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nixpkgs/lib/sources.nix
Michael Peyton Jones 07f363fae3
cleanSourceWith: don't use baseNameOf
Currently, not providing `name` to `cleanSourceWith` will use the name
of the imported directory. However, a common case is for this to be the
top level of some repository. In that case, the name will be the name of
the checkout on the current machine, which is not necessarily
reproducible across different settings, and can lead to e.g. cache
misses in CI.

This is documented in the comment on `cleanSourceWith`, but this does
not stop it being a subtle trap for users.

There are different tradeoffs in each case:

1. If `cleanSourceWith` defaults to `"source"`, then we may end up with a
user not knowing what directory a source store path corresponds to.
However, it being called "unnamed" may give them a clue that there is a
way for them to name it, and lead them to the definition of the
function, which has a clear `name` parameter.

2. If `cleanSoureWith` defaults to the directory name, then a user may face
occasional loss of caching, which is hard to notice, and hard to track
down. Tracking it down likely requires use of more advanced tools like
`nix-diff`, and reading the source of a lot of nix code.

I think the downside of the status quo is worse.

This is really another iteration of
https://github.com/NixOS/nix/issues/1305: that led to adding the `name`
argument in the first place, this just makes us use a better default
`name`.
2020-03-23 09:53:07 +00:00

160 lines
6.5 KiB
Nix

# Functions for copying sources to the Nix store.
{ lib }:
rec {
# Returns the type of a path: regular (for file), symlink, or directory
pathType = p: with builtins; getAttr (baseNameOf p) (readDir (dirOf p));
# Returns true if the path exists and is a directory, false otherwise
pathIsDirectory = p: if builtins.pathExists p then (pathType p) == "directory" else false;
# Returns true if the path exists and is a regular file, false otherwise
pathIsRegularFile = p: if builtins.pathExists p then (pathType p) == "regular" else false;
# Bring in a path as a source, filtering out all Subversion and CVS
# directories, as well as backup files (*~).
cleanSourceFilter = name: type: let baseName = baseNameOf (toString name); in ! (
# Filter out version control software files/directories
(baseName == ".git" || type == "directory" && (baseName == ".svn" || baseName == "CVS" || baseName == ".hg")) ||
# Filter out editor backup / swap files.
lib.hasSuffix "~" baseName ||
builtins.match "^\\.sw[a-z]$" baseName != null ||
builtins.match "^\\..*\\.sw[a-z]$" baseName != null ||
# Filter out generates files.
lib.hasSuffix ".o" baseName ||
lib.hasSuffix ".so" baseName ||
# Filter out nix-build result symlinks
(type == "symlink" && lib.hasPrefix "result" baseName)
);
# Filters a source tree removing version control files and directories using cleanSourceWith
#
# Example:
# cleanSource ./.
cleanSource = src: cleanSourceWith { filter = cleanSourceFilter; inherit src; };
# Like `builtins.filterSource`, except it will compose with itself,
# allowing you to chain multiple calls together without any
# intermediate copies being put in the nix store.
#
# lib.cleanSourceWith {
# filter = f;
# src = lib.cleanSourceWith {
# filter = g;
# src = ./.;
# };
# }
# # Succeeds!
#
# builtins.filterSource f (builtins.filterSource g ./.)
# # Fails!
#
# Parameters:
#
# src: A path or cleanSourceWith result to filter and/or rename.
#
# filter: A function (path -> type -> bool)
# Optional with default value: constant true (include everything)
# The function will be combined with the && operator such
# that src.filter is called lazily.
# For implementing a filter, see
# https://nixos.org/nix/manual/#builtin-filterSource
#
# name: Optional name to use as part of the store path.
# This defaults to `src.name` or otherwise `"source"`.
#
cleanSourceWith = { filter ? _path: _type: true, src, name ? null }:
let
isFiltered = src ? _isLibCleanSourceWith;
origSrc = if isFiltered then src.origSrc else src;
filter' = if isFiltered then name: type: filter name type && src.filter name type else filter;
name' = if name != null then name else if isFiltered then src.name else "source";
in {
inherit origSrc;
filter = filter';
outPath = builtins.path { filter = filter'; path = origSrc; name = name'; };
_isLibCleanSourceWith = true;
name = name';
};
# Filter sources by a list of regular expressions.
#
# E.g. `src = sourceByRegex ./my-subproject [".*\.py$" "^database.sql$"]`
sourceByRegex = src: regexes:
let
isFiltered = src ? _isLibCleanSourceWith;
origSrc = if isFiltered then src.origSrc else src;
in lib.cleanSourceWith {
filter = (path: type:
let relPath = lib.removePrefix (toString origSrc + "/") (toString path);
in lib.any (re: builtins.match re relPath != null) regexes);
inherit src;
};
# Get all files ending with the specified suffices from the given
# directory or its descendants. E.g. `sourceFilesBySuffices ./dir
# [".xml" ".c"]'.
sourceFilesBySuffices = path: exts:
let filter = name: type:
let base = baseNameOf (toString name);
in type == "directory" || lib.any (ext: lib.hasSuffix ext base) exts;
in cleanSourceWith { inherit filter; src = path; };
pathIsGitRepo = path: (builtins.tryEval (commitIdFromGitRepo path)).success;
# Get the commit id of a git repo
# Example: commitIdFromGitRepo <nixpkgs/.git>
commitIdFromGitRepo =
let readCommitFromFile = file: path:
with builtins;
let fileName = toString path + "/" + file;
packedRefsName = toString path + "/packed-refs";
absolutePath = base: path:
if lib.hasPrefix "/" path
then path
else toString (/. + "${base}/${path}");
in if pathIsRegularFile path
# Resolve git worktrees. See gitrepository-layout(5)
then
let m = match "^gitdir: (.*)$" (lib.fileContents path);
in if m == null
then throw ("File contains no gitdir reference: " + path)
else
let gitDir = absolutePath (dirOf path) (lib.head m);
commonDir' = if pathIsRegularFile "${gitDir}/commondir"
then lib.fileContents "${gitDir}/commondir"
else gitDir;
commonDir = absolutePath gitDir commonDir';
refFile = lib.removePrefix "${commonDir}/" "${gitDir}/${file}";
in readCommitFromFile refFile commonDir
else if pathIsRegularFile fileName
# Sometimes git stores the commitId directly in the file but
# sometimes it stores something like: «ref: refs/heads/branch-name»
then
let fileContent = lib.fileContents fileName;
matchRef = match "^ref: (.*)$" fileContent;
in if matchRef == null
then fileContent
else readCommitFromFile (lib.head matchRef) path
else if pathIsRegularFile packedRefsName
# Sometimes, the file isn't there at all and has been packed away in the
# packed-refs file, so we have to grep through it:
then
let fileContent = readFile packedRefsName;
matchRef = match (".*\n([^\n ]*) " + file + "\n.*") fileContent;
in if matchRef == null
then throw ("Could not find " + file + " in " + packedRefsName)
else lib.head matchRef
else throw ("Not a .git directory: " + path);
in readCommitFromFile "HEAD";
pathHasContext = builtins.hasContext or (lib.hasPrefix builtins.storeDir);
canCleanSource = src: src ? _isLibCleanSourceWith || !(pathHasContext (toString src));
}