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nixpkgs/lib/filesystem.nix
Silvan Mosberger 378bf1a619 lib/filesystem.nix: Update top comment
Co-Authored-By: Robert Hensing <robert@roberthensing.nl>
2023-05-22 14:17:42 +02:00

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Nix

# Functions for querying information about the filesystem
# without copying any files to the Nix store.
{ lib }:
# Tested in lib/tests/filesystem.sh
let
inherit (builtins)
readDir
pathExists
;
inherit (lib.strings)
hasPrefix
;
inherit (lib.filesystem)
pathType
;
in
{
/*
The type of a path. The path needs to exist and be accessible.
The result is either "directory" for a directory, "regular" for a regular file, "symlink" for a symlink, or "unknown" for anything else.
Type:
pathType :: Path -> String
Example:
pathType /.
=> "directory"
pathType /some/file.nix
=> "regular"
*/
pathType =
builtins.readFileType or
# Nix <2.14 compatibility shim
(path:
if ! pathExists path
# Fail irrecoverably to mimic the historic behavior of this function and
# the new builtins.readFileType
then abort "lib.filesystem.pathType: Path ${toString path} does not exist."
# The filesystem root is the only path where `dirOf / == /` and
# `baseNameOf /` is not valid. We can detect this and directly return
# "directory", since we know the filesystem root can't be anything else.
else if dirOf path == path
then "directory"
else (readDir (dirOf path)).${baseNameOf path}
);
/*
Whether a path exists and is a directory.
Type:
pathIsDirectory :: Path -> Bool
Example:
pathIsDirectory /.
=> true
pathIsDirectory /this/does/not/exist
=> false
pathIsDirectory /some/file.nix
=> false
*/
pathIsDirectory = path:
pathExists path && pathType path == "directory";
/*
Whether a path exists and is a regular file, meaning not a symlink or any other special file type.
Type:
pathIsRegularFile :: Path -> Bool
Example:
pathIsRegularFile /.
=> false
pathIsRegularFile /this/does/not/exist
=> false
pathIsRegularFile /some/file.nix
=> true
*/
pathIsRegularFile = path:
pathExists path && pathType path == "regular";
/*
A map of all haskell packages defined in the given path,
identified by having a cabal file with the same name as the
directory itself.
Type: Path -> Map String Path
*/
haskellPathsInDir =
# The directory within to search
root:
let # Files in the root
root-files = builtins.attrNames (builtins.readDir root);
# Files with their full paths
root-files-with-paths =
map (file:
{ name = file; value = root + "/${file}"; }
) root-files;
# Subdirectories of the root with a cabal file.
cabal-subdirs =
builtins.filter ({ name, value }:
builtins.pathExists (value + "/${name}.cabal")
) root-files-with-paths;
in builtins.listToAttrs cabal-subdirs;
/*
Find the first directory containing a file matching 'pattern'
upward from a given 'file'.
Returns 'null' if no directories contain a file matching 'pattern'.
Type: RegExp -> Path -> Nullable { path : Path; matches : [ MatchResults ]; }
*/
locateDominatingFile =
# The pattern to search for
pattern:
# The file to start searching upward from
file:
let go = path:
let files = builtins.attrNames (builtins.readDir path);
matches = builtins.filter (match: match != null)
(map (builtins.match pattern) files);
in
if builtins.length matches != 0
then { inherit path matches; }
else if path == /.
then null
else go (dirOf path);
parent = dirOf file;
isDir =
let base = baseNameOf file;
type = (builtins.readDir parent).${base} or null;
in file == /. || type == "directory";
in go (if isDir then file else parent);
/*
Given a directory, return a flattened list of all files within it recursively.
Type: Path -> [ Path ]
*/
listFilesRecursive =
# The path to recursively list
dir:
lib.flatten (lib.mapAttrsToList (name: type:
if type == "directory" then
lib.filesystem.listFilesRecursive (dir + "/${name}")
else
dir + "/${name}"
) (builtins.readDir dir));
}