lix/src/libstore/builtins/fetchurl.cc
Eelco Dolstra bbe97dff8b Make the Store API more type-safe
Most functions now take a StorePath argument rather than a Path (which
is just an alias for std::string). The StorePath constructor ensures
that the path is syntactically correct (i.e. it looks like
<store-dir>/<base32-hash>-<name>). Similarly, functions like
buildPaths() now take a StorePathWithOutputs, rather than abusing Path
by adding a '!<outputs>' suffix.

Note that the StorePath type is implemented in Rust. This involves
some hackery to allow Rust values to be used directly in C++, via a
helper type whose destructor calls the Rust type's drop()
function. The main issue is the dynamic nature of C++ move semantics:
after we have moved a Rust value, we should not call the drop function
on the original value. So when we move a value, we set the original
value to bitwise zero, and the destructor only calls drop() if the
value is not bitwise zero. This should be sufficient for most types.

Also lots of minor cleanups to the C++ API to make it more modern
(e.g. using std::optional and std::string_view in some places).
2019-12-10 22:06:05 +01:00

79 lines
2.6 KiB
C++

#include "builtins.hh"
#include "download.hh"
#include "store-api.hh"
#include "archive.hh"
#include "compression.hh"
namespace nix {
void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
{
/* Make the host's netrc data available. Too bad curl requires
this to be stored in a file. It would be nice if we could just
pass a pointer to the data. */
if (netrcData != "") {
settings.netrcFile = "netrc";
writeFile(settings.netrcFile, netrcData, 0600);
}
auto getAttr = [&](const string & name) {
auto i = drv.env.find(name);
if (i == drv.env.end()) throw Error(format("attribute '%s' missing") % name);
return i->second;
};
Path storePath = getAttr("out");
auto mainUrl = getAttr("url");
bool unpack = get(drv.env, "unpack").value_or("") == "1";
/* Note: have to use a fresh downloader here because we're in
a forked process. */
auto downloader = makeDownloader();
auto fetch = [&](const std::string & url) {
auto source = sinkToSource([&](Sink & sink) {
/* No need to do TLS verification, because we check the hash of
the result anyway. */
DownloadRequest request(url);
request.verifyTLS = false;
request.decompress = false;
auto decompressor = makeDecompressionSink(
unpack && hasSuffix(mainUrl, ".xz") ? "xz" : "none", sink);
downloader->download(std::move(request), *decompressor);
decompressor->finish();
});
if (unpack)
restorePath(storePath, *source);
else
writeFile(storePath, *source);
auto executable = drv.env.find("executable");
if (executable != drv.env.end() && executable->second == "1") {
if (chmod(storePath.c_str(), 0755) == -1)
throw SysError(format("making '%1%' executable") % storePath);
}
};
/* Try the hashed mirrors first. */
if (getAttr("outputHashMode") == "flat")
for (auto hashedMirror : settings.hashedMirrors.get())
try {
if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
auto ht = parseHashType(getAttr("outputHashAlgo"));
auto h = Hash(getAttr("outputHash"), ht);
fetch(hashedMirror + printHashType(h.type) + "/" + h.to_string(Base16, false));
return;
} catch (Error & e) {
debug(e.what());
}
/* Otherwise try the specified URL. */
fetch(mainUrl);
}
}