Merge remote-tracking branch 'origin/master' into flakes

23 files changed, 175 insertions, 156 deletions

diff --git a/src/libexpr/common-eval-args.cc b/src/libexpr/common-eval-args.cc
index f965c194f..47a57f91c 100644
--- a/src/libexpr/common-eval-args.cc
+++ b/src/libexpr/common-eval-args.cc
@@ -1,6 +1,6 @@
 #include "common-eval-args.hh"
 #include "shared.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "util.hh"
 #include "eval.hh"
 #include "fetchers.hh"
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 6fcb2917c..c5945adf0 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -5,7 +5,7 @@
 #include "derivations.hh"
 #include "globals.hh"
 #include "eval-inline.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "json.hh"
 #include "function-trace.hh"
 #include "flake/flake.hh"
@@ -1296,7 +1296,7 @@ void ExprWith::eval(EvalState & state, Env & env, Value & v)
 
 void ExprIf::eval(EvalState & state, Env & env, Value & v)
 {
-    (state.evalBool(env, cond) ? then : else_)->eval(state, env, v);
+    (state.evalBool(env, cond, pos) ? then : else_)->eval(state, env, v);
 }
 
 
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index f7e9105a4..25798cac6 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -209,9 +209,10 @@ struct ExprList : Expr
 
 struct Formal
 {
+    Pos pos;
     Symbol name;
     Expr * def;
-    Formal(const Symbol & name, Expr * def) : name(name), def(def) { };
+    Formal(const Pos & pos, const Symbol & name, Expr * def) : pos(pos), name(name), def(def) { };
 };
 
 struct Formals
@@ -261,8 +262,9 @@ struct ExprWith : Expr
 
 struct ExprIf : Expr
 {
+    Pos pos;
     Expr * cond, * then, * else_;
-    ExprIf(Expr * cond, Expr * then, Expr * else_) : cond(cond), then(then), else_(else_) { };
+    ExprIf(const Pos & pos, Expr * cond, Expr * then, Expr * else_) : pos(pos), cond(cond), then(then), else_(else_) { };
     COMMON_METHODS
 };
 
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index a30fb44b5..1993fa6c1 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -335,7 +335,7 @@ expr_function
   ;
 
 expr_if
-  : IF expr THEN expr ELSE expr { $$ = new ExprIf($2, $4, $6); }
+  : IF expr THEN expr ELSE expr { $$ = new ExprIf(CUR_POS, $2, $4, $6); }
   | expr_op
   ;
 
@@ -531,8 +531,8 @@ formals
   ;
 
 formal
-  : ID { $$ = new Formal(data->symbols.create($1), 0); }
-  | ID '?' expr { $$ = new Formal(data->symbols.create($1), $3); }
+  : ID { $$ = new Formal(CUR_POS, data->symbols.create($1), 0); }
+  | ID '?' expr { $$ = new Formal(CUR_POS, data->symbols.create($1), $3); }
   ;
 
 %%
@@ -544,7 +544,7 @@ formal
 #include <unistd.h>
 
 #include "eval.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "fetchers.hh"
 #include "store-api.hh"
 
@@ -690,7 +690,7 @@ std::pair<bool, std::string> EvalState::resolveSearchPathElem(const SearchPathEl
         try {
             res = { true, store->toRealPath(fetchers::downloadTarball(
                         store, resolveUri(elem.second), "source", false).storePath) };
-        } catch (DownloadError & e) {
+        } catch (FileTransferError & e) {
             printError(format("warning: Nix search path entry '%1%' cannot be downloaded, ignoring") % elem.second);
             res = { false, "" };
         }
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index fb7d5497b..ed0a97757 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1354,9 +1354,12 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
     }
 
     state.mkAttrs(v, args[0]->lambda.fun->formals->formals.size());
-    for (auto & i : args[0]->lambda.fun->formals->formals)
+    for (auto & i : args[0]->lambda.fun->formals->formals) {
         // !!! should optimise booleans (allocate only once)
-        mkBool(*state.allocAttr(v, i.name), i.def);
+        Value * value = state.allocValue();
+        v.attrs->push_back(Attr(i.name, value, &i.pos));
+        mkBool(*value, i.def);
+    }
     v.attrs->sort();
 }
 
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 4f66fc6c1..9d1f5b8d4 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -2,7 +2,7 @@
 #include "eval-inline.hh"
 #include "store-api.hh"
 #include "fetchers.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "registry.hh"
 
 #include <ctime>
diff --git a/src/libfetchers/github.cc b/src/libfetchers/github.cc
index f50c927eb..c01917dcc 100644
--- a/src/libfetchers/github.cc
+++ b/src/libfetchers/github.cc
@@ -1,4 +1,4 @@
-#include "download.hh"
+#include "filetransfer.hh"
 #include "cache.hh"
 #include "fetchers.hh"
 #include "globals.hh"
diff --git a/src/libfetchers/tarball.cc b/src/libfetchers/tarball.cc
index 4c4e5828e..695525b31 100644
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@@ -1,6 +1,6 @@
 #include "fetchers.hh"
 #include "cache.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "globals.hh"
 #include "store-api.hh"
 #include "archive.hh"
@@ -36,13 +36,13 @@ DownloadFileResult downloadFile(
     if (cached && !cached->expired)
         return useCached();
 
