Add 'third_party/nix/' from commit 'be66c7a6b24e3c3c6157fd37b86c7203d14acf10'

git-subtree-dir: third_party/nix
git-subtree-mainline: cf8cd640c1
git-subtree-split: be66c7a6b24e3c3c6157fd37b86c7203d14acf10

third_party/nix/src/libstore/builtins/fetchurl.cc

@@ -0,0 +1,78 @@
+#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", "") == "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);
+}
+
+}