lix/src/nix/prefetch.cc

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#include "command.hh"
#include "common-args.hh"
#include "shared.hh"
#include "store-api.hh"
#include "filetransfer.hh"
#include "finally.hh"
#include "progress-bar.hh"
#include "tarfile.hh"
#include "attr-path.hh"
#include "eval-inline.hh"
#include "legacy.hh"
#include <nlohmann/json.hpp>
using namespace nix;
/* If url starts with mirror://, then resolve it using the list of
mirrors defined in Nixpkgs. */
std::string resolveMirrorUrl(EvalState & state, const std::string & url)
{
if (url.substr(0, 9) != "mirror://") return url;
std::string s(url, 9);
auto p = s.find('/');
if (p == std::string::npos) throw Error("invalid mirror URL '%s'", url);
std::string mirrorName(s, 0, p);
Value vMirrors;
// FIXME: use nixpkgs flake
state.eval(state.parseExprFromString("import <nixpkgs/pkgs/build-support/fetchurl/mirrors.nix>", "."), vMirrors);
state.forceAttrs(vMirrors, noPos, "while evaluating the set of all mirrors");
auto mirrorList = vMirrors.attrs->find(state.symbols.create(mirrorName));
if (mirrorList == vMirrors.attrs->end())
throw Error("unknown mirror name '%s'", mirrorName);
state.forceList(*mirrorList->value, noPos, "while evaluating one mirror configuration");
if (mirrorList->value->listSize() < 1)
throw Error("mirror URL '%s' did not expand to anything", url);
std::string mirror(state.forceString(*mirrorList->value->listElems()[0], noPos, "while evaluating the first available mirror"));
return mirror + (hasSuffix(mirror, "/") ? "" : "/") + s.substr(p + 1);
}
std::tuple<StorePath, Hash> prefetchFile(
ref<Store> store,
std::string_view url,
std::optional<std::string> name,
HashType hashType,
std::optional<Hash> expectedHash,
bool unpack,
bool executable)
{
auto ingestionMethod = unpack || executable ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
/* Figure out a name in the Nix store. */
if (!name) {
name = baseNameOf(url);
if (name->empty())
throw Error("cannot figure out file name for '%s'", url);
}
std::optional<StorePath> storePath;
std::optional<Hash> hash;
/* If an expected hash is given, the file may already exist in
the store. */
if (expectedHash) {
hashType = expectedHash->type;
storePath = store->makeFixedOutputPath(ingestionMethod, *expectedHash, *name);
if (store->isValidPath(*storePath))
hash = expectedHash;
else
storePath.reset();
}
if (!storePath) {
AutoDelete tmpDir(createTempDir(), true);
Path tmpFile = (Path) tmpDir + "/tmp";
/* Download the file. */
{
auto mode = 0600;
if (executable)
mode = 0700;
AutoCloseFD fd = open(tmpFile.c_str(), O_WRONLY | O_CREAT | O_EXCL, mode);
if (!fd) throw SysError("creating temporary file '%s'", tmpFile);
FdSink sink(fd.get());
FileTransferRequest req(url);
req.decompress = false;
getFileTransfer()->download(std::move(req), sink);
}
/* Optionally unpack the file. */
if (unpack) {
Activity act(*logger, lvlChatty, actUnknown,
fmt("unpacking '%s'", url));
Path unpacked = (Path) tmpDir + "/unpacked";
createDirs(unpacked);
unpackTarfile(tmpFile, unpacked);
/* If the archive unpacks to a single file/directory, then use
that as the top-level. */
auto entries = readDirectory(unpacked);
if (entries.size() == 1)
tmpFile = unpacked + "/" + entries[0].name;
else
tmpFile = unpacked;
}
Activity act(*logger, lvlChatty, actUnknown,
fmt("adding '%s' to the store", url));
auto info = store->addToStoreSlow(*name, tmpFile, ingestionMethod, hashType, expectedHash);
storePath = info.path;
assert(info.ca);
hash = getContentAddressHash(*info.ca);
}
return {storePath.value(), hash.value()};
}
static int main_nix_prefetch_url(int argc, char * * argv)
{
{
HashType ht = htSHA256;
std::vector<std::string> args;
bool printPath = getEnv("PRINT_PATH") == "1";
bool fromExpr = false;
std::string attrPath;
bool unpack = false;
bool executable = false;
std::optional<std::string> name;
struct MyArgs : LegacyArgs, MixEvalArgs
{
using LegacyArgs::LegacyArgs;
};
MyArgs myArgs(std::string(baseNameOf(argv[0])), [&](Strings::iterator & arg, const Strings::iterator & end) {
if (*arg == "--help")
showManPage("nix-prefetch-url");
else if (*arg == "--version")
printVersion("nix-prefetch-url");
else if (*arg == "--type") {
auto s = getArg(*arg, arg, end);
ht = parseHashType(s);
}
else if (*arg == "--print-path")
