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Migrate from glibc's libcrypt to libxcrypt #181764

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merged 117 commits into from
Oct 9, 2022

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mweinelt
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This PR hopefully paves the way for a libxcrypt migration.

For that we disable crypt suppor in glibc and find out what packages break.
On these packages we add libxcrypt and things should build again.

Ideally we can achieve a shorter path to libxcrypt than drawn up in #112371.

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vcunat commented Jul 16, 2022

https://hydra.nixos.org/jobset/nixos/pr-181764-libxcrypt

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vcunat commented Jul 17, 2022

(gcc still doesn't build for me)

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mweinelt commented Jul 17, 2022

Yep, I was taking a look at perl yesterday, since libxcrypt requires it and therefore causes an infinite recursion. Two ideas came up:

  • Build Perl once without crypt support ✔️
  • Build Perl once with glibc's libcrypt
Outdated information Went for the second approach this morning, but I currently can't get perl to find `glibc.libcrypt`, probably because to build glibc I require bison, which in turn requires perl. I don't think I grok the dependency chain here.
❯ nix-build -A perl
error: attribute 'libcrypt' missing

       at /home/hexa/git/nixos/libxcrypt/pkgs/top-level/all-packages.nix:19795:40:

        19794|   libxcrypt = callPackage ../development/libraries/libxcrypt {
        19795|     perl = perl.override { libxcrypt = glibc.libcrypt; };
             |                                        ^
        19796|   };

I can build glibc.libcrypt otherwise.

@mweinelt mweinelt changed the title glibc: make crypt support optional Migrate from glibc's libcrypt to libxcrypt Jul 20, 2022
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fpletz commented Sep 27, 2022

@mweinelt I've continued your efforts and fixed most issues with obvious crypt users and most NixOS tests seem to be working including an expansion of the shadow test to check support of the new hashes. I've rebased and pushed my changes here master...fpletz:nixpkgs:glibc-without-libcrypt. Is it okay if I push to your branch?

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Feel free!

herrwiese added a commit to herrwiese/nixpkgs that referenced this pull request Nov 30, 2022
ff30c89 made libcrypt support optional (and off-by-default) in
glibc, which requires all packages still using it to depend on
libxcrypt.

See also NixOS#181764

(cherry picked from commit 49ec58b)
gefla pushed a commit to gefla/nixpkgs that referenced this pull request Nov 30, 2022
ff30c89 made libcrypt support optional (and off-by-default) in
glibc, which requires all packages still using it to depend on
libxcrypt.

See also NixOS#181764
@Majiir Majiir mentioned this pull request Dec 31, 2022
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Ma27 added a commit to Ma27/nixpkgs that referenced this pull request Mar 29, 2023
Closes NixOS#150801

Note: I decided against resuming directly on NixOS#150801 because the
conflict was too big (and resolving it seemed too error-prone to me).
Also the `this`-refactoring could be done in an easier manner, i.e. by
exposing JIT attributes with the correct configuration. More on that
below.

This patch creates variants of the `postgresql*`-packages with JIT[1]
support. Please note that a lot of the work was derived from previous
patches filed by other contributors, namely dasJ, andir and abbradar,
hence the co-authored-by tags below.

Effectively, the following things have changed:

* For JIT variants an LLVM-backed stdenv with clang is now used as
  suggested by dasJ[2]. We need LLVM and CLang[3] anyways to build the
  JIT-part, so no need to mix this up with GCC's stdenv. Also, using the
  `dev`-output of LLVM and clang's stdenv for building (and adding llvm
  libs as build-inputs) seems more cross friendly to me (which will
  become useful when cross-building for JIT-variants will actually be
  supported).

* Plugins inherit the build flags from the Makefiles in
  `$out/lib/pgxs/src` (e.g. `-Werror=unguarded-availability-new`). Since
  some of the flags are clang-specific (and stem from the use of the
  CLang stdenv) and don't work on gcc, the stdenv of `pkgs.postgresql`
  is passed to the plugins. I.e., plugins for non-JIT variants are built
  with a gcc stdenv on Linux and plugins for JIT variants with a clang
  stdenv.

  Since `plv8` hard-codes `gcc` as `$CC` in its Makefile[4], I marked it
  as broken for JIT-variants of postgresql only.

* Added a test-matrix to confirm that JIT works fine on each
  `pkgs.postgresql_*_jit` (thanks Andi for the original test in
  NixOS#124804!).

* For each postgresql version, a new attribute
  `postgresql_<version>_jit` (and a corresponding
  `postgresqlPackages<version>JitPackages`) are now exposed for better
  discoverability and prebuilt artifacts in the binary cache.

