Also speed up quite significantly due less forking.

If the ELF file is not an executable, we do not get a PT_INTERP section,
because after all, it's a *shared* library.

So instead of checking for PT_INTERP (to avoid statically linked
executables) for all ELF files, we add another check to see if it's an
executable and *only* skip it when it is and there's no PT_INTERP.

Signed-off-by: aszlig <aszlig@nix.build>

The "maxx" package recursively runs isExecutable on a bunch of files and
since the change to use "readelf" instead of "file" a lot of errors like
this one are printed during build:

  readelf: Error: Not an ELF file - it has the wrong magic bytes at the
  start

While the isExecutable was never meant to be used outside of the
autoPatchelfHook, it's still a good idea to silence the errors because
whenever readelf fails, it clearly indicates that the file in question
is not a valid ELF file.

Signed-off-by: aszlig <aszlig@nix.build>

The unfree variant of elasticsearch uses autoPatchelfHook and since we
removed the dependency on file for the hook itself in
58a97df we no longer have zlib
propagated.

So we need to explicitly state that dependency here.

Signed-off-by: aszlig <aszlig@nix.build>
Cc: @apeschar, @basvandijk

This includes the initialy commit was done by @Mic92 plus a few fixes
from my side. So essentially this avoids patching statically linked
executables and also speeds up searching for ELF files altogether.

I've tested this by comparing the outputs of all the derivations which
make use of this hook using the following Nix expression:

  let
    getPackagesForRev = rev: with import (builtins.fetchGit {
      url = ./.;
      inherit rev;
    }) { config.allowUnfree = true; }; [
      cups-kyodialog3 elasticsearch franz gurobi javacard-devkit
      masterpdfeditor maxx oracle-instantclient powershell reaper
      teamviewer unixODBCDrivers.msodbcsql17 virtlyst wavebox zoom-us
    ];

    pkgs = import <nixpkgs> {};
    baseRev = "ef764eb0d8314b81a012dae04642b4766199956d";

  in pkgs.runCommand "diff-contents" {
    chset = pkgs.lib.zipListsWith (old: new: pkgs.runCommand "diff" {
      inherit old new;
      nativeBuildInputs = [ pkgs.nukeReferences ];
    } ''
      mkdir -p "''${NIX_STORE#/}"
      cp --no-preserve=all -r "$old" "''${NIX_STORE#/}"
      cp --no-preserve=all -r "$new" "''${NIX_STORE#/}"
      find "''${old#/}" "''${new#/}" \
        \( -type f -exec nuke-refs {} + \) -o \( -type l -delete \)
      mkdir "$out"
      echo "$old" > "$out/old-path"
      echo "$new" > "$out/new-path"
      diff -Nur "''${old#/}" "''${new#/}" > "$out/diff" || :
    '') (getPackagesForRev baseRev) (getPackagesForRev "");
  } ''
    err=0
    for c in $chset; do
      if [ -s "$c/diff" ]; then
        echo "$(< "$c/old-path") -> $(< "$c/new-path")" \
             "differs, report: $c/diff" >&2
        err=1
      fi
    done
    [ $err -eq 0 ] && touch "$out"
  ''

With these changes there is only one derivation which has altered
contents, which is "franz". However the reason why it has differing
contents is not directly because of the autoPatchelfHook changes, but
because the "env-vars" file from the builder is in
"$out/opt/franz/env-vars" (Cc: @gnidorah) and we now have different
contents for NIX_CFLAGS_COMPILE and other environment variables.

I also tested this against a random static binary and the hook no longer
tries to patch it.

Merges: #47222