[Bug 1759248] Re: addr2line wrong search path for debug files

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: binutils (Ubuntu)
       Status: New => Confirmed

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Title:
  addr2line wrong search path for debug files

Status in binutils package in Ubuntu:
  Confirmed

Bug description:
  I cannot make `addr2line` to work. It does look for symbols at three (*unexisting*) paths:
  /usr/bin/*.debug
  /usr/bin/.debug/*.debug
  /usr/lib/debug/usr/bin/*.debug

  But it just seems to ignore the path where all debugging symbols are actually installed by default:
  /usr/lib/debug/.build-id/

  I run `addr2line` like this:
  addr2line -f -C -e <PathToExecFile> <Addr>

  Am I missing some configuration switch, system option, or anything
  similar?

  ------------

  Now some proofs for what I'm stating.
  Here, I'll be using the program `screen` as an example:

  $ sudo apt-get install screen screen-dbg
  $ file /usr/bin/screen
  > /usr/bin/screen: setgid ELF 64-bit LSB executable, x86-64, version 1 (SYSV),
    dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32,
    BuildID[sha1]=e9d3cd5073daa6b7365b3787673143edeec589d3, stripped
  $ dpkg -L screen-dbg
  > /usr/lib/debug/.build-id/e9/d3cd5073daa6b7365b3787673143edeec589d3.debug

  Here we empirically found out where the debug symbols for `screen` are:
  /usr/lib/debug/.build-id/e9/d3cd5073daa6b7365b3787673143edeec589d3.debug

  Now we run `strace addr2line` to see where it tries to access...

  # Get any valid object address
  $ objdump -T /usr/bin/screen
  > 00000000006697e0

  # Use the object address in addr2line
  $ strace -f addr2line -f -C \
      -e /usr/bin/screen 0x00000000006697e0 2>&1 | grep debug
  > open("/usr/bin/d3cd5073daa6b7365b3787673143edeec589d3.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
    open("/usr/bin/.debug/d3cd5073daa6b7365b3787673143edeec589d3.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
    open("/usr/lib/debug/usr/bin/d3cd5073daa6b7365b3787673143edeec589d3.debug", O_RDONLY) = -1 ENOENT (No such file or directory)

  Here we see the 3 paths I mentioned earlier, but no signs of the
  desired one.

  ------------

  Additional information:

  - Ubuntu release

  $ lsb_release -rd
  > Description:  Ubuntu 16.04.4 LTS
    Release:  16.04

  - Package version

  $ apt-cache policy binutils
  > binutils:
      Installed: 2.26.1-1ubuntu1~16.04.6
      Candidate: 2.26.1-1ubuntu1~16.04.6
      Version table:
     *** 2.26.1-1ubuntu1~16.04.6 500
            500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
            500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
            100 /var/lib/dpkg/status
         2.26-8ubuntu2 500
            500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages

  - What I expected to happen

  I expected that the `strace` command shown avobe would access the debug files at their actual location:
  /usr/lib/debug/.build-id/e9/d3cd5073daa6b7365b3787673143edeec589d3.debug

  - What happened instead

  The `addr2line` program does look for the debug file at three unexisting locations:
  /usr/bin/*.debug
  /usr/bin/.debug/*.debug
  /usr/lib/debug/usr/bin/*.debug
  but it does not look for the debug file at the correct location.

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