-    DownloadRequest request(url);
+    FileTransferRequest request(url);
     if (cached)
         request.expectedETag = getStrAttr(cached->infoAttrs, "etag");
-    DownloadResult res;
+    FileTransferResult res;
     try {
-        res = getDownloader()->download(request);
-    } catch (DownloadError & e) {
+        res = getFileTransfer()->download(request);
+    } catch (FileTransferError & e) {
         if (cached) {
             warn("%s; using cached version", e.msg());
             return useCached();
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 527d7ac42..0febb8dfb 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -7,7 +7,7 @@
 #include "affinity.hh"
 #include "builtins.hh"
 #include "builtins/buildenv.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "finally.hh"
 #include "compression.hh"
 #include "json.hh"
@@ -361,7 +361,7 @@ public:
     {
         actDerivations.progress(doneBuilds, expectedBuilds + doneBuilds, runningBuilds, failedBuilds);
         actSubstitutions.progress(doneSubstitutions, expectedSubstitutions + doneSubstitutions, runningSubstitutions, failedSubstitutions);
-        act.setExpected(actDownload, expectedDownloadSize + doneDownloadSize);
+        act.setExpected(actFileTransfer, expectedDownloadSize + doneDownloadSize);
         act.setExpected(actCopyPath, expectedNarSize + doneNarSize);
     }
 };
@@ -2161,7 +2161,7 @@ void DerivationGoal::startBuilder()
     if (needsHashRewrite()) {
 
         if (pathExists(homeDir))
-            throw Error(format("directory '%1%' exists; please remove it") % homeDir);
+            throw Error(format("home directory '%1%' exists; please remove it to assure purity of builds without sandboxing") % homeDir);
 
         /* We're not doing a chroot build, but we have some valid
            output paths.  Since we can't just overwrite or delete
diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc
index f6ae5d2e6..486babf14 100644
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@@ -1,5 +1,5 @@
 #include "builtins.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "store-api.hh"
 #include "archive.hh"
 #include "compression.hh"
@@ -26,9 +26,9 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
     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
+    /* Note: have to use a fresh fileTransfer here because we're in
        a forked process. */
-    auto downloader = makeDownloader();
+    auto fileTransfer = makeFileTransfer();
 
     auto fetch = [&](const std::string & url) {
 
@@ -36,13 +36,13 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
 
             /* No need to do TLS verification, because we check the hash of
                the result anyway. */
-            DownloadRequest request(url);
+            FileTransferRequest request(url);
             request.verifyTLS = false;
             request.decompress = false;
 
             auto decompressor = makeDecompressionSink(
                 unpack && hasSuffix(mainUrl, ".xz") ? "xz" : "none", sink);
-            downloader->download(std::move(request), *decompressor);
+            fileTransfer->download(std::move(request), *decompressor);
             decompressor->finish();
         });
 
diff --git a/src/libstore/download.cc b/src/libstore/filetransfer.cc
index af69699a8..e9684b3d4 100644
--- a/src/libstore/download.cc
+++ b/src/libstore/filetransfer.cc
@@ -1,4 +1,4 @@
-#include "download.hh"
+#include "filetransfer.hh"
 #include "util.hh"
 #include "globals.hh"
 #include "store-api.hh"
@@ -27,9 +27,9 @@ using namespace std::string_literals;
 
 namespace nix {
 
-DownloadSettings downloadSettings;
+FileTransferSettings fileTransferSettings;
 
-static GlobalConfig::Register r1(&downloadSettings);
+static GlobalConfig::Register r1(&fileTransferSettings);
 
 std::string resolveUri(const std::string & uri)
 {
@@ -39,21 +39,21 @@ std::string resolveUri(const std::string & uri)
         return uri;
 }
 
-struct CurlDownloader : public Downloader
+struct curlFileTransfer : public FileTransfer
 {
     CURLM * curlm = 0;
 
     std::random_device rd;
     std::mt19937 mt19937;
 
-    struct DownloadItem : public std::enable_shared_from_this<DownloadItem>
+    struct TransferItem : public std::enable_shared_from_this<TransferItem>
     {
-        CurlDownloader & downloader;
-        DownloadRequest request;
-        DownloadResult result;
+        curlFileTransfer & fileTransfer;
+        FileTransferRequest request;
+        FileTransferResult result;
         Activity act;
         bool done = false; // whether either the success or failure function has been called
-        Callback<DownloadResult> callback;
+        Callback<FileTransferResult> callback;
         CURL * req = 0;
         bool active = false; // whether the handle has been added to the multi object
         std::string status;
@@ -72,19 +72,26 @@ struct CurlDownloader : public Downloader
 
         curl_off_t writtenToSink = 0;
 
