lix/src/libexpr/primops/flake.cc

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#include "primops.hh"
#include "eval-inline.hh"
#include "fetchGit.hh"
#include "download.hh"
#include <queue>
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#include <regex>
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#include <nlohmann/json.hpp>
namespace nix {
const EvalState::FlakeRegistry & EvalState::getFlakeRegistry()
{
std::call_once(_flakeRegistryInit, [&]()
{
_flakeRegistry = std::make_unique<FlakeRegistry>();
if (!evalSettings.pureEval) {
auto registryUri = "file:///home/eelco/Dev/gists/nix-flakes/registry.json";
auto registryFile = getDownloader()->download(DownloadRequest(registryUri));
auto json = nlohmann::json::parse(*registryFile.data);
auto version = json.value("version", 0);
if (version != 1)
throw Error("flake registry '%s' has unsupported version %d", registryUri, version);
auto flakes = json["flakes"];
for (auto i = flakes.begin(); i != flakes.end(); ++i) {
FlakeRegistry::Entry entry;
entry.uri = i->value("uri", "");
if (entry.uri.empty())
throw Error("invalid flake registry entry");
_flakeRegistry->entries.emplace(i.key(), entry);
}
}
});
return *_flakeRegistry;
}
static void prim_flakeRegistry(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
auto registry = state.getFlakeRegistry();
state.mkAttrs(v, registry.entries.size());
for (auto & entry : registry.entries) {
auto vEntry = state.allocAttr(v, entry.first);
state.mkAttrs(*vEntry, 2);
mkString(*state.allocAttr(*vEntry, state.symbols.create("uri")), entry.second.uri);
vEntry->attrs->sort();
}
v.attrs->sort();
}
static RegisterPrimOp r1("__flakeRegistry", 0, prim_flakeRegistry);
struct Flake
{
std::string name;
std::string description;
Path path;
std::set<std::string> requires;
Value * vProvides; // FIXME: gc
};
std::regex flakeRegex("^flake:([a-zA-Z][a-zA-Z0-9_-]*)(/[a-zA-Z][a-zA-Z0-9_.-]*)?$");
std::regex githubRegex("^github:([a-zA-Z][a-zA-Z0-9_-]*)/([a-zA-Z][a-zA-Z0-9_-]*)(/([a-zA-Z][a-zA-Z0-9_-]*))?$");
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static Path fetchFlake(EvalState & state, const std::string & flakeUri)
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{
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std::smatch match;
if (std::regex_match(flakeUri, match, flakeRegex)) {
auto flakeName = match[1];
auto revOrRef = match[2];
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auto registry = state.getFlakeRegistry();
auto i = registry.entries.find(flakeName);
if (i == registry.entries.end())
throw Error("unknown flake '%s'", flakeName);
return fetchFlake(state, i->second.uri);
}
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else if (std::regex_match(flakeUri, match, githubRegex)) {
auto owner = match[1];
auto repo = match[2];
auto revOrRef = match[4].str();
if (revOrRef.empty()) revOrRef = "master";
// FIXME: require hash in pure mode.
// FIXME: use regular /archive URLs instead? api.github.com
// might have stricter rate limits.
auto storePath = getDownloader()->downloadCached(state.store,
fmt("https://api.github.com/repos/%s/%s/tarball/%s", owner, repo, revOrRef),
true, "source");
// FIXME: extract revision hash from ETag.
return storePath;
}
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else if (hasPrefix(flakeUri, "/") || hasPrefix(flakeUri, "git://")) {
auto gitInfo = exportGit(state.store, flakeUri, {}, "", "source");
return gitInfo.storePath;
}
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else
throw Error("unsupported flake URI '%s'", flakeUri);
}
static Flake getFlake(EvalState & state, const std::string & flakeUri)
{
auto flakePath = fetchFlake(state, flakeUri);
state.store->assertStorePath(flakePath);
Flake flake;
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Value vInfo;
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state.evalFile(flakePath + "/flake.nix", vInfo);
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state.forceAttrs(vInfo);
if (auto name = vInfo.attrs->get(state.sName))
flake.name = state.forceStringNoCtx(*(**name).value, *(**name).pos);
else
throw Error("flake lacks attribute 'name'");
if (auto description = vInfo.attrs->get(state.sDescription))
flake.description = state.forceStringNoCtx(*(**description).value, *(**description).pos);
if (auto requires = vInfo.attrs->get(state.symbols.create("requires"))) {
state.forceList(*(**requires).value, *(**requires).pos);
for (unsigned int n = 0; n < (**requires).value->listSize(); ++n)
flake.requires.insert(state.forceStringNoCtx(
*(**requires).value->listElems()[n], *(**requires).pos));
}
if (auto provides = vInfo.attrs->get(state.symbols.create("provides"))) {
state.forceFunction(*(**provides).value, *(**provides).pos);
flake.vProvides = (**provides).value;
} else
throw Error("flake lacks attribute 'provides'");
return flake;
}
static std::map<std::string, Flake> resolveFlakes(EvalState & state, const StringSet & flakeUris)
{
std::map<std::string, Flake> done;
std::queue<std::string> todo;
for (auto & i : flakeUris) todo.push(i);
while (!todo.empty()) {
auto flakeUri = todo.front();
todo.pop();
if (done.count(flakeUri)) continue;
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auto flake = getFlake(state, flakeUri);
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for (auto & require : flake.requires)
todo.push(require);
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done.emplace(flake.name, flake);
}
return done;
}
static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
std::string flakeUri = state.forceStringNoCtx(*args[0], pos);
auto flakes = resolveFlakes(state, {flakeUri});
auto vResult = state.allocValue();
state.mkAttrs(*vResult, flakes.size());
for (auto & flake : flakes) {
auto vFlake = state.allocAttr(*vResult, flake.second.name);
state.mkAttrs(*vFlake, 2);
mkString(*state.allocAttr(*vFlake, state.sDescription), flake.second.description);
auto vProvides = state.allocAttr(*vFlake, state.symbols.create("provides"));
mkApp(*vProvides, *flake.second.vProvides, *vResult);
vFlake->attrs->sort();
}
vResult->attrs->sort();
v = *vResult;
}
static RegisterPrimOp r2("getFlake", 1, prim_getFlake);
}