbol
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table if appropriate. */
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sym_count = sym_secsize / sizeof (Elfalpha_External_Sym);
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stripped = (bfd_get_symcount (abfd) == 0);
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/* Skip first symbol, which is a null dummy. */
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for (i = 1, x_symp = (Elfalpha_External_Sym *) sym_secptr + 1;
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i < sym_count;
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i++, x_symp++)
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{
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unsigned long strx;
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char *name;
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bfd_vma sym_value;
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unsigned char sym_info;
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unsigned int sym_shndx;
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int isglobal;
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enum minimal_symbol_type ms_type;
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strx = bfd_h_get_32 (abfd, (bfd_byte *) x_symp->st_name);
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if (strx >= str_secsize)
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continue;
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name = str_secptr + strx;
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if (*name == '\0' || *name == '.')
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continue;
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sym_value = bfd_h_get_64 (abfd, (bfd_byte *) x_symp->st_value);
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sym_info = bfd_h_get_8 (abfd, (bfd_byte *) x_symp->st_info);
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sym_shndx = bfd_h_get_16 (abfd, (bfd_byte *) x_symp->st_shndx);
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if (sym_shndx >= (SHN_LORESERVE & 0xffff))
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sym_shndx += SHN_LORESERVE - (SHN_LORESERVE & 0xffff);
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isglobal = (ELF_ST_BIND (sym_info) == STB_GLOBAL);
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if (sym_shndx == SHN_UNDEF)
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{
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/* Handle undefined functions which are defined in a shared
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library. */
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if (ELF_ST_TYPE (sym_info) != STT_FUNC
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|| ELF_ST_BIND (sym_info) != STB_GLOBAL)
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continue;
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ms_type = mst_solib_trampoline;
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/* If sym_value is nonzero, it points to the shared library
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trampoline entry, which is what we are looking for.
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If sym_value is zero, then we have to get the GOT entry
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for the symbol.
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If the GOT entry is nonzero, it represents the quickstart
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address of the function and we use that as the symbol
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value.
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If the GOT entry is zero, the function address has to be
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resolved by the runtime loader before the executable is
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started. We are unable to find any meaningful address
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for these functions in the executable file, so we skip
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them. */
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if (sym_value == 0)
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{
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int got_entry_offset =
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(i - dt_mips_gotsym + dt_mips_local_gotno) * got_entry_size;
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if (got_entry_offset < 0 || got_entry_offset >= got_secsize)
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continue;
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sym_value =
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bfd_h_get_64 (abfd,
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(bfd_byte *) (got_secptr + got_entry_offset));
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if (sym_value == 0)
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continue;
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}
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}
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else
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{
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/* Symbols defined in the executable itself. We only care
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about them if this is a stripped executable, otherwise
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they have been retrieved from the normal symbol table
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already. */
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if (!stripped)
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continue;
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if (sym_shndx == SHN_MIPS_TEXT)
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{
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if (isglobal)
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ms_type = mst_text;
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else
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ms_type = mst_file_text;
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}
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else if (sym_shndx == SHN_MIPS_DATA)
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{
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if (isglobal)
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ms_type = mst_data;
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else
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ms_type = mst_file_data;
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}
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else if (sym_shndx == SHN_MIPS_ACOMMON)
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{
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if (isglobal)
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ms_type = mst_bss;
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else
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ms_type = mst_file_bss;
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}
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else if (sym_shndx == SHN_ABS)
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{
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ms_type = mst_abs;
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}
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else
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{
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continue;
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}
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}
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prim_record_minimal_symbol (name, sym_value, ms_type, objfile);
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}
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do_cleanups (cleanups);
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}
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/* Initialization. */
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static const struct sym_fns ecoff_sym_fns =
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{
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mipscoff_new_init, /* init anything gbl to entire symtab */
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mipscoff_symfile_init, /* read initial info, setup for sym_read() */
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mipscoff_symfile_read, /* read a symbol file into symtab */
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NULL, /* sym_read_psymbols */
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mipscoff_symfile_finish, /* finished with file, cleanup */
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default_symfile_offsets, /* dummy FIXME til implem sym reloc */
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default_symfile_segments, /* Get segment information from a file. */
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NULL,
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default_symfile_relocate, /* Relocate a debug section. */
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NULL, /* sym_probe_fns */
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&psym_functions
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};
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/* Provide a prototype to silence -Wmissing-prototypes. */
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void _initialize_mipsread (void);
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void
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_initialize_mipsread (void)
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{
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add_symtab_fns (bfd_target_ecoff_flavour, &ecoff_sym_fns);
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}
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