binutils-gdb/gdb/build-id.h
Andrew Burgess 8358d39b4f gdb: unify build-id to objfile lookup code
There are 3 places where we currently call debuginfod_exec_query to
lookup an objfile for a given build-id.

In one of these places we first call build_id_to_exec_bfd which also
looks up an objfile given a build-id, but this function looks on disk
for a symlink in the .build-id/ sub-directory (within the
debug-file-directory).

I can't think of any reason why we shouldn't call build_id_to_exec_bfd
before every call to debuginfod_exec_query.

So, in this commit I have added a new function in build-id.c,
find_objfile_by_build_id, this function calls build_id_to_exec_bfd,
and if that fails, then calls debuginfod_exec_query.

Everywhere we call debuginfod_exec_query is updated to call the new
function, and in locate_exec_from_corefile_build_id, the existing call
to build_id_to_exec_bfd is removed as calling find_objfile_by_build_id
does this for us.

One slight weird thing is in core_target::build_file_mappings, here we
call find_objfile_by_build_id which returns a gdb_bfd_ref_ptr for the
opened file, however we immediately reopen the file as "binary".  The
reason for this is that all the bfds opened in ::build_file_mappings
need to be opened as "binary" (see the function comments for why).

I did consider passing a target type into find_objfile_by_build_id,
which could then be forwarded to build_id_to_exec_bfd and used to open
the BFD as "binary", however, if you follow the call chain you'll end
up in build_id_to_debug_bfd_1, where we actually open the bfd.  Notice
in here that we call build_id_verify to double check the build-id of
the file we found, this requires that the bfd not be opened as
"binary".

What this means is that we always have to first open the bfd using the
gnutarget target type (for the build-id check), and then we would have
to reopen it as "binary".  There seems little point pushing the reopen
logic into find_objfile_by_build_id, so we just do this in the
::build_file_mappings function.

I've extended the tests to cover the two cases which actually changed
in this commit.
2024-09-07 20:28:57 +01:00

108 lines
3.6 KiB
C++

/* build-id-related functions.
Copyright (C) 1991-2024 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/>. */
#ifndef BUILD_ID_H
#define BUILD_ID_H
#include "gdb_bfd.h"
#include "gdbsupport/rsp-low.h"
/* Locate NT_GNU_BUILD_ID from ABFD and return its content. */
extern const struct bfd_build_id *build_id_bfd_get (bfd *abfd);
/* Return true if ABFD has NT_GNU_BUILD_ID matching the CHECK value.
Otherwise, issue a warning and return false. */
extern int build_id_verify (bfd *abfd,
size_t check_len, const bfd_byte *check);
/* Find and open a BFD for a debuginfo file given a build-id. If no BFD
can be found, return NULL. */
extern gdb_bfd_ref_ptr build_id_to_debug_bfd (size_t build_id_len,
const bfd_byte *build_id);
/* Find the separate debug file for OBJFILE, by using the build-id
associated with OBJFILE's BFD. If successful, returns the file name for the
separate debug file, otherwise, return an empty string.
Any warnings that are generated by the lookup process should be added to
WARNINGS. If some other mechanism can be used to lookup the debug
information then the warning will not be shown, however, if GDB fails to
find suitable debug information using any approach, then any warnings
will be printed. */
extern std::string find_separate_debug_file_by_buildid
(struct objfile *objfile, deferred_warnings *warnings);
/* Find an objfile (executable or shared library) that matches BUILD_ID.
This is done by first checking in the debug-file-directory for a
suitable .build-id/ sub-directory, and looking for a file with the
required build-id (usually a symbolic link or hard link to the actual
file).
If that doesn't find us a file then we call to debuginfod to see if it
can provide the required file.
EXPECTED_FILENAME is used in output messages from debuginfod, this
should be the file we were looking for but couldn't find. */
extern gdb_bfd_ref_ptr find_objfile_by_build_id
(const bfd_build_id *build_id, const char *expected_filename);
/* Return an hex-string representation of BUILD_ID. */
static inline std::string
build_id_to_string (const bfd_build_id *build_id)
{
gdb_assert (build_id != NULL);
return bin2hex (build_id->data, build_id->size);
}
/* Compare the content of two build-ids. One build-id (A) is passed as a
build-id pointer, while the second is passed using BUILD_ID_LEN and
BUILD_ID_DATA. Return true if the build-ids match, otherwise false. */
static inline bool
build_id_equal (const bfd_build_id *a, const bfd_size_type build_id_len,
const bfd_byte *build_id_data)
{
gdb_assert (a != nullptr);
gdb_assert (build_id_data != nullptr);
return (a->size == build_id_len
&& memcmp (a->data, build_id_data, a->size) == 0);
}
/* Like the above, but take two build-id pointers A and B. */
static inline bool
build_id_equal (const bfd_build_id *a, const bfd_build_id *b)
{
gdb_assert (a != nullptr);
gdb_assert (b != nullptr);
return build_id_equal (a, b->size, b->data);
}
#endif /* BUILD_ID_H */