68 lines
2.4 KiB
Nix
68 lines
2.4 KiB
Nix
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{ pkgs, lib, ... }:
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# Write an execline script, represented as nested nix lists.
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# Everything is escaped correctly.
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# https://skarnet.org/software/execline/
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# TODO(Profpatsch) upstream into nixpkgs
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let
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# replaces " and \ to \" and \\ respectively and quote with "
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# e.g.
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# a"b\c -> "a\"b\\c"
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# a\"bc -> "a\\\"bc"
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escapeExeclineArg = arg:
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''"${builtins.replaceStrings [ ''"'' ''\'' ] [ ''\"'' ''\\'' ] (toString arg)}"'';
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# Escapes an execline (list of execline strings) to be passed to execlineb
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# Give it a nested list of strings. Nested lists are interpolated as execline
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# blocks ({}).
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# Everything is quoted correctly.
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#
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# Example:
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# escapeExecline [ "if" [ "somecommand" ] "true" ]
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# == ''"if" { "somecommand" } "true"''
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escapeExecline = execlineList: lib.concatStringsSep " "
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(let
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go = arg:
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if builtins.isString arg then [(escapeExeclineArg arg)]
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else if builtins.isPath arg then [(escapeExeclineArg "${arg}")]
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else if lib.isDerivation arg then [(escapeExeclineArg arg)]
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else if builtins.isList arg then [ "{" ] ++ builtins.concatMap go arg ++ [ "}" ]
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else abort "escapeExecline can only hande nested lists of strings, was ${lib.generators.toPretty {} arg}";
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in builtins.concatMap go execlineList);
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in
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name:
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{
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# "var": substitute readNArgs variables and start $@
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# from the (readNArgs+1)th argument
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# "var-full": substitute readNArgs variables and start $@ from $0
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# "env": don’t substitute, set # and 0…n environment vaariables, where n=$#
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# "none": don’t substitute or set any positional arguments
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# "env-no-push": like "env", but bypass the push-phase. Not recommended.
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argMode ? "var",
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# Number of arguments to be substituted as variables (passed to "var"/"-s" or "var-full"/"-S"
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readNArgs ? 0,
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}:
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# Nested list of lists of commands.
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# Inner lists are translated to execline blocks.
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argList:
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let
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env =
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if argMode == "var" then "s${toString readNArgs}"
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else if argMode == "var-full" then "S${toString readNArgs}"
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else if argMode == "env" then ""
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else if argMode == "none" then "P"
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else if argMode == "env-no-push" then "p"
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else abort ''"${toString argMode}" is not a valid argMode, use one of "var", "var-full", "env", "none", "env-no-push".'';
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in
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# TODO(Profpatsch): rewrite `writeScript` with `runExecline`
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pkgs.writeScript name ''
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#!${pkgs.execline}/bin/execlineb -W${env}
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${escapeExecline argList}
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''
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