blob: 5e963d5b47a670320c32b5672cef09687be8c7c2 [file] [log] [blame]
/* DWARF DWZ handling for GDB.
Copyright (C) 2003-2021 Free Software Foundation, Inc.
This file is part of GDB.
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
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, see <>. */
#include "defs.h"
#include "dwarf2/dwz.h"
#include "build-id.h"
#include "debuginfod-support.h"
#include "dwarf2/read.h"
#include "dwarf2/sect-names.h"
#include "filenames.h"
#include "gdb_bfd.h"
#include "gdbcore.h"
#include "gdbsupport/pathstuff.h"
#include "gdbsupport/scoped_fd.h"
const char *
dwz_file::read_string (struct objfile *objfile, LONGEST str_offset)
{ (objfile);
if (str.buffer == NULL)
error (_("DW_FORM_GNU_strp_alt used without .debug_str "
"section [in module %s]"),
bfd_get_filename (dwz_bfd.get ()));
if (str_offset >= str.size)
error (_("DW_FORM_GNU_strp_alt pointing outside of "
".debug_str section [in module %s]"),
bfd_get_filename (dwz_bfd.get ()));
gdb_assert (HOST_CHAR_BIT == 8);
if (str.buffer[str_offset] == '\0')
return NULL;
return (const char *) (str.buffer + str_offset);
/* A helper function to find the sections for a .dwz file. */
static void
locate_dwz_sections (bfd *abfd, asection *sectp, dwz_file *dwz_file)
/* Note that we only support the standard ELF names, because .dwz
is ELF-only (at the time of writing). */
if (dwarf2_elf_names.abbrev.matches (sectp->name))
dwz_file->abbrev.s.section = sectp;
dwz_file->abbrev.size = bfd_section_size (sectp);
else if ( (sectp->name))
dwz_file->info.s.section = sectp;
dwz_file->info.size = bfd_section_size (sectp);
else if (dwarf2_elf_names.str.matches (sectp->name))
dwz_file->str.s.section = sectp;
dwz_file->str.size = bfd_section_size (sectp);
else if (dwarf2_elf_names.line.matches (sectp->name))
dwz_file->line.s.section = sectp;
dwz_file->line.size = bfd_section_size (sectp);
else if (dwarf2_elf_names.macro.matches (sectp->name))
dwz_file->macro.s.section = sectp;
dwz_file->macro.size = bfd_section_size (sectp);
else if (dwarf2_elf_names.gdb_index.matches (sectp->name))
dwz_file->gdb_index.s.section = sectp;
dwz_file->gdb_index.size = bfd_section_size (sectp);
else if (dwarf2_elf_names.debug_names.matches (sectp->name))
dwz_file->debug_names.s.section = sectp;
dwz_file->debug_names.size = bfd_section_size (sectp);
/* Attempt to find a .dwz file (whose full path is represented by
FILENAME) in all of the specified debug file directories provided.
Return the equivalent gdb_bfd_ref_ptr of the .dwz file found, or
nullptr if it could not find anything. */
static gdb_bfd_ref_ptr
dwz_search_other_debugdirs (std::string &filename, bfd_byte *buildid,
size_t buildid_len)
/* Let's assume that the path represented by FILENAME has the
"/.dwz/" subpath in it. This is what (most) GNU/Linux
distributions do, anyway. */
size_t dwz_pos = filename.find ("/.dwz/");
if (dwz_pos == std::string::npos)
return nullptr;
/* This is an obvious assertion, but it's here more to educate
future readers of this code that FILENAME at DWZ_POS *must*
contain a directory separator. */
gdb_assert (IS_DIR_SEPARATOR (filename[dwz_pos]));
gdb_bfd_ref_ptr dwz_bfd;
std::vector<gdb::unique_xmalloc_ptr<char>> debugdir_vec
= dirnames_to_char_ptr_vec (debug_file_directory.c_str ());
for (const gdb::unique_xmalloc_ptr<char> &debugdir : debugdir_vec)
/* The idea is to iterate over the
debug file directories provided by the user and
replace the hard-coded path in the "filename" by each
For example, suppose that filename is:
And suppose that we have "$HOME/bar" as the