-        DownloadItem(CurlDownloader & downloader,
-            const DownloadRequest & request,
-            Callback<DownloadResult> && callback)
-            : downloader(downloader)
+        TransferItem(curlFileTransfer & fileTransfer,
+            const FileTransferRequest & request,
+            Callback<FileTransferResult> && callback)
+            : fileTransfer(fileTransfer)
             , request(request)
-            , act(*logger, lvlTalkative, actDownload,
+            , act(*logger, lvlTalkative, actFileTransfer,
                 fmt(request.data ? "uploading '%s'" : "downloading '%s'", request.uri),
                 {request.uri}, request.parentAct)
             , callback(std::move(callback))
             , finalSink([this](const unsigned char * data, size_t len) {
                 if (this->request.dataCallback) {
-                    writtenToSink += len;
-                    this->request.dataCallback((char *) data, len);
+                    long httpStatus = 0;
+                    curl_easy_getinfo(req, CURLINFO_RESPONSE_CODE, &httpStatus);
+
+                    /* Only write data to the sink if this is a
+                       successful response. */
+                    if (httpStatus == 0 || httpStatus == 200 || httpStatus == 201 || httpStatus == 206) {
+                        writtenToSink += len;
+                        this->request.dataCallback((char *) data, len);
+                    }
                 } else
                     this->result.data->append((char *) data, len);
               })
@@ -95,17 +102,17 @@ struct CurlDownloader : public Downloader
                 requestHeaders = curl_slist_append(requestHeaders, ("Content-Type: " + request.mimeType).c_str());
         }
 
-        ~DownloadItem()
+        ~TransferItem()
         {
             if (req) {
                 if (active)
-                    curl_multi_remove_handle(downloader.curlm, req);
+                    curl_multi_remove_handle(fileTransfer.curlm, req);
                 curl_easy_cleanup(req);
             }
             if (requestHeaders) curl_slist_free_all(requestHeaders);
             try {
                 if (!done)
-                    fail(DownloadError(Interrupted, format("download of '%s' was interrupted") % request.uri));
+                    fail(FileTransferError(Interrupted, format("download of '%s' was interrupted") % request.uri));
             } catch (...) {
                 ignoreException();
             }
@@ -149,7 +156,7 @@ struct CurlDownloader : public Downloader
 
         static size_t writeCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
         {
-            return ((DownloadItem *) userp)->writeCallback(contents, size, nmemb);
+            return ((TransferItem *) userp)->writeCallback(contents, size, nmemb);
         }
 
         size_t headerCallback(void * contents, size_t size, size_t nmemb)
@@ -191,7 +198,7 @@ struct CurlDownloader : public Downloader
 
         static size_t headerCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
         {
-            return ((DownloadItem *) userp)->headerCallback(contents, size, nmemb);
+            return ((TransferItem *) userp)->headerCallback(contents, size, nmemb);
         }
 
         int progressCallback(double dltotal, double dlnow)
@@ -206,7 +213,7 @@ struct CurlDownloader : public Downloader
 
         static int progressCallbackWrapper(void * userp, double dltotal, double dlnow, double ultotal, double ulnow)
         {
-            return ((DownloadItem *) userp)->progressCallback(dltotal, dlnow);
+            return ((TransferItem *) userp)->progressCallback(dltotal, dlnow);
         }
 
         static int debugCallback(CURL * handle, curl_infotype type, char * data, size_t size, void * userptr)
@@ -230,7 +237,7 @@ struct CurlDownloader : public Downloader
 
         static size_t readCallbackWrapper(char *buffer, size_t size, size_t nitems, void * userp)
         {
-            return ((DownloadItem *) userp)->readCallback(buffer, size, nitems);
+            return ((TransferItem *) userp)->readCallback(buffer, size, nitems);
         }
 
         void init()
@@ -241,7 +248,7 @@ struct CurlDownloader : public Downloader
 
             if (verbosity >= lvlVomit) {
                 curl_easy_setopt(req, CURLOPT_VERBOSE, 1);
-                curl_easy_setopt(req, CURLOPT_DEBUGFUNCTION, DownloadItem::debugCallback);
+                curl_easy_setopt(req, CURLOPT_DEBUGFUNCTION, TransferItem::debugCallback);
             }
 
             curl_easy_setopt(req, CURLOPT_URL, request.uri.c_str());
@@ -250,19 +257,19 @@ struct CurlDownloader : public Downloader
             curl_easy_setopt(req, CURLOPT_NOSIGNAL, 1);
             curl_easy_setopt(req, CURLOPT_USERAGENT,
                 ("curl/" LIBCURL_VERSION " Nix/" + nixVersion +
-                    (downloadSettings.userAgentSuffix != "" ? " " + downloadSettings.userAgentSuffix.get() : "")).c_str());
+                    (fileTransferSettings.userAgentSuffix != "" ? " " + fileTransferSettings.userAgentSuffix.get() : "")).c_str());
             #if LIBCURL_VERSION_NUM >= 0x072b00
             curl_easy_setopt(req, CURLOPT_PIPEWAIT, 1);
             #endif
             #if LIBCURL_VERSION_NUM >= 0x072f00
-            if (downloadSettings.enableHttp2)
+            if (fileTransferSettings.enableHttp2)
                 curl_easy_setopt(req, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS);
             else
                 curl_easy_setopt(req, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
             #endif
-            curl_easy_setopt(req, CURLOPT_WRITEFUNCTION, DownloadItem::writeCallbackWrapper);
+            curl_easy_setopt(req, CURLOPT_WRITEFUNCTION, TransferItem::writeCallbackWrapper);
             curl_easy_setopt(req, CURLOPT_WRITEDATA, this);
-            curl_easy_setopt(req, CURLOPT_HEADERFUNCTION, DownloadItem::headerCallbackWrapper);
+            curl_easy_setopt(req, CURLOPT_HEADERFUNCTION, TransferItem::headerCallbackWrapper);
             curl_easy_setopt(req, CURLOPT_HEADERDATA, this);
 
             curl_easy_setopt(req, CURLOPT_PROGRESSFUNCTION, progressCallbackWrapper);
@@ -290,10 +297,10 @@ struct CurlDownloader : public Downloader
                 curl_easy_setopt(req, CURLOPT_SSL_VERIFYHOST, 0);
             }
 
