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/* build-id-related functions.
Copyright (C) 1991-2021 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
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, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "bfd.h"
#include "gdb_bfd.h"
#include "build-id.h"
#include "gdbsupport/gdb_vecs.h"
#include "symfile.h"
#include "objfiles.h"
#include "filenames.h"
#include "gdbcore.h"
/* See build-id.h. */
const struct bfd_build_id *
build_id_bfd_get (bfd *abfd)
{
if (!bfd_check_format (abfd, bfd_object)
&& !bfd_check_format (abfd, bfd_core))
return NULL;
if (abfd->build_id != NULL)
return abfd->build_id;
/* No build-id */
return NULL;
}
/* See build-id.h. */
int
build_id_verify (bfd *abfd, size_t check_len, const bfd_byte *check)
{
const struct bfd_build_id *found;
int retval = 0;
found = build_id_bfd_get (abfd);
if (found == NULL)
warning (_("File \"%s\" has no build-id, file skipped"),
bfd_get_filename (abfd));
else if (found->size != check_len
|| memcmp (found->data, check, found->size) != 0)
warning (_("File \"%s\" has a different build-id, file skipped"),
bfd_get_filename (abfd));
else
retval = 1;
return retval;
}
/* Helper for build_id_to_debug_bfd. LINK is a path to a potential
build-id-based separate debug file, potentially a symlink to the real file.
If the file exists and matches BUILD_ID, return a BFD reference to it. */
static gdb_bfd_ref_ptr
build_id_to_debug_bfd_1 (const std::string &link, size_t build_id_len,
const bfd_byte *build_id)
{
if (separate_debug_file_debug)
{
printf_unfiltered (_(" Trying %s..."), link.c_str ());
gdb_flush (gdb_stdout);
}
/* lrealpath() is expensive even for the usually non-existent files. */
gdb::unique_xmalloc_ptr<char> filename;
if (access (link.c_str (), F_OK) == 0)
filename.reset (lrealpath (link.c_str ()));
if (filename == NULL)
{
if (separate_debug_file_debug)
printf_unfiltered (_(" no, unable to compute real path\n"));
return {};
}
/* We expect to be silent on the non-existing files. */
gdb_bfd_ref_ptr debug_bfd = gdb_bfd_open (filename.get (), gnutarget);
if (debug_bfd == NULL)
{
if (separate_debug_file_debug)
printf_unfiltered (_(" no, unable to open.\n"));
return {};
}
if (!build_id_verify (debug_bfd.get(), build_id_len, build_id))
{
if (separate_debug_file_debug)
printf_unfiltered (_(" no, build-id does not match.\n"));
return {};
}
if (separate_debug_file_debug)
printf_unfiltered (_(" yes!\n"));
return debug_bfd;
}
/* Common code for finding BFDs of a given build-id. This function
works with both debuginfo files (SUFFIX == ".debug") and executable
files (SUFFIX == ""). */
static gdb_bfd_ref_ptr
build_id_to_bfd_suffix (size_t build_id_len, const bfd_byte *build_id,
const char *suffix)
{
/* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
cause "/.build-id/..." lookups. */
std::vector<gdb::unique_xmalloc_ptr<char>> debugdir_vec
= dirnames_to_char_ptr_vec (debug_file_directory);
for (const gdb::unique_xmalloc_ptr<char> &debugdir : debugdir_vec)
{
const gdb_byte *data = build_id;
size_t size = build_id_len;
/* Compute where the file named after the build-id would be.
If debugdir is "/usr/lib/debug" and the build-id is abcdef, this will
give "/usr/lib/debug/.build-id/ab/cdef.debug". */
std::string link = debugdir.get ();
link += "/.build-id/";
if (size > 0)
{
size--;
string_appendf (link, "%02x/", (unsigned) *data++);
}
while (size-- > 0)
string_appendf (link, "%02x", (unsigned) *data++);
link += suffix;
gdb_bfd_ref_ptr debug_bfd
= build_id_to_debug_bfd_1 (link, build_id_len, build_id);
if (debug_bfd != NULL)
return debug_bfd;
/* Try to look under the sysroot as well. If the sysroot is
"/the/sysroot", it will give
"/the/sysroot/usr/lib/debug/.build-id/ab/cdef.debug".
Don't do it if the sysroot is the target system ("target:"). It
could work in theory, but the lrealpath in build_id_to_debug_bfd_1
only works with local paths. */
if (strcmp (gdb_sysroot, TARGET_SYSROOT_PREFIX) != 0)
{
link = gdb_sysroot + link;
debug_bfd = build_id_to_debug_bfd_1 (link, build_id_len, build_id);
if (debug_bfd != NULL)
return debug_bfd;
}
}
return {};
}
/* See build-id.h. */
gdb_bfd_ref_ptr
build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
{
return build_id_to_bfd_suffix (build_id_len, build_id, ".debug");
}
/* See build-id.h. */
gdb_bfd_ref_ptr
build_id_to_exec_bfd (size_t build_id_len, const bfd_byte *build_id)
{
return build_id_to_bfd_suffix (build_id_len, build_id, "");
}
/* See build-id.h. */
std::string
find_separate_debug_file_by_buildid (struct objfile *objfile)
{
const struct bfd_build_id *build_id;
build_id = build_id_bfd_get (objfile->obfd);
if (build_id != NULL)
{
if (separate_debug_file_debug)
printf_unfiltered (_("\nLooking for separate debug info (build-id) for "
"%s\n"), objfile_name (objfile));
gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size,
build_id->data));
/* Prevent looping on a stripped .debug file. */
if (abfd != NULL
&& filename_cmp (bfd_get_filename (abfd.get ()),
objfile_name (objfile)) == 0)
warning (_("\"%s\": separate debug info file has no debug info"),
bfd_get_filename (abfd.get ()));
else if (abfd != NULL)
return std::string (bfd_get_filename (abfd.get ()));
}
return std::string ();
}
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