lix/src/libstore/download.cc
Eelco Dolstra 38539b943a Add fetchgit builtin
The function builtins.fetchgit fetches Git repositories at evaluation
time, similar to builtins.fetchTarball. (Perhaps the name should be
changed, being confusing with respect to Nixpkgs's fetchgit function,
with works at build time.)

Example:

  (import (builtins.fetchgit git://github.com/NixOS/nixpkgs) {}).hello

or

  (import (builtins.fetchgit {
    url = git://github.com/NixOS/nixpkgs-channels;
    rev = "nixos-16.03";
  }) {}).hello

Note that the result does not contain a .git directory.
2016-04-29 20:47:36 +02:00

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#include "download.hh"
#include "util.hh"
#include "globals.hh"
#include "hash.hh"
#include "store-api.hh"
#include <curl/curl.h>
#include <iostream>
namespace nix {
double getTime()
{
struct timeval tv;
gettimeofday(&tv, 0);
return tv.tv_sec + (tv.tv_usec / 1000000.0);
}
std::string resolveUri(const std::string & uri)
{
if (uri.compare(0, 8, "channel:") == 0)
return "https://nixos.org/channels/" + std::string(uri, 8) + "/nixexprs.tar.xz";
else
return uri;
}
struct CurlDownloader : public Downloader
{
CURL * curl;
ref<std::string> data;
string etag, status, expectedETag;
struct curl_slist * requestHeaders;
bool showProgress;
double prevProgressTime{0}, startTime{0};
unsigned int moveBack{1};
size_t writeCallback(void * contents, size_t size, size_t nmemb)
{
size_t realSize = size * nmemb;
data->append((char *) contents, realSize);
return realSize;
}
static size_t writeCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
{
return ((CurlDownloader *) userp)->writeCallback(contents, size, nmemb);
}
size_t headerCallback(void * contents, size_t size, size_t nmemb)
{
size_t realSize = size * nmemb;
string line = string((char *) contents, realSize);
printMsg(lvlVomit, format("got header: %1%") % trim(line));
if (line.compare(0, 5, "HTTP/") == 0) { // new response starts
etag = "";
auto ss = tokenizeString<vector<string>>(line, " ");
status = ss.size() >= 2 ? ss[1] : "";
} else {
auto i = line.find(':');
if (i != string::npos) {
string name = trim(string(line, 0, i));
if (name == "ETag") { // FIXME: case
etag = trim(string(line, i + 1));
/* Hack to work around a GitHub bug: it sends
ETags, but ignores If-None-Match. So if we get
the expected ETag on a 200 response, then shut
down the connection because we already have the
data. */
printMsg(lvlDebug, format("got ETag: %1%") % etag);
if (etag == expectedETag && status == "200") {
printMsg(lvlDebug, format("shutting down on 200 HTTP response with expected ETag"));
return 0;
}
}
}
}
return realSize;
}
static size_t headerCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
{
return ((CurlDownloader *) userp)->headerCallback(contents, size, nmemb);
}
int progressCallback(double dltotal, double dlnow)
{
if (showProgress) {
double now = getTime();
if (prevProgressTime <= now - 1) {
string s = (format(" [%1$.0f/%2$.0f KiB, %3$.1f KiB/s]")
% (dlnow / 1024.0)
% (dltotal / 1024.0)
% (now == startTime ? 0 : dlnow / 1024.0 / (now - startTime))).str();
std::cerr << "\e[" << moveBack << "D" << s;
moveBack = s.size();
std::cerr.flush();
prevProgressTime = now;
}
}
return _isInterrupted;
}
static int progressCallbackWrapper(void * userp, double dltotal, double dlnow, double ultotal, double ulnow)
{
return ((CurlDownloader *) userp)->progressCallback(dltotal, dlnow);
}
CurlDownloader()
: data(make_ref<std::string>())
{
requestHeaders = 0;
curl = curl_easy_init();
if (!curl) throw nix::Error("unable to initialize curl");
}
~CurlDownloader()
{
if (curl) curl_easy_cleanup(curl);
if (requestHeaders) curl_slist_free_all(requestHeaders);
}
bool fetch(const string & url, const DownloadOptions & options)
{
showProgress =
options.showProgress == DownloadOptions::yes ||
(options.showProgress == DownloadOptions::automatic && isatty(STDERR_FILENO));
curl_easy_reset(curl);
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_USERAGENT, ("Nix/" + nixVersion).c_str());
curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallbackWrapper);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *) this);
curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, headerCallbackWrapper);
curl_easy_setopt(curl, CURLOPT_HEADERDATA, (void *) this);
curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progressCallbackWrapper);
curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, (void *) this);
curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0);
curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
if (options.verifyTLS)
curl_easy_setopt(curl, CURLOPT_CAINFO, getEnv("SSL_CERT_FILE", "/etc/ssl/certs/ca-certificates.crt").c_str());
else {
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
}
data->clear();
if (requestHeaders) {
curl_slist_free_all(requestHeaders);
requestHeaders = 0;
}
if (!options.expectedETag.empty()) {
this->expectedETag = options.expectedETag;
requestHeaders = curl_slist_append(requestHeaders, ("If-None-Match: " + options.expectedETag).c_str());
}
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, requestHeaders);
if (options.head)
curl_easy_setopt(curl, CURLOPT_NOBODY, 1);
if (showProgress) {
std::cerr << (format("downloading %1%... ") % url);
std::cerr.flush();
startTime = getTime();
}
CURLcode res = curl_easy_perform(curl);
if (showProgress)
//std::cerr << "\e[" << moveBack << "D\e[K\n";
std::cerr << "\n";
checkInterrupt();
if (res == CURLE_WRITE_ERROR && etag == options.expectedETag) return false;
long httpStatus = -1;
curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &httpStatus);
if (res != CURLE_OK) {
Error err =
httpStatus == 404 ? NotFound :
httpStatus == 403 ? Forbidden : Misc;
throw DownloadError(err, format("unable to download %1%: %2% (%3%)")
% url % curl_easy_strerror(res) % res);
}
if (httpStatus == 304) return false;
return true;
}
DownloadResult download(string url, const DownloadOptions & options) override
{
DownloadResult res;
if (fetch(resolveUri(url), options)) {
res.cached = false;
res.data = data;
} else
res.cached = true;
res.etag = etag;
return res;
}
};
ref<Downloader> makeDownloader()
{
return make_ref<CurlDownloader>();
}
Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpack)
{
auto url = resolveUri(url_);
Path cacheDir = getCacheDir() + "/nix/tarballs";
createDirs(cacheDir);
string urlHash = printHash32(hashString(htSHA256, url));
Path dataFile = cacheDir + "/" + urlHash + ".info";
Path fileLink = cacheDir + "/" + urlHash + "-file";
Path storePath;
string expectedETag;
int ttl = settings.get("tarball-ttl", 60 * 60);
bool skip = false;
if (pathExists(fileLink) && pathExists(dataFile)) {
storePath = readLink(fileLink);
store->addTempRoot(storePath);
if (store->isValidPath(storePath)) {
auto ss = tokenizeString<vector<string>>(readFile(dataFile), "\n");
if (ss.size() >= 3 && ss[0] == url) {
time_t lastChecked;
if (string2Int(ss[2], lastChecked) && lastChecked + ttl >= time(0))
skip = true;
else if (!ss[1].empty()) {
printMsg(lvlDebug, format("verifying previous ETag %1%") % ss[1]);
expectedETag = ss[1];
}
}
} else
storePath = "";
}
string name;
auto p = url.rfind('/');
if (p != string::npos) name = string(url, p + 1);
if (!skip) {
try {
DownloadOptions options;
options.expectedETag = expectedETag;
auto res = download(url, options);
if (!res.cached)
storePath = store->addTextToStore(name, *res.data, PathSet(), false);
assert(!storePath.empty());
replaceSymlink(storePath, fileLink);
writeFile(dataFile, url + "\n" + res.etag + "\n" + std::to_string(time(0)) + "\n");
} catch (DownloadError & e) {
if (storePath.empty()) throw;
printMsg(lvlError, format("warning: %1%; using cached result") % e.msg());
}
}
if (unpack) {
Path unpackedLink = cacheDir + "/" + baseNameOf(storePath) + "-unpacked";
Path unpackedStorePath;
if (pathExists(unpackedLink)) {
unpackedStorePath = readLink(unpackedLink);
store->addTempRoot(unpackedStorePath);
if (!store->isValidPath(unpackedStorePath))
unpackedStorePath = "";
}
if (unpackedStorePath.empty()) {
printMsg(lvlInfo, format("unpacking %1%...") % url);
Path tmpDir = createTempDir();
AutoDelete autoDelete(tmpDir, true);
// FIXME: this requires GNU tar for decompression.
runProgram("tar", true, {"xf", storePath, "-C", tmpDir, "--strip-components", "1"}, "");
unpackedStorePath = store->addToStore(name, tmpDir, true, htSHA256, defaultPathFilter, false);
}
replaceSymlink(unpackedStorePath, unpackedLink);
return unpackedStorePath;
}
return storePath;
}
bool isUri(const string & s)
{
if (s.compare(0, 8, "channel:") == 0) return true;
size_t pos = s.find("://");
if (pos == string::npos) return false;
string scheme(s, 0, pos);
return scheme == "http" || scheme == "https" || scheme == "file" || scheme == "channel" || scheme == "git";
}
}