tvl-depot/users/Profpatsch/lib.nix

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{ depot, pkgs, ... }:
let
bins = depot.nix.getBins pkgs.coreutils [ "printf" "echo" "cat" "printenv" "tee" ]
// depot.nix.getBins pkgs.bash [ "bash" ]
// depot.nix.getBins pkgs.fdtools [ "multitee" ]
;
# Print `msg` and and argv to stderr, then execute into argv
debugExec = msg: depot.nix.writeExecline "debug-exec" {} [
"if" [
"fdmove" "-c" "1" "2"
"if" [ bins.printf "%s: " msg ]
"if" [ bins.echo "$@" ]
]
"$@"
];
# Print stdin to stderr and stdout
eprint-stdin = depot.nix.writeExecline "eprint-stdin" {} [
"pipeline" [ bins.multitee "0-1,2" ] "$@"
];
# Assume the input on stdin is netencode, pretty print it to stderr and forward it to stdout
eprint-stdin-netencode = depot.nix.writeExecline "eprint-stdin-netencode" {} [
"pipeline" [
# move stdout to 3
"fdmove" "3" "1"
# the multitee copies stdin to 1 (the other pipeline end) and 3 (the stdout of the outer pipeline block)
"pipeline" [ bins.multitee "0-1,3" ]
# make stderr the stdout of pretty, merging with the stderr of pretty
"fdmove" "-c" "1" "2"
depot.users.Profpatsch.netencode.pretty
]
"$@"
];
# print the given environment variable in $1 to stderr, then execute into the rest of argv
eprintenv = depot.nix.writeExecline "eprintenv" { readNArgs = 1; } [
"ifelse" [ "fdmove" "-c" "1" "2" bins.printenv "$1" ]
[ "$@" ]
"if" [ depot.tools.eprintf "eprintenv: could not find \"\${1}\" in the environment\n" ]
"$@"
];
# Split stdin into two commands, given by a block and the rest of argv
#
# Example (execline):
#
# pipeline [ echo foo ]
# split-stdin [ fdmove 1 2 foreground [ cat ] echo "bar" ] cat
#
# stdout: foo\n
# stderr: foo\nbar\n
split-stdin = depot.nix.writeExecline "split-stdin" { argMode = "env"; } [
"pipeline" [
# this is horrible yes but the quickest way I knew how to implement it
"runblock" "1" bins.bash "-c" ''${bins.tee} >("$@")'' "bash-split-stdin"
]
"runblock" "-r" "1"
];
# remove everything but a few selected environment variables
runInEmptyEnv = keepVars:
let
importas = pkgs.lib.concatMap (var: [ "importas" "-i" var var ]) keepVars;
# we have to explicitely call export here, because PATH is probably empty
export = pkgs.lib.concatMap (var: [ "${pkgs.execline}/bin/export" var ''''${${var}}'' ]) keepVars;
in depot.nix.writeExecline "empty-env" {}
(importas ++ [ "emptyenv" ] ++ export ++ [ "${pkgs.execline}/bin/exec" "$@" ]);
in {
inherit
debugExec
eprint-stdin
eprint-stdin-netencode
eprintenv
split-stdin
runInEmptyEnv
;
}