* In NixOS#150801 the `this`-argument was replaced by an internal recursion.
  I decided against this approach because it'd blow up the diff even
  more which makes the readability way harder and also harder to revert
  this if necessary.

  Instead, it is made sure that `this` always points to the correct
  variant of `postgresql` and re-using that in an additional
  `.override {}`-expression is trivial because the JIT-variant is
  exposed in `all-packages.nix`.

* I think the changes are sufficiently big to actually add myself as
  maintainer here.

* Added `libxcrypt` to `buildInputs` for versions <v13. While
  building things with an LLVM stdenv, these versions complained that
  the extern `crypt()` symbol can't be found. Not sure what this is
  exactly about, but since we want to switch to libxcrypt for `crypt()`
  usage anyways[5] I decided to add it. For >=13 it's not relevant
  anymore anyways[6].

* JIT support doesn't work with cross-compilation. It is attempted to
  build LLVM-bytecode (`%.bc` is the corresponding `make(1)`-rule) for
  each sub-directory in `backend/` for the JIT apparently, but with a
  $(CLANG) that can produce binaries for the build, not the host-platform.

  I managed to get a cross-build with JIT support working with
  `depsBuildBuild = [ llvmPackages.clang ] ++ buildInputs`, but
  considering that the resulting LLVM IR isn't platform-independent this
  doesn't give you much. In fact, I tried to test the result in a VM-test,
  but as soon as JIT was used to optimize a query, postgres would
  coredump with `Illegal instruction`.

A common concern of the original approach - with llvm as build input -
was the massive increase of closure size. With the new approach of using
the LLVM stdenv directly and patching out references to the clang drv in
`$out` the effective closure size changes are:

    $ nix path-info -Sh $(nix-build -A postgresql_14)
    /nix/store/kssxxqycwa3c7kmwmykwxqvspxxa6r1w-postgresql-14.7	306.4M
    $ nix path-info -Sh $(nix-build -A postgresql_14_jit)
    /nix/store/xc7qmgqrn4h5yr4vmdwy56gs4bmja9ym-postgresql-14.7	689.2M

Most of the increase in closure-size stems from the `lib`-output of
LLVM

    $ nix path-info -Sh /nix/store/5r97sbs5j6mw7qnbg8nhnq1gad9973ap-llvm-11.1.0-lib
    /nix/store/5r97sbs5j6mw7qnbg8nhnq1gad9973ap-llvm-11.1.0-lib	349.8M

which is why this shouldn't be enabled by default.

While this is quite much because of LLVM, it's still a massive
improvement over the simple approach of adding llvm/clang as
build-inputs and building with `--with-llvm`:

    $ nix path-info -Sh $(nix-build -E '
	with import ./. {};
	postgresql.overrideAttrs ({ configureFlags ? [], buildInputs ? [], ... }: {
	  configureFlags = configureFlags ++ [ "--with-llvm" ];
	  buildInputs = buildInputs ++ [ llvm clang ];
	})' -j0)
    /nix/store/i3bd2r21c6c3428xb4gavjnplfqxn27p-postgresql-14.7	  1.6G

Co-authored-by: Andreas Rammhold <andreas@rammhold.de>
Co-authored-by: Janne Heß <janne@hess.ooo>
Co-authored-by: Nikolay Amiantov <ab@fmap.me>

[1] https://www.postgresql.org/docs/current/jit-reason.html
[2] NixOS#124804 (comment)
    & NixOS#150801 (comment)
[3] This fails with the following error otherwise:
    ```
    configure: error: clang not found, but required when compiling --with-llvm, specify with CLANG=
    ```
[4] https://github.com/plv8/plv8/blob/v3.1.5/Makefile#L14
[5] NixOS#181764
[6] postgres/postgres@c45643d
rtimush pushed a commit to rtimush/nixpkgs that referenced this pull request Sep 21, 2023
I guess with NixOS#181764 this might've broken for cross.
Perl propagates libxcrypt, but is only listed in nativeBuildInputs.
List libxcrypt in buildInputs to ensure it's picked up properly.
tomfitzhenry added a commit to tomfitzhenry/nixpkgs that referenced this pull request Apr 28, 2024
tm-drtina pushed a commit to awakesecurity/nixpkgs that referenced this pull request Jul 23, 2024
tm-drtina pushed a commit to awakesecurity/nixpkgs that referenced this pull request Jul 29, 2024
tm-drtina pushed a commit to awakesecurity/nixpkgs that referenced this pull request Aug 13, 2024
bacchanalia pushed a commit to awakesecurity/nixpkgs that referenced this pull request Aug 27, 2024
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7 participants