binutils-gdb modified for the FreeChainXenon project
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Sergio Durigan Junior 2bf3b79d05 Search for DWZ files in debug-file-directories as well
When Debian (and Ubuntu) builds its binaries, it (still) doesn't use
dwz's "--relative" option.  This causes their debuginfo files to
carry a .gnu_debugaltlink section containing a full pathname to the
DWZ alt debug file, like this:

  $ readelf -wk /usr/bin/cat
  Contents of the .gnu_debugaltlink section:

    Separate debug info file: /usr/lib/debug/.dwz/x86_64-linux-gnu/coreutils.debug
    Build-ID (0x14 bytes):
   ee 76 5d 71 97 37 ce 46 99 44 32 bb e8 a9 1a ef 99 96 88 db

  Contents of the .gnu_debuglink section:

    Separate debug info file: 06d3bee37b8c7e67b31cb2689cb351102ae73b.debug
    CRC value: 0x53267655

This usually works OK, because most of the debuginfo files installed
via apt will be present in /usr/lib/debug anyway.  However, imagine
the following scenario:

- You are using /usr/bin/cat, it crashes on you and generates a
  corefile.

- You don't want/need to "apt install" the debuginfo file for
  coreutils from the repositories.  Instead, you already have the
  debuginfo files in a separate directory (e.g., $HOME/dbgsym).

- You start GDB and "set debug-file-directory $HOME/dbgsym/usr/lib/debug".
  You then get the following message:

  $ gdb -ex 'set debug-file-directory ./dbgsym/usr/lib/debug' -ex 'file /bin/cat' -ex 'core-file ./cat.core'
  GNU gdb (Ubuntu 10.1-0ubuntu1) 10.1
  ...
  Reading symbols from /bin/cat...
  Reading symbols from /home/sergio/gdb/dbgsym/usr/lib/debug/.build-id/bc/06d3bee37b8c7e67b31cb2689cb351102ae73b.debug...
  could not find '.gnu_debugaltlink' file for /home/sergio/gdb/dbgsym/usr/lib/debug/.build-id/bc/06d3bee37b8c7e67b31cb2689cb351102ae73b.debug

This error happens because GDB is trying to locate the build-id
link (inside /home/sergio/gdb/dbgsym/usr/lib/debug/.build-id) for the
DWZ alt debug file, which doesn't exist.  Arguably, this is a problem
with how dh_dwz works in Debian, and it's something I'm also planning
to tackle.  But, back at the problem at hand.

Besides not being able to find the build-id link in the directory
mentioned above, GDB also tried to open the DWZ alt file using its
filename.  The problem here is that, since we don't have the distro's
debuginfo installed, it can't find anything under /usr/lib/debug that
satisfies it.

It occurred to me that a good way to workaround this problem is to
actually try to locate the DWZ alt debug file inside the
debug-file-directories (that were likely provided by the user).  So
this is what the proposed patch does.

The idea here is simple: get the filename extracted from the
.gnu_debugaltlink section, and manipulate it in order to replace the
initial part of the path (everything before "/.dwz/") by whatever
debug-file-directories the user might have provided.

I talked with Mark Wielaard and he agrees this is a sensible approach.
In fact, apparently this is something that eu-readelf also does.

I regtested this code, and no regressions were found.

