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