printPath = true;
else if (*arg == "--attr" || *arg == "-A") {
fromExpr = true;
attrPath = getArg(*arg, arg, end);
}
else if (*arg == "--unpack")
unpack = true;
else if (*arg == "--executable")
executable = true;
else if (*arg == "--name")
name = getArg(*arg, arg, end);
else if (*arg != "" && arg->at(0) == '-')
return false;
else
args.push_back(*arg);
return true;
});
myArgs.parseCmdline(argvToStrings(argc, argv));
if (args.size() > 2)
throw UsageError("too many arguments");
Finally f([]() { stopProgressBar(); });
if (isatty(STDERR_FILENO))
startProgressBar();
auto store = openStore();
auto state = std::make_unique<EvalState>(myArgs.searchPath, store);
Bindings & autoArgs = *myArgs.getAutoArgs(*state);
/* If -A is given, get the URL from the specified Nix
expression. */
std::string url;
if (!fromExpr) {
if (args.empty())
throw UsageError("you must specify a URL");
url = args[0];
} else {
Path path = resolveExprPath(lookupFileArg(*state, args.empty() ? "." : args[0]));
Value vRoot;
state->evalFile(path, vRoot);
Value & v(*findAlongAttrPath(*state, attrPath, autoArgs, vRoot).first);
state->forceAttrs(v, noPos, "while evaluating the source attribute to prefetch");
/* Extract the URL. */
auto * attr = v.attrs->get(state->symbols.create("urls"));
if (!attr)
throw Error("attribute 'urls' missing");
state->forceList(*attr->value, noPos, "while evaluating the urls to prefetch");
if (attr->value->listSize() < 1)
throw Error("'urls' list is empty");
url = state->forceString(*attr->value->listElems()[0], noPos, "while evaluating the first url from the urls list");
/* Extract the hash mode. */
auto attr2 = v.attrs->get(state->symbols.create("outputHashMode"));
if (!attr2)
printInfo("warning: this does not look like a fetchurl call");
else
unpack = state->forceString(*attr2->value, noPos, "while evaluating the outputHashMode of the source to prefetch") == "recursive";
/* Extract the name. */
if (!name) {
auto attr3 = v.attrs->get(state->symbols.create("name"));
if (!attr3)
name = state->forceString(*attr3->value, noPos, "while evaluating the name of the source to prefetch");
}
}
std::optional<Hash> expectedHash;
if (args.size() == 2)
expectedHash = Hash::parseAny(args[1], ht);
auto [storePath, hash] = prefetchFile(
store, resolveMirrorUrl(*state, url), name, ht, expectedHash, unpack, executable);
stopProgressBar();
if (!printPath)
printInfo("path is '%s'", store->printStorePath(storePath));
std::cout << printHash16or32(hash) << std::endl;
if (printPath)
std::cout << store->printStorePath(storePath) << std::endl;
return 0;
}
}
static RegisterLegacyCommand r_nix_prefetch_url("nix-prefetch-url", main_nix_prefetch_url);
struct CmdStorePrefetchFile : StoreCommand, MixJSON
{
std::string url;
bool executable = false;
std::optional<std::string> name;
HashType hashType = htSHA256;
std::optional<Hash> expectedHash;
CmdStorePrefetchFile()
{
addFlag({
.longName = "name",
.description = "Override the name component of the resulting store path. It defaults to the base name of *url*.",
.labels = {"name"},
.handler = {&name}
});
addFlag({
.longName = "expected-hash",
.description = "The expected hash of the file.",
.labels = {"hash"},
.handler = {[&](std::string s) {
expectedHash = Hash::parseAny(s, hashType);
}}
});
addFlag(Flag::mkHashTypeFlag("hash-type", &hashType));
addFlag({
.longName = "executable",
.description =
"Make the resulting file executable. Note that this causes the "
"resulting hash to be a NAR hash rather than a flat file hash.",
.handler = {&executable, true},
});
expectArg("url", &url);
}
std::string description() override
{
return "download a file into the Nix store";
}
std::string doc() override
{
return
#include "store-prefetch-file.md"
;
}
void run(ref<Store> store) override
{
auto [storePath, hash] = prefetchFile(store, url, name, hashType, expectedHash, false, executable);
if (json) {
auto res = nlohmann::json::object();
res["storePath"] = store->printStorePath(storePath);
res["hash"] = hash.to_string(SRI, true);
logger->cout(res.dump());
} else {
notice("Downloaded '%s' to '%s' (hash '%s').",
url,
store->printStorePath(storePath),
hash.to_string(SRI, true));
}
}
};
static auto rCmdStorePrefetchFile = registerCommand2<CmdStorePrefetchFile>({"store", "prefetch-file"});