-            curl_easy_setopt(req, CURLOPT_CONNECTTIMEOUT, downloadSettings.connectTimeout.get());
+            curl_easy_setopt(req, CURLOPT_CONNECTTIMEOUT, fileTransferSettings.connectTimeout.get());
 
             curl_easy_setopt(req, CURLOPT_LOW_SPEED_LIMIT, 1L);
-            curl_easy_setopt(req, CURLOPT_LOW_SPEED_TIME, downloadSettings.stalledDownloadTimeout.get());
+            curl_easy_setopt(req, CURLOPT_LOW_SPEED_TIME, fileTransferSettings.stalledDownloadTimeout.get());
 
             /* If no file exist in the specified path, curl continues to work
                anyway as if netrc support was disabled. */
@@ -394,14 +401,14 @@ struct CurlDownloader : public Downloader
 
                 auto exc =
                     code == CURLE_ABORTED_BY_CALLBACK && _isInterrupted
-                    ? DownloadError(Interrupted, fmt("%s of '%s' was interrupted", request.verb(), request.uri))
+                    ? FileTransferError(Interrupted, fmt("%s of '%s' was interrupted", request.verb(), request.uri))
                     : httpStatus != 0
-                    ? DownloadError(err,
+                    ? FileTransferError(err,
                         fmt("unable to %s '%s': HTTP error %d",
                             request.verb(), request.uri, httpStatus)
                         + (code == CURLE_OK ? "" : fmt(" (curl error: %s)", curl_easy_strerror(code)))
                         )
-                    : DownloadError(err,
+                    : FileTransferError(err,
                         fmt("unable to %s '%s': %s (%d)",
                             request.verb(), request.uri, curl_easy_strerror(code), code));
 
@@ -415,13 +422,13 @@ struct CurlDownloader : public Downloader
                         || writtenToSink == 0
                         || (acceptRanges && encoding.empty())))
                 {
-                    int ms = request.baseRetryTimeMs * std::pow(2.0f, attempt - 1 + std::uniform_real_distribution<>(0.0, 0.5)(downloader.mt19937));
+                    int ms = request.baseRetryTimeMs * std::pow(2.0f, attempt - 1 + std::uniform_real_distribution<>(0.0, 0.5)(fileTransfer.mt19937));
                     if (writtenToSink)
                         warn("%s; retrying from offset %d in %d ms", exc.what(), writtenToSink, ms);
                     else
                         warn("%s; retrying in %d ms", exc.what(), ms);
                     embargo = std::chrono::steady_clock::now() + std::chrono::milliseconds(ms);
-                    downloader.enqueueItem(shared_from_this());
+                    fileTransfer.enqueueItem(shared_from_this());
                 }
                 else
                     fail(exc);
@@ -432,12 +439,12 @@ struct CurlDownloader : public Downloader
     struct State
     {
         struct EmbargoComparator {
-            bool operator() (const std::shared_ptr<DownloadItem> & i1, const std::shared_ptr<DownloadItem> & i2) {
+            bool operator() (const std::shared_ptr<TransferItem> & i1, const std::shared_ptr<TransferItem> & i2) {
                 return i1->embargo > i2->embargo;
             }
         };
         bool quit = false;
-        std::priority_queue<std::shared_ptr<DownloadItem>, std::vector<std::shared_ptr<DownloadItem>>, EmbargoComparator> incoming;
+        std::priority_queue<std::shared_ptr<TransferItem>, std::vector<std::shared_ptr<TransferItem>>, EmbargoComparator> incoming;
     };
 
     Sync<State> state_;
@@ -449,7 +456,7 @@ struct CurlDownloader : public Downloader
 
     std::thread workerThread;
 
-    CurlDownloader()
+    curlFileTransfer()
         : mt19937(rd())
     {
         static std::once_flag globalInit;
@@ -462,7 +469,7 @@ struct CurlDownloader : public Downloader
         #endif
         #if LIBCURL_VERSION_NUM >= 0x071e00 // Max connections requires >= 7.30.0
         curl_multi_setopt(curlm, CURLMOPT_MAX_TOTAL_CONNECTIONS,
-            downloadSettings.httpConnections.get());
+            fileTransferSettings.httpConnections.get());
         #endif
 
         wakeupPipe.create();
@@ -471,7 +478,7 @@ struct CurlDownloader : public Downloader
         workerThread = std::thread([&]() { workerThreadEntry(); });
     }
 
-    ~CurlDownloader()
+    ~curlFileTransfer()
     {
         stopWorkerThread();
 
@@ -497,7 +504,7 @@ struct CurlDownloader : public Downloader
             stopWorkerThread();
         });
 
