autoPatchelfHook: add keep_libc flag (#332617)

* autoPatchelfHook: add keep_libc flag

- Add keep_libc flag to disable the default libc handling. Intended
  to be used by systemd.
- Add autoPatchelfFlags to autoPatchelfHook for passing arguments to
  the autoPatchelf script

This reverts part of the change made in #307068 / 80be926.

Fixes #332533

pkgs/build-support/setup-hooks/auto-patchelf.py

@@ -197,7 +197,7 @@ class Dependency:
     found: bool = False     # Whether it was found somewhere
 
 
-def auto_patchelf_file(path: Path, runtime_deps: list[Path], append_rpaths: list[Path] = [], extra_args: list[str] = []) -> list[Dependency]:
+def auto_patchelf_file(path: Path, runtime_deps: list[Path], append_rpaths: list[Path] = [], keep_libc: bool = False, extra_args: list[str] = []) -> list[Dependency]:
     try:
         with open_elf(path) as elf:
 
@@ -257,26 +257,36 @@ def auto_patchelf_file(path: Path, runtime_deps: list[Path], append_rpaths: list
             # 1. If a candidate is an absolute path, it is already a
             #    valid dependency if that path exists, and nothing needs
             #    to be done. It should be an error if that path does not exist.
-            # 2. If a candidate is found in our library dependencies, that
+            # 2. If a candidate is found within libc, it should be dropped
+            #    and resolved automatically by the dynamic linker, unless
+            #    keep_libc is enabled.
+            # 3. If a candidate is found in our library dependencies, that
             #    dependency should be added to rpath.
-            # 3. If a candidate is found in libc, it will be correctly
-            #    resolved by the dynamic linker automatically.
+            # 4. If all of the above fail, libc dependencies should still be
+            #    considered found. This is in contrast to step 2, because
+            #    enabling keep_libc should allow libc to be found in step 3
+            #    if possible to preserve its presence in rpath.
             #
             # These conditions are checked in this order, because #2
             # and #3 may both be true. In that case, we still want to
             # add the dependency to rpath, as the original binary
             # presumably had it and this should be preserved.
 
+            is_libc = (libc_lib / candidate).is_file()
+
             if candidate.is_absolute() and candidate.is_file():
                 was_found = True
                 break
+            elif is_libc and not keep_libc:
+                was_found = True
+                break
             elif found_dependency := find_dependency(candidate.name, file_arch, file_osabi):
                 rpath.append(found_dependency)
                 dependencies.append(Dependency(path, candidate, found=True))
                 print(f"    {candidate} -> found: {found_dependency}")
                 was_found = True
                 break
-            elif (libc_lib / candidate).is_file():
+            elif is_libc and keep_libc:
                 was_found = True
                 break
 
@@ -306,6 +316,7 @@ def auto_patchelf(
         recursive: bool = True,
         ignore_missing: list[str] = [],
         append_rpaths: list[Path] = [],
+        keep_libc: bool = False,
         extra_args: list[str] = []) -> None:
 
     if not paths_to_patch:
@@ -319,7 +330,7 @@ def auto_patchelf(
     dependencies = []
     for path in chain.from_iterable(glob(p, '*', recursive) for p in paths_to_patch):
         if not path.is_symlink() and path.is_file():
-            dependencies += auto_patchelf_file(path, runtime_deps, append_rpaths, extra_args)
+            dependencies += auto_patchelf_file(path, runtime_deps, append_rpaths, keep_libc, extra_args)
 
     missing = [dep for dep in dependencies if not dep.found]
 
@@ -377,6 +388,12 @@ def main() -> None:
         type=Path,
         help="Paths to append to all runtime paths unconditionally",
     )
+    parser.add_argument(
+        "--keep-libc",
+        dest="keep_libc",
+        action="store_true",
+        help="Attempt to search for and relink libc dependencies.",
+    )
     parser.add_argument(
         "--extra-args",
         # Undocumented Python argparse feature: consume all remaining arguments
@@ -398,6 +415,7 @@ def main() -> None:
         args.recursive,
         args.ignore_missing,
         append_rpaths=args.append_rpaths,
+        keep_libc=args.keep_libc,
         extra_args=args.extra_args)
 
 

pkgs/build-support/setup-hooks/auto-patchelf.sh

@@ -58,11 +58,13 @@ autoPatchelf() {
         local appendRunpathsArray=( "${appendRunpaths[@]}" )
         local runtimeDependenciesArray=( "${runtimeDependencies[@]}" )
         local patchelfFlagsArray=( "${patchelfFlags[@]}" )
+        local autoPatchelfFlagsArray=( "${autoPatchelfFlags[@]}" )
     else
         readarray -td' ' ignoreMissingDepsArray < <(echo -n "$autoPatchelfIgnoreMissingDeps")
         local appendRunpathsArray=($appendRunpaths)
         local runtimeDependenciesArray=($runtimeDependencies)
         local patchelfFlagsArray=($patchelfFlags)
+        local autoPatchelfFlagsArray=($autoPatchelfFlags)
     fi
 
     # Check if ignoreMissingDepsArray contains "1" and if so, replace it with
@@ -85,6 +87,7 @@ autoPatchelf() {
                "${extraAutoPatchelfLibs[@]}"                            \
         --runtime-dependencies "${runtimeDependenciesArray[@]/%//lib}"  \
         --append-rpaths "${appendRunpathsArray[@]}"                     \
+        "${autoPatchelfFlagsArray[@]}"                                  \
         --extra-args "${patchelfFlagsArray[@]}"
 }
 

pkgs/os-specific/linux/systemd/default.nix

@@ -336,6 +336,8 @@ stdenv.mkDerivation (finalAttrs: {
     ]
   ;
 
+  autoPatchelfFlags = [ "--keep-libc" ];
+
   buildInputs =
     [
       libxcrypt