2020-12-01  Sergio Durigan Junior  <sergiodj@sergiodj.net>

	* dwarf2/read.c (dwz_search_other_debugdirs): New function.
	(dwarf2_get_dwz_file): Convert 'filename' to a
	std::string.  Use dwz_search_other_debugdirs to search for DWZ
	files in the debug-file-directories provided by the user as well.
2020-12-01 22:03:18 -05:00
bfd Automatic date update in version.in 2020-12-02 00:00:17 +00:00
binutils Allow spaces in the name of the external preprocessor used by windres. 2020-11-27 14:19:56 +00:00
config sync libiberty from gcc 2020-09-08 20:12:57 +09:30
contrib Import mklog.py from gcc repo 2020-09-25 10:24:44 -04:00
cpu Fix spelling mistakes 2020-10-05 14:20:15 +01:00
elfcpp gold: Update GNU_PROPERTY_X86_XXX macros 2020-10-13 05:21:05 -07:00
etc texi2pod.pl: import support for @t{...} from gcc 2020-01-15 12:58:09 -05:00
gas RISC-V: Support to add implicit extensions for G. 2020-12-01 15:23:02 +08:00
gdb Search for DWZ files in debug-file-directories as well 2020-12-01 22:03:18 -05:00
gdbserver gdbserver: add missing --disable-packet options to help text 2020-11-11 09:08:31 +00:00
gdbsupport gdbsupport/tdesc: print enum fields using 'evalue' syntax 2020-12-01 11:22:24 +00:00
gnulib gnulib: Ensure all libraries are used when building gdb/gdbserver 2020-10-09 09:31:43 +01:00
gold gold: Add endbr64 to IBT TLSDESC PLT entry 2020-11-29 11:41:47 -08:00
gprof Unify Solaris procfs and largefile handling 2020-07-30 15:41:50 +02:00
include RISC-V: Support to add implicit extensions for G. 2020-12-01 15:23:02 +08:00
intl Regen with blessed automake-1.15.1 2020-02-20 13:02:24 +10:30
ld arc: Enable -Ttext-segment 2020-12-01 04:27:41 -08:00
libctf libctf: Pass format argument to asprintf 2020-11-25 19:11:36 +00:00
libdecnumber Run autoreconf -vf throughout 2020-07-29 16:03:55 -04:00
libiberty Sync libiberty and include with GCC for get_DW_UT_name. 2020-09-24 22:55:24 +02:00
opcodes RISC-V: Remove the unimplemented extensions. 2020-12-01 15:13:06 +08:00
readline Update readline/README to mention patchlevel 2020-06-30 15:17:07 -06:00
sim sim: pru: Add support for LMBD instruction 2020-11-12 22:41:10 +02:00
texinfo
zlib Merge changes from GCC for the config/ directory 2020-02-19 17:51:24 +00:00
.cvsignore
.gitattributes
.gitignore Add profiling outputs to .gitignore 2019-12-26 06:54:58 +01:00
ar-lib Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
ChangeLog Use sha256 for hashes in the release process 2020-10-28 10:35:28 -04:00
compile
config-ml.in
config.guess Update top level config files with copies from the official repository. 2020-01-18 13:43:19 +00:00
config.rpath
config.sub Update top level config files with copies from the official repository. 2020-01-18 13:43:19 +00:00
configure config/debuginfod.m4: Use PKG_CHECK_MODULES 2020-07-24 15:16:20 -04:00
configure.ac config/debuginfod.m4: Use PKG_CHECK_MODULES 2020-07-24 15:16:20 -04:00
COPYING
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB
COPYING3
COPYING3.LIB
depcomp
djunpack.bat
install-sh
libtool.m4 Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
ltgcc.m4
ltmain.sh
ltoptions.m4
ltsugar.m4
ltversion.m4
lt~obsolete.m4
MAINTAINERS Move gdbserver to top level 2020-02-07 08:42:25 -07:00
Makefile.def gdb/gdbserver: add dependencies for distclean-gnulib 2020-10-14 15:05:14 +01:00
Makefile.in gdb/gdbserver: add dependencies for distclean-gnulib 2020-10-14 15:05:14 +01:00
Makefile.tpl Revert "Sync top level files with versions from gcc." 2019-05-30 11:17:19 +01:00
makefile.vms
missing
mkdep
mkinstalldirs
move-if-change
multilib.am Merge autoconf / automake update changes from GCC. 2018-10-31 17:10:56 +00:00
README
README-maintainer-mode Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
setup.com
src-release.sh Use sha256 for hashes in the release process 2020-10-28 10:35:28 -04:00
symlink-tree
test-driver Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
ylwrap

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.