Add debug symbols to ./download

[152334H]

This is a tentative attempt at automating the process of grabbing debug .sos and libc sources, which are useful for providing source-level libc debugging in gdb.

The scope of this PR is limited to ubuntu only; non-apt-based libc packages are really outside of my knowledge and I'd rather not attempt that. I tried checking debian packages but a lot of their libc6-dbg packages only contain .debug files that I don't really know what to do with.

The added code has also not been extensively tested. It might work on my machine, but bash is notoriously easy to mess up. Here's an example of what a correct run might look like:

~/libc-database$ ./download libc6_2.27-3ubuntu1_amd64
Getting libc6_2.27-3ubuntu1_amd64
  -> Location: http://security.ubuntu.com/ubuntu/pool/main/g/glibc//libc6_2.27-3ubuntu1_amd64.deb
  -> Downloading package
  -> Extracting package
  -> Package saved to libs/libc6_2.27-3ubuntu1_amd64
Getting debug materials for libc6_2.27-3ubuntu1_amd64
  -> Location: http://security.ubuntu.com/ubuntu/pool/universe/g/glibc//glibc-source_2.27-3ubuntu1_all.deb
  -> Downloading package
  -> Extracting package
  -> Location: http://security.ubuntu.com/ubuntu/pool/main/g/glibc//libc6-dbg_2.27-3ubuntu1_amd64.deb
  -> Downloading package
  -> Extracting package
~/libc-database$ ls libs/libc6_2.27-3ubuntu1_amd64
debug                 libBrokenLocale-2.27.so  libcrypt-2.27.so  libm-2.27.so     libnsl-2.27.so         libnss_dns.so.2        libnss_nis-2.27.so      libpthread-2.27.so  librt.so.1           libutil.so.1
ld-2.27.so            libBrokenLocale.so.1     libcrypt.so.1     libmemusage.so   libnsl.so.1            libnss_files-2.27.so   libnss_nisplus-2.27.so  libpthread.so.0     libSegFault.so       source
ld-linux-x86-64.so.2  libc-2.27.so             libc.so.6         libm.so.6        libnss_compat-2.27.so  libnss_files.so.2      libnss_nisplus.so.2     libresolv-2.27.so   libthread_db-1.0.so
libanl-2.27.so        libcidn-2.27.so          libdl-2.27.so     libmvec-2.27.so  libnss_compat.so.2     libnss_hesiod-2.27.so  libnss_nis.so.2         libresolv.so.2      libthread_db.so.1
libanl.so.1           libcidn.so.1             libdl.so.2        libmvec.so.1     libnss_dns-2.27.so     libnss_hesiod.so.2     libpcprofile.so         librt-2.27.so       libutil-2.27.so
~/libc-database$ ls libs/libc6_2.27-3ubuntu1_amd64/debug/
ld-2.27.so               libc-2.27.so      libdl-2.27.so   libmvec-2.27.so        libnss_dns-2.27.so     libnss_nis-2.27.so      libresolv-2.27.so  libthread_db-1.0.so
libanl-2.27.so           libcidn-2.27.so   libm-2.27.so    libnsl-2.27.so         libnss_files-2.27.so   libnss_nisplus-2.27.so  librt-2.27.so      libutil-2.27.so
libBrokenLocale-2.27.so  libcrypt-2.27.so  libmemusage.so  libnss_compat-2.27.so  libnss_hesiod-2.27.so  libpcprofile.so         libSegFault.so
~/libc-database$ ls libs/libc6_2.27-3ubuntu1_amd64/source/
glibc-2.27
~/libc-database$ ls libs/libc6_2.27-3ubuntu1_amd64/source/glibc-2.27/
abi-tags    ChangeLog       COPYING      dlfcn           gnulib     include    libio              mach         manual   nptl_db        README    shadow          streams  test-skeleton.c
aclocal.m4  ChangeLog.old   COPYING.LIB  elf             grp        inet       libof-iterator.mk  MAINTAINERS  math     nscd           resolv    shlib-versions  string   time
argp        config.h.in     crypt        extra-lib.mk    gshadow    INSTALL    libpthread         Makeconfig   mathvec  nss            resource  signal          sunrpc   timezone
assert      config.make.in  csu          fbtl            hesiod     intl       LICENSES           Makefile     misc     o-iterator.mk  rt        socket          support  version.h
benchtests  configure       ctype        fbtl_db         hurd       io         locale             Makefile.in  NEWS     po             Rules     soft-fp         sysdeps  wcsmbs
bits        configure.ac    debug        gen-locales.mk  iconv      libc-abis  localedata         Makerules    nis      posix          scripts   stdio-common    sysvipc  wctype
catgets     conform         dirent       gmon            iconvdata  libidn     login              malloc       nptl     pwd            setjmp    stdlib          termios

Any feedback is welcome.

[niklasb]

Just to set expectations right, I won't have time to look at this in detail within the coming weeks or months. If somebody else like @peace-maker or @ajabep wants to review this, I'll be happy to consider merging it if their feedback is positive

[Dragoncraft89]

BTW this fails for some libcs, e.g. libc6_2.31-0ubuntu9.7_amd64 on https://github.com/niklasb/libc-database/blob/c7b6d38b7f6178d6ecf9c1b472b0af2ea48c5c09/download#L91

The reason is some weird directory layout in this version, where $tmp/lib/*/* also matches some directory. Maybe this should be $tmp/lib/*/*.so instead (or cp -r if we want to copy that directory as well)

[Dragoncraft89]

Also, maybe this should unpack to .debug instead of debug, because then gdb will pick them up automatically (unless I'm doing something wrong)

But this might be confusing as dotfiles are hidden