Add fetchTarball builtin

This function downloads and unpacks the given URL at evaluation
time. This is primarily intended to make it easier to deal with Nix
expressions that have external dependencies. For instance, to fetch
Nixpkgs 14.12:

  with import (fetchTarball https://github.com/NixOS/nixpkgs-channels/archive/nixos-14.12.tar.gz) {};

Or to fetch a specific revision:

  with import (fetchTarball 2766a4b44e.tar.gz) {};

This patch also adds a ‘fetchurl’ builtin that downloads but doesn't
unpack its argument. Not sure if it's useful though.
This commit is contained in:
Eelco Dolstra 2015-03-25 17:12:07 +01:00
parent 7ea6ecf855
commit 000b5a000f
2 changed files with 120 additions and 1 deletions

View file

@ -8,7 +8,7 @@ libexpr_SOURCES := $(wildcard $(d)/*.cc) $(d)/lexer-tab.cc $(d)/parser-tab.cc
libexpr_LIBS = libutil libstore libformat
libexpr_LDFLAGS = -ldl
libexpr_LDFLAGS = -ldl -lcurl
# The dependency on libgc must be propagated (i.e. meaning that
# programs/libraries that use libexpr must explicitly pass -lgc),

View file

@ -18,6 +18,8 @@
#include <cstring>
#include <dlfcn.h>
#include <curl/curl.h>
namespace nix {
@ -1479,6 +1481,119 @@ static void prim_compareVersions(EvalState & state, const Pos & pos, Value * * a
}
/*************************************************************
* Networking
*************************************************************/
struct Curl
{
CURL * curl;
string data;
static size_t writeCallback(void * contents, size_t size, size_t nmemb, void * userp)
{
Curl & c(* (Curl *) userp);
size_t realSize = size * nmemb;
c.data.append((char *) contents, realSize);
return realSize;
}
Curl()
{
curl = curl_easy_init();
if (!curl) throw Error("unable to initialize curl");
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_CAINFO, getEnv("SSL_CERT_FILE", "/etc/ssl/certs/ca-certificates.crt").c_str());
curl_easy_setopt(curl, CURLOPT_USERAGENT, ("Nix/" + nixVersion).c_str());
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallback);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *) &curl);
}
~Curl()
{
if (curl) curl_easy_cleanup(curl);
}
string fetch(const string & url)
{
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
data.clear();
CURLcode res = curl_easy_perform(curl);
if (res != CURLE_OK)
throw Error(format("unable to download %1%: %2%")
% url % curl_easy_strerror(res));
return data;
}
};
void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
const string & who, bool unpack)
{
if (state.restricted) throw Error(format("%1% is not allowed in restricted mode") % who);
string url;
state.forceValue(*args[0]);
if (args[0]->type == tAttrs) {
state.forceAttrs(*args[0], pos);
for (auto & attr : *args[0]->attrs) {
string name(attr.name);
if (name == "url")
url = state.forceStringNoCtx(*attr.value, *attr.pos);
else
throw EvalError(format("unsupported argument %1% to %2%, at %3%") % attr.name % who % attr.pos);
}
if (url.empty())
throw EvalError(format("url argument required, at %1%") % pos);
} else
url = state.forceStringNoCtx(*args[0], pos);
// TODO: cache downloads.
Curl curl;
string data = curl.fetch(url);
string name;
string::size_type p = url.rfind('/');
if (p != string::npos) name = string(url, p + 1);
Path storePath = store->addTextToStore(name, data, PathSet(), state.repair);
if (unpack) {
Path tmpDir = createTempDir();
AutoDelete autoDelete(tmpDir, true);
runProgram("tar", true, {"xf", storePath, "-C", tmpDir, "--strip-components", "1"}, "");
storePath = store->addToStore(name, tmpDir, true, htSHA256, defaultPathFilter, state.repair);
}
mkString(v, storePath, singleton<PathSet>(storePath));
}
static void prim_fetchurl(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
fetch(state, pos, args, v, "fetchurl", false);
}
static void prim_fetchTarball(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
fetch(state, pos, args, v, "fetchTarball", true);
}
/*************************************************************
* Primop registration
*************************************************************/
@ -1617,6 +1732,10 @@ void EvalState::createBaseEnv()
// Derivations
addPrimOp("derivationStrict", 1, prim_derivationStrict);
// Networking
addPrimOp("__fetchurl", 1, prim_fetchurl);
addPrimOp("fetchTarball", 1, prim_fetchTarball);
/* Add a wrapper around the derivation primop that computes the
`drvPath' and `outPath' attributes lazily. */
string path = findFile("nix/derivation.nix");