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Alyssa Ross 7c112351d9
libutil: EPERM from kill(-1, ...) is fine
I tested a trivial program that called kill(-1, SIGKILL), which was
run as the only process for an unpriveleged user, on Linux and
FreeBSD.  On Linux, kill reported success, while on FreeBSD it failed
with EPERM.

POSIX says:

> If pid is -1, sig shall be sent to all processes (excluding an
> unspecified set of system processes) for which the process has
> permission to send that signal.

and

> The kill() function is successful if the process has permission to
> send sig to any of the processes specified by pid.  If kill() fails,
> no signal shall be sent.

and

> [EPERM]
>     The process does not have permission to send the signal to any
>     receiving process.

My reading of this is that kill(-1, ...) may fail with EPERM when
there are no other processes to kill (since the current process is
ignored).  Since kill(-1, ...) only attempts to kill processes the
user has permission to kill, it can't mean that we tried to do
something we didn't have permission to kill, so it should be fine to
interpret EPERM the same as success here for any POSIX-compliant
system.

This fixes an issue that Mic92 encountered[1] when he tried to review a
Nixpkgs PR on FreeBSD.

[1]: https://github.com/NixOS/nixpkgs/pull/81459#issuecomment-606073668
2021-02-07 13:56:50 +00:00
.github Bump cachix/install-nix-action from v11 to v12 (#4237) 2020-11-09 23:21:55 +00:00
config Update config.guess for proper arm64 macOS detection 2020-12-02 19:14:34 -06:00
contrib function-trace: always show the trace 2019-09-18 23:23:21 +02:00
doc/manual Remove newline in operator table. 2021-02-01 17:42:14 +01:00
m4 autoconf: Fix C++17 detection not working on Ubuntu 16.04. 2019-07-03 04:32:25 +02:00
maintainers set Content-Type to "text/plain" for install script 2020-08-20 13:21:22 +02:00
misc Add some missing clean-files 2020-10-18 20:32:59 +02:00
mk Remove 'dist' target 2020-12-03 16:17:58 +01:00
nix-rust Remove 'dist' target 2020-12-03 16:17:58 +01:00
perl Make sodium a required dependency 2021-01-06 17:56:53 +01:00
scripts scripts/install-nix-from-closure: only show progress if a terminal is used 2021-01-22 10:35:02 +01:00
src libutil: EPERM from kill(-1, ...) is fine 2021-02-07 13:56:50 +00:00
tests Add a trace to readLine() failures 2021-02-05 12:18:11 +01:00
.dir-locals.el .dir-locals.el: Set c-block-comment-prefix 2020-07-10 11:21:06 +02:00
.editorconfig Add .editorconfig 2017-06-05 22:57:28 +01:00
.gitignore Generate separate manpages for each nix subcommand 2020-12-02 23:23:23 +01:00
.version Revert "Bump version to 3.0" 2020-10-26 11:30:18 +01:00
bootstrap.sh
configure.ac Make sodium a required dependency 2021-01-06 17:56:53 +01:00
COPYING
default.nix Simplify shell.nix and default.nix 2020-06-17 19:21:46 +02:00
flake.lock Update to lowdown 0.7.9 2021-01-26 10:47:40 +01:00
flake.nix Merge pull request #4495 from Infinisil/perl-bindings-passthru 2021-02-05 12:22:52 +01:00
local.mk Remove 'dist' target 2020-12-03 16:17:58 +01:00
Makefile Move command plugin interface to libnixcmd 2021-01-26 06:22:24 -05:00
Makefile.config.in Make sodium a required dependency 2021-01-06 17:56:53 +01:00
precompiled-headers.h Config: Use nlohmann/json 2020-08-20 11:02:16 +02:00
README.md README: fix link to hacking guide 2020-12-28 09:30:14 -08:00
shell.nix Add back flake-compat shell.nix 2020-07-17 14:58:59 +00:00

Nix

Open Collective supporters Test

Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. Please refer to the Nix manual for more details.

Installation

On Linux and macOS the easiest way to install Nix is to run the following shell command (as a user other than root):

$ curl -L https://nixos.org/nix/install | sh

Information on additional installation methods is available on the Nix download page.

Building And Developing

See our Hacking guide in our manual for instruction on how to build nix from source with nix-build or how to get a development environment.

Additional Resources

License

Nix is released under the LGPL v2.1.