tvl-depot/nix/utils/default.nix
sterni 32de4cbd93 refactor(users/grfn/gws.fyi): implement isDirectory in pure nix
Another day, another import from derivation avoided by
builtins.unsafeDiscardStringContext!

Change-Id: I67274b1ba13ba980bb3346b22f2955c702aa3151
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3372
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: tazjin <mail@tazj.in>
2021-08-24 12:13:06 +00:00

131 lines
3.5 KiB
Nix

{ depot, lib, ... }:
let
/* Takes an attribute set and adds a meta.targets
attribute to it which contains all direct children
of the attribute set which are derivations.
Type: attrs -> attrs
*/
drvTargets = attrs:
attrs // {
meta = {
targets = builtins.filter
(x: lib.isDerivation attrs."${x}")
(builtins.attrNames attrs);
} // (attrs.meta or {});
};
/* Get the basename of a store path without
the leading hash.
Type: (path | drv | string) -> string
Example:
storePathName ./foo.c
=> "foo.c"
storePathName (writeText "foo.c" "int main() { return 0; }")
=> "foo.c"
storePathName "${hello}/bin/hello"
=> "hello"
*/
storePathName = p:
if lib.isDerivation p
then p.name
else if builtins.isPath p
then builtins.baseNameOf p
else if builtins.isString p
then
let
# strip leading storeDir and trailing slashes
noStoreDir = lib.removeSuffix "/"
(lib.removePrefix "${builtins.storeDir}/" p);
# a basename of a child of a store path isn't really
# referring to a store path, so removing the string
# context is safe (e. g. "hello" for "${hello}/bin/hello").
basename = builtins.unsafeDiscardStringContext
(builtins.baseNameOf p);
in
# If p is a direct child of storeDir, we need to remove
# the leading hash as well to make sure that:
# `storePathName drv == storePathName (toString drv)`.
if noStoreDir == basename
then builtins.substring 33 (-1) basename
else basename
else builtins.throw "Don't know how to get (base)name of "
+ lib.generators.toPretty {} p;
/* Get the type of a path itself as it would be returned for a
directory child by builtins.readDir.
Type: path(-like) -> option<string>
Example:
pathType ./foo.c
=> "regular"
pathType /home/lukas
=> "directory"
pathType ./result
=> "symlink"
pathType /does/not/exist
=> null
*/
pathType = path:
let
# baseNameOf is very annoyed if we proceed with string context.
# We need to call toString to prevent unsafeDiscardStringContext
# from importing a path into store which messes with base- and
# dirname of course.
path'= builtins.unsafeDiscardStringContext (toString path);
# To read the containing directory we absolutely need
# to keep the string context, otherwise a derivation
# would not be realized before our check (at eval time)
containingDir = builtins.readDir (builtins.dirOf path);
in
containingDir.${builtins.baseNameOf path'} or null;
pathType' = path:
let
p = pathType path;
in
if p == null
then builtins.throw "${lib.generators.toPretty {} path} does not exist"
else p;
/* Check whether the given path is a directory.
Throws if the path in question doesn't exist.
Type: path(-like) -> bool
*/
isDirectory = path: pathType' path == "directory";
/* Check whether the given path is a regular file.
Throws if the path in question doesn't exist.
Type: path(-like) -> bool
*/
isRegularFile = path: pathType' path == "regular";
/* Check whether the given path is a symbolic link.
Throws if the path in question doesn't exist.
Type: path(-like) -> bool
*/
isSymlink = path: pathType' path == "symlink";
in {
inherit
drvTargets
storePathName
pathType
isDirectory
isRegularFile
isSymlink
;
}