From dc294be54c96414035eed7d53dafdea0a6f31a72 Mon Sep 17 00:00:00 2001 From: Tom Tromey <tromey@redhat.com> Date: Tue, 8 Oct 2013 19:56:15 +0000 Subject: fix PR symtab/15597 This patch fixes gdb PR symtab/15597. The bug is that the .gnu_debugaltlink section includes the build-id of the alt file, but gdb does not use it. This patch fixes the problem by changing gdb to do what it ought to always have done: verify the build id of the file found using the filename in .gnu_debugaltlink; and if that does not match, try to find the correct debug file using the build-id and debug-file-directory. This patch touches BFD. Previously, gdb had its own code for parsing .gnu_debugaltlink; I changed it to use the BFD functions after those were introduced. However, the BFD functions are incorrect -- they assume that .gnu_debugaltlink is formatted like .gnu_debuglink. However, it it is not. Instead, it consists of a file name followed by the build-id -- no alignment, and the build-id is not a CRC. Fixing this properly is a bit of a pain. But, because separate_alt_debug_file_exists just has a FIXME for the build-id case, I did not fix it properly. Instead I introduced a hack. This leaves BFD working just as well as it did before my patch. I'm willing to do something better here but I could use some guidance as to what. It seems that the build-id code in BFD is largely punted on. FWIW gdb is the only user of bfd_get_alt_debug_link_info outside of BFD itself. I moved the build-id logic out of elfread.c and into a new file. This seemed cleanest to me. Writing a test case was a bit of a pain. I added a couple new features to the DWARF assembler to handle this. Built and regtested on x86-64 Fedora 18. * bfd-in2.h: Rebuild. * opncls.c (bfd_get_alt_debug_link_info): Add buildid_len parameter. Change type of buildid_out. Update. (get_alt_debug_link_info_shim): New function. (bfd_follow_gnu_debuglink): Use it. * Makefile.in (SFILES): Add build-id.c. (HFILES_NO_SRCDIR): Add build-id.h. * build-id.c: New file, largely from elfread.c. Modified most functions. * build-id.h: New file. * dwarf2read.c (dwarf2_get_dwz_file): Update for change to bfd_get_alt_debug_link_info. Verify dwz file's build-id. Search for dwz file using build-id. * elfread.c (build_id_bfd_get, build_id_verify) (build_id_to_debug_filename, find_separate_debug_file): Remove. * gdb.dwarf2/dwzbuildid.exp: New file. * lib/dwarf.exp (Dwarf::_section): Add "flags" and "type" parameters. (Dwarf::_defer_output): Change "section" parameter to "section_spec"; update. (Dwarf::gnu_debugaltlink, Dwarf::_note, Dwarf::build_id): New procs. --- gdb/build-id.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 gdb/build-id.h (limited to 'gdb/build-id.h') diff --git a/gdb/build-id.h b/gdb/build-id.h new file mode 100644 index 00000000000..b3ea4fbf82d --- /dev/null +++ b/gdb/build-id.h @@ -0,0 +1,44 @@ +/* build-id-related functions. + + Copyright (C) 1991-2013 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 + +/* 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 given a build-id. If no BFD can be found, + return NULL. The returned reference to the BFD must be released by + the caller. */ + +extern bfd *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 a malloc'd + file name for the separate debug file. The caller must free this. + Otherwise, returns NULL. */ + +extern char *find_separate_debug_file_by_buildid (struct objfile *objfile); + +#endif /* BUILD_ID_H */ -- cgit v1.2.1