[all-commits] [llvm/llvm-project] a86f4e: [lldb] Use correct path for debugserver (#131609)

[Yuval Deutscher via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a86f4ee774e6d2eb9f38502ddda65842179a246a
      https://github.com/llvm/llvm-project/commit/a86f4ee774e6d2eb9f38502ddda65842179a246a
  Author: Yuval Deutscher <yuvald at sweet.security>
  Date:   2025-04-22 (Tue, 22 Apr 2025)

  Changed paths:
    M lldb/test/API/commands/platform/launchgdbserver/TestPlatformLaunchGDBServer.py
    M lldb/tools/lldb-server/SystemInitializerLLGS.h

  Log Message:
  -----------
  [lldb] Use correct path for debugserver (#131609)

This solves an issue that arises when running lldb-server through a
symlink which is not named exactly `lldb-server`. For example, in many
distros lldb-server is packaged as e.g.
`/usr/lib/llvm-19/bin/lldb-server` which is then accessed through a
symlink such as `/usr/bin/lldb-server-19`.

It turns out that there is a cascade of bugs here:
* `GetShlibDir` attempts to locate the LLVM library directory by calling
`GetModuleFileSpecForHostAddress` on the address of the function
`ComputeSharedLibraryDirectory`, assuming that it is inside
`liblldb.so`. However, in every packaging I've seen of lldb-server the
function `ComputeSharedLibraryDirectory` is statically linked into the
`lldb-server` binary and is not in `liblldb.so`.
* When run through a symlink, `GetModuleFileSpecForHostAddress` on an
address that is in `lldb-server` returns the path of the symlink, not
the path of the binary itself. So we get e.g. `/usr/bin/` and not
`/usr/lib/llvm-19/bin/`.
* `GetDebugserverPath` attempts to concat `"lldb-server"` to the
directory we obtained, and thus fails when the symlink is not named
exactly `lldb-server`.
* Ironically, the reason that this works in the first place is precisely
because `GetModuleFileSpecForHostAddress` returns an incorrect path -
when the server is run as `lldb-server-19 ...` it returns
`"lldb-server-19"` which then causes `ComputePathRelativeToLibrary` to
fail and then `ComputeSupportExeDirectory` falls back to just using
`GetProgramFileSpec` instead (which is the only option that actually
yields a correct path).



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications