nix-super/src/libexpr/flake/flakeref.cc

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#include "flakeref.hh"
#include "store-api.hh"
#include "url.hh"
#include "url-parts.hh"
#include "fetchers.hh"
#include "registry.hh"
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namespace nix {
#if 0
// 'dir' path elements cannot start with a '.'. We also reject
// potentially dangerous characters like ';'.
const static std::string subDirElemRegex = "(?:[a-zA-Z0-9_-]+[a-zA-Z0-9._-]*)";
const static std::string subDirRegex = subDirElemRegex + "(?:/" + subDirElemRegex + ")*";
#endif
std::string FlakeRef::to_string() const
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{
std::map<std::string, std::string> extraQuery;
if (subdir != "")
extraQuery.insert_or_assign("dir", subdir);
return input.toURLString(extraQuery);
}
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fetchers::Attrs FlakeRef::toAttrs() const
{
auto attrs = input.toAttrs();
if (subdir != "")
attrs.emplace("dir", subdir);
return attrs;
}
std::ostream & operator << (std::ostream & str, const FlakeRef & flakeRef)
{
str << flakeRef.to_string();
return str;
}
bool FlakeRef::operator ==(const FlakeRef & other) const
{
return input == other.input && subdir == other.subdir;
}
FlakeRef FlakeRef::resolve(ref<Store> store) const
{
auto [input2, extraAttrs] = lookupInRegistries(store, input);
return FlakeRef(std::move(input2), fetchers::maybeGetStrAttr(extraAttrs, "dir").value_or(subdir));
}
FlakeRef parseFlakeRef(
const std::string & url,
const std::optional<Path> & baseDir,
bool allowMissing,
bool isFlake)
{
auto [flakeRef, fragment] = parseFlakeRefWithFragment(url, baseDir, allowMissing, isFlake);
if (fragment != "")
throw Error("unexpected fragment '%s' in flake reference '%s'", fragment, url);
return flakeRef;
}
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std::optional<FlakeRef> maybeParseFlakeRef(
const std::string & url, const std::optional<Path> & baseDir)
{
try {
return parseFlakeRef(url, baseDir);
} catch (Error &) {
return {};
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}
}
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std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
const std::string & url,
const std::optional<Path> & baseDir,
bool allowMissing,
bool isFlake)
{
using namespace fetchers;
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static std::string fnRegex = "[0-9a-zA-Z-._~!$&'\"()*+,;=]+";
static std::regex pathUrlRegex(
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"(/?" + fnRegex + "(?:/" + fnRegex + ")*/?)"
+ "(?:\\?(" + queryRegex + "))?"
+ "(?:#(" + queryRegex + "))?",
std::regex::ECMAScript);
static std::regex flakeRegex(
Respect lock files of inputs + fine-grained lock file control When computing a lock file, we now respect the lock files of flake inputs. This is important for usability / reproducibility. For example, the 'nixops' flake depends on the 'nixops-aws' and 'nixops-hetzner' repositories. So when the 'nixops' flake is used in another flake, we want the versions of 'nixops-aws' and 'nixops-hetzner' locked by the the 'nixops' flake because those presumably have been tested. This can lead to a proliferation of versions of flakes like 'nixpkgs' (since every flake's lock file could depend on a different version of 'nixpkgs'). This is not a major issue when using Nixpkgs overlays or NixOS modules, since then the top-level flake composes those overlays/modules into *its* version of Nixpkgs and all other versions are ignored. Lock file computation has been made a bit more lazy so it won't try to fetch all those versions of 'nixpkgs'. However, in case it's necessary to minimize flake versions, there now are two input attributes that allow this. First, you can copy an input from another flake, as follows: inputs.nixpkgs.follows = "dwarffs/nixpkgs"; This states that the calling flake's 'nixpkgs' input shall be the same as the 'nixpkgs' input of the 'dwarffs' input. Second, you can override inputs of inputs: inputs.nixpkgs.url = github:edolstra/nixpkgs/<hash>; inputs.nixops.inputs.nixpkgs.url = github:edolstra/nixpkgs/<hash>; or equivalently, using 'follows': inputs.nixpkgs.url = github:edolstra/nixpkgs/<hash>; inputs.nixops.inputs.nixpkgs.follows = "nixpkgs"; This states that the 'nixpkgs' input of the 'nixops' input shall be the same as the calling flake's 'nixpkgs' input. Finally, at '-v' Nix now prints the changes to the lock file, e.g. $ nix flake update ~/Misc/eelco-configurations/hagbard inputs of flake 'git+file:///home/eelco/Misc/eelco-configurations?subdir=hagbard' changed: updated 'nixpkgs': 'github:edolstra/nixpkgs/7845bf5f4b3013df1cf036e9c9c3a55a30331db9' -> 'github:edolstra/nixpkgs/03f3def66a104a221aac8b751eeb7075374848fd' removed 'nixops' removed 'nixops/nixops-aws' removed 'nixops/nixops-hetzner' removed 'nixops/nixpkgs'
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"((" + flakeIdRegexS + ")(?:/(?:" + refAndOrRevRegex + "))?)"
+ "(?:#(" + queryRegex + "))?",
std::regex::ECMAScript);
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std::smatch match;
/* Check if 'url' is a flake ID. This is an abbreviated syntax for
'flake:<flake-id>?ref=<ref>&rev=<rev>'. */
if (std::regex_match(url, match, flakeRegex)) {
auto parsedURL = ParsedURL{
.url = url,
.base = "flake:" + match.str(1),
.scheme = "flake",
.authority = "",
.path = match[1],
};
return std::make_pair(
FlakeRef(Input::fromURL(parsedURL), ""),
percentDecode(match.str(6)));
}
else if (std::regex_match(url, match, pathUrlRegex)) {
std::string path = match[1];
std::string fragment = percentDecode(match.str(3));
if (baseDir) {
/* Check if 'url' is a path (either absolute or relative
to 'baseDir'). If so, search upward to the root of the
repo (i.e. the directory containing .git). */
path = absPath(path, baseDir);
if (isFlake) {
if (!allowMissing && !pathExists(path + "/flake.nix")){
notice("path '%s' does not contain a 'flake.nix', searching up",path);
// Save device to detect filesystem boundary
dev_t device = lstat(path).st_dev;
bool found = false;
while (path != "/") {
if (pathExists(path + "/flake.nix")) {
found = true;
break;
} else if (pathExists(path + "/.git"))
throw Error("path '%s' is not part of a flake (neither it nor its parent directories contain a 'flake.nix' file)", path);
else {
if (lstat(path).st_dev != device)
throw Error("unable to find a flake before encountering filesystem boundary at '%s'", path);
}
path = dirOf(path);
}
if (!found)
throw BadURL("could not find a flake.nix file");
}
if (!S_ISDIR(lstat(path).st_mode))
throw BadURL("path '%s' is not a flake (because it's not a directory)", path);
if (!allowMissing && !pathExists(path + "/flake.nix"))
throw BadURL("path '%s' is not a flake (because it doesn't contain a 'flake.nix' file)", path);
auto flakeRoot = path;
std::string subdir;
while (flakeRoot != "/") {
if (pathExists(flakeRoot + "/.git")) {
auto base = std::string("git+file://") + flakeRoot;
auto parsedURL = ParsedURL{
.url = base, // FIXME
.base = base,
.scheme = "git+file",
.authority = "",
.path = flakeRoot,
.query = decodeQuery(match[2]),
};
if (subdir != "") {
if (parsedURL.query.count("dir"))
throw Error("flake URL '%s' has an inconsistent 'dir' parameter", url);
parsedURL.query.insert_or_assign("dir", subdir);
}
if (pathExists(flakeRoot + "/.git/shallow"))
parsedURL.query.insert_or_assign("shallow", "1");
return std::make_pair(
FlakeRef(Input::fromURL(parsedURL), getOr(parsedURL.query, "dir", "")),
fragment);
}
subdir = std::string(baseNameOf(flakeRoot)) + (subdir.empty() ? "" : "/" + subdir);
flakeRoot = dirOf(flakeRoot);
}
}
} else {
if (!hasPrefix(path, "/"))
throw BadURL("flake reference '%s' is not an absolute path", url);
auto query = decodeQuery(match[2]);
path = canonPath(path + "/" + getOr(query, "dir", ""));
}
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fetchers::Attrs attrs;
attrs.insert_or_assign("type", "path");
attrs.insert_or_assign("path", path);
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return std::make_pair(FlakeRef(Input::fromAttrs(std::move(attrs)), ""), fragment);
}
else {
auto parsedURL = parseURL(url);
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std::string fragment;
std::swap(fragment, parsedURL.fragment);
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auto input = Input::fromURL(parsedURL);
input.parent = baseDir;
return std::make_pair(
FlakeRef(std::move(input), getOr(parsedURL.query, "dir", "")),
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fragment);
}
}
std::optional<std::pair<FlakeRef, std::string>> maybeParseFlakeRefWithFragment(
const std::string & url, const std::optional<Path> & baseDir)
{
try {
return parseFlakeRefWithFragment(url, baseDir);
} catch (Error & e) {
return {};
}
}
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FlakeRef FlakeRef::fromAttrs(const fetchers::Attrs & attrs)
{
auto attrs2(attrs);
attrs2.erase("dir");
return FlakeRef(
fetchers::Input::fromAttrs(std::move(attrs2)),
fetchers::maybeGetStrAttr(attrs, "dir").value_or(""));
}
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std::pair<fetchers::Tree, FlakeRef> FlakeRef::fetchTree(ref<Store> store) const
{
auto [tree, lockedInput] = input.fetch(store);
return {std::move(tree), FlakeRef(std::move(lockedInput), subdir)};
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}
std::tuple<FlakeRef, std::string, ExtendedOutputsSpec> parseFlakeRefWithFragmentAndExtendedOutputsSpec(
const std::string & url,
const std::optional<Path> & baseDir,
bool allowMissing,
bool isFlake)
{
auto [prefix, extendedOutputsSpec] = ExtendedOutputsSpec::parse(url);
auto [flakeRef, fragment] = parseFlakeRefWithFragment(std::string { prefix }, baseDir, allowMissing, isFlake);
return {std::move(flakeRef), fragment, extendedOutputsSpec};
}
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}