-        std::map<CURL *, std::shared_ptr<DownloadItem>> items;
+        std::map<CURL *, std::shared_ptr<TransferItem>> items;
 
         bool quit = false;
 
@@ -554,7 +561,7 @@ struct CurlDownloader : public Downloader
                     throw SysError("reading curl wakeup socket");
             }
 
-            std::vector<std::shared_ptr<DownloadItem>> incoming;
+            std::vector<std::shared_ptr<TransferItem>> incoming;
             auto now = std::chrono::steady_clock::now();
 
             {
@@ -602,7 +609,7 @@ struct CurlDownloader : public Downloader
         }
     }
 
-    void enqueueItem(std::shared_ptr<DownloadItem> item)
+    void enqueueItem(std::shared_ptr<TransferItem> item)
     {
         if (item->request.data
             && !hasPrefix(item->request.uri, "http://")
@@ -634,8 +641,8 @@ struct CurlDownloader : public Downloader
     }
 #endif
 
-    void enqueueDownload(const DownloadRequest & request,
-        Callback<DownloadResult> callback) override
+    void enqueueFileTransfer(const FileTransferRequest & request,
+        Callback<FileTransferResult> callback) override
     {
         /* Ugly hack to support s3:// URIs. */
         if (hasPrefix(request.uri, "s3://")) {
@@ -653,9 +660,9 @@ struct CurlDownloader : public Downloader
 
                 // FIXME: implement ETag
                 auto s3Res = s3Helper.getObject(bucketName, key);
-                DownloadResult res;
+                FileTransferResult res;
                 if (!s3Res.data)
-                    throw DownloadError(NotFound, fmt("S3 object '%s' does not exist", request.uri));
+                    throw FileTransferError(NotFound, fmt("S3 object '%s' does not exist", request.uri));
                 res.data = s3Res.data;
                 callback(std::move(res));
 #else
@@ -665,26 +672,26 @@ struct CurlDownloader : public Downloader
             return;
         }
 
-        enqueueItem(std::make_shared<DownloadItem>(*this, request, std::move(callback)));
+        enqueueItem(std::make_shared<TransferItem>(*this, request, std::move(callback)));
     }
 };
 
-ref<Downloader> getDownloader()
+ref<FileTransfer> getFileTransfer()
 {
-    static ref<Downloader> downloader = makeDownloader();
-    return downloader;
+    static ref<FileTransfer> fileTransfer = makeFileTransfer();
+    return fileTransfer;
 }
 
-ref<Downloader> makeDownloader()
+ref<FileTransfer> makeFileTransfer()
 {
-    return make_ref<CurlDownloader>();
+    return make_ref<curlFileTransfer>();
 }
 
-std::future<DownloadResult> Downloader::enqueueDownload(const DownloadRequest & request)
+std::future<FileTransferResult> FileTransfer::enqueueFileTransfer(const FileTransferRequest & request)
 {
-    auto promise = std::make_shared<std::promise<DownloadResult>>();
-    enqueueDownload(request,
-        {[promise](std::future<DownloadResult> fut) {
+    auto promise = std::make_shared<std::promise<FileTransferResult>>();
+    enqueueFileTransfer(request,
+        {[promise](std::future<FileTransferResult> fut) {
             try {
                 promise->set_value(fut.get());
             } catch (...) {
@@ -694,15 +701,21 @@ std::future<DownloadResult> Downloader::enqueueDownload(const DownloadRequest &
     return promise->get_future();
 }
 
-DownloadResult Downloader::download(const DownloadRequest & request)
+FileTransferResult FileTransfer::download(const FileTransferRequest & request)
 {
-    return enqueueDownload(request).get();
+    return enqueueFileTransfer(request).get();
 }
 
-void Downloader::download(DownloadRequest && request, Sink & sink)
+FileTransferResult FileTransfer::upload(const FileTransferRequest & request)
+{
+    /* Note: this method is the same as download, but helps in readability */
+    return enqueueFileTransfer(request).get();
+}
+
+void FileTransfer::download(FileTransferRequest && request, Sink & sink)
 {
     /* Note: we can't call 'sink' via request.dataCallback, because
-       that would cause the sink to execute on the downloader
+       that would cause the sink to execute on the fileTransfer
        thread. If 'sink' is a coroutine, this will fail. Also, if the
        sink is expensive (e.g. one that does decompression and writing
        to the Nix store), it would stall the download thread too much.
@@ -748,8 +761,8 @@ void Downloader::download(DownloadRequest && request, Sink & sink)
         state->avail.notify_one();
     };
 
-    enqueueDownload(request,
-        {[_state](std::future<DownloadResult> fut) {
+    enqueueFileTransfer(request,
+        {[_state](std::future<FileTransferResult> fut) {
             auto state(_state->lock());
             state->quit = true;
             try {
@@ -794,7 +807,6 @@ void Downloader::download(DownloadRequest && request, Sink & sink)
     }
 }
 
