[PATCH] D111164: Regenerate LC_CODE_SIGNATURE during llvm-objcopy operations

[Nico Weber via Phabricator via llvm-commits]

thakis added a comment.
Herald added a project: All.

cctools's strip only resigns after stripping if the signature was linker-generated (i.e. `MachO::CS_ADHOC | MachO::CS_LINKER_SIGNED` are set), and otherwise emits a warning:

  % cat hello.cc
  #include <stdio.h>
  int main() { printf("hello\n"); }
  % clang hello.cc && codesign --sign - a.out && strip a.out
  /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/strip: warning: changes being made to the file will invalidate the code signature in: /Users/thakis/src/llvm-project/a.out
  % ./a.out
  zsh: killed     ./a.out. # because signature is now wrong

This makes some sense: If a binary was explicitly signed, the explicit signature will be wrong.

On the other hand, if we re-sign, the binary can at least run, so I'm not sure if we should fully adopt cctools's behavior. But maybe we should emit a warning if we re-sign a binary that doesn't have a linker-generated signature?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D111164/new/

https://reviews.llvm.org/D111164