2397fd8d56
Passed strings will be treated as a relative path below the given root, which is quite convenient when using depot.path by eliminating a lot of repetition. Change-Id: I3da6058094484f4a6ffbb84f89ad4472b502a00c Reviewed-on: https://cl.tvl.fyi/c/depot/+/3704 Tested-by: BuildkiteCI Reviewed-by: tazjin <mail@tazj.in>
70 lines
2.3 KiB
Nix
70 lines
2.3 KiB
Nix
# Build a “sparse” version of a given directory, only including contained files
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# and directories if they are listed in a supplied list:
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#
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# # A very minimal depot
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# sparseTree ./depot [
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# ./default.nix
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# ./depot/nix/readTree/default.nix
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# ./third_party/nixpkgs
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# ./third_party/overlays
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# ]
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{ pkgs, lib, ... }:
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# root path to use as a reference point
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root:
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# list of paths below `root` that should be
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# included in the resulting directory
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#
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# If path, need to refer to the actual file / directory to be included.
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# If a string, it is treated as a string relative to the root.
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paths:
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let
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rootLength = builtins.stringLength (toString root);
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# Count slashes in a path.
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#
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# Type: path -> int
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depth = path: lib.pipe path [
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toString
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(builtins.split "/")
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(builtins.filter builtins.isList)
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builtins.length
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];
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# (Parent) directories will be created from deepest to shallowest
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# which should mean no conflicts are caused unless both a child
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# and its parent directory are in the list of paths.
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# TODO(sterni): improve error messages in such cases
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fromDeepest = lib.sort (a: b: depth a < depth b) paths;
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# Create a set which contains the source path to copy / symlink and
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# it's destination, so the path below the destination root including
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# a leading slash. Additionally some sanity checking is done.
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makeSymlink = path:
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let
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withLeading = p: if builtins.substring 0 1 p == "/" then p else "/" + p;
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fullPath =
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/**/ if builtins.isPath path then path
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else if builtins.isString path then (root + withLeading path)
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else builtins.throw "Unsupported path type ${builtins.typeOf path}";
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strPath = toString fullPath;
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contextPath = "${fullPath}";
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belowRoot = builtins.substring rootLength (-1) strPath;
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prefix = builtins.substring 0 rootLength strPath;
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in assert toString root == prefix; {
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src = contextPath;
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dst = belowRoot;
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};
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symlinks = builtins.map makeSymlink fromDeepest;
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in
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# TODO(sterni): teach readTree to also read symlinked directories,
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# so we ln -sT instead of cp -aT.
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pkgs.runCommandNoCC "sparse-${builtins.baseNameOf root}" {} (
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lib.concatMapStrings ({ src, dst }: ''
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mkdir -p "$(dirname "$out${dst}")"
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cp -aT --reflink=auto "${src}" "$out${dst}"
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'') symlinks
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)
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