-
 bool isUri(const string & s)
 {
     if (s.compare(0, 8, "channel:") == 0) return true;
diff --git a/src/libstore/download.hh b/src/libstore/filetransfer.hh
index 28c8a9162..2347f363d 100644
--- a/src/libstore/download.hh
+++ b/src/libstore/filetransfer.hh
@@ -9,7 +9,7 @@
 
 namespace nix {
 
-struct DownloadSettings : Config
+struct FileTransferSettings : Config
 {
     Setting<bool> enableHttp2{this, true, "http2",
         "Whether to enable HTTP/2 support."};
@@ -31,15 +31,15 @@ struct DownloadSettings : Config
         "How often Nix will attempt to download a file before giving up."};
 };
 
-extern DownloadSettings downloadSettings;
+extern FileTransferSettings fileTransferSettings;
 
-struct DownloadRequest
+struct FileTransferRequest
 {
     std::string uri;
     std::string expectedETag;
     bool verifyTLS = true;
     bool head = false;
-    size_t tries = downloadSettings.tries;
+    size_t tries = fileTransferSettings.tries;
     unsigned int baseRetryTimeMs = 250;
     ActivityId parentAct;
     bool decompress = true;
@@ -47,7 +47,7 @@ struct DownloadRequest
     std::string mimeType;
     std::function<void(char *, size_t)> dataCallback;
 
-    DownloadRequest(const std::string & uri)
+    FileTransferRequest(const std::string & uri)
         : uri(uri), parentAct(getCurActivity()) { }
 
     std::string verb()
@@ -56,7 +56,7 @@ struct DownloadRequest
     }
 };
 
-struct DownloadResult
+struct FileTransferResult
 {
     bool cached = false;
     std::string etag;
@@ -67,40 +67,43 @@ struct DownloadResult
 
 class Store;
 
-struct Downloader
+struct FileTransfer
 {
-    virtual ~Downloader() { }
+    virtual ~FileTransfer() { }
 
-    /* Enqueue a download request, returning a future to the result of
-       the download. The future may throw a DownloadError
+    /* Enqueue a data transfer request, returning a future to the result of
+       the download. The future may throw a FileTransferError
        exception. */
-    virtual void enqueueDownload(const DownloadRequest & request,
-        Callback<DownloadResult> callback) = 0;
+    virtual void enqueueFileTransfer(const FileTransferRequest & request,
+        Callback<FileTransferResult> callback) = 0;
 
-    std::future<DownloadResult> enqueueDownload(const DownloadRequest & request);
+    std::future<FileTransferResult> enqueueFileTransfer(const FileTransferRequest & request);
 
     /* Synchronously download a file. */
-    DownloadResult download(const DownloadRequest & request);
+    FileTransferResult download(const FileTransferRequest & request);
+
+    /* Synchronously upload a file. */
+    FileTransferResult upload(const FileTransferRequest & request);
 
     /* Download a file, writing its data to a sink. The sink will be
        invoked on the thread of the caller. */
-    void download(DownloadRequest && request, Sink & sink);
+    void download(FileTransferRequest && request, Sink & sink);
 
     enum Error { NotFound, Forbidden, Misc, Transient, Interrupted };
 };
 
-/* Return a shared Downloader object. Using this object is preferred
+/* Return a shared FileTransfer object. Using this object is preferred
    because it enables connection reuse and HTTP/2 multiplexing. */
-ref<Downloader> getDownloader();
+ref<FileTransfer> getFileTransfer();
 
-/* Return a new Downloader object. */
-ref<Downloader> makeDownloader();
+/* Return a new FileTransfer object. */
+ref<FileTransfer> makeFileTransfer();
 
-class DownloadError : public Error
+class FileTransferError : public Error
 {
 public:
-    Downloader::Error error;
-    DownloadError(Downloader::Error error, const FormatOrString & fs)
+    FileTransfer::Error error;
+    FileTransferError(FileTransfer::Error error, const FormatOrString & fs)
         : Error(fs), error(error)
     { }
 };
diff --git a/src/libstore/http-binary-cache-store.cc b/src/libstore/http-binary-cache-store.cc
index 011794c62..451a64785 100644
--- a/src/libstore/http-binary-cache-store.cc
+++ b/src/libstore/http-binary-cache-store.cc
@@ -1,5 +1,5 @@
 #include "binary-cache-store.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "globals.hh"
 #include "nar-info-disk-cache.hh"
 
@@ -85,14 +85,14 @@ protected:
         checkEnabled();
 
         try {
-            DownloadRequest request(cacheUri + "/" + path);
+            FileTransferRequest request(cacheUri + "/" + path);
             request.head = true;
-            getDownloader()->download(request);
+            getFileTransfer()->download(request);
             return true;
-        } catch (DownloadError & e) {
+        } catch (FileTransferError & e) {
             /* S3 buckets return 403 if a file doesn't exist and the
                bucket is unlistable, so treat 403 as 404. */
-            if (e.error == Downloader::NotFound || e.error == Downloader::Forbidden)
+            if (e.error == FileTransfer::NotFound || e.error == FileTransfer::Forbidden)
                 return false;
             maybeDisable();
             throw;
@@ -103,19 +103,19 @@ protected:
         const std::string & data,
         const std::string & mimeType) override
     {
-        auto req = DownloadRequest(cacheUri + "/" + path);
+        auto req = FileTransferRequest(cacheUri + "/" + path);
         req.data = std::make_shared<string>(data); // FIXME: inefficient
         req.mimeType = mimeType;
         try {
-            getDownloader()->download(req);
-        } catch (DownloadError & e) {
+            getFileTransfer()->upload(req);
+        } catch (FileTransferError & e) {
             throw UploadToHTTP("while uploading to HTTP binary cache at '%s': %s", cacheUri, e.msg());
         }
     }
 