debug-file-directory. We would then adjust filename
to look like:
which would hopefully allow us to find the alt debug
file. */
std::string ddir = debugdir.get ();
if (ddir.empty ())
/* Make sure the current debug-file-directory ends with a
directory separator. This is needed because, if FILENAME
contains something like "/usr/lib/abcde/.dwz/foo.dwz" and
DDIR is "/usr/lib/abc", then could wrongfully skip it
below. */
if (!IS_DIR_SEPARATOR (ddir.back ()))
/* Check whether the beginning of FILENAME is DDIR. If it is,
then we are dealing with a file which we already attempted to
open before, so we just skip it and continue processing the
remaining debug file directories. */
if (filename.size () > ddir.size ()
&& (0, ddir.size (), ddir) == 0)
/* Replace FILENAME's default debug-file-directory with
DDIR. */
std::string new_filename = ddir + &filename[dwz_pos + 1];
dwz_bfd = gdb_bfd_open (new_filename.c_str (), gnutarget);
if (dwz_bfd == nullptr)
if (!build_id_verify (dwz_bfd.get (), buildid_len, buildid))
dwz_bfd.reset (nullptr);
/* Found it. */
return dwz_bfd;
/* See dwz.h. */
struct dwz_file *
dwarf2_get_dwz_file (dwarf2_per_bfd *per_bfd, bool require)
bfd_size_type buildid_len_arg;
size_t buildid_len;
bfd_byte *buildid;
if (per_bfd->dwz_file != NULL)
return per_bfd->dwz_file.get ();
bfd_set_error (bfd_error_no_error);
gdb::unique_xmalloc_ptr<char> data
(bfd_get_alt_debug_link_info (per_bfd->obfd,
&buildid_len_arg, &buildid));
if (data == NULL)
if (bfd_get_error () == bfd_error_no_error)
if (!require)
return nullptr;
error (_("could not read '.gnu_debugaltlink' section"));
error (_("could not read '.gnu_debugaltlink' section: %s"),
bfd_errmsg (bfd_get_error ()));
gdb::unique_xmalloc_ptr<bfd_byte> buildid_holder (buildid);
buildid_len = (size_t) buildid_len_arg;
std::string filename = data.get ();
if (!IS_ABSOLUTE_PATH (filename.c_str ()))
gdb::unique_xmalloc_ptr<char> abs
= gdb_realpath (bfd_get_filename (per_bfd->obfd));
filename = ldirname (abs.get ()) + SLASH_STRING + filename;
/* First try the file name given in the section. If that doesn't
work, try to use the build-id instead. */
gdb_bfd_ref_ptr dwz_bfd (gdb_bfd_open (filename.c_str (), gnutarget));
if (dwz_bfd != NULL)
if (!build_id_verify (dwz_bfd.get (), buildid_len, buildid))
dwz_bfd.reset (nullptr);
if (dwz_bfd == NULL)
dwz_bfd = build_id_to_debug_bfd (buildid_len, buildid);
if (dwz_bfd == nullptr)
/* If the user has provided us with different
debug file directories, we can try them in order. */
dwz_bfd = dwz_search_other_debugdirs (filename, buildid, buildid_len);
if (dwz_bfd == nullptr)
gdb::unique_xmalloc_ptr<char> alt_filename;
const char *origname = bfd_get_filename (per_bfd->obfd);
scoped_fd fd (debuginfod_debuginfo_query (buildid,
if (fd.get () >= 0)
/* File successfully retrieved from server. */
dwz_bfd = gdb_bfd_open (alt_filename.get (), gnutarget);
if (dwz_bfd == nullptr)
warning (_("File \"%s\" from debuginfod cannot be opened as bfd"),
alt_filename.get ());
else if (!build_id_verify (dwz_bfd.get (), buildid_len, buildid))
dwz_bfd.reset (nullptr);
if (dwz_bfd == NULL)
error (_("could not find '.gnu_debugaltlink' file for %s"),
bfd_get_filename (per_bfd->obfd));
std::unique_ptr<struct dwz_file> result
(new struct dwz_file (std::move (dwz_bfd)));
for (asection *sec : gdb_bfd_sections (result->dwz_bfd))
locate_dwz_sections (result->dwz_bfd.get (), sec, result.get ());
gdb_bfd_record_inclusion (per_bfd->obfd, result->dwz_bfd.get ());
per_bfd->dwz_file = std::move (result);
return per_bfd->dwz_file.get ();