-    DownloadRequest makeRequest(const std::string & path)
+    FileTransferRequest makeRequest(const std::string & path)
     {
-        DownloadRequest request(cacheUri + "/" + path);
+        FileTransferRequest request(cacheUri + "/" + path);
         return request;
     }
 
@@ -124,9 +124,9 @@ protected:
         checkEnabled();
         auto request(makeRequest(path));
         try {
-            getDownloader()->download(std::move(request), sink);
-        } catch (DownloadError & e) {
-            if (e.error == Downloader::NotFound || e.error == Downloader::Forbidden)
+            getFileTransfer()->download(std::move(request), sink);
+        } catch (FileTransferError & e) {
+            if (e.error == FileTransfer::NotFound || e.error == FileTransfer::Forbidden)
                 throw NoSuchBinaryCacheFile("file '%s' does not exist in binary cache '%s'", path, getUri());
             maybeDisable();
             throw;
@@ -142,12 +142,12 @@ protected:
 
         auto callbackPtr = std::make_shared<decltype(callback)>(std::move(callback));
 
-        getDownloader()->enqueueDownload(request,
-            {[callbackPtr, this](std::future<DownloadResult> result) {
+        getFileTransfer()->enqueueFileTransfer(request,
+            {[callbackPtr, this](std::future<FileTransferResult> result) {
                 try {
                     (*callbackPtr)(result.get().data);
-                } catch (DownloadError & e) {
-                    if (e.error == Downloader::NotFound || e.error == Downloader::Forbidden)
+                } catch (FileTransferError & e) {
+                    if (e.error == FileTransfer::NotFound || e.error == FileTransfer::Forbidden)
                         return (*callbackPtr)(std::shared_ptr<std::string>());
                     maybeDisable();
                     callbackPtr->rethrow();
@@ -174,4 +174,3 @@ static RegisterStoreImplementation regStore([](
 });
 
 }
-
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index f2e4b63e0..b24e7b7d6 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -6,7 +6,7 @@
 #include "nar-info-disk-cache.hh"
 #include "globals.hh"
 #include "compression.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "istringstream_nocopy.hh"
 
 #include <aws/core/Aws.h>
@@ -132,7 +132,7 @@ ref<Aws::Client::ClientConfiguration> S3Helper::makeConfig(const string & region
     return res;
 }
 
-S3Helper::DownloadResult S3Helper::getObject(
+S3Helper::FileTransferResult S3Helper::getObject(
     const std::string & bucketName, const std::string & key)
 {
     debug("fetching 's3://%s/%s'...", bucketName, key);
@@ -146,7 +146,7 @@ S3Helper::DownloadResult S3Helper::getObject(
         return Aws::New<std::stringstream>("STRINGSTREAM");
     });
 
-    DownloadResult res;
+    FileTransferResult res;
 
     auto now1 = std::chrono::steady_clock::now();
 
diff --git a/src/libstore/s3.hh b/src/libstore/s3.hh
index ef5f23d0f..2042bffcf 100644
--- a/src/libstore/s3.hh
+++ b/src/libstore/s3.hh
@@ -18,13 +18,13 @@ struct S3Helper
 
     ref<Aws::Client::ClientConfiguration> makeConfig(const std::string & region, const std::string & scheme, const std::string & endpoint);
 
-    struct DownloadResult
+    struct FileTransferResult
     {
         std::shared_ptr<std::string> data;
         unsigned int durationMs;
     };
 
-    DownloadResult getObject(
+    FileTransferResult getObject(
         const std::string & bucketName, const std::string & key);
 };
 
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index fa5c84a27..bb437cf1c 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -198,7 +198,7 @@ bool handleJSONLogMessage(const std::string & msg,
 
         if (action == "start") {
             auto type = (ActivityType) json["type"];
-            if (trusted || type == actDownload)
+            if (trusted || type == actFileTransfer)
                 activities.emplace(std::piecewise_construct,
                     std::forward_as_tuple(json["id"]),
                     std::forward_as_tuple(*logger, (Verbosity) json["level"], type,
diff --git a/src/libutil/logging.hh b/src/libutil/logging.hh
index beb5e6b64..108b5dcb0 100644
--- a/src/libutil/logging.hh
+++ b/src/libutil/logging.hh
@@ -17,7 +17,7 @@ typedef enum {
 typedef enum {
     actUnknown = 0,
     actCopyPath = 100,
-    actDownload = 101,
+    actFileTransfer = 101,
     actRealise = 102,
     actCopyPaths = 103,
     actBuilds = 104,
diff --git a/src/nix-channel/nix-channel.cc b/src/nix-channel/nix-channel.cc
index 2a9defb4e..abd390414 100755
--- a/src/nix-channel/nix-channel.cc
+++ b/src/nix-channel/nix-channel.cc
@@ -1,6 +1,6 @@
 #include "shared.hh"
 #include "globals.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "store-api.hh"
 #include "../nix/legacy.hh"
 #include "fetchers.hh"
@@ -113,7 +113,7 @@ static void update(const StringSet & channelNames)
             // Download the channel tarball.
             try {
                 filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.xz", "nixexprs.tar.xz", false).storePath);
-            } catch (DownloadError & e) {
+            } catch (FileTransferError & e) {
                 filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.bz2", "nixexprs.tar.bz2", false).storePath);
             }
         }
diff --git a/src/nix-prefetch-url/nix-prefetch-url.cc b/src/nix-prefetch-url/nix-prefetch-url.cc
index 2b9254659..748554b9c 100644
--- a/src/nix-prefetch-url/nix-prefetch-url.cc
+++ b/src/nix-prefetch-url/nix-prefetch-url.cc
@@ -1,6 +1,6 @@
 #include "hash.hh"
 #include "shared.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "store-api.hh"
 #include "eval.hh"
 #include "eval-inline.hh"
@@ -180,9 +180,9 @@ static int _main(int argc, char * * argv)
 
                 FdSink sink(fd.get());
 
-                DownloadRequest req(actualUri);
+                FileTransferRequest req(actualUri);
                 req.decompress = false;
-                getDownloader()->download(std::move(req), sink);
+                getFileTransfer()->download(std::move(req), sink);
             }
 
             /* Optionally unpack the file. */
diff --git a/src/nix/main.cc b/src/nix/main.cc
index c5ca089ee..15f412dae 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -8,7 +8,7 @@
 #include "shared.hh"
 #include "store-api.hh"
 #include "progress-bar.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "finally.hh"
 
 #include <sys/types.h>
@@ -177,10 +177,10 @@ void mainWrapped(int argc, char * * argv)
             settings.useSubstitutes = false;
         if (!settings.tarballTtl.overriden)
             settings.tarballTtl = std::numeric_limits<unsigned int>::max();
-        if (!downloadSettings.tries.overriden)
-            downloadSettings.tries = 0;
-        if (!downloadSettings.connectTimeout.overriden)
-            downloadSettings.connectTimeout = 1;
+        if (!fileTransferSettings.tries.overriden)
+            fileTransferSettings.tries = 0;
+        if (!fileTransferSettings.connectTimeout.overriden)
+            fileTransferSettings.connectTimeout = 1;
     }
 
     if (args.refresh)
diff --git a/src/nix/progress-bar.cc b/src/nix/progress-bar.cc
index 26631416c..adc9b9a5d 100644
--- a/src/nix/progress-bar.cc
+++ b/src/nix/progress-bar.cc
@@ -190,8 +190,8 @@ public:
             i->s = fmt("querying " ANSI_BOLD "%s" ANSI_NORMAL " on %s", name, getS(fields, 1));
         }
 
-        if ((type == actDownload && hasAncestor(*state, actCopyPath, parent))
-            || (type == actDownload && hasAncestor(*state, actQueryPathInfo, parent))
+        if ((type == actFileTransfer && hasAncestor(*state, actCopyPath, parent))
+            || (type == actFileTransfer && hasAncestor(*state, actQueryPathInfo, parent))
             || (type == actCopyPath && hasAncestor(*state, actSubstitute, parent)))
             i->visible = false;
 
@@ -416,7 +416,7 @@ public:
             if (!s2.empty()) { res += " ("; res += s2; res += ')'; }
         }
 
-        showActivity(actDownload, "%s MiB DL", "%.1f", MiB);
+        showActivity(actFileTransfer, "%s MiB DL", "%.1f", MiB);
 
         {
             auto s = renderActivity(actOptimiseStore, "%s paths optimised");
diff --git a/src/nix/run.cc b/src/nix/run.cc
index 7fd9c4c7e..901b87fbb 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -59,14 +59,14 @@ struct RunCommon : virtual Command
 
 struct CmdRun : InstallablesCommand, RunCommon, MixEnvironment
 {
-    std::vector<std::string> command = { "bash" };
+    std::vector<std::string> command = { getEnv("SHELL").value_or("bash") };
 
     CmdRun()
     {
         mkFlag()
             .longName("command")
             .shortName('c')
-            .description("command and arguments to be executed; defaults to 'bash'")
+            .description("command and arguments to be executed; defaults to '$SHELL'")
             .labels({"command", "args"})
             .arity(ArityAny)
             .handler([&](std::vector<std::string> ss) {
diff --git a/src/nix/upgrade-nix.cc b/src/nix/upgrade-nix.cc
index c05c29517..4fcc6a721 100644
--- a/src/nix/upgrade-nix.cc
+++ b/src/nix/upgrade-nix.cc
@@ -1,7 +1,7 @@
 #include "command.hh"
 #include "common-args.hh"
 #include "store-api.hh"
-#include "download.hh"
+#include "filetransfer.hh"
 #include "eval.hh"
 #include "attr-path.hh"
 #include "names.hh"
@@ -138,8 +138,8 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand
         Activity act(*logger, lvlInfo, actUnknown, "querying latest Nix version");
 
         // FIXME: use nixos.org?
-        auto req = DownloadRequest(storePathsUrl);
-        auto res = getDownloader()->download(req);
+        auto req = FileTransferRequest(storePathsUrl);
+        auto res = getFileTransfer()->download(req);
 
         auto state = std::make_unique<EvalState>(Strings(), store);
         auto v = state->allocValue();